Journal of Anxiety Disorders

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1 Journal of Anxiety Disorders 25 (2011) Contents lists available at ScienceDirect Journal of Anxiety Disorders Obsessive compulsive personality traits: How are they related to OCD severity? Chad T. Wetterneck a,b,, Tannah E. Little a, Gregory S. Chasson c, Angela H. Smith b,d, John M. Hart b,e,f, Melinda A. Stanley g,h,i, Thröstur Björgvinsson b,j a University of Houston-Clear Lake, United States b The Houston OCD Program, United States c Towson University, United States d University of Houston, United States e The Menninger Clinic, United States f Center for Anxiety and Depression Treatment of Houston, United States g VA Health Services Research and Development Houston Center of Excellence, United States h Michael E. DeBakey Veterans Affairs Medical Center, United States i Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, United States j McLean Hospital, United States a r t i c l e i n f o Article history: Received 14 February 2011 Received in revised form 17 June 2011 Accepted 25 June 2011 Keywords: Obsessive compulsive disorder Obsessive compulsive personality disorder Perfectionism Comorbidity Obsessive compulsive disorder personality traits a b s t r a c t Previous research has demonstrated that comorbid obsessive compulsive personality disorder (OCPD) in patients with obsessive compulsive disorder (OCD) is associated with greater overall OCD severity, functional impairment, and poorer treatment outcomes (Coles et al., 2008; Lochner et al., 2010; Pinto, 2009). However, research has only examined the effects of OCPD categorically and has yet to thoroughly examine the impact of individual OCPD characteristics dimensionally. Thus, the present study sought to investigate the relationships between various OCPD-related dimensions (e.g., perfectionism, rigidity) and OCD symptomology and severity. The study recruited a sample of OCD patients (n = 51) in the OCD units of two residential treatment facilities. Findings yielded significant relationships between OCD severity and the following OCPD dimensions: flexibility, doubts about actions (a dimension of perfectionism), and hoarding. Interpretations of these results and the implications for diagnosis, prognosis, and treatment outcome are discussed. Furthermore, the current study provides insight into a unique perspective which leaves room for more symptom overlap and variability between OCD and OCPD. Published by Elsevier Ltd. Obsessive compulsive disorder (OCD) is characterized by obsessions (recurrent and persistent thoughts or images that are experienced as intrusive and elicit marked distress and anxiety) and compulsions (repetitive behaviors or mental acts aimed at attenuating anxiety caused by obsessions) (American Psychiatric Association [APA], 2000). Exposure and response prevention (ERP), cognitive-behavioral therapy, and pharmacological treatments (e.g., selective serotonin reuptake inhibitors) have demonstrated effectiveness in reducing OCD symptoms (Abramowitz, 1997; Rowa et al., 2007). However, 20 60% of patients with OCD refuse, drop out from, or fail to benefit from treatment (Abramowitz, 2006; Abramowitz, Taylor, & McKay, 2005; Fisher & Wells, 2005; Pallanti & Quercioli, 2006). Thus, research has begun to focus on factors that may predict poor treatment response. One area of Corresponding author at: University of Houston-Clear Lake, Bayou Building # , 2700 Bay Area Blvd., Houston, TX 77058, United States. Tel.: ; fax: address: wetterneck@uhcl.edu (C.T. Wetterneck). interest examines the effects of comorbid personality disorders (PDs) on OCD treatment outcome. While inconsistent, research generally indicates a high prevalence of comorbid PDs in individuals with OCD, with prevalence rates ranging from 32% to 86%. Studies suggest high co-occurrence rates of obsessive compulsive personality disorder (OCPD) with OCD, ranging from 9% to 32% (Denys, Tenney, van Megen, de Geus, & Westenberg, 2004; Maina, Albert, Pessina, & Bogetto, 2007; Samuels et al., 2000). OCPD is characterized by an excessive need for perfectionism, orderliness, control, and doing things the right way. OCPD features eight personality traits, including perfectionism, rigidity, preoccupation with details, excessive devotion to work, overconscientiousness and inflexibility regarding morals and values, miserliness, inability to discard useless possessions (hoarding), and an inability to delegate tasks (APA, 2000). Individuals with concomitant OCPD and OCD tend to show greater OCD chronicity, as well as higher comorbidity rates with other disorders (Albert, Maina, Forner, & Bogetto, 2004; Coles, Pinto, Mancebo, Rassmussen, & Eisen, 2008; Lochner et al., 2010; Maina, Bellino, Bogetto, & Ravizza, 1993; Nestadt et al., 2009). Furthermore, OCD patients /$ see front matter. Published by Elsevier Ltd. doi: /j.janxdis

2 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) with comorbid OCPD demonstrate greater functional impairment and overall OCD severity, as well as poorer treatment response (Cavedini, Erzegovesi, Ronchi, & Bellodi, 1997; Coles et al., 2008; Lochner et al., 2010; Pinto, 2009; Pinto et al., 2009a). While a considerable amount of research has investigated the relationships between OCPD and OCD in terms of comorbidity, symptom presentation, level of impairment, and treatment response, these investigations have primarily adopted a categorical and diagnostic framework for characterizing the presence/absence of OCPD rather than a dimensional approach focused more on individual OCPD characteristics. That is, prior studies enroll participants based on meeting at least four out of the eight OCPD criteria, generally discounting the dimensional nature of the OCPD characteristics. Given the recent shift in the field to conceptualize PDs dimensionally (Krueger, Skodol, Livesley, Shrout, & Huang, 2007; Trull & Durrette, 2005), further research examining relationships between dimensional OCPD criteria and OCD is warranted. Furthermore, patients characterized as having a diagnosis of OCPD may present with a plethora of different combinations of four or more of the eight criteria (163 possible combinations), suggesting a high level of group heterogeneity. Considering that certain OCPD dimensions may be more problematic than others for individuals with OCD, a categorical approach discounting such heterogeneity may obscure research findings and implications. In addition, in patients undergoing ERP, Pinto and colleagues (2009b) found an indirect relationship between treatment response and the number of comorbid OCPD criteria. The potential impact of this within-group variability on treatment response further supports the need to evaluate comorbidity using individual OCPD dimensional attributes as opposed to a categorical approach. Thus, the current study opts to utilize a dimensional approach to investigate OCPD characteristics in relation to OCD severity and symptoms. To our knowledge, only two existing empirical studies have examined the overlap in criteria presentation of OCD and OCPD, and