Application of nomogram model in predicting mortality of patients infected with avian influenza A (H7 N9) / 中华临床感染病杂志

ABSTRACT

Objective To develop and validate a mortality risk prediction model for patients infected with avian influenza A H 7N9 virus.Methods A stratified and random sampling method was adopted for selection of subjects .A total of 102 patients infected with avian influenza A H7N9 virus, who were admitted to the designated hospitals in Zhejiang Province during March 2013 and March 2015, were enrolled.Standard questionnaires were used to collect data about demographic , epidemiologic and clinical characteristics , and the data were retrospectively reviewed . Univariate analysis and stepwise logistic regression analysis were used to identify the mortality risk factors of patients infected with avian influenza A H7N9 virus, and nomogram was applied to develop the risk prediction model .The accuracy of the prediction model was assessed using Concordance index (C-index) and receiver operating characteristic (ROC) curve. Results Stepwise multiple logistic regression analysis showed that age ≥60 years (χ2 =3.98, OR=2.99, 95%CI1.05-9.21, P<0.05), increased initial neutrophil count (χ2 =6.66,OR=5.06, 95%CI1.56-18.83, P<0.05), C-reactive protein≥120mg/L (χ2 =8.63, OR=5.15, 95%CI1.79-16.31, P<0. 01), poor hand hygiene (χ2 =6.83, OR =10.29, 95%CI2.18-81.49, P <0.01) and 5 days of incubation period or shorter (χ2 =7.23, OR=4.75, 95%CI1.59-15.80, P<0.01) were independent risk factors for mortality of patients .Based on the above study , a risk prediction model of nomogram was developed.Poor hand hygiene (grade A, 100.0 points) ranked on the top of all risk factors, followed by C-reactive protein≥120 mg/L (grade B, 76.5 points), increased initial neutrophil count (grade C, 70.5 points), 5 days of incubation period or shorter (grade D, 62.0 points) and age ≥60 years (grade E, 51.0 points).The C-index and the area under the curve were 0.833 and 0.817 for the nomogram model , respectively;and the nomogram model fitted well .Conclusion Nomogram model can effectively predict and estimate the risk of death for patients infected with avian influenza A H 7N9 virus.