Impact of length of stay after coronary bypass surgery on short-term readmission rate: An instrumental variable analysis

Yue Li, Xueya Cai, Dana B. Mukamel, Peter Cram

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To determine the effect of postoperative length of stay (LOS) on 30-day readmission after coronary artery bypass surgery. Data Sources/Study Setting: We analyzed a final database consisting of Medicare claims of a cohort (N=157,070) of all fee-for-service beneficiaries undergoing bypass surgery during 2007-2008, the American Hospital Association annual survey file, and the rural urban commuting area file. Study Design: We regressed the probability of 30-day readmission on postoperative LOS using (1) a (naive) logit model that controlled for observed patient and hospital covariates only; and (2) a residual inclusion instrumental variable (IV) logit model that further controlled for unobserved confounding. The IV was defined using a measure of the hospital's risk-adjusted LOS for patients admitted for gastrointestinal hemorrhage. Principal Findings: The naive logit model predicted that a 1-day reduction in median postoperative LOS (ie, from a median of 6-5 d) lowered the 30-day readmission rate by 2 percentage points. The IV model predicted that a 1-day reduction in median postoperative LOS increased 30-day readmission rate by 3 percentage points. Conclusions: The findings indicate that a reduction in postoperative LOS is associated with an increased risk for 30-day readmission among Medicare patients undergoing bypass surgery, after both observed and unobserved confounding effects are corrected.

Original languageEnglish (US)
Pages (from-to)45-51
Number of pages7
JournalMedical care
Volume51
Issue number1
DOIs
StatePublished - Jan 2013
Externally publishedYes

Keywords

  • 30-day readmission
  • Bypass surgery
  • instrumental variables
  • length of stay
  • Medicare
  • quality of care

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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