Data from: Methods for estimating causal relationships of adverse events with dietary supplements

Objective: Dietary supplement use has increased over past decades, resulting in reports of potentially serious adverse events. The aim of this study was to develop optimized methods to evaluate the causal relationships between adverse events and dietary supplements, and to test these methods using case reports.
Design: Causal relationship assessment using prospectively collected data.
Setting & Participants: Four dietary supplement experts, 4 pharmacists, and 11 registered dietitians (5 men and 14 women) examined 200 case reports of suspected adverse events using the modified Naranjo scale and the modified FDA algorithm.
Primary outcome measures: The distribution of evaluation results was analyzed and inter-rater (multi-rater) reliability was evaluated for the two modified methods employed, using intraclass correlation coefficients (ICC) and Fleiss’ kappa.
Results: Using these two methods, most of the 200 case reports were categorized as “lack of information” or “possible” adverse events. Inter-rater (multi-rater) reliability among entire assessors ratings for the two modified methods, based on intraclass correlation coefficients (ICC) and Fleiss’ kappa, were classified as more than substantial (Modified Naranjo scale: ICC [95%CI], 0.873 [0.850, 0.895]; Fleiss’ kappa [95%CI], 0.615 [0.615, 0.615]. Modified FDA algorithm: Fleiss’ kappa [95%CI], 0.622 [0.622, 0.622]).
Conclusions: These methods may help to assess the causal relationships between adverse events and dietary supplements. By conducting additional studies of these methods in different populations, researchers can expand the possibilities for the application of our methods.