Confounding adjustment in observational studies on cardiothoracic interventions: a systematic review of methodological practice

European Journal of Cardio-Thoracic Surgery, vol. 64

Abstract

OBJECTIVES: It is unknown which confounding adjustment methods are currently used in the field of cardiothoracic surgery and whether these are appropriately applied. The aim of this study was to systematically evaluate the quality of conduct and reporting of confounding adjustment methods in observational studies on cardiothoracic interventions. METHODS: A systematic review was performed, which included all observational studies that compared different interventions and were published between 1 January and 1 July 2022, in 3 European and American cardiothoracic surgery journals. Detailed information on confounding adjustment methods was extracted and subsequently described. RESULTS: Ninety-two articles were included in the analysis. Outcome regression (n = 49, 53%) and propensity score (PS) matching (n = 44, 48%) were most popular (sometimes used in combination), whereas 11 (12%) studies applied no method at all. The way of selecting confounders was not reported in 42 (46%) of the studies, solely based on previous literature or clinical knowledge in 14 (16%), and (partly) data-driven in 25 (27%). For the studies that applied PS matching, the matched cohorts comprised on average 46% of the entire study population (range 9-82%). CONCLUSIONS: Current reporting of confounding adjustment methods is insufficient in a large part of observational studies on cardiothoracic interventions, which makes quality judgement difficult. Appropriate application of confounding adjustment methods is crucial for causal inference on optimal treatment strategies for clinical practice. Reporting on these methods is an important aspect of this, which can be improved.

Authors 6

1. Bart J.J. Velders corresponding Aachen Department of Cardiothoracic Surgery Department of Clinical Epidemiology

   Leiden University Medical Center

   Affiliation as printed

   Department of Cardiothoracic Surgery, Leiden University Medical Center , Leiden, Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden, Netherlands

   Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands

2. J.W. Taco Boltje

   Amsterdam UMC Location University of Amsterdam · Amsterdam University Medical Centers

   Affiliation as printed

   Department of Cardiothoracic Surgery, Amsterdam University Medical Center , Amsterdam, Netherlands

   Department of Cardiothoracic Surgery, Amsterdam University Medical Center, Amsterdam, The Netherlands

3. Michiel D. Vriesendorp Aachen Department of Cardiothoracic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Cardiothoracic Surgery, Leiden University Medical Center , Leiden, Netherlands

   Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands

4. Robert J.M. Klautz Aachen Department of Cardiothoracic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Cardiothoracic Surgery, Leiden University Medical Center , Leiden, Netherlands

   Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands

5. Saskia le Cessie Aachen Department of Biomedical Data Science Department of Clinical Epidemiology

   Leiden University Medical Center

   Affiliation as printed

   Department of Biomedical Data Science, Leiden University Medical Center , Leiden, Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden, Netherlands

   Department of Biomedical Data Science, Leiden University Medical Center, Leiden, The Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands

6. Rolf H. H. Groenwold Aachen Department of Biomedical Data Science Department of Clinical Epidemiology

   Leiden University Medical Center

   Affiliation as printed

   Department of Biomedical Data Science, Leiden University Medical Center , Leiden, Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden, Netherlands

   Department of Biomedical Data Science, Leiden University Medical Center, Leiden, The Netherlands

   Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands