Low Body Mass Index Increases Risk for Premature Death in Rheumatoid Arthritis Patients

For rheumatoid arthritis (RA) patients, losing weight may increase the risk for premature death, according to research published in Arthritis & Rheumatology.

Researchers from the Hospital of the University of Pennsylvania sampled 1,674 RA patients in order to assess whether weight loss may explain the paradoxical observations between body mass index (BMI) and mortality in this patient population. The patients were identified using the Veterans Affairs (VA) RA Registry.

The researchers tracked BMI at each study visit and analyzed the changes noted from the previous visit. Additionally, the researchers were able to obtain the maximum BMI of each patient from the medical records observed. The researchers analyzed the annualized rate of BMI loss, and determined the changes per year based on BMI numbers from visits in the prior 13 months.

The researchers then identified 312 deaths from VA electronic medical records encompassing 9,183 person years. Losing ≥ 1 kg/ m² in BMI was linked to a greater risk of death, the researchers found. This risk was similarly found after the researchers had adjusted for demographics, comorbidities, BMI, smoking, and RA therapies.

“Weight loss is a strong predictor of death in patients with RA,” the authors concluded in the paper. “These observations may explain the observed obesity paradox and do not support a biologically protective role of obesity.” The “obesity paradox” the researchers referenced is the opposing ideas that a lot BMI is associated with an accelerated mortality in RA patients, perplexing researchers.

The researchers added that the association between losing ≥ 1 kg/ m² in BMI and risk of death was significant in another sample used in the analysis, which had adjusted for C reactive protein and physical function.

The greatest risk of death was found in patients who lost ≥ 3 kg/ m² in BMI at an annualized rate, the researchers determined. A low BMI (defined as < 20 kg/ m² by the researchers) in patients with a history of obesity (defined as > 30 kg/ m²) was associated with the highest risk of premature death in this patient population.