Survival of hospitalized COVID-19 Patients Using the Nested Frailty Model

Document Type : Original Article


1 Modeling in Health Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran

2 Health Services Management Research Center, Institute for Futures Studies in Health, Kerman University of medical sciences, Kerman, Iran.



Aims: COVID-19 disease is considered a global threat. The disease started with an unknown cause in Wuhan, China, and quickly spread worldwide. The aim of this study was to investigate the survival of hospitalized patients in the largest province in southeastern Iran, Kerman.
Methods: In this study, the survival of hospitalized patients was examined using the nested frailty Cox model. The dependent variable was the time of survival of COVID-19 patients, defined as the time from hospital admission to death or the end of the study period. Independent variables included age group, sex, comorbidities, and others. Variables reported the frequency and percentage of deaths. The hazard factors for death were assessed using hazard ratio and confidence interval.
Findings: A total of 5087 individuals participated in the study, of whom 15.2% died due to COVID-19. Among the deceased, 59.9% were male, and 67.4% were in the 41-80 age group. 37.8% of those who died had a fever, and 46.1% had a cough. The hazard of death was 1.35 times higher in men than in women. The hazard of death in the 40-80 age group was 1.59 times higher than in the under 40 age group. Having comorbidities such as cancer and hypertension increased the hazard of death by 1.70 and 1.21 times, respectively.
Conclusions: Special care and treatment services should be provided to elderly individuals and those with comorbidities such as cancer and hypertension. Necessary education about the symptoms of the disease should also be given to individuals.


Main Subjects

Articles in Press, Accepted Manuscript
Available Online from 26 February 2024
  • Receive Date: 07 August 2023
  • Revise Date: 23 January 2024
  • Accept Date: 19 February 2024