Nail psoriasis in Germany: epidemiology and burden of disease M. Augustin, K. Reich,* C. Blome, I. Schäfer, A. Laass and M.A.

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1 EPIDEMIOLOGY AND HEALTH SERVICES RESEARCH BJD British Journal of Dermatology Nail psoriasis in Germany: epidemiology and burden of disease M. Augustin, K. Reich,* C. Blome, I. Schäfer, A. Laass and M.A. Radtke CVderm German Center for Health Services Research in Dermatology, Institute for Health Services Research in Dermatology and Nursing, University Clinics of Hamburg, Martinistrasse 52, 2246 Hamburg, Germany *Dermatologikum Hamburg, Germany Summary Correspondence Matthias Augustin. Accepted for publication 17 April 2 Key words disease severity, health services research, nail psoriasis, psoriasis, quality of life Conflicts of interest This study was supported by research grants from Wyeth Pharma GmbH, Münster, Germany and from Essex Pharma GmbH, Munich, Germany. M.A., K.R. and M.A.R. have received funding from Wyeth Pharma GmbH and Essex Pharma GmbH for research and were invited speakers and consultants for both companies. C.B., I.S. and A.L. have no conflicts of interest to declare. DOI.1111/j x Background Although nail psoriasis affects a marked proportion of patients with psoriasis and causes significant psychological stress, only few epidemiological data characterizing patients with nail involvement are available. Objectives To gain robust data on the epidemiology and disease burden of nail psoriasis in Germany. Methods Two nationwide, noninterventional, cross-sectional studies on psoriasis health care were conducted in 25 and 27, involving 48 (25) and 13 (27) German office-based and clinic-based dermatological centres. Data of n = 3531 patients with psoriasis were collected using standardized questionnaires and physical examinations by trained dermatologists. Patients with nail psoriasis were compared with patients without any nail involvement concerning sex, age, disease duration, family history, disease severity, presence of psoriatic arthritis (PsA), health-related quality of life (HRQoL), number of inpatient therapies, and days off work. Results Nail psoriasis was diagnosed in 4Æ9% of the patients; prevalence was 11Æ2 percentage points higher in men than in women. Patients with nail involvement had a longer disease duration (21Æ9 vs. 18Æ1 years), higher disease severity (mean Psoriasis Area and Severity Index 12Æ7 vs. 9Æ3), higher frequency of PsA (26Æ% vs. 12Æ7%), stronger impairment of HRQoL (mean Dermatology Life Quality Index 8Æ9 vs. 7Æ3), and a 2Æ5-fold higher rate of inpatient treatments. Conclusions Nail involvement is a relevant manifestation of psoriasis and is associated with a higher disease severity and quality of life impairment. Accordingly, management of psoriasis should include a special focus on nail involvement. Nail psoriasis affects a great proportion of patients with psoriasis and can cause significant physical and psychological impairment. 1 Prevalence data vary between % and 55% of patients with psoriasis. 2,3 About 1 5% of patients manifest with nail changes alone. 4 The clinical differentiation between onychomycosis and psoriasis of the nails may be difficult, as both can present with subungual hyperkeratosis, onycholysis and discoloration of the nail plate. The spectrum of findings in nail psoriasis includes signs of nail matrix involvement such as leuconychia, erythema of the lunula, pitting, and nail plate crumbling as well as manifestations of nail bed involvement such as oil drop discoloration, splinter haemorrhages, subungual hyperkeratosis and distal onycholysis. 5 In most cases, the diagnosis of nail psoriasis is established according to clinical criteria. In certain cases biopsies may be needed. 6 Compared with the efficacy of treatment options for psoriatic skin lesions and the recent advances in the treatment of psoriatic arthritis (PsA), the management of nail psoriasis remains challenging. 7 As more is understood about the pathogenesis of psoriasis, biologics and other new options for treating nail psoriasis have been developed which may be safer and more effective than traditional systemic therapies. Of the topical agents, vitamin D analogues as well as nail lacquer containing potent corticosteroids have been reported to improve lesions of nail bed and nail matrix involvement. 8 The difficulty remains to deliver sufficient concentrations of antipsoriatic drugs in the involved parts of the nail apparatus by topical application. 9 Psoriasis on highly visible areas of the skin, such as the face, hands and nails, can be psychologically devastating. Psychological impairment has been observed in social settings 58

