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Center-specific differences in mortality: preliminary analyses using the Risk Adjustment in Congenital Heart Surgery
Kathy J Jenkins1, Kimberlee Gauvreau
1Department of Cardiology, Children's Hospital, Boston, MA 02115, USA. jenkins@cardio.tch.harvard.edu
Insights
The Risk Adjustment in Congenital Heart Surgery (RACHS-1) method effectively compares hospital mortality rates for pediatric heart surgery. It allows for risk-adjusted comparisons, identifying institutional performance variations.
Area of Science:
- Cardiovascular Surgery
- Pediatric Cardiology
- Health Services Research
Background:
- Comparing mortality rates after congenital heart surgery is complex due to varying patient risk.
- The Risk Adjustment in Congenital Heart Surgery (RACHS-1) method was developed to standardize these comparisons.
- Accurate risk adjustment is crucial for evaluating and improving institutional performance.
Purpose of the Study:
- To assess the utility of the RACHS-1 method for comparing institutional mortality after congenital heart disease surgery.
- To explore how RACHS-1 categorizes surgical procedures and patient risk.
- To evaluate the effectiveness of RACHS-1 in identifying performance differences among centers.
Main Methods:
- Utilized 1996 hospital discharge data from six states, focusing on centers with at least 100 congenital heart disease operations.
- Grouped procedures into six risk categories using the RACHS-1 method.
- Employed multivariate models incorporating age, prematurity, and noncardiac anomalies to calculate risk-adjusted ranks based on standardized mortality ratios.
Main Results:
- Of 109 centers, 22 met the criteria, performing 72.3% of total operations.
- Unadjusted mortality rates varied significantly (2.5%–11.4%).
- Risk-adjusted analysis revealed consistent performance, threshold increases/decreases in mortality by risk category, and identified centers performing above or below expected rates.
Conclusions:
- The RACHS-1 method is a useful tool for judging relative institutional performance in congenital heart surgery.
- It facilitates comparisons through within-risk-category analysis and observed-to-expected mortality ratios.
- RACHS-1 aids in identifying centers that excel or require improvement in managing complex pediatric cardiac cases.
Objective:
We sought to explore the usefulness of the Risk Adjustment in Congenital Heart Surgery method (designated RACHS-1) of adjusting for case-mix differences when comparing institutional mortality after surgery for congenital heart disease.
Methods:
By using 1996 hospital discharge data from 6 states, centers performing at least 100 operations for congenital heart disease (patient age <18 years) were identified. Using the RACHS-1 method, procedures were grouped into 6 risk categories, and institutions were ranked in order of increasing mortality rate. A graphic display of ranks by risk category identified patterns of performance. Incorporating age, prematurity, and presence of a major noncardiac structural anomaly into multivariate models allowed computation of an overall risk-adjusted rank for each institution on the basis of its standardized mortality ratio.
Results:
Among 109 centers performing 7177 operations for congenital heart disease, 22 performed at least 100 cases (72.3% of total operations). Unadjusted mortality rates ranged from 2.5% to 11.4%. A total of 4318 cases could be placed into 1 of the 6 risk categories. Few deaths occurred in risk category 1, and few institutions performed procedures in risk categories 5 and 6, making institutional comparisons in these categories uninformative. Considering mortality rates in categories 2 through 4, institutions displayed either relatively consistent ranks, a threshold increase in mortality as higher-risk procedures were performed, or a threshold decrease in mortality. Standardized mortality ratios indicated which institutions performed better or worse than expected on the basis of their case mix.
Conclusions:
The RACHS-1 method can be used to judge relative institutional performance, either by evaluating within-risk-category differences or by comparisons of observed and expected mortality rates.
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