ALDEN, drug causality in SJS/TEN

Scores the probability that a specific drug caused Stevens-Johnson syndrome or toxic epidermal necrolysis. Score each candidate drug separately, then rank them. This is the SJS/TEN-specific replacement for the generic Naranjo scale.

Evidence tier: Validated instrument.

Formula / logic

ALDEN = delay + drug-present + prechallenge/rechallenge + dechallenge + notoriety + other-cause. Intermediate score (criteria 1-5) ranges -11 to +10; the final score (after criterion 6) ranges -12 to +10. Interpretation: <0 very unlikely; 0-1 unlikely; 2-3 possible; 4-5 probable; >=6 very probable.

Interpretation

ALDEN is scored SEPARATELY for every systemic drug the patient took in roughly the 4 weeks before onset, then the drugs are ranked. The highest-scoring drug is the most likely culprit; a patient can have several drugs scored, and criterion 6 down-weights a drug when a stronger competitor exists. It is a causality tool, not a diagnostic one, it does not diagnose SJS/TEN, it attributes it. Pin the index day (onset day) precisely, because an error there shifts the delay category and can swing the score by several points.

Evidence & citations

  1. Sassolas B, Haddad C, Mockenhaupt M, et al. ALDEN, an algorithm for assessment of drug causality in Stevens-Johnson syndrome and toxic epidermal necrolysis: comparison with case-control analysis. Clin Pharmacol Ther. 2010;88(1):60-68. PMID 20375998

Clinician decision support. Verify against the cited source. Not a substitute for clinical judgment. 100% on-device; no patient data is stored or transmitted.