Older Age Affects Initial Dosage of MTX Among Patients With RA

March 5, 2021
Larry Hanover

Elderly onset rheumatoid arthritis (RA) can be brought under control with a lower methotrexate (MTX) dosage than that required for young-onset disease.

A new study has found that bringing elderly onset rheumatoid arthritis (EORA) under control can be accomplished with a lower dosage of methotrexate (MTX) than that required for young-onset disease. It also found a much lower rate of biologic use—biologics are genetically engineered proteins that target specific parts of the immune system more efficiently than MTX—to achieve low-disease activity (LDA) among patients with EORA than for those with young-onset rheumatoid arthritis (YORA).

The research, published in Modern Rheumatology, was based on a survey of patients at a hospital in Japan. There were 70 patients with EORA and 190 with YORA in the study who achieved LDA. The authors considered LDA a more appropriate goal than remission for those with elderly onset disease due to the adverse effects typically experienced by those taking the medications used in the study.

The authors said they pursued the research because the rapid development of new RA therapies, such as biological disease-modifying antirheumatic drugs, and increased life expectancy have prompted more elderly patients to seek treatment. EORA is defined as RA that develops after age 60.

The MTX dose to control the disease for patients with EORA was significantly lower than for patients who had YORA (2.89 vs 4.09 mg/week: P = .011), they found. Overall biologics use was lower for patients with EORA as well (32.9% vs 56.3%: P = .0012).

In addition, the patients with EORA had a greater frequency of hypertension and diabetes than the patients with YORA. The results suggest that clinicians’ reasons for reducing the amount of MTX might be more heavily influenced by comorbidities than efforts to control the RA. The authors said these findings need further study due to the small sample size.

Tumor necrosis factor inhibitors were the most used biologics in both patient groups. Etanercept (Enbrel) was most often the first biologic drug administered in both groups (48.1% for EORA, 44.2% for YORA). For subsequent biologics, abatacept (Orencia) was the drug most used in the EORA group (21.3%) and tocilizumab (Actemra) was the most used in the YORA group (27.6%).

The authors said studying the characteristics of EORA is complicated by how comorbidities are handled in drug trials. Some patients with EORA typically are excluded from randomized controlled trials because of comorbidities or health-related problems. Further confounding comparisons is that the effectiveness of disease-modifying antirheumatic drugs, including tumor necrosis factor inhibitors and MTX, appeared different in clinical practice than in trials due to variation in age, treatment protocols, and other factors. These issues made a cohort study to evaluate EORA characteristics necessary.

The average ages of the groups were 73.8 years for patients with EORA vs 57.8 years for patients with YORA. Disease duration was 6.66 vs 14.7 years, respectively, and the share of female patients was 62.9% and 83.7%. It is widely known that women are 3 times more likely to be stricken by RA than men.

Reference

Kumagai K, Okumura N, Amano Y, et al. Consideration of differences in drug usage between young-onset and elderly-onset rheumatoid arthritis with target of low disease activity. Mod Rheumatol. Published online February 22, 2021. doi:10.1080/14397595.2021.1883251