Effects of overweight and underweight on the treatment outcomes of rheumatoid arthritis patients treated with biological drugs: A retrospective observational descriptive study.

The effects of the body size condition (overweight and underweight) on the outcome of antirheumatic drugs are unclear. The aim of this study was to elucidate the relationship between body size and treatment outcomes in rheumatoid arthritis patients treated with biological antirheumatic drugs.A retrospective observational descriptive study was conducted at Tokyo Women's Medical University, Medical Center East, from June 2015 to May 2018. Primary and secondary outcomes were defined as antirheumatic treatment ineffectiveness and antirheumatic treatment discontinuation due to any side effects, respectively. Multivariate logistic regression analysis was used to determine the risk factors for the outcomes and to calculate the odds ratio (OR) and the 95% confidence interval (95% CI).

A total of 297 patients were included. Primary and secondary outcomes were observed in 42 (14%) and 11 (4%) of the patients, respectively. Multivariate logistic regression analysis demonstrated that a body mass index (BMI) ≥25 kg/m² (OR = 4.22, 95% CI; 1.69-10.5, P = .002) was associated with rheumatoid arthritis treatment ineffectiveness and that BMI <18.5 kg/m² (OR = 5.87, 95% CI; 1.25-27.5, P = .025) and tacrolimus use (OR = 9.06, 95% CI; 1.37-60.1, P = .022) were associated with antirheumatic treatment discontinuation due to any side effects. The cut-off dose for tacrolimus was 0.5 mg/day.

Overweight affects antirheumatic drug efficacy. Underweight and tacrolimus use increased the discontinuation of antirheumatic drugs due to side effects. A validation study is needed to confirm the reliability of these results.