Association between an ability to work and disease activity in patients with axial psoriatic arthritis

Objective: to assess the association between an ability to work (AW) and disease activity in patients with psoriatic arthritis (PsA) combined with spinal involvement. Material and methods. The study included 114 patients with PsA (50.8% men and 49.2% women) who met the 2006 CASPAR criteria (ClASsification criteria for Psoriatic ARthritis) and had spinal involvement confirmed by imaging of axial structures (syndesmophytes and/or radiographically definite sacroiliitis (SI) and/or active SI on magnetic resonance imaging). The mean age of the patients was 46.1±11.6 years; PsA duration was 48.6±41.5 months, psoriasis duration – 197.9±159.7 months, and chronic back pain duration – 67.5±63 months. All patients underwent a standard rheumatologic assessment, including tender and swollen joint counts (TJC/68 and SJC/66, respectively), physician/patient global assessment of health (PhGA/PtGA), and assessment of pain intensity using a visual analog scale; night back pain (NBP) using a numeric rating scale; blood CRP level; and the activity indices BASDAI (Bath Ankylosing Spondylitis Disease Activity Index), DAPSA (Disease Activity in Psoriatic Arthritis), and ASDAS (Ankylosing Spondylitis Disease Activity Score). AW was assessed using the WPAI-SHP (Work Productivity and Activity Impairment; Specific Heath Problem) questionnaire on the scales of absenteeism, presenteeism, overall work productivity loss (OWPL), and activity impairment (AI). Additionally, the proportion of patients (%) with an overall reduction in AW across all scales >50% (ORAW50) was evaluated. Results and discussion. Absenteeism, presenteeism, OWPL, and AI were identified in 44.6%, 49.7%, 55.6%, and 43.1% of patients, respectively. ORAW50 was observed in 57.8% (66 of 114) of patients. A significant positive correlation was found between impaired AW across all WPAI scales (p<0.05) and female sex and PsA activity: SJC66 >5, DAPSA ≥14, ASDAS ≥2.1, and BASDAI ≥4. Factors contributing to ORAW50 were identified: presence of ≥1 enthesitis (odds ratio (OR) 1.72; 95% confidence interval (CI) 0.745–3.714), DAPSA ≥14 (OR 1.814; 95% CI 0.486–6.158), ASDAS ≥2.1 (OR 1.296; 95% CI 0.6877–2.444), for all cases p<0.05. In patients with high ASDAS activity, impairment was noted on all WPAI scales except OWPL. DAPSA activity affected absenteeism (p=0.04) and AI (p=0.01). High BASDAI activity statistically significantly worsened all WPAI outcomes. Separately, factors associated with impaired AW and high ASDAS activity were identified: inflammatory back pain (IBP; OR 5.285; 95% CI 0.373–6.836), enthesitis by the LEI index ≥1 (OR 2.268; 95% CI 0.479–10.733), and SJC >5 (OR 1.037; 95% CI 0.243–4.418). Impaired AW with high DAPSA activity was associated with significant factors such as SJC >5 (OR 1.145; 95% CI 0.27–4.85), TJC >5 (OR 1.789; 95% CI 0.405–7.905), presence of enthesitis by LEI ≥1 (OR 2.683; 95% CI 0.633–11.377), and CRP >5 mg/L (OR 1.007; 95% CI 0.978–1.036). Impaired AW and high BASDAI activity were associated with TJC >5 (OR 1.489; 95% CI 0.322–6.895), presence of enthesitis by LEI ≥1 (OR 2.33; 95% CI 0.524–10.363), IBP (OR 20.11; 95% CI 11.128–36.45), and NBP (OR 1.435; 95% CI 0.344–5.984). Conclusion. In half of patients with PsA and spinal involvement, predominantly women, reduced AW was found on the absenteeism, presenteeism, OWPL, and AI scales, which was associated with high activity of spondylitis and peripheral arthritis. The use of biologic disease-modifying agents makes it possible to reduce PsA activity and improve patients’ AW, which may have major socio-economic significance.