suggested that hoarding, preoccupation with details, and perfectionism are linked to OCD diagnosis and OCD subtype presentation (Baer, 1994; Eisen et al., 2006). However, these studies did not analyze the OCPD criteria dimensionally, in terms of the degree to which an OCD individual may exhibit each dimensional trait (i.e., higher versus lower levels of perfectionism). Instead, participants were analyzed based on simply meeting one or more of the individual OCPD criteria. On the contrary, the current investigation adds to previous literature by further exploring the associations between OCPD-related characteristics and OCD severity and symptoms from a dimensional perspective, which, compared to a categorical approach, provides more information about the degree to which OCPD traits are expressed. With the recent shift to a dimensional perspective of personality disorders, researchers have also begun to analyze personality disorders in terms of extremes on continuums of normal personality traits, such as the Big Five Factors (Costa & McCrae, 2010; Moran, Coffee, Mann, Carlin, & Patton, 2006; Saulsman & Page, 2004; Trull & Durrette, 2005; Widiger & Mullins-Sweatt, 2010; Widiger & Simonsen, 2005). For instance, OCPD has shown to be positively correlated with the order, dutifulness, and deliberation facets of conscientiousness and negatively correlated with the conscientiousness facet, achievement striving (Reynolds & Clark, 2001). OCPD has also demonstrated negative associations with the warmth, assertiveness, and altruism facets of extroversion, as well as openness to values and feelings (Reynolds & Clark, 2001). Given the apparent utility of this perspective (Widiger & Mullins- Sweatt, 2010), DSM-V discussions for incorporating a conceptual framework similar to the Five Factor Model of normal personality traits for personality disorders are currently underway (American Psychiatric Association [APA], 2011). Therefore, the present investigation adopts this perspective in analyzing OCPD dimensions in terms of extremes in normal OCPD-related personality traits (e.g., perfectionism, conscientiousness), as they relate to OCD severity and symptomology. More specifically, preliminary conceptualizations of personality disorders for DSM-V adopt a mix of dimensional and categorical elements. With respect to the dimensional elements, six global personality dimensions have been proposed for DSM-V PD nosology, including negative emotionality, detachment, antagonism, disinhibition, compulsivity, and schizotypy (APA, 2011). The current study will examine facets that are congruent with the DSM-V compulsivity domain, as, overall, it describes characteristics most aligned with OCPD (see Table 1 for a list of DSM-V compulsivity facets). By utilizing the DSM-V proposed dimensional approach to analyzing relationships between OCD severity and OCPD dimensions, the current study may offer more substantive findings based on updated methods and perspectives of PDs. Some research has examined associations between OCD and personality dimensions that are similar to OCPD criteria. However, most studies do not analyze these dimensions as proxies for OCPD criteria, instead examining them independently of an OCPD context. Further, many of these studies primarily focus on one OCPD-related dimension or a select few (e.g., perfectionism), rather than exploring a full range of OCPD-related dimensions. As a result, it is difficult to determine which particular dimensions associate uniquely with OCD without simultaneously analyzing a large range of OCPD dimensions. For instance, a substantial amount of research has cited relationships between various measures of perfectionism and OCD severity and symptomology (e.g., Chik, Whittal, & O Neill, 2008; Julien, O Connor, Aardema, & Todorov, 2006; Manos et al., 2010). One such measure, the Frost Multi-Dimensional Perfectionism Scale (FMPS; Frost, Marten, Lahart, & Rosenblate, 1990), measures six dimensions of perfectionism, of which concern over mistakes and doubts about actions have shown to be highly prominent in OCD and have demonstrated a significant correlation with OCD severity (Chik et al., 2008; Lee et al., 2009; Moretz & McKay, 2009; Suzuki, 2005). Aside from perfectionism, other studies show some evidence indicating overlap between OCD and other OCPD-related dimensions. Interestingly, conscientiousness has demonstrated no statistically significant relationship with OCD in studies using the NEO Personality Inventory and the Big Five Inventory assessments (Nestadt et al., 2009; Samuels et al., 2000; Wu, Clark, & Watson, 2006). There is a dearth of research examining associations between OCPD-related dimensions and OCD using assessments designed to measure characteristics specifically related to OCPD criteria. Studies using the Schedule for Nonadaptive and Adaptive Personality (SNAP; Clark, 1993), a measure of personality dimensions and DSM-IV PDs, have primarily demonstrated that individuals with OCD score significantly higher than non-clinical samples on workaholism, which may represent a proxy for the OCPD criterion excessive devotion to work, as well as propriety, which corresponds to the OCPD criteria of inflexibility regarding moral standards (e.g., Wu, 2004; Wu et al., 2006). However, while the SNAP aims to dimensionally assess characteristics of PDs, it only assesses for about two to three traits associated with each PD. Further, items on the SNAP assess for personality dimensions based on a true-false answer choice scale, as opposed to a Likert scale, which would better assess for varying degrees of the dimensions. In the present study, the OMNI Personality Inventory (OMNI; Loranger, 2001) is utilized for this purpose, as it assesses for a relatively large range of OCPD-related dimensions individually on a Likert scale. It is important to note the dimension of hoarding, which is currently not only an OCD subtype (McKay et al., 2004), but is also listed in the eight criteria for OCPD as an inability to discard useless possessions. Prior research has indicated that OCPD hoarding is associated with OCD (Baer, 1994; Eisen et al., 2006), and when

