Characterization of Drug Utilization Studies (DUS) Submitted to The European Union (EU) Electronic Register of Post-Authorisation Studies (PAS)

The EU PAS Register is a publicly available register of non-interventional post-authorisation studies. Main categories of scope include disease epidemiology, risk assessment, drug utilization study, and effectiveness evaluation. Here we aim to characterize DUS in terms of study design and types of variables collected. We searched the ENCEPP website on 05-Jan-18 using following search terms: finalized, observational study, adults, drug utilization studies. 112 of 321 observational studies are DUS (36%). The number of DUS increased over time: 1 in 2012-2014, 11 in 2015, 43 in 2016, and 55 in 2017. 62 (55%) were requested by a regulator (74% by the EMA) and 47 (42%) were required by a risk management plan (RMP). 11 (10%) studies assess off-label use. 71% and 17% of DUS include “risk assessment” and “effectiveness evaluation” as part of the scope, respectively. In terms of design, 80% are cohort studies; the remainder are case-control studies (6%), surveys (6%), cross-sectional studies (5%), or case series (3%). 71% use retrospective data, 28% prospective data and 2% are hybrid (i.e. retrospective/prospective). 89% involve analysis of longitudinal data (11% cross-sectional). 64% use databases, 29% involve primary data collection, and 7% employ retrospective chart review/EMR analysis methods. In addition to drug usage, 42% collect cohort characteristics, 37% safety, 14% effectiveness, 11% HRU, and 4% PRO. DUS requested by regulators were all labelled as RMPs and are predominantly retrospective cohort studies using existing databases. In the PAS register, we observed a trend in increasing numbers of observational studies, including DUS. Most DUS include “risk assessment” as additional scope and therefore cover safety endpoints in addition to drug usage. The majority of DUS are retrospective cohort studies using existing database, but approximately a third are prospective observational studies.