Modeling the recovery time of patients with coronavirus disease 2019 using an accelerated failure time model

Thiruvengadam, Gayathri; Ramanujam, Ravanan; Marappa, Lakshmi

OBJECTIVE: To identify factors associated with recovery time from coronavirus disease 2019 (COVID-19). METHODS: In this retrospective study, data for patients with COVID-19 were obtained between 21 June and 30 August 2020. An accelerated failure time (AFT) model was used to identify covariates associated with recovery time (days from hospital admission to discharge). AFT models with different distributions (exponential, log-normal, Weibull, generalized gamma, and log-logistic) were generated. Akaike’s information criterion (AIC) was used to identify the most suitable model. RESULTS: A total of 730 patients with COVID-19 were included (92.5% recovered and 7.5% censored). Based on its low AIC value, the log-logistic AFT model was the best fit for the data. The covariates affecting length of hospital stay were oxygen saturation, lactate dehydrogenase, neutrophil-lymphocyte ratio, D-dimer, ferritin, creatinine, total leucocyte count, age > 80 years, and coronary artery disease. CONCLUSIONS: The log-logistic AFT model accurately described the recovery time of patients with COVID-19.