3 1026 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) Table 1 OCPD dimensions assessed in the study versus DSM-IV criteria for OCPD. Personality dimensions for OCPD assessed in the study The eight DSM-IV criteria for OCPD Proposed DSM-V facets of the compulsivity trait domain Dutifulness (OMNI) Excessive devotion to work Perseveration Conscientiousness (OMNI) Overconscientiousness and inflexibility regarding morals and values Flexibility (OMNI) (low scores indicate Rigidity Rigidity high rigidity/inflexibility) Hoarding (OCI-R) Inability to discard useless possessions (i.e., hoarding) Orderliness (OMNI) Preoccupation with details Orderliness Perfectionism (FMPS) Perfectionism Perfectionism Doubts about actions Concern over mistakes Parental criticism Parental expectations Personal standards Organization Miserliness Reluctance to delegate tasks Risk aversion OMNI: OMNI Personality Inventory; OCI-R: Obsessive Compulsive Inventory-Revised, FMPS: Frost Multidimensional Perfectionism Scale. compared to OCD patients without comorbid OCPD, comorbid OCPD patients tend to present with prominent hoarding symptoms (Baer, 1994; Coles et al., 2008; Lochner et al., 2010; Nestadt et al., 2009). Further, research suggests a direct relationship between hoarding severity and an OCD patient s presenting number of OCPD criteria (Mataix-Cols, Baer, Rauch, & Jenike, 2000; Pertusa et al., 2008). Thus, it is possible that hoarding symptoms account for a large degree of the overlap in presentation between OCD and OCPD. To date, previous research has primarily examined relationships between OCD and OCPD categorically, despite recent shifts in the field to analyze PDs dimensionally as they associate with maladaptive extremes in normal personality traits. Furthermore, research has yet to simultaneously investigate a large spectrum of OCPDrelated dimensions as they individually relate to OCD severity and symptoms. Thus, the current study aims to fill these holes in the literature by dimensionally investigating OCPD-related traits and their relations to OCD severity and subtypes. Moreover, the present study is the first to simultaneously investigate a wide range of OCPD dimensions as they relate to OCD. As such, the investigation is exploratory in nature, as it is difficult to determine which dimensions will uniquely contribute to OCD severity when a variety of OCPD traits are entered into the same statistical model. However, given previous research indicating that the concern over mistakes, perfectionistic doubts about actions and OCPD hoarding are associated with OCD severity or symptom presentation, we expect our findings to yield congruent relationships. In light of previous categorical analyses indicating a negative impact of comorbid OCPD on the functioning and symptom severity of those with OCD, further understanding the dimensional relationships between OCPD and OCD may yield insight into the factors that specifically hinder treatment. 1. Methods 1.1. Sample characteristics and procedure Fifty-one individuals who were admitted for treatment at the Menninger Clinic OCD Program (n = 30) or the Houston OCD Program (n = 21) participated in the study. Demographic and clinical characteristics of the sample are presented in Table 2. Participants in each treatment setting did not differ significantly in age, sex, or ethnicity. Upon admission, patients at both treatment facilities completed an admissions packet consisting of various questionnaires related Table 2 Demographic and clinical characteristics. Variable Demographic characteristics Mean age (S.D.) (10.56) No. of female (%) 26 (51.0) Racial/ethnic background No. of White (%) 44 (86.3) No. of African Amer. (%) 2 (3.9) No. of Asian (%) 2 (3.9) No. of others (%) 3 (5.9) Clinical characteristics Co-occurring diagnoses with Primary OCD No. of major depressive disorder (%) 14 (27.4) No. of social phobia (%) 2 (3.9) No. of other (%) 5 (10.0) Co-occurring diagnoses with Secondary OCD No. of social phobia (%) 3 (6.0) No. of other (%) 3 (6.0) Variable M (SD) OCI-R (9.96) OCI-R Hoarding 2.80 (2.74) FMPS Total (20.66) Concern over mistakes (8.46) Doubts about actions (3.84) Organizing (4.46) Parental criticism (4.20) Parental expectations (5.12) Personal standards (5.20) OMNI OCPD (9.84) Dutifulness (10.44) Flexibility (10.59) Orderliness (10.03) Conscientiousness (10.12) OCI-R Total: Obsessive Compulsive Inventory-Revised total score without the Hoarding subscale; OMNI OCPD: Obsessive Compulsive Personality Disorder subscale of the OMNI Personality Inventory; FMPS: Frost Multidimensional Perfectionism Scale. to symptom severity. Although data was collected as part of routine clinical care, participation was voluntary. Data collection at the Menninger Clinic was approved by the Internal Review Board of Baylor College of Medicine, and informed consents were obtained for all participants. Archival use of the data collected from the Houston OCD Program was approved by the Committee for the Protection of Human Subjects at the University of Houston-Clear

4 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) Lake. Only individuals who met criteria for primary or secondary OCD (n = 45 and 6, respectively) were included in the present study. In both settings, a multidisciplinary treatment team consisting of psychiatrists, psychologists, and behavior therapists experienced in OCD diagnosis and treatment met to review relevant clinical data, including medical records, questionnaire responses, and unstructured clinical interviews. Review of this data facilitated the formulation of a diagnosis for each patient. Whether patients met primary or secondary diagnoses of OCD was dependent on the level of impairment of OCD symptoms compared to other consensus diagnoses. Of note, each member of the Houston OCD Program treatment team formerly treated patients at the Menninger Clinic OCD Program, supporting diagnostic consistency across groups Measures Obsessive Compulsive Inventory-Revised (OCI-R; Foa et al., 2002) is an 18-item, self report questionnaire assessing OCD symptoms with six subscales including washing, obsessing, hoarding, ordering, checking, and neutralizing symptoms. The OCI-R measures the level of distress caused by these symptoms by means of a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (Extremely). The OCI-R has shown to be a reliable and valid measure of OCD severity with sound internal consistency, test-retest reliability, and validity (Foa et al., 2002). The present study refers to the OCI-R total score as a dimensional assessment of OCD severity. The internal consistency for each subscale ranged from adequate to excellent (Cronbach s : Ordering =.77; Neutralizing =.82; Hoarding =.82; Obsessing =.84; Checking =.86; Washing =.91). The sample mean and standard deviation of OCI-R total scores are displayed in Table 2. OMNI Personality Inventory (OMNI; Loranger, 2001) is a 375- item, standardized self report questionnaire comprised of 35 scales assessing normal and abnormal personality dimensions, which were designed to reflect DSM-IV criteria for the ten personality disorders. For the purposes of this study, only subscales related to OCPD were used (i.e., Dutifulness, Flexibility, Orderliness, Conscientiousness, and the Obsessive Compulsive Personality subscale). The Dutifulness subscale measures a sense of responsibility, diligence, and reliability similar to OCPD criteria describing excessive devotion to work and overconscientiousness. The Dutifulness subscale has shown to be significantly related to other personality measures of conscientiousness, such as the NEO PI (Loranger, 2001). The Flexibility subscale of the OMNI measures adaptability and receptiveness to change, with low scores indicating high rigidity and inflexibility. This subscale corresponds similarly with traits characteristic of OCPD, including rigidity, inflexibility, and a need for doing things the right way. The Orderliness subscale assesses the degree to which individuals are neat, meticulous, organized, and