A recent study has found that Psoriatic Arthritis (PsA) patients in the United Kingdom are equally included across all socioeconomic levels, suggesting minimal recruitment bias and consistent timing from diagnosis to the initiation of biologic disease-modifying antirheumatic drug (bDMARD) therapy.
Study Overview
The study, led by Max Lyon from the Centre for Musculoskeletal Research at the University of Manchester, is part of the Outcomes of Treatment in Psoriatic Arthritis Study Syndicate (OUTPASS) trial. The research aimed to investigate the relationship between deprivation and health outcomes in PsA patients.
“Interestingly, higher levels of education, a key determinant of deprivation, are associated with a lower incidence of PsA, but the association with treatment response has not yet been explored,” Lyon and colleagues noted. “We aimed to assess the impact of deprivation on access to biologic treatment and the clinical response to these medications.”
Methods
The OUTPASS trial is a nationally representative, observational, and prospective study. It evaluated UK patients diagnosed with PsA who began treatment with either targeted bDMARDs or synthetic DMARDs. Patients’ baseline assessments occurred before starting bDMARD therapy, followed by evaluations at 3, 6, and 12 months.
The study measured patient global visual analogue scale scores, joint counts (28 and 66/68 swollen and tender joints), physician assessments, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels, and patient global assessments.
Researchers used the Index of Multiple Deprivation (IMD) to assess patients’ deprivation levels. The IMD ranks small regions within England from 1 (most deprived) to 32,844 (least deprived). Patients were stratified into three deprivation cohorts.
Results
The study found no significant differences in the time from diagnosis to the initiation of biologic treatment across socioeconomic groups. For the most deprived 20%, middle 40%, and least deprived 40%, the variations were minimal:
- Most deprived 20% vs. middle 40%: β = −0.52 (95% CI −2.60, 1.55), P = .62
- Most deprived 20% vs. least deprived 40%: β = 0.86 (−1.23, 2.94), P = .42
Therapeutic responses, as measured by changes in the Disease Activity Score in 28 joints (DAS28) and the Psoriatic Arthritis Response Criteria (PsARC), also showed no substantial differences:
Changes in DAS28:
- Most deprived: β = −.091 (95% CI −.48, .29), P = .64
- Middle 40%: β = −.048 (95% CI −.43, .33), P = .80
PsARC shifts over 3 months:
- Most deprived vs. middle: OR 1.86 (95% CI .92, 3.73), P = .082
- Most deprived vs. least: OR 1.53 (95% CI .77, 3.02), P = .22
Conclusion
The findings indicate that socioeconomic deprivation does not significantly impact PsA patients’ access to biologic treatment or their response to therapy within the UK’s healthcare system. The study highlights the role of the UK’s health service, which provides care based on need and free at the point of delivery, in mitigating socioeconomic disparities.
However, the researchers caution that these results might not be applicable to other healthcare systems where deprivation could affect access to healthcare. They also noted the need for further data due to the study’s relatively small sample size and the lack of certain variables.
“This study assesses the impact of deprivation in a context where care is provided based on need and free at the point of delivery,” the researchers concluded. “This cannot be applied to healthcare systems where deprivation may impact access to healthcare.”
