Association of Comorbidities in Spondyloarthritis With Poor Function, Work Disability, and Quality of Life: Results From the Assessment of SpondyloArthritis International Society Comorbidities in Spondyloarthritis Study

Abstract

Objective: Comorbidities add to the burden of disease and its complexity, and may prevent the achievement of treat-to-target goals. The objective of this study was to study the relationship between comorbidities and key disease outcomes in spondyloarthritis (SpA), namely function, work ability, and quality of life.

Methods: Patients from the multinational (22 countries), cross-sectional Assessment in SpondyloArthritis international Society (ASAS) Comorbidities in Spondyloarthritis study were included in the analysis, provided they fulfilled the ASAS criteria. Data on comorbidities based on both self- and physician-report were collected through questionnaires and were subsequently used to compute the Rheumatic Disease Comorbidity Index (RDCI). Univariable and multivariable (adjusted for relevant confounders) multilevel (with country as a random effect) linear or logistic (as appropriate) regression analyses were conducted to investigate the relationship between the RDCI and functional ability, work ability, and quality of life.

Results: In total, 3,370 of 3,984 recruited patients (85%) fulfilled the ASAS criteria: 66% were male, mean ± SD age was 43 ± 14 years, mean ± SD disease duration was 8.4 ± 9.5 years, and mean ± SD RDCI was 0.7 ± 1.1. At least 1 comorbidity was reported in 51% of patients; 9% had ≥3 comorbidities. RDCI was independently associated with a higher Bath Ankylosing Spondylitis Functional Index score (β = 0.37, 95% confidence interval [95% CI] 0.30, 0.43), lower EuroQol 5-domain questionnaire (β = -0.03, 95% CI -0.04, -0.02), less work employment (odds ratio [OR] 0.83, 95% CI 0.76, 0.91), higher absenteeism (OR 1.18, 95% CI 1.04, 1.34), and higher presenteeism (OR 1.42, 95% CI 1.26, 1.61).

Conclusion: Comorbidities in SpA adversely influence physical function, work ability, and quality of life and are important to take into account in daily clinical practice.