Low Back Pain: Epidemiology of Consultations

Transcription

1 Arthritis Care & Research Vol. 64, No. 7, July 2012, pp DOI /acr , American College of Rheumatology BRIEF REPORT Low Back Pain: Epidemiology of Consultations ANNA JÖUD, 1 INGEMAR F. PETERSSON, 1 AND MARTIN ENGLUND 2 Objective. Low back pain (LBP) affects most people at some stage in life. However, the burden on the health care system is unclear. We studied: 1) the 1-year consultation prevalence, 2) the rate of first-time consultation for LBP and the relationship of the frequency to other musculoskeletal conditions, and 3) the health care utilization of patients with LBP compared to the general population. Methods. Using the health care register in Southern Sweden (population 1.2 million), including diagnoses (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision) by physicians, we identified all patients who in 2009 were diagnosed with LBP, defined as lumbago with sciatica, low back pain, or other/unspecified dorsalgia. We defined first-time consultation as a consultation in 2009 without a record of an LBP diagnosis in Standardized health care utilization ratios were calculated for LBP patients compared to the general population seeking care. Results. The 1-year consultation prevalence of LBP in the population was 3.8% (4.3% for women, 3.3% for men) and increased with age. LBP had been recorded in 17.1% of all patients (16.5% for women, 18.0% for men) who had been diagnosed with any musculoskeletal condition. The rate of first-time consultation was 238 per 10,000 adults (265 for women, 209 for men). The health care utilization ratios in female and male patients with LBP were 1.74 (95% confidence interval [95% CI] ) and 1.81 (95% CI ), respectively. Conclusion. LBP, diagnosed in every sixth patient who consulted due to a musculoskeletal problem, is a public health concern that needs structured management. Patients with LBP consume close to twice as much health care as the general population and this warrants more awareness. Introduction Low back pain (LBP) is one of the most frequent symptoms in adults within the western world. However, estimates of the occurrence based on subjects self-report differ drastically, with a prevalence for a 1-year period between 2% and 65%, depending on the definitions and other methodologic aspects (1 3). Studies have indicated that approximately 40 70% of those experiencing back pain seek health care for their back pain at some stage in life (4,5), often due to more severe pain (4 6). This may result in a greater cost to society, which is why this is an important Supported by grants from the regional health service authorities in Skåne County (Region Skåne), the Swedish Social Insurance Agency, the Swedish Research Council, and the Faculty of Medicine, Lund University, Lund, Sweden. 1 Anna Jöud, MPH, Ingemar F. Petersson, MD, PhD: Lund University and WHO Collaborating Centre for Evidence- Based Healthcare in Musculoskeletal Disorders, Lund, Sweden; 2 Martin Englund, MD, PhD: Lund University and WHO Collaborating Centre for Evidence-Based Healthcare in Musculoskeletal Disorders, Lund, Sweden, and Boston University School of Medicine, Boston, Massachusetts. Address correspondence to Anna Jöud, MPH, Department of Orthopedics, Klinikgatan 22, Skåne University Hospital, SE Lund, Sweden. anna.joud@med.lu.se. Submitted for publication September 9, 2011; accepted in revised form February 8, group to study. The objectives of this study were to investigate 1) the 1-year consultation prevalence, 2) the rate of first-time consultation for LBP and the relationship of the frequency to other musculoskeletal conditions, and 3) the health care utilization of patients with LBP compared to the general population. The consultation prevalence and first-time consultation rate are standardized to the 2000 US standard population. Materials and Methods Skåne Health Care Register (SHCR). In Sweden, the responsibility for providing health care is decentralized to the county councils. Both public and private health care providers have the same tax-based financing system and apart from a small co-pay, the residents are