Ann Intern Med

Few surprises in long-term lab tests for RA treatments

September 1, 2025

Study details: This retrospective cohort study analyzed 59,555 long-term routine laboratory toxicity monitoring test sets from 4,774 patients with rheumatoid arthritis (RA) treated with disease-modifying antirheumatic drugs (DMARDs) across 18,383 patient-years in the Netherlands. Patients had been on DMARDs for ≥6 months, and tests included ALT, eGFR, hemoglobin, leukocyte count, and platelet count. The study aimed to quantify abnormal and very abnormal results and assess their clinical relevance.

Results: Very abnormal lab results were rare (<1%), with cumulative 5-year incidence ranging from 0.3% (leukocyte count) to 11% (eGFR). Nearly half of these were already known or suspected, and 24% were unrelated to DMARDs. Only 449 tests revealed new, very abnormal findings. Most abnormal results occurred after a dose increase (6.5%), were often already known or suspected (47.7%), were considered to be unrelated to DMARD use (24.1%), or didn’t lead to action (35.8%).

Clinical impact: These findings challenge the utility of frequent long-term lab monitoring for all RA patients on DMARDs. Authors suggest reconsidering such monitoring practices to reduce unnecessary testing and healthcare burden.

Source:

Ulijn E, et al. (2025, August 26). Ann Intern Med. Long-Term Routine Laboratory Toxicity Monitoring of Immunomodulatory Drugs in Rheumatoid Arthritis: A Retrospective Cohort Study. https://pubmed.ncbi.nlm.nih.gov/40854212/