Unexpected beneficial effects of drugs: an analysis of cases in the Dutch spontaneous reporting system.

INTRODUCTION Drug use is inherently related to both beneficial effects on health as well as the occurrence of risks. The beneficial effects may be related to efficacy, the treatment range of a product, or even to user-friendliness of a product. However, in addition to the occurrence of adverse drug reactions, a drug can also have an unexpected beneficial effect on a patient's health, not related to the indication for which the drug was used. The aim of this article is to characterize the reports of unexpected beneficial effects of drugs in the Dutch spontaneous reporting system. METHODS A descriptive analysis was used to gain insight in number of reports and drug classes responsible for unexpected beneficial effects of drugs. Grouping of positive side effects into classes was done by a conventional qualitative content analysis of the cases. RESULTS Four hundred nine reports which described unexpected beneficial effects of drugs were included, which mentioned 451 associations between suspected drugs and unexpected beneficial effects. There were 147 drug classes on the 4th ATC level involved. Content analysis of the reports gave rise to 22 categories of unexpected beneficial effects of drugs, including one "other category". DISCUSSION AND CONCLUSION: The analysis showed a diverse spectrum of reported reactions and drugs with some categories of unexpected beneficial effects of drugs mentioned multiple times for certain drug classes on the 4th ATC level. Most of these findings are consistent with the existing literature and knowledge on the pharmacological mechanism of the drugs in question. Coding harmonization would make it possible to study these effects in international databases.