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Expected pharmacological effect
Causality assessment · Expected pharmacological effect
Methotrexate and Pancytopenia: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Methotrexate ↔ Pancytopenia
n=5,955 co-reports · PRR 5.9 · ROR 6.0
Methotrexate is a folate antagonist that can cause marrow suppression with pancytopenia, especially with renal impairment, low folate, or high-dose regimens; 5,955 co-reports give PRR 5.9. The label advises blood-count monitoring and folate supplementation.
Regulatory basis: methotrexate prescribing information — myelosuppression/pancytopenia; blood-count monitoring and folate.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Days to weeks |
| Strength | met | PRR 5.9 with 5,955 co-reports |
| Consistency | met | Consistent across cohorts |
| Specificity | not established | Cytopenias have many causes |
| Biological gradient | met | Dose and folate-dependent |
| Plausibility | met | Known antifolate mechanism |
| Coherence | met | Fits methotrexate myelosuppression |
| Experiment | n/a | Often coded in trials |
| Analogy | met | Analogous to other antifolate toxicity |
This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for methotrexate captured pancytopenia as a tracked adverse event in a usable structure. Cytopenias are monitored but co-reported against the underlying disease and concomitant therapy.