A review of the sampling methodology used in studies evaluating the effectiveness of risk minimisation measures in Europe

PURPOSE: This review aims to describe the sampling methodology used in studies assessing effectiveness of risk minimisation measures (RMMs) in the European Union. METHODS: The European Union electronic Register of Post‐Authorization Studies (EU PAS Register) was searched to identify studies that assessed the effectiveness of RMMs and recruited a target population of healthcare professionals (HCPs), sites or patients. Studies with both protocol and report were included and data was extracted from these documents to describe study characteristics and variables involved in the sampling methodology. RESULTS: Out of 1092 studies finalised between June 2017 and May 2019, 17 studies were eligible for review. Thirteen were surveys, three chart reviews and one combined both methodologies. All the 17 studies recruited HCPs/sites and 8 of them also recruited patients. The most common rationale for country sampling was market uptake (10/17), while for HCP/site sampling, it was representativeness of the prescribing practices (14/17). Only a minority of the studies (4/17) provided supporting evidence to inform this theoretical framework. HCP/site sampling frames were mainly network of physicians (5/17) or HCP databases (5/17), with only one study providing a detailed description of the sampling frame. HCPs were selected mainly using probabilistic sampling (10/17) and patients using non‐probabilistic sampling (6/8). Only a few studies compared participating with non‐participating HCPs/sites (5/17) and patients (3/8). Eight studies reported that their results were generalisable. CONCLUSIONS: Overall, the study documents provided insufficient details to understand the rationale behind the sampling decisions. More standardisation and guidance in reporting the sampling strategy and operational considerations applicable to these types of studies would support transparency and facilitate the evaluation of representativeness of the study results.