2 Nail psoriasis in Germany, M. Augustin et al. 581 and in the workplace.,11 Accordingly, nail psoriasis can significantly reduce health-related quality of life (HRQoL). The economic implications of nail psoriasis as a distinct condition have not yet been identified although several studies underline the economic importance of psoriasis in general. 12,13 Thus, nail psoriasis appears as a health care problem that has not received sufficient attention in the past. The aim of the current project was to examine the health care situation of patients with nail psoriasis in two nationwide studies in Germany, conducted in 25 and 27. The following aspects were addressed: 1 Epidemiology. What is the prevalence of nail psoriasis among patients with psoriasis seen by dermatologists in Germany? 2 Clinical characteristics. How can patients with nail psoriasis be characterized compared with patients without nail psoriasis? 3 Burden of disease. Are there any differences in HRQoL between patients with psoriasis with and without nail involvement? Materials and methods Study design and outcomes measures Two independent, nationwide, cross-sectional studies on psoriasis health care in dermatology centres were performed in 25 and 27, respectively. Patients were recruited consecutively in dermatological practices and outpatient clinics. Details on patient recruitment were published elsewhere In both studies, a common data set on psoriasis history, clinical findings including nail involvement, health care and patientreported outcomes was collected with standardized questionnaires filled in by patients and their respective dermatologists. 16 Psoriasis severity was measured using the Psoriasis Area and Severity Index (PASI). Affected body surface area was computed using the respective information given in the PASI. HRQoL was assessed with the Dermatology Life Quality Index (DLQI). 17 All clinical features of psoriasis and nail involvement were assessed by the attending dermatologist. Prospectively assigned indicators to evaluate differences between patients with and without nail involvement were: mean severity of psoriasis (PASI); proportion of patients with severe psoriasis (PASI > 2); percentage of patients with a positive family history of psoriasis; mean quality of life (DLQI); proportion of patients with severe impact on quality of life (DLQI > ); percentage of patients with PsA; percentage of patients with inpatient therapy due to psoriasis in the last 12 months; mean number of days absent from work due to psoriasis. Approval of the local ethics committee of the Hamburg Board of Physicians was obtained for both studies. Patients Patients > 18 years with clinically confirmed psoriasis who were willing and able to participate and who had given written consent were included. The data collection aimed at the inclusion of n = 15 patients (year 25) and n = 2 patients (year 27). Patients were consecutively enrolled by dermatologists in the participating centres. The physician questionnaire was completed by the dermatologist in the presence of the patient. The patient questionnaire was filled in by the patient and then returned to the physician. Statistical analyses Data entry was performed by two independent persons (double entries) into Excel spreadsheets, followed by plausibility tests. In cases of discrepancy, an independent coder determined the correct entry using the original questionnaires. For the purpose of this study on nail psoriasis, data from both studies were pooled into a single database and analysed jointly. Data on women and men were analysed separately. For interval data, means and SDs were computed; patients with and without nail psoriasis were compared using t-tests for independent samples; moreover, effect sizes were calculated. Categorial data were given as numbers and percentages of all cases, i.e. number of patients including missing values; group differences were given as differences in percentage points and were analysed using v 2 tests. Significance level was set at P =Æ5 and was not corrected for multiple testing. Data management and descriptive data analysis were performed using SPSS version 12. and 15. for Windows (SPSS, Chicago, IL, U.S.A.). Results Study centres and patients In the 25 study, data from n = 1522 patients enrolled in 48 dermatology centres were analysed. In the 27 study, data from n = 29 patients in 13 dermatology centres were evaluated. Thus, n = 3531 patients were included in this study. Sociodemographic and clinical characteristics Of the patients, 56Æ% were male, 42Æ4% female (1Æ6% missing data). The mean ± SD age of the patients was 51Æ1 ± 14Æ8 years (men 5Æ6 ± 14Æ3, women 51Æ8 ± 15Æ3); psoriasis had been diagnosed 19Æ7 ±15Æ years ago (mean ± SD; men 19Æ1 ± 13Æ9, women 2Æ5 ± 16Æ4). The mean ± SD PASI was Æ7 ±9Æ2 (men 11Æ6 ±9Æ7, women 9Æ4 ±8Æ3; P < Æ1). Of the patients, 58Æ7% were working (men 64Æ1%, women 51Æ3%); of these, 5Æ7% were unfit for work because of psoriasis at the time of questioning (men 6Æ%, women 5Æ2%), with about half having been incapacitated for 4 days or more (median 4 days; men 4Æ5, women 5). Of those working, 15Æ3% had been unfit for work because of the psoriasis at least once in the past year (men 15Æ8%, women 14Æ2%).

