The Societal and Patient-Level Burden of Sickness Absenteeism in Patients with Rheumatoid Arthritis, Psoriatic Arthritis and Ankylosing Spondylitis Across Two Decades in Slovenia.

Introduction: To analyse the long-term dynamics of the burden of sickness absenteeism (SA) at the societal and patient levels in employed patients with selected inflammatory rheumatic diseases (IRDs). Methods: The burden of SA was analysed over 2 decades prior to the COVID-19 pandemic, with a focus on the subperiod following the introduction of the rheumatology clinical registry biorx.si. Population data for full-time employees on sick leave due to rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) were obtained from the national administrative database. The societal burden of SA was defined as the total annual number of calendar days on sick leave. The patient-level burden of SA was defined as the average annual number of days on sick leave per patient which was further disaggregated into the average annual number of sick leave episodes per patient and the average annual number of days per sick leave episode. The costs of SA were estimated using the human capital approach. An exponential trend method was used for analysis, and time series were tested for structural breaks. Results: The societal burden of SA during the subperiod following the registry introduction decreased, on average, by 3.3% annually among RA patients. The average annual increase in the societal burden of SA was marginal for PsA patients (0.4%) and substantial for AS patients (8.7%). The societal and patient-level burdens of SA varied by sex and job sector. The patient-level burden of SA, however, decreased on average by 2.5% annually for RA patients and increased marginally for both PsA and AS patients. The key pattern suggesting potential improvements in the patient-level burden of SA for the analysed IRDs was an increase in the number of sick leave episodes per patient, offset by shorter episode duration. Conclusions: A study of the societal burden of SA, including its components, and the patient-level burden of SA can support the development of more effective strategies for managing SA and facilitating a faster return to work.