entitled to free health care. By law, and to be eligible for free health care, a 10-digit personal identification number, a unique number automatically assigned to the population, is recorded. Within the county of Skåne, the southernmost part of Sweden with a population of 1.2 million inhabitants (representing one-eighth of the total Swedish population), all types of both inpatient and outpatient services are offered for the entire population. Each health care consultation generates data entries that transfer to central databases, such as the SHCR, and these constitute the basis for reimbursement. Similar regulations apply to both public 1084

2 Epidemiology of Low Back Pain 1085 Significance & Innovations Epidemiologic findings from Swedish health care registries reveal the burden on the health care system from people diagnosed with low back pain. People diagnosed with low back pain consume twice as much health care as the general population. Common other diagnoses among patients with low back pain were depression, respiratory infections, and chronic obstructive pulmonary disease. Statistical analysis. Annual consultation prevalence. Diagnostic codes from private health care providers are not forwarded to the SHCR, although other data are, e.g., the personal identification number, date of visit, and information on the health care provider. In 2009, 28% of a total 3,823,535 outpatient doctor consultations were within private care and we needed to compensate for this loss in the calculation of period prevalence and the rate of first-time consultation. Therefore, to compensate for the individuals only seeking private care for their LPB (not captured with diagnosis in the SHCR), we reduced the denominator by 30%. Rate of first-time consultation for LBP. For consultation rates, we were interested in subjects with first- or newonset symptoms of LBP, rendering their first consultation. We identified adults with an LBP diagnosis in 2009 that did not have a previous consultation record with a physician due to LBP in the prior 5 calendar years ( ). Health care contacts. Health care contacts in this study are considered visits to any health care professional, including physicians, nurses, physiotherapists, etc. (excluding practitioners of alternative or integrative medicine). A standardized health care utilization ratio was calculated by dividing the observed number of health care con- and private alternatives, with the only difference that diagnostic codes in private care are not transferred automatically. The register data are continuously and prospectively ascertained, and there is very limited selection bias with respect to social class or income. Diagnoses are those made since 1998, classified according to the Swedish translation of the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) system, available online ( Swedish population register. In Sweden, everyone can seek health care wherever they want to. For this study we were only interested in identifying patients residing in Skåne County. Therefore, SHCR data were linked by personal identification numbers with the Swedish population register. The register is the civil registration of vital events (e.g., births, deaths, marriages, change of residential address), administered by the Swedish Tax Agency. Criteria for LBP. We defined LBP as a diagnostic code (ICD-10) in the SHCR for any of the following diagnoses: lumbago with sciatica (M54.4), low back pain (M54.5), other dorsalgia (M54.8), dorsalgia unspecified (M54.9), and an ICD-10 code referred to as dorsalgia not specified (M54.9P), specifically used by general practitioners. These diagnoses were agreed upon after discussions with general practitioners and specialists working in the clinical field. Patients ages 20 years diagnosed by a physician in 2009 were included. Figure 1. Flow chart detailing the number (percentage) of doctor consultations and patients within public care in 2009 in Skåne County, Sweden (with a total population of 1.2 million). ICD-10 International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; MSK musculoskeletal or connective tissue (ICD-10, chapter XIII).