3 582 Nail psoriasis in Germany, M. Augustin et al. PASI No Nail involvement was present in 4Æ9% of cases. The 95% confidence interval (CI) was 39Æ3 42Æ5% which means that the real prevalence presumably lies within this range (men 46Æ%, 95% CI 43Æ8 48Æ2%; women 34Æ8%, 95% CI 32Æ4 37Æ2%). Correlates of nail involvement Fig 1. Mean psoriasis severity as measured with the Psoriasis Area and Severity Index (PASI) in patients with psoriasis with and without nail involvement ( and No, respectively; men n = 1949; women n = 147; bars indicate SD). Patients with nail involvement had a significantly higher mean ± SD PASI than those without nail involvement in both men (13Æ5 ±Æ7 vs. Æ ±8Æ6) and women (11Æ3 ±9Æ5 vs. 8Æ4 ± 7Æ3) (Fig. 1, Table 1). Psoriasis severity as measured by the affected body surface area was also significantly higher in patients with nail psoriasis (men 23Æ5 ±19Æ3 vs. 17Æ6 ±15Æ2; women 19Æ9 ±17Æ vs. 15Æ6 ±14Æ3) (Fig. 2). On average, men and women with nail psoriasis reported a mean duration of disease which was about 4 years greater than in patients without nail psoriasis (men 21Æ4 ± 13Æ5 vs. 17Æ1 ± 14Æ; women 23Æ1 ± 15Æ8 vs. 19Æ1 ± 16Æ6) (Table 1). Onset of disease in patients with nail psoriasis was at 28Æ7 ±14Æ9 vs. 34Æ1 ±17Æ4 years in men and at 29Æ3 ±17Æ1 vs. 32Æ4 ±18Æ8 years in women (data not shown). PsA was found in more than twice as many patients in the nail psoriasis group than in the unaffected group (men 24Æ4% vs. 11Æ9%; women 28Æ7% vs. 13Æ7%) (Table 2). The percentage of patients who had received inpatient treatment for psoriasis in the last 5 years was also more than twice as high among patients with nail psoriasis (men 34Æ8% vs. 14Æ9%; women 29Æ2% vs. 14Æ3%) (Table 2). The proportion of patients with a positive family history of psoriasis was 11 percentage points higher in men with nail Body surface area No Fig 2. Mean affected body surface area in patients with psoriasis with and without nail involvement ( and No, respectively; men n = 1933; women n = 1452; bars indicate SD). Table 1 Sociodemographic and clinical characteristics of patients with and without nail involvement Nail involvement (n = 143), mean ± SD (n) No nail involvement (n = 237), All patients (n = 3473), mean ± SD (n) P-value a d b mean ± SD (n) Affected body surface area 19Æ9 ± 17Æ (56) 15Æ6 ± 14Æ3 (945) < Æ1 Æ27 17Æ1 ± 15Æ4 (1452) 23Æ5 ± 19Æ3 (895) 17Æ6 ± 15Æ2 (36) < Æ1 Æ34 2Æ3 ± 17Æ4 (1933) PASI 11Æ3 ± 9Æ5 (511) 8Æ4 ± 7Æ3 (958) < Æ1 Æ34 9Æ4 ± 8Æ3 (147) 13Æ5 ± Æ7 (894) Æ ± 8Æ6 (53) < Æ1 Æ36 11Æ6 ± 9Æ7 (1949) Duration of disease (years) 23Æ1 ± 15Æ8 (493) 19Æ1 ± 16Æ6 (933) < Æ1 Æ25 2Æ5 ± 16Æ4 (1427) 21Æ4 ± 13Æ5 (887) 17Æ1 ± 14Æ (28) < Æ1 Æ31 19Æ1 ± 13Æ9 (1915) DLQI c 9Æ5 ± 7Æ1 (55) 7Æ6 ± 6Æ4 (945) < Æ1 Æ28 8Æ3 ± 6Æ7 (1451) 8Æ6 ± 7Æ1 (897) 6Æ9 ± 6Æ3 (45) < Æ1 Æ24 7Æ7 ± 6Æ7 (1944) Days unfit for work, last 12 months d 8Æ5 ± 32Æ1 (247) 2Æ4 ± 12Æ8 (486) < Æ1 Æ25 4Æ4 ± 21Æ5 (733) 6Æ ± 21Æ9 (583) 2Æ9 ± 17Æ1 (644) < Æ1 Æ16 4Æ4 ± 19Æ6 (1227) Nail involvement n = 143 (52 women and 9 men); no nail involvement n = 237 (973 women and 64 men); all patients n = 3473 (1496 women and 1977 men). PASI, Psoriasis Area and Severity Index; DLQI, Dermatology Life Quality Index. a Level of significance in t-test for independent samples. b Effect size. c DLQI ranging from = no impairment in quality of life to 3 = maximal impairment. d In this analysis, only working patients were included.

