Metformin adherence tied to reduced risk of developing rheumatoid arthritis

Takeaway

• Adherence to metformin treatment is associated with a significant reduction in the risk of developing rheumatoid arthritis (RA), particularly in women with type 2 diabetes mellitus (T2DM).

Why this matters

• Findings warrant further studies to determine the effects of metformin on RA development in other patients.

Study design

• A retrospective cohort study of 113 749 patients with T2DM who initiated metformin therapy between 1998 and 2014.
• Adherence assessed by calculating the mean proportion of follow-up days covered (PDC) with metformin.
• Funding: Pfizer, AbbVie, and Janssen.

Key results

• During the follow-up period, 558 patients had incident RA (crude incidence rate, 61/100 000 person-years).
• Adherence to metformin treatment was associated with a lower risk of developing RA in patients with PDC of 40–59% vs those with PDC < 20% (adjusted HR [aHR], 0.62, 95% CI, 0.45-0.84).
• Patients who received a mean daily metformin dose of ≥2550 mg were at lower risk of developing RA vs those who received 850 mg or lower dose (aHR, 0.62; 95% CI, 0.46-0.84).
• In stratified analyses by gender, a negative association was observed between metformin adherence and the risk of RA which was limited to women alone.

Limitations

• Possibility of misdiagnosis.