3 1086 Jöudetal tacts in 2009 by the expected number based on data from the general population, stratified by age and sex. This ratio describes the burden on the health care system by the patients with LBP in relation to persons in general. Since the patients with LBP had had at least 1 consultation with a physician (in order to be included in the LBP cohort), we reduced the number of observed contacts in 2009 for LBP patients by 1 per subject. We also calculated a standardized morbidity prevalence ratio (SMR). The SMR was calculated by dividing the observed prevalence of other common diagnostic codes in the LBP cohort by the expected prevalence based on data from the general population seeking care, standardized for age and sex. The SMR was calculated for the 20 most common diagnoses among the patients with LBP. In addition to the methodology described above, we also present consultation prevalence and first-time consultation rates standardized to the 2000 US standard population with 95% confidence intervals (95% CIs). Statistical analyses were performed using SAS software, version 9.2. The study was approved by the Institutional Review Board of Lund University. Figure 2. A, Rate of first-time doctor consultations due to low back pain (LBP) in 2009 (first time defined as the number of unique individuals without consultation with a physician for LBP between 2004 and 2008; n 15,601). B, Standardized health care utilization ratios for patients with LBP (n 24,949) compared to the general population (n 938,397) in 2009 in Skåne County, Sweden. A value of 1 indicates no difference. Results Annual consultation prevalence for LBP patients. In 2009, 24,949 individuals (57.3% women) ages 20 years were diagnosed with LBP. The mean SD age was years. The 1-year consultation prevalence of LBP in the adult population was 3.8% (4.3% for women and 3.3% for men). Standardized to the 2000 US standard population, the figure was 3.57% (95% CI ), for women Table 1. SMRs for the 20 most common other diagnostic codes (listed in decreasing order) among patients with low back pain compared to the general population* Diagnosis (ICD-10 code) Women, SMR (99% CI) Men, SMR (99% CI) Essential (primary) hypertension (I10) 0.91 ( ) 0.87 ( ) Other soft tissue disorder (M79) 1.91 ( ) 1.83 ( ) Abdominal and pelvic pain (R10) 1.71 ( ) 1.50 ( ) Acute upper respiratory infection of multiple sites (J06) 1.23 ( ) 1.07 ( ) Cystitis (N30) 1.34 ( ) 1.16 ( ) Depressive episode (F32) 1.29 ( ) 1.33 ( ) Pain not elsewhere classified (R52) 2.36 ( ) 2.37 ( ) Type 2 diabetes mellitus (E11) 0.99 ( ) 1.01 ( ) Other joint disorders, not elsewhere classified (M25) 1.47 ( ) 1.36 ( ) Other intervertebral disc disorders (M51) 8.93 ( ) 8.71 ( ) Pain in throat and chest (R07) 1.48 ( ) 1.40 ( ) Other anxiety disorders (F41) 1.38 ( ) 1.26 ( ) Chronic ischemic heart disease (I25) 1.04 ( ) 1.04 ( ) Atrial fibrillation and flutter (I48) 0.93 ( ) 0.94 ( ) Disorders of glycoprotein metabolism (E78) 0.88 ( ) 0.79 ( ) Senile cataract (H25) 0.98 ( ) 0.97 ( ) Dizziness and giddiness (R42) 1.31 ( ) 1.26 ( ) Other spondylopathies (M48) 5.01 ( ) 6.20 ( ) Unspecified acute lower respiratory infection (J22) 1.23 ( ) 1.19 ( ) Other chronic obstructive pulmonary disease (J44) 1.33 ( ) 1.19 ( ) * SMR standardized morbidity prevalence ratio; ICD-10 International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; 99% CI 99% confidence interval.

4 Epidemiology of Low Back Pain 1087 was 3.94% (95% CI ), and for men was 3.18% (95% CI ). For every 10,000 adults consulting a physician in 2009, 436 were diagnosed with LBP, 446 per 10,000 women and 424 per 10,000 men. LBP accounted for 13.2% of all consultations with a musculoskeletal or connective tissue (MSK) diagnosis, and of all patients with an MSK diagnosis, 17.1% had received an LBP diagnosis (Figure 1). Rate of first-time consultation. A total of 15,601 individuals were identified as having their first-time consultation for LBP in 2009 (56.9% women). The mean SD age at diagnosis was years ( years for women and years for men). The 2009 first-time consultation rate was 238 per 10,000 adults, 265 for women and 209 for men (Figure 2A). Adjusted to the 2000 US standard population, the figures were 219 per 10,000 persons (95% CI 189 5,249), 242 per 10,000 women (95% CI ), and 196 per 10,000 men (95% CI ). Health care contacts by LBP patients. In 2009, 45.9% of all contacts by patients with LBP were to a physician, 27.9% were to a physiotherapist, 16.2% were to a nurse, 2.4% were to a