Representativeness of diabetes patients participating in a web-based adverse drug reaction monitoring system

Lareb Intensive Monitoring, LIM, is a non-interventional observational cohort method which follows first-time users of certain drugs during a certain period of time and collects information about adverse drug reactions, ADRs. In order for LIM to be a useful pharmacovigilance tool, it is important to know whether the LIM population is comparable to the whole population using the drug. The aim of this study is to compare the LIM diabetes population with an external diabetes reference population on characteristics that may influence the patient's susceptibility for ADRs.

In this study, a LIM diabetes population was compared to a reference diabetes population derived from The Groningen Initiative to ANalyse Type 2 diabetes Treatment project. Comparisons were made regarding age, gender, body mass index and polypharmacy, as well as diabetes medication used and disease/treatment duration.

LIM patients were more often men (58.5% vs 50.8%) and in general younger (59.1 vs 64.7 years) and healthier, by that meaning they had a higher percentage of de novo treated patients (55.5% vs 53.2%), a shorter diabetes treatment duration (3.7 vs 5.5 years) and used less co-medication than patients in the reference population.

This study shows that diabetes patients participating in a web-based intensive monitoring system differ from a reference population. The observed differences might lead to an underestimation of ADRs, but it is not clear whether this would also influence the type or time-course of the reported ADRs. When interpreting results from LIM studies, one should take these differences into account.