Prevalence, physical activity and work in patients with spondyloarthritis

Sammanfattning: Spondyloarthritis (SpA) is a group of interrelated inflammatory rheumatic diseases with the sub-diagnoses ankylosing spondylitis (AS), psoriatic arthritis (PsA), arthritis-associated inflammatory bowel disease (Aa-IBD), undifferentiated SpA (USpA), where stiffness and pain are key symptoms. Insidious onset back pain, morning stiffness, waking up at night, and improvement from exercise are common characteristics. The disease is life-long, often with early onset, and can cause limitations in physical function, affecting the ability to work, and has a negative effect on health-related quality of life. The overall aim of the present work was to describe the prevalence of SpA and to study the consequences for the individual and society regarding physical activity and work in a population-based cohort of patients seeking health care. The studies are based on a cohort of patients with SpA, identified through the Skåne Health Care Register by searching for 12 ICD-10 codes for SpA that had led to a doctor’s consultation 2003–2007. Two questionnaire surveys in 2009 and 2011 were sent to all the patients in the cohort >18 years and data from these formed the basis of the studies II, III, and IV. Study I: The estimation of SpA prevalence based on almost 4,000 patients was 0.45% in adults (≥ 15 years), and equally common in women and men. The prevalence in different subgroups was 0.12% in AS, 0.25% in PsA, 0.0015% in Aa-IBD, and 0.10% in USpA. Study II dealt with the proportion of patients who met the WHO recommendations for physical activity. Seven out of ten patients with SpA met the recommendations, more frequently in women than in men, and with a somewhat higher proportion in the SpAScania cohort than in the general Swedish population. Studies III and IV examined the patterns of reduced productivity at work both cross-sectionally and longitudinally. Just under half of the patients with SpA reported reduced productivity at work, and more reduction was reported in women than in men. Reduced productivity at work was associated with, and could be predicted from several patient-reported outcome measures (PROMs) such as reduced health-related quality of life (HRQoL), higher disease activity, lower physical function, lower self-efficacy, worse mental health and low education level. To conclude, 45 individuals out of 10,000 have a diagnosis of SpA, and affected individuals report significant consequences of the disease. The findings presented in this thesis could help clinicians to identify patients at an early stage at risk of a worse prognosis using simple clinical questions in routine practice, and tailor the activities, treatment, and care for patients with SpA.