High-dimensional propensity scores improved the control of indication bias in surgical comparative effectiveness studies

Cécile Payet, Stéphanie Polazzi, Jean-François Obadia, Xavier Armoiry, José Labarère, Muriel Rabilloud, Antoine Duclos.

Journal of Clinical Epidemiology / February 2021


Objectives: The objective of the study is to evaluate the performance of high-dimensional propensity scores (hdPSs) for controlling indication bias as compared with propensity scores (PSs) in surgical comparative effectiveness studies.

Study design and setting: Patients who underwent interventional transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR) between 2013 and 2017 were included from the French nationwide hospitals. At each hospital level, matched pairs of patients who underwent TAVI and SAVR were formed using PSs, considering 20 patient baseline characteristics, and hdPSs, considering the same patient characteristics and 300 additional variables from procedure and diagnosis codes the year before surgery. We compared death, reoperation, and stroke up to 3 years between TAVI and SAVR using Cox or Fine and Gray models.

Results: Before matching, 12 of 20 patient characteristics were imbalanced between the included patients who underwent TAVI and SAVR. No significant imbalance persisted after matching with both methods. Hazard ratio of 1-year death, reoperation, and stroke was 1.3 [1.1; 1.4], 1.6 [1.1; 2.4], and 1.4 [1.2; 1.7] for TAVI relative to SAVR with PSs (n = 9,498 pairs) and 1.1 [1.0; 1.3], 1.3 [0.8; 2.0], and 1.3 [1.0; 1.6] with hdPSs (n = 7,157).

Conclusion: HdPS estimations were more consistent with results seen in randomized controlled trials. The HdPS is a promising alternative for the PS to control indication bias in comparative studies of surgical procedures.

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