To examine the added benefit of outcome event adjudication by an independent panel of neurologists on findings from the Insulin Resistance Intervention After Stroke (IRIS) trial.

In randomized clinical trials of therapies for cardiovascular disease, the current methodologic standard is adjudication of outcomes by a panel of independent experts.  Despite the theoretical benefits, the process adds costs and complexity.

IRIS was a randomized, double blind trial comparing pioglitazone with placebo among patients with ischemic stroke or TIA.  The main outcome was stroke or myocardial infarction.  Neurological events were classified as stroke/no stroke by site investigators first, but final classification was made by an independent panel of neurologists.  Cardiac events were identified locally but classified only by a separate panel of cardiologists.  We compared hazard ratios for the study outcomes using outcome classification by neurology site investigators and the independent panel of neurologists.   

The hazard ratio for the main trial outcome was 0.76 (95% CI, 0.63, 0.92) using classification by site investigators and 0.76 (95% CI, 0.62, 0.93) using classification by the panel. The hazard ratio for stroke was 0.80 (95% CI, 0.63, 0.999) using classification by site investigators and 0.82 (95% CI, 0.65, 1.03) for the panel.  The only factor associated with greater disagreement between site investigators and the panel for stroke classification was on duration time of symptoms for patients with symptoms  <24h. 

Adjudication by an independent panel of neurologists did not affect the main findings of the IRIS trial. If a panel of independent neurologists is used for outcome classification, it may be most helpful when questions are regarding transient symptoms.