Spondyloarthritis & psoriatic arthritis
Global Recruiting Patterns and Placebo Response Rates in Clinical Trials of Psoriatic Arthritis and Plaque Psoriasis
Authors' conclusion
The global expansion of trial recruitment to less affluent countries may increase placebo rates in studies of psoriatic arthritis and plaque psoriasis.
Study context
- Population
- Patients in placebo-arm RCTs of biologic and targeted synthetic therapeutics in PsA (52% ± 5.7% female) and plaque psoriasis (32% ± 7.1% female)51 PsA and 43 psoriasis trials
- Participants
- 6,843 vs 5,671
- Comparison
- PsA trials vs Plaque psoriasis trials
- PsA trialsn = 6,843
- Plaque psoriasis trialsn = 5,671
- Primary endpoint
- Association of average per capita GNI (proxy of global recruitment patterns) with placebo response rates on the primary endpoints
Methodological detailslinear mixed models, gross national income (GNI) weighted for recruiting study centres per country
- Linear mixed models
- GNI weighted for recruiting study centres per country
Primary result
As reported in the abstract
Placebo response rate vs GNI (β per 10,000 international dollars)
Β (ACR20 placebo response per 10,000 international dollars GNI)
−5.7 %
95% CI −7.8% to −3.5%P < 0.001
PsA trials
Β (PASI 75 placebo response)
−1.1 %
95% CI −2.0 to −0.3P = 0.011
Plaque psoriasis trials
Further findings
Sensitivity analyses (other outcome measures; UN Human Development Index, WHO out-of-pocket health expenditures)
- Confirmatory
Original publication
Global Recruiting Patterns and Placebo Response Rates in Clinical Trials of Psoriatic Arthritis and Plaque Psoriasis. Arthritis Rheumatol. Published 23 September 2025. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →