Diagnostic delay and less intensive therapy for people with psoriatic arthritis compared with rheumatoid arthritis: a study nested within an English and Welsh audit data set

This study aimed to compare time to diagnosis among patients with psoriatic arthritis (PsA) with that of patients with rheumatoid arthritis (RA) and compare initial treatment and outcomes. Patients with PsA were identified from the National Early Inflammatory Arthritis Audit between May 2018 and October 31, 2019, and matched to patients with RA (1:1) on age and sex. Patient characteristics and time to diagnosis were compared between PsA and RA groups. Further comparisons were made, restricted to matched pairs of patients with polyarticular PsA, including disease activity, disease impact, and treatment initiation. In total, 2120 patients with PsA were matched to patients with RA, of which 1250 had polyarticular disease. Symptom duration before referral was longer in patients with PsA than that in patients with RA. Patients with PsA had a longer time from general practitioner (GP) presentation to diagnosis (mean, 112 v 89 days; hazard ratio [HR], 0.87; 95% CI, 0.79-0.96; P = .007), including a delay in diagnosis once referrals were received in secondary care (HR, 0.86; 95% CI, 0.80-0.95; P = .002). In patients with polyarticular disease, less disease-modifying antirheumatic drugs (DMARDs) were prescribed at baseline to patients with PsA compared with those to patients with RA (54.0% and 69.0%, respectively; P < .001). Patients with RA had a higher Disease Activity Score in 28 joints at baseline, but by 3 months, the average score was 0.27 (95% CI, 0.13-0.4) higher in patients with PsA. Compared with patients with RA, patients with PsA have a longer duration of symptoms before referral and a longer interval between presentation to the GP and receiving a diagnosis. Most people agreed a treat-to-target strategy but fewer DMARDs were commenced for patients with PsA than those for patients with RA and a lower improvement in disease activity was achieved at 3 months, suggesting undertreatment.