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Published on: March 27, 2018
Institutional variation in early mortality following isolated coronary artery bypass graft surgery
Aayush Patel1, Linh Ngo2, Richard J Woodman3
1Adelaide Medical School, The University of Adelaide, Adelaide, Australia.
Insights
Thirty-day mortality after coronary artery bypass grafting (CABG) varies significantly between hospitals in Australia and New Zealand. This highlights potential quality disparities and the continued importance of tracking CABG outcomes.
Area of Science:
- Cardiovascular Surgery
- Health Services Research
- Quality Improvement
Background:
- Thirty-day mortality after coronary artery bypass grafting (CABG) is a key quality indicator in cardiac surgery.
- While overall surgical mortality has decreased, its utility for profiling institutional quality requires ongoing assessment.
- Assessing institutional variation in risk-standardised mortality rates (RSMR) for isolated CABG in Australia and New Zealand (ANZ) is crucial.
Purpose of the Study:
- To evaluate the variation in risk-standardised mortality rates (RSMR) following isolated coronary artery bypass grafting (CABG) across hospitals in Australia and New Zealand (ANZ).
- To determine if 30-day mortality remains a relevant measure for assessing quality of care in CABG procedures.
- To identify potential disparities in care quality among institutions performing CABG.
Main Methods:
- Utilized an administrative dataset encompassing isolated CABG procedures from 2010-2015 across ANZ hospitals.
- Defined the primary outcome as all-cause death within 30 days of discharge or in-hospital.
- Estimated hospital-specific RSMRs using a hierarchical generalized linear model, adjusting for patient characteristics.
Main Results:
- Analyzed 60,953 isolated CABG procedures across 47 hospitals, with an observed early mortality rate of 1.69%.
- A 3.9-fold variation in RSMR was observed among hospitals (median 1.72%, range 0.84-3.29%) after risk adjustment.
- In-hospital mortality alone showed a 5.6-fold variation (median 1.40%, range 0.57-3.19%), indicating significant institutional differences.
Conclusions:
- Despite low average mortality, significant variations in in-hospital and 30-day mortality exist across ANZ hospitals performing CABG.
- These variations underscore potential disparities in care quality and confirm the enduring utility of 30-day mortality as an outcome measure.
- Clinical and policy interventions, including participation in quality registries, are recommended to standardize CABG care and improve outcomes.
Background:
Thirty-day mortality following coronary artery bypass grafting (CABG) is a widely accepted marker for quality of care. Although surgical mortality has declined, the utility of this measure to profile quality has not been questioned. We assessed the institutional variation in risk-standardised mortality rates (RSMR) following isolated CABG within Australia and New Zealand (ANZ).
Methods:
We used an administrative dataset from all public and most private hospitals across ANZ to capture all isolated CABG procedures recorded between 2010 and 2015. The primary outcome was all-cause death occurring in-hospital or within 30-days of discharge. Hospital-specific RSMRs and 95% CI were estimated using a hierarchical generalised linear model accounting for differences in patient characteristics.
Results:
Overall, 60,953 patients (mean age 66.1 ± 10.1y, 18.7% female) underwent an isolated CABG across 47 hospitals. The observed early mortality rate was 1.69% (n = 1029) with 81.8% of deaths recorded in-hospital. The risk-adjustment model was developed with good discrimination (C-statistic = 0.81). Following risk-adjustment, a 3.9-fold variation was observed in RSMRs among hospitals (median:1.72%, range:0.84-3.29%). Four hospitals had RSMRs significantly higher than average, and one hospital had RSMR lower than average. When in-hospital mortality alone was considered, the median in-hospital RSMR was 1.40% with a 5.6-fold variation across institutions (range:0.57-3.19%).
Conclusions:
Average mortality following isolated CABG is low across ANZ. Nevertheless, in-hospital and 30-day mortality vary among hospitals, highlighting potential disparities in care quality and the enduring usefulness of 30-day mortality as an outcome measure. Clinical and policy interventions, including participating in clinical quality registries, are needed to standardise CABG care.
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