Socioeconomic Status Associated With TNF Inhibitor Treatment Outcomes for RA

A reduced response to treatment with tumor necrosis factor (TNF) inhibitors was observed among patients with rheumatoid arthritis (RA) who are of lower socioeconomic status, according to research published in Rheumatology. 

The intersection of socioeconomic factors and disease outcomes in patients with RA may offer insight into potential areas for intervention among both patients and providers. Researchers aimed to assess the association between socioeconomic status and treatment outcomes among patients with RA receiving TNF inhibitor therapy.

An analysis of 2 prospective studies was conducted using data from the British Society for Rheumatology Biologics Register for RA (BSRBR-RA) and the Biologics in RA Genetics and Genomics Study Syndicate (BRAGGSS) cohort. Both studies were designed to analyze disease activity using the 28-joint disease activity score (DAS28), low disease activity (LDA) score, and the European League Against Rheumatism (EULAR) response (good, moderate, no response). Disease activity was stratified by baseline demographics and comorbidities. Participants from each study were excluded if they had received prior treatment with a TNF inhibitor.

The primary outcome of interest was the Index of Multiple Deprivation (IMD), a composite weighted-score that measures relative socioeconomic deprivation across multiple domains (income, employment, health deprivation, disability, education, skills and training, crime, barriers to housing and services, and living environment).

The researchers assigned IMD scores to participants in both studies at baseline; analyses were performed in quintiles, using quintile 1 (top 20% most deprived), 2 and 3 (middle 40%), 4 and 5 (40% least deprived).

Of 15,830 participants analyzed in the BSRBR-RA study, 6-month DAS28 scores were 0.30 units higher among patients with IMD scores in quintile 1 and 0.17 units higher among those with scores in quintiles 2 and 3. Logistic regression models revealed that patients with IMD scores in quintile 1 had 24% lower odds of achieving LDA (95% CI, 0.68-0.84) and 11% lower odds of achieving remission (95% CI, 0.81-0.98).

Additionally, compared with IMD scores in quintiles 4 and 5, IMD scores in quintile 1 (hazard ratio [HR], 1.18; 95% CI, 1.12-1.25) and quintiles 2 and 3 (HR, 1.07; 95% CI, 1.03-1.12) were associated with increased risk for all-cause treatment discontinuation.

Participants from the BRAGGSS study (n=3459) had similar results. Increasing deprivation was associated with a 0.23-unit higher DAS28 score at 3 months, when compared with IMD scores in quintiles 4 and 5 (95% CI, 0.11-0.36). Adjusted estimates also revealed that patients with IMD scores in quintile 1 had lower odds of achieving LDA (odds ratio, 0.77; 95% CI, 0.63-0.94).

This study was limited by its reliance on IMD scores, as they relate to a geographic rather than individual-level index. Additionally, treatment outcomes of other drugs may potentially offer contrasting data.

With evidence suggesting socioeconomic deprivation is associated with a reduced response to TNF inhibitors, as well as increased risk for treatment discontinuation, the researchers concluded, “Improvements in determinants of health other than lifestyle factors are needed to address socioeconomic inequities.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.