An algorithm for the operational assessment of adverse drug reactions. II. Demonstration of reproducibility and validity.

The reproducibility and validity of an algorithm for diagnosis of adverse drug reactions (ADRs) were tested in a clinical spectrum of 30 suspect cases. Using a questionnaire derived from the algorithm the three algorithm developers (nonexperts) agreed on the probability of ADR in 67% of cases, with pair-wise agreement varying from 73% to 87%. The pair-wise agreement of two clinical pharmacologic experts rose from 47% without the algorithm to 63% with the algorithm, with Kw, a chance-corrected index of weighted agreement, increasing from 0.26 to 0.57. The algorithmic assessments of the three nonexperts agreed with expert consensus in 80% to 83% of cases. The ADR algorithm appears to provide a reproducible and valid method of evaluating the likelihood of ADRs in individual patients. Its use can help improve the diagnostic and epidemiologic approach to these important, complex clinical phenomena.