Hospital Case Volume, Health Care Providers, and Mortality in Patients Undergoing Coronary Artery Bypass Grafting: a Nationwide Cohort Study in South Korea

BACKGROUND AND OBJECTIVES: Surgical quality is evaluated by measuring the annual hospital case volume; a higher case volume is associated with better survival after various surgeries. We aimed to investigate if the annual hospital case volume and the health care providers were associated with a 90-day mortality after coronary artery bypass grafting (CABG). METHODS: For this population-based cohort study, we used data from a National Health Insurance Service database in South Korea. We included all adult patients diagnosed with ischemic heart disease who underwent isolated CABG between January 2012 and December 2017. Data on the annual surgical volume for CABG in each hospital where the patients received CABG and the total number of health care providers (including physicians [trainees and specialists] from all department of the hospitals, nurses, and pharmacists) were collected. RESULTS: The final analysis included 15,790 adult patients; of these, 1,039 (6.6%) died within 90 days. The annual CABG volume was divided into 4 groups (Q1: ≤33, Q2: 34–86, Q3: 87–223, and Q4: ≥224). Multivariable Cox regression analysis revealed that the 90-day mortality rates in the Q4, Q3, Q2 groups were 75%, 32%, and 31% lower than that in the Q1 group, respectively. Additionally, an increase in the ratio of the total number of specialist physicians to 100 hospital beds was associated with a 4% decrease in the 90-day mortality after CABG. CONCLUSION: Both, a higher annual hospital case volume and overall specialist physician volume were associated with better 90-day mortality rates after isolated CABG.