Center-specific differences in mortality: preliminary analyses using the Risk Adjustment in Congenital Heart Surgery (RACHS-1) method.
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.
Jenkins
Kathy J
KJ
Department of Cardiology, Children's Hospital, Boston, MA 02115, USA. jenkins@cardio.tch.harvard.edu
Gauvreau
Kimberlee
K
D000293:Adolescent; D006348:Cardiac Surgical Procedures / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D006330:Heart Defects, Congenital / Q000401:mortality* / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D020379:Risk Adjustment / Q000379:methods / Q000706:statistics & numerical data