perfectionistic, which corresponds to traits of OCPD describing orderliness, preoccupation with details, and perfectionism. Finally, Conscientiousness measures the extent to which individuals are responsible, dependable, orderly, and hard-working, all of which are related to characteristics of OCPD including, overconscientiousness, orderliness, and excessive devotion to work. The Obsessive Compulsive Personality subscale assesses a variation of the aforementioned personality constructs. See Table 1 for the full list of OCPD-related dimensions analyzed in the study, as well as a list of DSM-IV OCPD criteria. All subscale items are rated on a 7-point Likert scale ranging from 1 (definitely agree) to 7 (definitely disagree). The OMNI has demonstrated good internal consistency, test-retest reliability, and validity when both normal and abnormal personality trait measures have been compared against other similar self-report measures (Loranger, 2001). The internal consistency for each subscale ranged from adequate to good (Cronbach s : Flexibility =.71; Conscientiousness =.71; Dutifulness =.73; Orderliness =.83). The Obsessive Compulsive Personality scale is based on an algorithm, therefore internal consistency could not be computed. The sample means and standard deviations for all of the OMNI subscales related to OCPD are displayed in Table 2. Furthermore, Table 3 displays the average t-scores for all of the personality disorder subscales, illustrating that OCPD was one of the most highly rated personality disorders within the sample. Table 3 also displays correlations between personality disorder subscales and OCD severity, showing significant correlations between OCD severity and Obsessive compulsive, Borderline, and Dependent personality disorders. Frost Multi-Dimensional Perfectionism Scale (FMPS; Frost et al., 1990) is a 35-item, self report questionnaire comprised of six subscales, assessing perfectionism and its constituent dimensions. The concern over mistakes (CM) subscale assesses negative reactions and beliefs related to making a mistake (e.g., If I fail at work/school, I am a failure as a person). Doubts about actions (DA) measures how unsatisfied one becomes while completing tasks (e.g., It takes me a long time to do something right ). The Parental expectations (PE) subscale evaluates the degree to which one s parents set high standards and expectations (e.g., My parents have expected excellence from me). Parental criticism (PC) measures the extent to which one s parents were overly critical (e.g., As a child, I was punished for doing things less than perfect). Personal standards (PS) assesses the degree to which one sets high standards for self-evaluation (e.g., I set higher goals than most people). Finally, organization (O) measures individuals preference for and belief in the importance of being neat and organized (e.g., Organization is very important to me). CM, DA, PC, and PE are regarded as the maladaptive dimensions of perfectionism, while PS and O are regarded as the adaptive dimensions. Items are rated on a 5-point Likert scale ranging from strongly disagree to strongly agree. Scoring for each factor is calculated by summing the items in each subscale; summing the six subscale scores yields the overall perfectionism score. Higher scores indicate higher levels of perfectionism. The FMPS has demonstrated internal reliability with sound psychometric properties and has shown to be a valid measure of perfectionism (Frost et al., 1990; Parker & Adkins, 1995). The internal consistency for each subscale ranged from good to excellent (Cronbach s : PS =.82; DA =.82; PC =.85; O =.88; PE =.91; CM =.92). The sample means and standard deviations for the FMPS total score and subscale scores are presented in Table Hoarding We opted to use the Hoarding subscale of the OCI-R as the hoarding OCPD dimension in the study. Thus, the Hoarding subscale was removed from the OCI-R total score and used as a predictor variable. This was a conservative approach, since using an unamended OCI-R total score as the criterion plus the Hoarding subscale as a predictor would have likely yielded an artificially inflated model effect size and a spuriously large degree of association between hoarding and OCD severity. In addition, given recent debates regarding the taxonomic placement of hoarding and its possible diagnostic separation from OCD and OCPD altogether (Mataix-Cols et al., 2010; Pertusa et al., 2010), the removal of the hoarding subscale from the OCI-R is not without precedent. The internal consistency for the OCI-R total score without the Hoarding subscale was acceptable (Cronbach s =.86) Data analysis To assess the covariation between OCD symptom severity and the aforementioned OCPD-related dimensions, the statistical

5 1028 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) Table 3 Average t-scores for the 10 OMNI Personality Disorder Subscales and correlations between the 10 OMNI Personality Disorder Subscales and OCD severity. Average t-scores Correlations with OCI-R severity Paranoid personality disorder Schizoid personality disorder Schizotypal personality disorder Antisocial personality disorder Borderline personality disorder ** Histrionic personality disorder Narcissistic personality disorder Avoidant personality disorder Dependant personality disorder ** Obsessive compulsive personality disorder * OCI-R Total: Obsessive Compulsive Inventory-Revised total score without the Hoarding subscale. analysis consisted of an exploratory correlation analysis followed by a multiple regression. The correlation analysis was conducted for two primary reasons. First, the analysis provided an opportunity to support previous findings by evaluating the relationship between indices of OCD and OCPD: the OCI-R and the OCPD subscale of the OMNI, respectively. Second, the correlation analysis explored the covariation between the OCI-R total score and each of the multiple OCPD-related dimensions to determine which, if any, may account for overlapping variability between OCD and OCPD. Based on results from the correlation analysis, we conducted a multiple regression, regressing OCD severity on the OCPD-related dimensions that were significantly correlated with OCD severity, to distill the model to the most robust predictors after accounting for overlapping variance between the dimensions. Lastly, for exploratory reasons, we conducted a second correlation analysis between the remaining robust OCPD-related predictors and the various subscales of the OCI-R. Data analyses were performed using Statistical Analysis Software (v. 9.2; SAS Institute, Inc., 2009). The data analytic approach is partly driven by the data, as we opted to define the regression model based on the significant findings from the correlation analysis. We approached the research question this way because the investigation is exploratory in nature. Given the dearth of research on the link between OCD and OCPD dimensions, it was difficult to select and justify which variables were the most promising for including in the regression model a priori, and not all of the variables could have been included in the model based on preserving a reasonable level of statistical power. Thus, given the lack of research in this area, we opted to emphasize model building rather than model testing, with the hope that it facilitates future research and cross-validation. 