Background Spondyloarthritis (SpA) impacts on several aspects of affected individuals' lives and restricts patients' ability to participate in society. After diagnosis is set, a period follows during which treatment regimens are adjusted to fit the individual patient's needs. Better patient functioning is often obtained if treatment is successful or if the natural course of the disease is favorable. This might be reflected by reduced sickness absence over time following diagnosis.
Patients with different subgroups of SpA report different impact of the disease on self-reported functioning and participation. Thus, different trends in the subgroup-specific sickness-absence patterns might be present over the years following diagnosis.
Objectives The aim was to assess whether the trends in the amount of sickness absence during the ten-year period following a SpA diagnosis differed between well-defined cohorts of patients with ankylosing spondylitis (AS), psoriatic arthritis (PsA) and undifferentiated spondyloarthritis (USpA).
Methods Patients with AS, PsA or USpA were identified through the Skåne Healthcare Register, covering a population of 1.3 million in southern Sweden. First year of diagnosis by a physician between 2003 and 2007 was set as the inclusion year. Information on sickness absence (sick leave and disability pension) during the years following diagnosis up until 2012 was obtained from the Swedish Social Insurance Agency. Years when the patient was between 18 and 67 years of age, resident in the Skåne region and alive by December 31st were considered valid for inclusion. The average number of full days of sickness absence per patient and year following diagnosis was calculated for each cohort. The results were standardized according to the sex and age distribution of all identified SpA patients. Linear regression on the aggregated data was used to test for differences in trends between the cohorts.
Results The cohorts included 12 476, 18 542 and 6360 person-years from 2408, 3388, and 1251 patients diagnosed with AS, PsA and USpA, respectively. In the USpA cohort, the average number of full days of sickness absence per patient was reduced by 14% during the ten years following diagnosis (Figure). Assuming linear trends, the reduction in average number of full days of sickness absence in the USpA cohort was 1.7 per year following diagnosis (p<0.001) whereas no marked changes occurred in the AS and PsA cohorts.
Conclusions A decrease in the average number of days of sickness absence occurred among USpA patients during the ten-year period following diagnosis. This suggests that USpA patients regained some of their physical function after diagnosis, likely as the result of successful treatment regimens or a favourable natural course of the disease. No improvement as regards sickness absence was observed in AS and PsA patients.
Disclosure of Interest None declared