To investigate the response to biologic drugs in psoriatic arthritis and to quantify non-response and outcome from switching agents.
60 patients (33 men and 27 women, mean age 46 years, median disease duration 16 years) prescribed biologic drugs for psoriatic arthritis between 2001 and 2006 were studied. Response was evaluated using joint counts, C-reactive protein levels and disease activity scores (using 28 joints; DAS28).
The mean percentage improvements seen were 56% in tender joint count, 70% in swollen joint count, 64% in C-reactive protein level and 36% in the overall disease activity score. Improvements were sustained beyond 24 months with no loss of effect. Side-effects leading to cessation or switching of first-line therapy were only seen in 5% of patients and non-response occurred in 20% long term. Overall, 90% of patients achieved a significant response, using switching in 20% of cases. Outcomes were similar regardless of drug used, duration of disease and subtype of arthritis.
Treatment of active psoriatic arthritis with anti-tumour necrosis factor agents leads to a sustained response over 3 years with most patients tolerating these drugs well. The rate of non-response is low with the majority of patients responding to second- and third-line therapies.