psychologist, and the remaining contacts (7.5%) were to other health care providers such as audiologists (1%), chiropractors (0.6%), and others. Of all contacts by patients with LBP, 77% were in public care. The proportions were essentially the same among both women and men. The health care utilization ratio was 1.74 (95% CI ) for women and 1.81 (95% CI ) for men, i.e., both female and male LBP patients had almost twice as many consultations as women and men in the general population seeking care standardized for age. The ratios declined by increasing age, reaching a ratio closer to 1 in the oldest men and women (Figure 2B). When studying physician contacts, only the physician health care utilization ratio was 1.50 (95% CI ). The most frequent diagnostic code among the patients with LBP was hypertension (as in the general population). Apart from different pain diagnoses, depressive episodes, anxiety disorders, and dizziness were more frequent in patients with LBP. Also, respiratory tract infections and chronic obstructive pulmonary disease were more frequent (Table 1). Discussion The 2009 consultation prevalence of LBP in Southern Sweden was 3.8% of the adult population. For every 10,000 persons consulting a physician, 436 were diagnosed with LBP. Among all patients consulting with an MSK diagnosis (ICD-10, chapter XIII), 17.1% had been diagnosed with LBP in the same calendar year. First-time consultation for LBP was more frequent among women than men and also more frequent with increasing age. In previous reports, more than 30% of the population has been reported to experience varying degrees of selfreported LBP (2,7,8). However, the pain does not necessarily lead to consultation. Studies on consultation patterns suggest that people with more severe pain seek health care more frequently than others (4 6). Recent research on LBP suggests that elderly persons experience more severe pain (9,10). Our finding that the older population is overrepresented, both in consultation prevalence and rate of first consultation, corroborates these findings and warrants concern in a steadily aging population. It is plausible that many of these LBP diagnoses reflect pain from more specific conditions such as osteoporosis-related vertebral fractures and spinal stenosis. Few studies on LBP consultations or equivalent measures of occurrence have been published. However, our rate of first-time consultations (254 per 10,000 women and 200 per 10,000 men) were lower than figures on new episodes of LBP, i.e., 500 and 300 per 10,000 women and men, respectively, reported from the UK (11). An explanation could be the fact that the former study used a wider definition of LBP. In a more recent study on consultation rate, defined as the number of patients with an LBP consultation of all individuals who consult, Bartholomeeusen et al reported annual consultation estimates of 530 and 499 per 10,000 women and men, respectively (12). These figures are close to ours (446 and 424 per 10,000 women and men, respectively). As could be expected, we found that patients consulting with LBP consumed substantially more health care than the general population. The total excess health care utilization was approximately 2-fold for both women and men. The patients with LBP who consumed the most health care in relative measures were younger patients; the average male LBP patient age years had 2.8 times as many health care contacts compared to the general population in this age category. For both women and men, the health care utilization ratios approached 1 with increasing age, i.e., neither increased nor decreased health care consumption for the oldest patients with LBP, suggesting that other symptoms may become more prevalent and concerning with older age in general. The most notable other common diagnostic code recorded for the patients with LBP included, as expected, specific back pain diagnoses such as intervertebral disc disorders. However, we also noted more frequent diagnostic codes for more generalized pain, e.g., from soft tissues and other sites. Previous data have shown that regional pain such as LBP is a future risk factor for developing generalized pain (13). Further, in accordance with previous studies, we found depression, anxiety, upper and lower respiratory infections (upper only in women), and chronic obstructive pulmonary disease to be more frequently diagnosed in patients with LBP (12,14,15). The strength of our study is the large population-based data set encompassing prospectively collected data on all consultations in all levels of health care within a welldefined geographic area. However, there are also several important limitations to acknowledge. First, our case criterion, i.e., at least 1 of a selected set of ICD-10 diagnoses, means that the individual has to be diagnosed with LBP. The terminology and diagnostic criteria may vary. We chose to only include 5 ICD-10 codes (M54.4 [lumbago with sciatica], M54.5 [low back pain], M54.8 [other dorsalgia], and M54.9 and M54.9P [dorsalgia unspecified]). Different doctors and different clinics may use different