4 Nail psoriasis in Germany, M. Augustin et al. 583 Table 2 Comparison of patients with and without nail involvement Nail involvement (n = 143), n (%) No nail involvement (n = 237), n (%) Difference (%) a P-value b All patients (n = 3473), n (%) PASI > 2 81 (15Æ6) 85 (8Æ7) 6Æ9 < Æ1 166 (11Æ1) 195 (21Æ4) 13 (12Æ2) 9Æ2 < Æ1 325 (16Æ4) DLQI > 199 (38Æ3) 277 (28Æ5) 9Æ8 < Æ1 476 (31Æ8) 293 (32Æ2) 271 (25Æ5) 6Æ7 Æ1 564 (28Æ5) Positive family history 237 (45Æ6) 45 (41Æ6) 4Æ NS 643 (43Æ) 391 (43Æ) 341 (32Æ) 11Æ < Æ1 732 (37Æ) Admission to hospital, last 5 years 152 (29Æ2) 139 (14Æ3) 14Æ9 < Æ1 291 (19Æ5) 317 (34Æ8) 159 (14Æ9) 2Æ1 < Æ1 476 (24Æ1) Psoriatic arthritis 149 (28Æ7) 133 (13Æ7) 15Æ < Æ1 282 (18Æ9) 222 (24Æ4) 127 (11Æ9) 7Æ5 < Æ1 349 (17Æ7) Nail involvement n = 143 (52 women and 9 men); no nail involvement n = 237 (973 women and 64 men); all patients n = 3473 (1496 women and 1977 men). PASI, Psoriasis Area and Severity Index; DLQI, Dermatology Life Quality Index; NS, not significant. a Difference between the two groups nail involvement and no nail involvement, given in percentage points. b Level of significance in v 2 test. psoriasis than in men without nail psoriasis (43Æ% vs. 32Æ%). In women, the proportion was 4 percentage points higher; however, this difference was not statistically significant (P =Æ143) (Fig. 3, Table 2). In both working men and working women, patients with nail psoriasis had more days off from work due to psoriasis in the previous 12 months (men 6Æ ± 21Æ9 vs. 2Æ9 ± 17Æ1; women 8Æ5 ± 32Æ1 vs. 2Æ4 ± 12Æ8) (Table 1). Patients with nail psoriasis also had significantly higher impairments in quality of life as measured with the DLQI (men 8Æ6 ±7Æ1 vs. 6Æ9 ±6Æ3; women 9Æ5 ±7Æ1 vs. 7Æ6 ±6Æ4) (Fig. 4, Table 1). DLQI No Discussion To date, few studies on the epidemiology and clinical patterns of nail psoriasis have been conducted, and the evidence for Fig 4. Mean quality of life as measured with the Dermatology Life Quality Index (DLQI) in patients with psoriasis with and without nail involvement ( and No, respectively; men n = 1944; women n = 1451; bars indicate SD). Family history (%) No Fig 3. Proportion (%) with a positive family history in patients with psoriasis with and without nail involvement ( and No, respectively; men n = 1977; women n = 1496). treating nail disease is still unconvincing. The aim of the studies presented was to gain reliable data on the prevalence of nail psoriasis among German patients referred to dermatologists and to characterize differences between patients with and without nail psoriasis. Moreover, the disease burden from the patient s point of view was to be assessed. The project is part of a national programme for the assessment and quality assurance of psoriasis care in Germany. 18 The data were planned also to serve as a first approach for the future improvement of health care in nail psoriasis. For higher validity, all data on nail involvement were collected by trained dermatologists. According to our findings, nail psoriasis is common among unselected patients in the dermatologist s practice, involving about 32 37% of women and 44 48% of men with psoriasis.

