The outcomes of many clinical trials involving the use of biologics in rheumatoid arthritis could be skewed because they overlook the socio-economic status of patients, researchers say.

Writing in a letter published in Rheumatology the team of researchers led by Dr Helen Benham from the University of Queensland said it was well known that lower socio-economic status (SES) was associated with an increased risk of developing RA and with poorer patient outcomes.

“SES is an important potential confounder in RA clinical trials and may impact both the clinical outcomes and generalizability of the findings,” they wrote.

Their review of 100 recent consecutive RA bDMARD RCTs published in leading general medicine (n=28) and rheumatology (n=72) journals found that direct SES measures of employment status, income and educational attainment were recorded in 2%, 2% and 1% of the studies, respectively.

Indirect measure of SES such as ethnicity was reported in just over half of the trials (54%), while smoking and weight/BMI were measured in just 4% and 36% of the trials.

“Although further research is required to examine the relationships between SES and RA outcomes, we suggest that increased reporting of SES in RA bDMARD clinical trials would improve the capacity of clinicians to assess the applicability of trial results in everyday clinical practice,” the study authors concluded.