Relationships of Work Productivity and Activity Impairment With Patient-Reported Outcomes in Ankylosing Spondylitis: Results From Two Trials

Objective: We examined the relationships of work productivity and activity impairment with key patient-reported outcomes (PROs) assessing pain, disease activity, and health-related quality of life (HRQoL) in patients with ankylosing spondylitis (AS). Methods: This post hoc analysis pooled available data from baseline to end of the double-blind phase of phase 2 and 3 placebo-controlled tofacitinib trials in patients with active AS. A repeated-measures longitudinal model assessed the relationships (linear or nonlinear) between Work Productivity and Activity Impairment questionnaire in Spondyloarthritis (WPAI:SpA) domains (absenteeism, activity impairment, presenteeism, and productivity loss) as outcomes and key PROs (total back pain, nocturnal spinal pain, Patient Global Assessment of Disease Activity, AS Quality of Life, EuroQol 5-Dimension 3-Level [EQ-5D-3L], and EQ-5D Visual Analog Scale [EQ-5D-VAS]) as predictors. Results: Data from 330 to 475 patients were available, depending on the analysis. Relationships between WPAI:SpA domains and PROs were approximately linear. The worst PRO scores were associated with a decline in patients’ work capacity (measured by activity impairment, presenteeism, and productivity loss [>65%]); the best scores were associated with improvements in WPAI:SpA domains (8%–23%). Incremental PRO improvements were associated with improvement of activity impairment, presenteeism, and productivity loss. Relationships between absenteeism and PROs were the weakest, owing to absenteeism being low in the study population. Conclusion: Evidence of linear relationships between work productivity and activity impairment with patient-reported pain, disease activity, and HRQoL was observed. Interventions to control pain and disease activity and improve HRQoL are therefore likely to improve work productivity and reduce activity impairment in patients with AS.