Development and Validation of a Risk Score for Predicting Death in Chagas' Heart Disease

NEJM -- Development and Validation of a Risk Score for Predicting Death in Chagas' Heart Disease:
Anis Rassi, Jr., M.D., Ph.D., Anis Rassi, M.D., William C. Little, M.D., Sérgio S. Xavier, M.D., Ph.D., Sérgio G. Rassi, M.D., Alexandre G. Rassi, M.D., Gustavo G. Rassi, M.D., Alejandro Hasslocher-Moreno, M.D., Andrea S. Sousa, M.D., Ph.D., and Maurício I. Scanavacca, M.D., Ph.D.
"ABSTRACT
Background Chagas' disease is an important health problem in Latin America, and cardiac involvement is associated with substantial morbidity and mortality. We developed a model to predict the risk of death in patients with Chagas' heart disease.
Methods We retrospectively evaluated 424 outpatients from a regional Brazilian cohort. The association of potential risk factors with death was tested by Cox proportional-hazards analysis, and a risk score was created. The model was validated in 153 patients from a separate community hospital.
Results During a mean follow-up of 7.9 years, 130 patients in the development cohort died. Six independent prognostic factors were identified, and each was assigned a number of points proportional to its regression coefficient: New York Heart Association class III or IV (5 points), evidence of cardiomegaly on radiography (5 points), left ventricular systolic dysfunction on echocardiography (3 points), nonsustained ventricular tachycardia on 24-hour Holter monitoring (3 points), low QRS voltage on electrocardiography (2 points), and male sex (2 points). We calculated risk scores for each patient and defined three risk groups: low risk (0 to 6 points), intermediate risk (7 to 11 points), and high risk (12 to 20 points). In the development cohort, the 10-year mortality rates for these three groups were 10 percent, 44 percent, and 84 percent, respectively. In the validation cohort, the corresponding mortality rates were 9 percent, 37 percent, and 85 percent. The C statistic for the point system was 0.84 in the development cohort and 0.81 in the validation cohort.
Conclusions A simple risk score was developed to predict death in Chagas' heart disease and was validated in an independent cohort. "