(P-278) A Review of the Sampling Methodology Used in Studies Evaluating the Effectiveness of Risk Minimization Measures in Europe

Background: European Medicines Agency (EMA) guidelines emphasize that consideration should be given to the representativeness of the sample in studies assessing the effectiveness of risk minimization measures (RMMs).

Objectives: This review aims to describe the sampling methodology and supporting evidence reported by investigators to address representativeness in studies assessing the effectiveness of RMMs available in the public European Union electronic Register of Post‐Authorization Studies (EU PAS Register).

Methods: The 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. Data to describe study characteristics and sampling methodology variables were extracted from studies’ protocols and reports.

Results: Of 1,092 studies finalised between June 2017 and May 2019, 17 studies (13 surveys, 3 chart reviews, 1 combined) were eligible for review. All 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 1 study substantiated the country selection by presenting drug sales distribution. HCP/site sampling frames mainly included physician networks (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 convenience 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 documents revealed the awareness of the investigators about the importance of a representative sample in studies assessing the effectiveness of RMM, as a rationale for sampling strategy was often provided. However, there were limited details to substantiate the sampling decisions and operationalization of the sampling strategy . More standardization and guidance in reporting the sampling strategy and operational considerations applicable to these studies would facilitate transparent evaluation of representativeness of the study results.