Work Productivity and Costs Related to Patients with Ankylosing Spondylitis, Rheumatoid Arthritis, and Psoriasis

Abstract

Objectives: To determine and compare the impact of rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriasis on work productivity, to calculate the productivity costs (PC), and to map out factors that influence (functional status and disease activity) work productivity.

Methods: The Work Productivity and Activity Impairment questionnaire was used to evaluate productivity losses of patients with RA (n = 77), AS (n = 230), and psoriasis (n = 93). Demographic data, patient-reported outcomes (PROs) (Health Assessment Questionnaire [HAQ] and Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]), and clinical parameters (Disease Activity Score in 28 joints [DAS28], body surface area [BSA], and Psoriasis Area and Severity Index [PASI]) were collected. The correlations among PROs, clinical parameters, and overall productivity loss were examined, and multiple regression models were used to examine relationships among parameters and productivity loss. PC were calculated using the friction cost approach.

Results: Mean patient age and disease duration were 47.1 and 15.7 years, respectively. The mean HAQ and DAS28 in patients with RA were 1.22 and 5.6, respectively. The mean BASDAI score in patients with AS was 4.43. The mean BSA and PASI score in patients with psoriasis were 21.1% and 12.9, respectively. The percentage of patients with psoriatic arthritis (in those with psoriasis) was 24.7%. We did not find significant differences in Work Productivity and Activity Impairment domains among various diagnoses. Patients with AS, RA, and psoriasis reported overall work productivity losses of 40.9%, 42.9%, and 42.8%, respectively. Daily activity impairments were approximately 50.0%. Overall work productivity loss strongly correlated with PROs, whereas correlations with clinical parameters were weak. The HAQ and BASDAI were identified as major predictors of productivity impairment.

Conclusions: The greatest loss in productivity was in those with psoriatic arthritis; however, it was not significant. In contrast to clinical parameters (DAS28, BSA, and PASI score), PROs (HAQ and BASDAI score) significantly influence loss of productivity. The average annual lost PC per patient was estimated to be €2000.

Keywords: WPAI; ankylosing spondylitis; productivity costs; psoriasis; psoriatic arthritis; rheumatoid arthritis; work productivity.