5 1088 Jöudetal diagnostic codes for the same symptoms and diseases. It is also possible that subjects with LBP receive a myalgia diagnosis, in particular if the LBP is linked to musculoskeletal pain elsewhere. This would result in an underestimation of the burden of LBP on the health care system. Second, only diagnoses set by physicians are recorded. Therefore, patients with LBP who have consulted a physiotherapist without consulting a physician are not captured. The proportion of patients only consulting physiotherapists varies locally. Third, although the SHCR includes information on all patients who have used health care, both inpatient and outpatient, the diagnostic codes connected to doctor consultations within private care are not forwarded to the SHCR. However, we have compensated for this in order to not substantially underestimate the consultation prevalence and consultation rate. The present detailed data on consultation patterns warrant concern in an aging population and could also benefit from benchmarking studies between different countries and systems. A larger proportion of women than men consult, and the increase in consultation prevalence with age suggests that structured management plans are highly needed in the daily clinical setting to distinguish potential chronic inflammatory diseases, malignancies, or other serious diseases from the more common and benign conditions. AUTHOR CONTRIBUTIONS All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Ms Jöud had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study conception and design. Jöud, Petersson, Englund. Acquisition of data. Jöud, Petersson. Analysis and interpretation of data. Jöud, Englund. REFERENCES 1. Freburger JK, Holmes GM, Agans RP, Jackman AM, Darter JD, Wallace AS, et al. The rising prevalence of chronic low back pain. Arch Intern Med 2009;169: Hoy D, Brooks P, Blyth F, Buchbinder R. The epidemiology of low back pain. Best Pract Res Clin Rheumatol 2010;24: Rossignol M, Rozenberg S, Leclerc A. Epidemiology of low back pain: what s new? Joint Bone Spine 2009;76: Carey TS, Evans A, Hadler N, Kalsbeek W, McLaughlin C, Fryer J. Care-seeking among individuals with chronic low back pain. Spine 1995;20: Carey TS, Evans AT, Hadler NM, Lieberman G, Kalsbeek WD, Jackman AM, et al. Acute severe low back pain: a populationbased study of prevalence and care-seeking. Spine 1996;21: Cote P, Cassidy JD, Carroll L. The treatment of neck and low back pain: who seeks care? Who goes where? Med Care 2001; 39: Loney PL, Stratford PW. The prevalence of low back pain in adults: a methodological review of the literature. Phys Ther 1999;79: Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to J Spinal Disord 2000;13: Baek SR, Lim JY, Park JH, Lee JJ, Lee SB, Kim KW, et al. Prevalence of musculoskeletal pain in an elderly Korean population: results from the Korean Longitudinal Study on Health and Aging (KLoSHA). Arch Gerontol Geriatr 2010;51: e Dionne CE, Dunn KM, Croft PR. Does back pain prevalence really decrease with increasing age? A systematic review. Age Ageing 2006;35: Jordan K, Kadam U, Hayward R, Porcheret M, Young C, Croft P. Annual consultation prevalence of regional musculoskeletal problems in primary care: an observational study. BMC Musculoskelet Disord 2010;11: Bartholomeeusen S, Van Zundert J, Truyers C, Buntinx F, Paulus D. Higher incidence of common diagnoses in patients with low back pain in primary care. Pain Pract 2012;12: Bergman S, Herrstrom P, Jacobsson LT, Petersson IF. Chronic widespread pain: a three year followup of pain distribution and risk factors. J Rheumatol 2002;29: Reme SE, Tangen T, Moe T, Eriksen HR. Prevalence of psychiatric disorders in sick listed chronic low back pain patients. Eur J Pain 2011;15: Ritzwoller DP, Crounse L, Shetterly S, Rublee D. The association of comorbidities, utilization and costs for patients identified with low back pain. BMC Musculoskelet Disord 2006; 7:72.