Greedy caliper propensity score matching can yield variable estimates of the treatment-outcome association-A simulation study.

PURPOSE: Greedy caliper propensity score (PS) matching is dependent on randomness, which can ultimately affect causal estimates. We sought to investigate the variation introduced by this randomness. METHODS: Based on a literature search to define the simulation parameters, we simulated 36 cohorts of different sizes, treatment prevalence, outcome prevalence, treatment-outcome-association. We performed 1:1 caliper and nearest neighbor (NN) caliper PS-matching and repeated this 1000 times in the same cohort, before calculating the treatment-outcome association. RESULTS: Repeating caliper and NN caliper matching in the same cohort yielded large variations in effect estimates, in all 36 scenarios, with both types of matching. The largest variation was found in smaller cohorts, where the odds ratio (OR) ranged from 0.53 to 10.00 (IQR of ORs: 1.11-1.67). The 95% confidence interval was not consistently overlapping a neutral association after repeating the matching with both algorithms. We confirmed these findings in a noninterventional example study. CONCLUSION: Caliper PS-matching can yield highly variable estimates of the treatment-outcome association if the analysis is repeated.

Ethnicity-Specific Drug Safety Data in European Medicines Agency Registration Dossiers, European Public Assessment Reports, and European and Singapore Drug Labels: Lost in Translation?

BACKGROUND: Information on drug safety in different ethnic populations reported in public documents such as the European Public Assessment Reports (EPARs), European Summary of Product Characteristics (SmPCs) or Singapore Package Inserts (SGPIs) generally appears limited. OBJECTIVE: This study aimed to clarify the extent of drug safety data in ethnic populations that is available in drug registration dossiers used for registration in the European Union (EU) and Singapore, and how much of this information is then included in the EPARs and SmPCs or SGPIs. METHODS: For this purpose, drug registration dossiers and these public documents for a selection of 25 drugs authorized both in the EU and Singapore were compared (note, the number of available full registration dossiers was only 24 due to a technical issue). RESULTS: Detailed safety data in ethnic groups were present in 23/24 (96%) of the drug registration dossiers, but was only present in 12/25 (48%) of the EPARs, 8/25 (32%) of the SmPCs, and 9/25 (36%) of the SGPIs. Furthermore, in many cases where ethnicity-specific safety information was provided in the SmPC or SGPIs, details on the ethnic subpopulations was not provided. CONCLUSIONS: Despite the fact that safety data analyzed with respect to ethnic populations are available in almost all screened registration dossiers, this information is often unknown to patients or prescribers as it was often not included in the EPARs, EU SmPCs or SGPIs. In order to increase the availability of such potentially important safety information, it is recommended to at least provide ethnic populations and group size in these public documents. In this way, trust in the registered drugs in different ethnic populations may be increased, and more robust treatment decisions may be obtained in clinical practice.