5 584 Nail psoriasis in Germany, M. Augustin et al. Unlike in some other countries, dermatologists in Germany provide a great proportion of health care in psoriasis, prescribing as many drugs as general practitioners. For this reason, the data represent a substantial proportion of all patients with psoriasis. However, it cannot be ruled out that nail psoriasis is less common in patients with mild psoriasis not consulting a doctor. Nail psoriasis seems to be a risk factor both for a clinically more severe disease course and for a greater burden of disease. The high visibility of the nail condition and the associated stigmatization and shame may constitute important determinants of diminished quality of life. 19 Nail involvement as a predictor for more severe disease seems to have a greater impact in men than in women. Moreover, patients with nail psoriasis more often had joint involvement, as already described in other studies Both the more severe disease (PASI) and the higher proportion of arthritis probably contribute to the findings of impaired HRQoL and more working days lost in patients with nail involvement. As stated by Samman and Fenton, 23 the lifetime incidence of nail involvement in patients with psoriasis is approximated to be between 8% and 9%. Far beyond a cosmetic disorder, nail involvement in patients with psoriasis is also an important clinical feature of the disease that has been underestimated so far. Moreover, it leads to substantial disease burden, impairment in daily activity, and stigmatization. Decisions to choose a particular treatment for psoriasis, however, should be based on a variety of factors: diagnosis, disease activity, prognosis, comorbid conditions, individual patient preferences and the anticipated benefits and risks of treatment. Quality of life issues, political and social considerations may also play a role. 24 Within this context, nail involvement is still underestimated, particularly when developing therapeutic strategies for the patient and taking patients HRQoL into account. Future psoriasis research must also focus on providing more evidence for the efficacy and real-world effectiveness of nail treatment in psoriasis. The implementation of useful tools to measure clinical improvement and patient benefits in nail psoriasis treatment may be of value in guiding medical therapy and standardized clinical trials. Furthermore, it should be examined whether current nail involvement is predictive of a more severe course of psoriasis in future which would allow for an early identification of patients with a high need for treatment. What s already known about this topic? Psoriasis on highly visible areas of the skin, such as the face, hands and nails, can be psychologically devastating. Psychological impairment has been observed in social settings and in the workplace. Accordingly, nail psoriasis can significantly reduce health-related quality of life (HRQoL). Thus, nail psoriasis appears as a health care problem that has not received sufficient attention in the past. What does this study add? The aim of the current project was to examine the health care situation of patients with nail psoriasis in two nationwide studies in Germany, conducted in 25 and 27. The following aspects were addressed: Epidemiology. What is the prevalence of nail psoriasis among patients with psoriasis seen by dermatologists in Germany? Clinical characteristics. How can patients with nail psoriasis be characterized compared with patients without nail psoriasis? Burden of disease. Are there any differences in HRQoL between patients with psoriasis with and without nail involvement? References 1 Lawry M. Biological therapy and nail psoriasis. Dermatol Ther 27; 2: Farber EM, Nall L. Nail psoriasis. Cutis 1992; 5: van