2. Results 2.1. Preliminary correlation analysis We calculated the Pearson product moment correlations between the OCI-R and the OCPD subscale of the OMNI, as well as each of the OCPD-related dimensions. Based on visual inspection of the scatter plot and descriptive statistics, all variables met the standard assumptions of linearity and homoscedascity, While most variables met the assumption of normality, three variables were skewed based on the criterion outlined by Tabachnick and Fidell (1996): skewness statistic greater than 2[ (6/N)]. As a result, the negatively skewed FMPS DA and O subscales were transformed by taking the square root and log of the reverse score, respectively (Howell, 2001). The OMNI Conscientiousness subscale was positively skewed and was therefore linearly transformed by taking the square root (Howell, 2001). A slight ceiling and floor effect was noted with the FMPS DA subscale and OCI-R Hoarding subscale, respectively, which may result in slight attenuation of their observed correlations (Table 4). Results of the correlation analysis are presented in Table 3. The findings indicated a significant correlation between OCI-R and the OCPD subscale of the OMNI, suggesting a direct relationship between OCD severity scores and a composite indicator of OCPD dimensions. Additional results suggest an association between OCD Table 4 Correlations between OCD severity, OCPD, and OCPD dimensions a 6. a b 1. OCI-R Total 1 2. OCI-R Hoard.48 *** 1 3. FMPS Total * 1 4. FMPS-CM **.82 **** 1 5. FMPS-DA a.49 *** **.43 ** 1 6. FMPS-O a * FMPS-PC ****.37 ** FMPS-PE ****.54 **** **** 1 9. FMPS-PS ****.54 **** * ** OMNI-OCPD.29 *.48 ***.32 *.30 *.34 * OMNI-Du OMNI-Fl.43 ** * ** OMNI-Or.29 * ***.37 **.32 *.42 ** *.35 * OMNI-Con b *.49 *** ** *.40 **.72 ****.51 ***.30 *.56 **** 1 n = 51. OCI-R Total: Obsessive Compulsive Inventory-Revised total score without the Hoarding subscale; OCI-R Hoard: Hoarding subscale; FMPS: Frost Multidimensional Perfectionism Scale; CM: concern over mistakes; DA: doubts about actions; O: organizing; PC: parental criticism; PE: parental expectations; PS: personal standards; OMNI OCPD: Obsessive Compulsive Personality Disorder subscale of the OMNI Personality Inventory; Du: dutifulness; Fl: flexibility; Or: orderliness; Con: conscientiousness. a Transformed using reverse score square root or logarithm. Interpret in the opposite direction. b Transformed using square root. * p <.05. ** p <.01. *** p <.001. **** p <.0001.

6 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) Table 5 Multiple regression model results (with OCI-R as criterion). Predictor ˇ t OCI-R Hoarding * OMNI Flexibility * FMPS DA a * OMNI Orderliness n = 51. OCI-R Hoarding: Hoarding subscale of the Obsessive Compulsive Inventory- Revised; FMPS: Frost Multidimensional Perfectionism Scale; DA: doubts about actions. a Transformed using reverse score square root. Interpret in the opposite direction. * p <.05. severity and four OCPD-related dimensions: hoarding, flexibility, doubts about actions, and orderliness. The aforementioned slight ceiling and floor effects did not appear to affect any tests of statistical significance, but the magnitude of the correlations may be somewhat underestimated (i.e., smaller correlations of OCI-R with both the FMPS DA and OCI-R Hoarding subscales) Multiple regression We subsequently conducted a multiple regression predicting OCD severity from hoarding, flexibility, doubts about actions, and orderliness the four variables that were significantly associated with OCD severity in the preliminary correlation analysis. Results indicated a statistically significant prediction model, F (4, 46) = 8.89, p <.0001, with a robust R 2 of.44 and Adjusted R 2 of.39. Evaluation of the main effects indicated that 3 of the 4 predictors were statistically significant: flexibility, doubts about actions, and hoarding. The results of the main effects are provided in Table Exploratory correlation analysis between significant predictors and OCI-R Subscales To investigate differential associations between the subscales of the OCI-R and the OCPD-related dimensions borne out of the multiple regression we conducted an exploratory correlation analysis. Based on visual inspection of the scatter plots and descriptive statistics, all OCI-R subscales met the standard assumptions of linearity and homoscedascity. However, the OCI-R Mental Neutralizing subscale was skewed, mostly due to a sizeable floor effect. For the correlation analysis, the OCI-R Mental Neutralizing subscale was transformed by taking the square root. However, because of the moderate floor effect, any correlations incorporating this subscale must be interpreted with caution due to possible attenuation. The results are presented in Table 6. Table 6 Correlations of OCI-R Subscales with significant regression model predictors. OCI-R Hoarding OMNI Flexibility FMPS DA a 1. OCI-R Hoarding 1 2. OMNI Flexibility FMPS DA a * 1 4. OCI-R Washing OCI-R Checking * 6. OCI-R Ordering.73 *** * 7. OCI-R Obsessing OCI-R Neutralizing ** n = 51. OCI-R: Obsessive Compulsive Inventory-Revised; FMPS: Frost Multidimensional Perfectionism Scale; DA: doubts about actions. a Transformed using reverse score square root. Interpret in the opposite direction. p <.10. * p <.05. ** p <.01. *** p < Discussion The present study examined the relationships between various OCPD-related dimensions and OCD symptoms and severity. Our results indicated that obsessive compulsive personality, as assessed by the OMNI, was significantly correlated with OCD severity. This finding bolsters support for previous research citing an association between OCPD and greater severity in OCD (Coles et al., 2008; Lochner et al., 2010). In addition, the results yielded several significant relationships between OCD severity and individual OCPD-related dimensions. For instance, only one of the two maladaptive dimensions of the FMPS scale that were previously found to correlate with OCD severity, DA, demonstrated a positive correlation with OCD severity (the ˇ-weight is negative only because of the data transformation). Interestingly, CM and total perfectionism did not show a significant correlation with OCD severity, which is contrary to previous findings by Chik et al. (2008) who, to our knowledge, conducted the only other existing investigation of relationships between OCD severity and FMPS dimensions. However, Chik et al. (2008) used the YBOCS total score as an assessment of OCD severity and found significant associations between these three FMPS dimensions and compulsions, but not obsessions. After excluding its hoarding items, the OCI-R total score in the current study may have resulted in more obsession-based than compulsion-based items in our calculation of overall OCD severity. This alteration to the