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Expected pharmacological effect
Causality assessment · Expected pharmacological effect
Azathioprine 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.
Azathioprine ↔ Pancytopenia
n=1,126 co-reports · PRR 4.9 · ROR 5.0
Azathioprine suppresses the marrow, and pancytopenia is a recognised toxicity, greatly amplified in thiopurine-methyltransferase deficiency; 1,126 co-reports give PRR 4.9. The label advises blood-count monitoring and thiopurine-enzyme awareness.
Regulatory basis: azathioprine prescribing information — myelosuppression/pancytopenia; blood-count monitoring and TPMT caution.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Weeks of therapy |
| Strength | met | PRR 4.9 with 1,126 co-reports |
| Consistency | met | Consistent across cohorts |
| Specificity | not established | Cytopenias have many causes |
| Biological gradient | met | Metabolism/TPMT-dependent |
| Plausibility | met | Known purine-antagonist mechanism |
| Coherence | met | Fits azathioprine myelosuppression |
| Experiment | n/a | Often coded in trials |
| Analogy | met | Analogous to mercaptopurine myelosuppression |
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.
✓ Trial evidence found — Efficacy and Safety of Belimumab in Patients With Active Lupus Nephritis (NCT01639339)
| Adverse event | Placebo (n=224) · Belimumab 10 mg/kg (n=224) · Placebo to Belimumab 10 mg/kg (n=123) · Belimumab 10 mg/kg to Belimumab 10 mg/kg (n=132) | |||
|---|---|---|---|---|
| Pancytopenia | 0/224 | 2/224 | 0/123 | 0/132 |
Post-marketing signal terms appear in this trial's posted adverse-event tables; per-arm counts shown as affected/at-risk. View on ClinicalTrials.gov →