PsA on advanced therapy: only a quarter reached minimal disease activity at a year

Design

Prospective national register cohort

Population

815 people with psoriatic arthritis starting b/tsDMARD therapy, UK

Primary outcome

Drug discontinuation and 12-month response

Effect

MDA 24%, ACR50 24% at 12 months; PDE4i vs TNFi discontinuation HR 2.25 (1.45–3.50)

The British Society for Rheumatology Psoriatic Arthritis Register followed 815 people starting a biologic or targeted synthetic DMARD, with median disease activity high at baseline.

At a median of 31 months, 65% remained on their first therapy; stopping was mostly for inefficacy (55%) or intolerance (26%). Those starting a PDE4 inhibitor were more than twice as likely to discontinue as those starting a TNF inhibitor (HR 2.25, 95% CI 1.45–3.50); other mechanisms did not differ markedly. At 12 months, 24% had reached minimal disease activity, 24% an ACR50 and 49% a PsARC response. Men, younger patients and those in work were more likely to respond; worse baseline clinical and patient-reported measures predicted non-response.

These real-world response rates are lower than in trials and underline how hard PsA remains to control. The finding on PDE4 inhibition fits its generally more modest effect.

• Set realistic expectations: about one in four reached minimal disease activity at 12 months.
• Consider a TNF inhibitor or another biologic over a PDE4 inhibitor when persistence matters.
• Assess and address high baseline pain, fatigue and function scores, which predicted non-response.
• Review at 3–6 months and switch promptly if targets are not being met.

Why it matters

Trial response rates often set patient expectations that real-world practice does not meet.

Don't overread it

Registry data — demographic predictors are associations and should not guide who is treated.

The statistics, in plain English

A hazard ratio of 2.25 means people on a PDE4 inhibitor stopped at more than twice the rate. Predictors such as sex and employment come from imputed outcomes and are associations, not reasons to withhold treatment.

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