total score might explain the non-significant relationships between OCD severity and CM and total perfectionism. To evaluate the possibility that an imbalance in the number of obsession-based versus compulsion-based items on the amended OCI-R resulted in the lack of a relationship between OCD severity and both FMPS Total and FMPS CM, we re-ran some correlations. This time, however, we did not remove the hoarding subscale from the OCI-R. The correlation between the unamended OCI-R and FMPS total approached statistical significance (r =.28, p =.051), while the correlation between the unamended OCI-R and FMPS CM subscale was statistically significant (r =.30, p <.05). These correlations lend some support to the notion that removing the hoarding subscale from the OCI-R might have resulted in a bias towards obsessions in the index of OCD severity an imbalance which likely would affect the measurement of hoarding. Alternatively, it is possible that the link between perfectionism and OCD severity is influenced in part by hoarding. Further research exploring hoarding as a mediator or moderator would be necessary to tease apart these findings further. Results regarding the OMNI personality dimensions revealed significant associations between OCD severity and flexibility, with less flexibility correlating with higher OCD severity. The present study found no significant relationships between OCD severity and the remaining three OMNI subscales, dutifulness, orderliness, and conscientiousness. Given previous findings indicating that conscientiousness is unrelated to OCD, the lack of a significant relationship between OMNI conscientiousness and OCD severity in the current study is not surprising. However, contrary to our findings, previous research suggests a link between OCD severity and an inflated sense of responsibility (Manos et al., 2010; Salkovskis et al., 2000), which appears similar in nature to dutifulness as operationally defined in the OMNI. As these previous studies used the Obsessional Beliefs Questionnaire (OBQ) to assess for inflated perceptions of responsibility, our utilization of the OMNI dutifulness measure may not have assessed responsibility to the same degree or with the same adequacy. The combination of Flexibility and DA, which were significantly correlated with OCD severity, may make for an interesting clinical presentation resembling not just right experiences (NJREs). In fact, it is possible that the link between OCD and OCPD might be explained in part by NJREs, which in turn may partially consist of

7 1030 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) high DA and low flexibility. Lee et al. (2009) found that comorbid OCPD in patients with OCD was associated with the presence of NJR perceptions when compared to healthy control participants, suggesting NJREs to be a prominent feature for those with comorbid OCPD and OCD. In addition, NJREs have also shown to be positively associated with FMPS dimensions of perfectionism including DA, as well as total perfectionism (Aardema, Radomsky, O Connor, & Julien, 2008; Coles, Frost, Heimberg, & Rheaume, 2003; Coles et al., 2008; Lee et al., 2009; Moretz & McKay, 2009). Given the current and previous findings, future research should investigate the role of OCPD-related dimensions in NJREs. Consistent with the hypotheses and previous literature, the relationship between OCD severity and hoarding was significant. Thus, hoarding appears to be one of the few OCPD-related dimensions independently associated with OCD severity. While still undetermined, upcoming changes to the diagnostic nosology in psychiatry may have a profound effect on comorbidity rates between OCD and OCPD. For example, if hoarding is removed from the definitions of OCD and OCPD in the DSM-V (APA, 2011; Mataix-Cols et al., 2010), one may presume a decline in comorbidity rates between OCPD and OCD based on this relationship. However, our findings indicate a notable phenomenological overlap between OCD and OCPD-related dimensions even with the hoarding subscale included in the model (i.e., while controlling the influence of hoarding, flexibility and DA were independently linked with OCD severity). Therefore, based on these results, the comorbidity risk between OCPD and OCD would likely remain above zero. It is important to note that we only evaluated individuals with OCD and hoarding, but not those with hoarding alone. There is growing research that supports differentiating the various classes of hoarding (e.g., traditional hoarding versus hoarding to prevent spread of contamination) (e.g., Pertusa et al., 2008, 2010). Thus, the current study can only draw meaningful inferences about those with OCD-related hoarding symptoms and not necessarily those with hoarding-only or primary hoarding with secondary OCD symptoms, which may be a limitation to the generalizability of our results. Using an exploratory analysis to examine the relationships between OCPD-related dimensions and OCD subtypes, our findings indicated that DA was significantly correlated with neutralizing, checking, and ordering symptoms. Considering the nature of DA, described as a feeling of dissatisfaction with the way tasks are carried out and an insatiable need for achieving a correct way of doing things, it is possible that OCD individuals with high DA may employ more neutralizing, checking, or ordering compulsions to reduce anxiety elicited by DA, compared to those with low DA. The present study has certain limitations. For example, the OCPD dimensions we examined with the OMNI and FMPS may not precisely map on to the actual OCPD criteria. The OMNI, for instance, does not assess for all dimensions related to the OCPD criteria. However, the OMNI was designed to measure personality dimensions specifically related to DSM-IV criteria for personality disorders, including OCPD (Loranger, 2001). Moreover, as the OMNI is not used as a diagnostic measure of OCPD, the current study did not diagnose individuals with OCPD, but rather, only assessed for OCPD characteristics. Indeed, our purpose in doing so was to steer clear of adopting a categorical approach in order to investigate individual OCPD traits dimensionally. Likewise, the FMPS was not originally developed to assess for perfectionism as a diagnostic criterion of OCPD. However, we opted to use the FMPS because it is a psychometrically valid and reliable measure of perfectionism (Frost et al., 1990; Parker & Adkins, 1995), allowing for a more thorough examination of perfectionism by breaking down the construct into individual dimensions. In addition, the current study did not assess for categorical diagnoses of OCPD to compare with the study s dimensional analysis. Such a comparison may have yielded interesting analyses of disparities between the two approaches. Future research should investigate such disparities in these approaches when examining personality disorder comorbidity. Further, Table 3 indicates high ratings of other types of personality disorder pathology in addition to OCPD, particularly in Dependant, Avoidant, and Borderline personality