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In International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases

OBJECTIVES : To develop:(1) two validated risk prediction models for COVID-19 positivity using readily available parameters in a general hospital setting; (2) nomograms and probabilities to allow clinical utilisation.

METHODS : Patients with and without COVID-19 were included from 4 Hong Kong hospitals. Database was randomly split 2:1 for model development database (n = 895) and validation database (n = 435). Multivariable logistic regression was utilised for model creation and validated with the Hosmer-Lemeshow (H-L) test and calibration plot. Nomograms and probabilities set at 0.1, 0.2, 0.4, 0.6 were calculated to determine sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

RESULTS : 1330 patients (mean age 58.2 ± 24.5 years; 50.7% males; 296 COVID-19 positive) were recruited. First prediction model developed had age, total white blood cell count, chest x-ray appearances and contact history as significant predictors (AUC = 0.911 [CI = 0.880-0.941]). Second model developed has same variables except contact history (AUC = 0.880 [CI = 0.844-0.916]). Both were externally validated on H-L test (p = 0.781 and 0.155 respectively) and calibration plot. Models were converted to nomograms. Lower probabilities give higher sensitivity and NPV; higher probabilities give higher specificity and PPV.

CONCLUSION : Two simple-to-use validated nomograms were developed with excellent AUCs based on readily available parameters and can be considered for clinical utilisation.

Ng Ming-Yen, Wan Eric Yuk Fai, Wong Ho Yuen Frank, Leung Siu Ting, Lee Jonan Chun Yin, Chin Thomas Wing-Yan, Lo Christine Shing Yen, Lui Macy Mei-Sze, Chan Edward Hung Tat, Fong Ambrose Ho-Tung, Yung Fung Sau, Ching On Hang, Chiu Keith Wan-Hang, Chung Tom Wai Hin, Vardhanbhuti Varut, Lam Hiu Yin Sonia, To Kelvin Kai Wang, Chiu Jeffrey Long Fung, Lam Tina Poy Wing, Khong Pek Lan, Liu Raymond Wai To, Man Chan Johnny Wai, Ka Lun Alan Wu, Lung Kwok-Cheung, Hung Ivan Fan Ngai, Lau Chak Sing, Kuo Michael D, Ip Mary Sau-Man


COVID-19, Nomogram, Prediction Model, chest x-ray, white cell count