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Greedy caliper propensity score matching can yield variable estimates of the treatment‐outcome association—A simulation study
Author(s) -
Komen Joris J.,
Belitser Svetlana V.,
Wyss Richard,
Schneeweiss Sebastian,
Taams Anne C.,
Pajouheshnia Romin,
Forslund Tomas,
Klungel Olaf H.
Publication year - 2021
Publication title -
pharmacoepidemiology and drug safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.023
H-Index - 96
eISSN - 1099-1557
pISSN - 1053-8569
DOI - 10.1002/pds.5232
Subject(s) - calipers , propensity score matching , medicine , matching (statistics) , odds ratio , outcome (game theory) , confidence interval , statistics , cohort , randomness , mathematics , geometry , mathematical economics
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.