Laborde S, Scher RK. Developments in the treatment of nail psoriasis, melanonychia striata, and onychomycosis. A review of the literature. Dermatol Clin 2; 18: Grover C, Reddy BSN, Uma Chaturvedi K. Diagnosis of nail psoriasis: importance of biopsy and histopathology. Br J Dermatol 25; 153: Rich P, Scher RK. Nail Psoriasis Severity Index: a useful tool for evaluation of nail psoriasis. J Am Acad Dermatol 23; 49: Kovich OI, Soldano AC. Clinical pathologic correlations for diagnosis and treatment of nail disorders. Dermatol Ther 27; 2: Kacar N, Ergin S, Erdogan BS. The comparison of Nail Psoriasis Severity Index with a less time-consuming qualitative system. J Eur Acad Dermatol Venereol 28; 22: Sanchez-Regana M, Umbert P. Diagnosis and management of nail psoriasis. Actas Dermosifiliogr 28; 99: Wozel G. Psoriasis treatment in difficult locations: scalp, nails, and intertriginous areas. Clin Dermatol 28; 26: Zachariae R, Zachariae H, Blomqvist K et al. Quality of life in 6497 Nordic patients with psoriasis. Br J Dermatol 22; 146: De Jong EM, Seegers BA, Gulinck MK et al. Psoriasis of the nails associated with disability in a large number of patients: results of a recent interview with 1,728 patients. Dermatology 1996; 193: Sohn S, Schöffski O, Prinz J et al. Cost of moderate to severe plaque psoriasis in Germany: a multicenter cost-of-illness study. Dermatology 26; 212: Berger K, Ehlken B, Kugland B, Augustin M. Cost-of-illness in patients with moderate and severe chronic psoriasis vulgaris in Germany. J Dtsch Dermatol Ges 25; 3: Reich K, Krüger K, Mössner R, Augustin M. Epidemiology and clinical pattern of psoriatic arthritis in Germany: a prospective interdisciplinary epidemiological study of 1511 patients with plaque-type psoriasis. Br J Dermatol 29; 16: Augustin M, Krüger K, Radtke MA et al. Disease severity, quality of life and health care in plaque-type psoriasis: a multicenter prospective cross-sectional study in Germany. 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6 Nail psoriasis in Germany, M. Augustin et al Augustin M, Reich K, Reich C et al. Quality of psoriasis care in Germany results of the national study PsoHealth 27. J Dtsch Dermatol Ges 28; 6: Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI) a simple practical measure for routine clinical use. Clin Exp Dermatol 1994; 19: Augustin M, Reich K, Reusch M et al. Health services research in psoriasis the German approach. Dermatology 29; 218: Leray MR, Rapp SR, Herbst KC et al. Interpersonal concerns and psychological difficulties of psoriasis patients. Effects of disease severity and fear of negative evaluation. Health Psychol 1998; 17: Jones SM, Armas JB, Cohen MG et al. Psoriatic arthritis: outcome of disease subsets and relationship of joint disease to nail and skin disease. Br J Rheumatol 1994; 33: Cohen MR, Reda DJ, Clegg DO. Baseline relationships between psoriasis and psoriatic arthritis: analysis of 221 patients with active psoriatic arthritis. Department of Veterans Affairs Cooperative Study Group on Seronegative Spondyloarthropathies. J Rheumatol 1999; 26: McGonagle D. Enthesitis: an autoinflammatory lesion linking nail and joint involvement in psoriatic disease. J Eur Acad Dermatol Venereol 29; 23 (Suppl. 1): Samman PD, Fenton DA. The Nail in Disease, 5th edn. London: Butterworth-Heinemann Ltd, Kavanaugh A, Ritchlin A, Boehncke WH. Quality indicators in psoriatic arthritis. Clin Exp Rheumatol 27; 25 (Suppl. 47):98 1.