A Risk Classification Model to Predict Mortality among Laboratory-Confirmed Avian Influenza A H7N9 Patients: A Population-Based Observational Cohort Study

Abstract

Background: Avian influenza A H7N9 (A/H7N9) is characterized by rapid progressive pneumonia and respiratory failure. Mortality among laboratory-confirmed cases is above 30%; however, the clinical course of disease is variable and patients at high risk for death are not well characterized. Methods: We obtained demographic, clinical, and laboratory information on all A/H7N9 patients in Zhejiang province from China Centers for Disease Control and Prevention electronic databases. Risk factors for death were identified using logistic regression and a risk score was created using regression coefficients from multivariable models. We externally validated this score in an independent cohort from Jiangsu province. Results: Among 305 A/H7N9 patients, 115 (37.7%) died. Four independent predictors of death were identified: older age, diabetes, bilateral lung infection, and neutrophil percentage. We constructed a score with 0-13 points. Mortality rates in low-(0-3), medium-(4-6), and high-risk (7-13) groups were 4.6%, 32.1%, and 62.7% (Ptrend