Impact of Six‐Month Monitoring Compared to Three‐Month Monitoring of Laboratories During Methotrexate Therapy
Authors' conclusion
Extending routine MTX monitoring from every three months to every six months was not associated with more severe abnormalities or delayed detection of toxicity
Study context
- Population
- Patients receiving methotrexate (MTX) with at least two measurements of ALT, AST, white blood cell (WBC), hematocrit (HCT), mean corpuscular volume (MCV) and/or platelet (PLT)
- Participants
- 2,439 patients14,199 laboratory encounters
- Exposure
- MTX laboratory monitoring every 6 months vs every 3 months
- Outcome
- Incident clinically relevant laboratory abnormalities (timely detection of MTX-related toxicity)
Methodological detailsobservational, propensity-score matched
- Observational
- Propensity-score matched
Main finding
As reported in the abstract
Incident abnormal results
Six-month vs Three-monthOdds ratio (95% CI)
ALT >1× upper limit of normal
0.72(0.52–0.99)
MCV >100 fL
0.67(0.46–0.96)
- Six-month equally or less likely to develop incident abnormal results; most odds ratios (ORs) not statistically significant
- P > 0.05
Observational data: associations, not effects.
Further findings
Correlation of testing frequency with changes in ALT, AST, WBC, HCT, MCV, PLT, FIB-4
- No meaningful correlation (all R2 < 0.01)
Mean laboratory changes
- Did not differ meaningfully between monitoring intervals
Original publication
Impact of Six‐Month Monitoring Compared to Three‐Month Monitoring of Laboratories During Methotrexate Therapy. Arthritis Care Res (Hoboken). Published 22 July 2026. doi:10.
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