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 d...

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Published inPharmacoepidemiology and drug safety Vol. 30; no. 7; pp. 934 - 951
Main Authors Komen, Joris J., Belitser, Svetlana V., Wyss, Richard, Schneeweiss, Sebastian, Taams, Anne C., Pajouheshnia, Romin, Forslund, Tomas, Klungel, Olaf H.
Format Journal Article
LanguageEnglish
Published Chichester, UK John Wiley & Sons, Inc 01.07.2021
Wiley Subscription Services, Inc
Subjects
caliper matching
greedy
matching
Medicin och hälsovetenskap
nearest neighbor matching
Original
pharmacoepidemiology
propensity score
simulation
Variation
simulation
caliper matching
greedy
nearest neighbor matching
matching
pharmacoepidemiology
propensity score
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Summary: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.
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ISSN:1053-8569
1099-1557
1099-1557
DOI:10.1002/pds.5232