Unmeasured Confounders in Observational Studies Comparing Bilateral Versus Single Internal Thoracic Artery for Coronary Artery Bypass Grafting: A Meta-Analysis. Review uri icon

Overview

abstract

  • BACKGROUND: Observational studies suggest a survival advantage with bilateral single internal thoracic artery (BITA) versus single internal thoracic artery grafting for coronary surgery, whereas this conclusion is not supported by randomized trials. We hypothesized that this inconsistency is attributed to unmeasured confounders intrinsic to observational studies. To test our hypothesis, we performed a meta-analysis of the observational literature comparing BITA and single internal thoracic artery, deriving incident rate ratio for mortality at end of follow-up and at 1 year. We postulated that BITA would not affect 1-year survival based on the natural history of coronary artery bypass occlusion, so that a difference between groups at 1 year could not be attributed to the intervention. METHODS AND RESULTS: We searched MEDLINE and Pubmed to identify all observational studies comparing the outcome of BITA versus single internal thoracic artery. One-year and long-term mortality for BITA and single internal thoracic artery were compared in the propensity-score-matched (PSM) series, that is, the form of observational evidence less prone to confounders. Thirty-eight observational studies (174 205 total patients) were selected for final comparison. In the 12 propensity-score-matched series (34 019 patients), the mortality reduction for BITA was similar at 1 year and at the end of follow-up (incident rate ratio, 0.70; 95% confidence interval, 0.60-0.82 versus 0.77; 95% confidence interval, 0.70-0.85; P for subgroup difference=0.43). CONCLUSIONS: Unmeasured confounders, rather than biological superiority, may explain the survival advantage of BITA in observational series.

publication date

  • January 6, 2018

Research

keywords

  • Coronary Artery Bypass
  • Coronary Artery Disease
  • Coronary Vessels
  • Mammary Arteries

Identity

PubMed Central ID

  • PMC5778975

Scopus Document Identifier

  • 85040509344

Digital Object Identifier (DOI)

  • 10.1161/JAHA.117.008010

PubMed ID

  • 29306899

Additional Document Info

volume

  • 7

issue

  • 1