disorders, as assessed by the OMNI. These findings are consistent with previous research indicating high comorbidity rates of these four personality disorders (Denys et al., 2004; Maina et al., 2007). Each of these personality disorders, except for Avoidant personality disorder, were also significantly correlated with OCD severity. Thus, future research should analyze the effects of other types of personality disorder dimensions in OCD. Since the Hoarding subscale is a component of the OCI-R, shared method variance may have increased the correlation between hoarding and OCD severity. It is important to note, however, that the hoarding subscale was not significantly associated with most of the other OCI-R subscales (see Table 6), which would not be expected if method variance exhibited a large influence on the correlation analysis. Additionally, the exploratory steps of the study s data analytic approach can be considered a limitation of the study as well. However, given the paucity of research in the area, it was our goal to first establish a foundation of knowledge on which to build theory and future research. Furthermore, the study was not completely atheoretical, as extant research and theory provided the initial set of finite variables to include in the analysis. These benefits were weighed against the negative possibility of inflated effect sizes due to capitalizing off of chance factors in our dataset. Given this limitation, the current investigation should be cross-validated with a priori methods in new samples before any concrete conclusions can be drawn. In short, the current study found that OCD severity was significantly associated with the following OCPD dimensions: Flexibility, DA, and Hoarding. These findings have important implications. For instance, practitioners may have difficulty discriminating the diagnostic lines between OCD and OCPD, which may be obscured due to considerable overlap and definitional similarity. The findings of the present study may help clinicians differentiate between the two clinical presentations. Further, the study illustrates the utility of the recently evolving conceptualizations of PDs based on extremes in normal, global personality dimensions, indicating that maladaptive extremes in inflexibility and DA may be linked to OCD severity and symptom presentation. Thus, this dimensional approach may be necessary to address the broader range of dysfunction found in patients with this presentation. Moreover, given previous research findings indicating that OCD patients with OCPD show greater severity and functional impairment, as well as poorer treatment outcomes (Cavedini et al., 1997; Coles et al., 2008; Lochner et al., 2010; Pinto, 2009; Pinto et al., 2008, 2009a), this dimensional perspective may be beneficial for practitioners in determining the optimum approach to treatment. This also perhaps indicates a need for research to further investigate treatment approaches targeting OCPD dimensions which may hinder treatment effectiveness for individuals with OCD. Ultimately, the findings of the present study shed light over an array of taxonomic, diagnostic, and treatment issues. By analyzing the impact of individual OCPD characteristics dimensionally, as opposed to categorically, the current study may aid in generating a clearer diagnostic perspective that leaves less room for incorrect labels and misapplications of treatment. Further, the study may also provide insights for developing innovative strategies that target this comorbid clinical population in treatment, potentially affecting many individuals with OCD who fail to benefit from standard

8 C.T. Wetterneck et al. / Journal of Anxiety Disorders 25 (2011) treatments. In the end, more individuals with OCD and OCPD can be identified and treated accordingly. Acknowledgements This work was supported in part by the VA HSR&D Houston Center of Excellence (HFP90-020). The views expressed reflect those of the authors and not necessarily those of the Department of Veterans Affairs/Baylor College of Medicine. References Aardema, F., Radomsky, A. S., O Connor, K. P., & Julien, D. (2008). Inferential confusion, obsessive beliefs, and obsessive-compulsive symptoms: a multidimensional investigation of cognitive domains. Clinical Psychology and Psychotherapy, 15, Abramowitz, J. S. (1997). Effectiveness of psychological and pharmacological treatments for obsessive-compulsive disorder: a quantitative review. Journal of Consulting and Clinical Psychology, 65, Abramowitz, J. S. (2006). The psychological treatment of obsessive-compulsive disorder. The Canadian Journal of Psychiatry, 51, Abramowitz, J. S., Taylor, S., & McKay, D. (2005). Potentials and limitations of cognitive treatments for obsessive-compulsive disorder. Cognitive Behaviour Therapy, 34, Albert, U., Maina, G., Forner, F., & Bogetto, F. (2004). DSM-IV obsessive-compulsive personality disorder: prevalence in patients with anxiety disorders and in healthy comparison subjects. Comprehensive Psychiatry, 45, American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders IV-TR (4th ed.). Washington, DC: Author. American Psychiatric Association. (2011). DSM-5: the future of psychiatric diagnosis. Retrieved from Baer, L. (1994). Factor analysis of symptom subtypes of obsessive compulsive disorder and their relation to personality and tic disorders. Journal of Clinical Psychiatry, 55, Cavedini, P., Erzegovesi, S., Ronchi, P., & Bellodi, L. (1997). Predictive value of obsessive-compulsive personality disorder in antiobsessional pharmacological treatment. European Neuropsychopharmacology, 7, Chik, H. M., Whittal, M. L., & O Neill, M. L. (2008). Perfectionism and treatment outcome in obsessive-compulsive disorder. Cognitive Therapy Research, 32, Clark, L. A. (1993). Manual for the schedule for nonadaptive and adaptive personality. Minneapolis, MN: University of Minnesota Press. Coles, M. E., Frost, R. O., Heimberg, R. G., & Rheaume, J. (2003). Not just right experiences: perfectionism, obsessive-compulsive features and general psychopathology. Behaviour Research and Therapy, 41, Coles, M. E., Pinto, A., Mancebo, M. C., Rassmussen, S. A., & Eisen, J. L. (2008). OCD with comorbid OCPD: a subtype of OCD? Journal of Psychiatric Research, 42, Costa, P. T., & McCrae, R. R. (2010). Bridging the gap with the five-factor model. Personality Disorders: Theories, Research, and Treatment, 1, Denys, D., Tenney, N., van Megen, H., de Geus, F., & Westenberg, H. (2004). Axis I and II comorbidity in a large sample of patients with obsessive-compulsive disorder. Journal of Affective Disorders, 80, Eisen, J. L., Coles, M. E., Shea, M. T., Pagano, M. E., Stout, R. L., Yen, S., et al. (2006). Clarifying the convergence between obsessive-compulsive personality disorder criteria and obsessive compulsive disorder. Journal of Personality Disorders, 20, Fisher, P. L., & Wells, A. (2005). How effective are cognitive and behavioral treatments for obsessive-compulsive disorder? A clinical significance analysis. Behaviour Research and Therapy, 43, Foa, E. B., Huppert, J. D., Leiberg, S., Langner, R., Kichic, R., Hajcak, G., et al. (2002). The Obsessive-Compulsive Inventory: development and validation of a short version. Psychological Assessment, 14(4), Frost, R. O., Marten, P., Lahart, C., & Rosenblate, R. (1990). The dimensions of perfectionism. Cognitive Therapy and Research, 14, Howell, D. C. (2001). Statistical methods for psychology (5th ed.). Belmont, CA: Wadsworth Publishing. Julien, D., O Connor, K. P., Aardema, F., & Todorov, C. (2006). The specificity of belief domains in obsessive-compulsive symptom subtypes. Personality and Individual Differences, 41, Krueger, R. F, Skodol, A. E., Livesley, W. J., Shrout, P. E., & Huang, Y. (2007). Synthesizing dimensional and categorical approaches to personality disorders: refining the research agenda for DSM-V Axis II. International Journal of Methods in Psychiatric Research, 16, Lee, J. C., Prado, H. S., Diniz, J. B., Borcato, S., da Silva, C. B., Hounie, A. G., et al. (2009). Perfectionism and sensory phenomena: phenotypic components of obsessivecompulsive disorder. Comprehensive Psychiatry, 50, Lochner, C., Serebro, P., van der Merwe, L., Hemmings, S., Kinnear, C., Seedat, S., et al. (2010). Comorbid obsessive-compulsive personality disorder in obsessivecompulsive disorder: a marker of severity. The 30th Annual Convention of the Anxiety Disorders Association of America, Baltimore, Massachusetts. Loranger, A. W. (2001). OMNI Personality Inventories: professional manual. Lutz, FL: Psychological Assessment Resources. Maina, G., Albert, U., Pessina, E., & Bogetto, F. (2007). Bipolar obsessive-compulsive disorder and personality disorders. Bipolar Disorders, 9, Maina, G., Bellino, S., Bogetto, F., & Ravizza, L. (1993). Personality disorders in obsessive-compulsive patients: a study report. The European Journal of Psychiatry, 7, Manos, R. C., Cahill, S. P., Wetterneck, C. T., Conelea, C. A., Ross, A. R., & Riemann, B. C. (2010). The impact of experiential avoidance and obsessive beliefs on obsessivecompulsive symptoms in a severe clinical sample. Journal of Anxiety Disorders, 24, Mataix-Cols, D., Baer, L., Rauch, S. L., & Jenike, M. A. (2000). Relation of factoranalyzed symptom dimensions of obsessive-compulsive disorder to personality disorders. Acta Psychiatrica Scandinavica, 102, Mataix-Cols, D., Frost, R. O., Pertusa, A., Clark, L. A., Saxena, S., Leckman, J. F., et al. (2010). Hoarding disorder: a new diagnosis for DSM-V? Depression and Anxiety, 27, McKay, D., Abramowitz F, S., Calamari, J. E., Kyrios, M., Radomsky, A., Sookman, D., et al. (2004). A critical evaluation of obsessive-compulsive disorder subtypes: symptoms versus mechanisms. Clinical Psychology Review, 24, Moran, P., Coffee, C., Mann, A., Carlin, J. B., & Patton, G. C. (2006). Dimensional characteristics of DSM-IV personality disorders in a large epidemiological sample. Acta Psychiatrica Scandinavica, 113, Moretz, M. W., & McKay, D. (2009). The role of perfectionism in obsessivecompulsive symptoms: not just right experiences and checking compulsions. Journal of Anxiety Disorders, 23, Nestadt, G., Di, C. Z., Riddle, M. A., Grados, M. A., Greenberg, B. D., Fyer, A. J., et al. (2009). Obsessive-compulsive disorder: subclassification based on comorbidity. Psychological Medicine, 39, Pallanti, S., & Quercioli, L. (2006). Treatment refractory obsessive-compulsive disorder: methodological issues, operational definitions, and therapeutic lines. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 30, Parker, W. D., & Adkins, K. K. (1995). A psychometric examination of the multidimensional perfectionism scale. Journal of Psychopathology and Behavioral Assessment, 17, Pertusa, A., Frost, R. O., Fullana, M. A., Samuels, J., Steketee, G., Tolin, D., et al. (2010). Refining the diagnostic boundaries of compulsive hoarding: a critical review. Clinica Psychology Review, 30, Pertusa, A., Fullana, M. A., Singh, S., Alonso, P., Menchon, J. M., & Mataix-Cols, D. (2008). Compulsive hoarding: OCD symptom, distinct clinical syndrome, or both? American Journal of Psychiatry, 165, Pinto, A. (2009). Understanding obsessive-compulsive personality disorder and its impact on obsessive-compulsive disorder. Paper presented at Obsessive- Compulsive Foundation Conference, Minneapolis, MN. Pinto, A., Coles, M. E., Mancebo, M. C., Rasmussen, S., & Eisen, J. (2008). Does the presence of OCPD increase the morbidity of OCD? 42nd Annual Convention for the Association of Behavioral and Cognitive Therapies, Orlando, Florida. Pinto, A., Liebowitz, M., Foa, E., & Simpson, H. B. (2009a). OCPD severity as a predictor of CBT outcome for OCD. Paper presented at the Congress of the International Society for the Study of Personality Disorders, New York City, New York. Pinto, A., Liebowitz, M., Foa, E., & Simpson, H. B. (2009b). Does the severity of OCPD predict CBT outcome for OCD? 43rd Annual Convention for the Association of Behavioral and Cognitive Therapies, New York City, New York. Reynolds, S. K., & Clark, L. A. (2001). Predicting dimensions of personality disorder from domains and facets of the five-factor model. Journal of Personality, 69, Rowa, K., Antony, M. M., & Swinson, R. P. (2007). In: C. Purdon, M. M. Antony, & L. J. Summerfeldt (Eds.), Psychological treatment of obsessive-compulsive disorder: fundamentals and beyond. Washington, DC: American Psychological Association. Salkovskis, P. M., Wroe, A. L., Gledhill, A., Morrison, N., Forrester, E., Richards, C., et al. (2000). Responsibility attitudes and interpretations are characteristic of obsessive-compulsive disorder. Behaviour Research and Therapy, 38, Samuels, J., Nestadt, G., Bienvenu, O. J., Costa, P., Riddle, M., Liang, K., et al. (2000). Personality disorders and normal personality dimensions in obsessive-compulsive disorder. British Journal of Psychiatry, 177, SAS Institute Inc. (2009). The SAS System for Windows (Version 9.2). Cary, NC: SAS Institute Inc. Saulsman, L. M., & Page, A. C. (2004). The five-factor model and personality disorder empirical literature: a meta-analytic review. Clinical Psychology Review, 23, Suzuki, T. (2005). Relationship between two aspects of perfectionism and obsessivecompulsive symptoms. Psychological Reports, 96, Tabachnick, B. G., & Fidell, L. S. (1996). Using multivariate statistics: third edition. New York: Harper Collins. Trull, T. J., & Durrette, C. A. (2005). Categorical versus dimensional models of personality disorder. Annual Review of Clinical Psychology, 1, Widiger, T. A., & Mullins-Sweatt, S. N. (2010). Clinical utility of a dimensional model of personality disorder. Professional Psychology: Research and Practice, 41, Widiger, T. A., & Simonsen, E. (2005). Alternative dimensional models of personality disorder: finding a common ground. Journal of Personality Disorders, 19, Wu, K. D. (2004). Obsessive-compulsive disorder: relations among obsessional symptoms and personality. Retrieved from ProQuest Digital Dissertations (AAT ). Wu, K. D., Clark, L. A., & Watson, D. (2006). Relations between obsessive-compulsive disorder and personality: beyond axis I-axis II comorbidity. Journal of Anxiety Disorders, 20,