The Effect of Age-Threshold on COVID-19 Patients Cure Rate: A Historical Cohort Study

Background: The COVID-19 pandemic had caused unexpected strain on healthcare systems in most countries in 2020. Although different survival models were used in clinical decision-making for COVID-19 patients, the effect of different risk factors in patients has not been identified clearly. Elderly patients, especially with comorbidities, were introduced as the most susceptible group at the risk of death. This study aimed to determine the threshold of age that influences chronic diseases and other factors that increase the cure rate of COVID-19 patients. Methods: This observational study was conducted at Shahid Sadoughi hospital in Yazd, Iran. All participants were older than 18 years old with confirmed COVID-19 and completed the day-30 and day-180 follow-ups. The Bayesian method was used through the cure rate models, practical models in survival with a single change-point to detect the threshold of age, illustrating each risk factor’s effect on the cure rate of patients. Results: The analysis included 901 confirmed COVID-19 cases with a mean age of 54.93±17.37 years. From all, 58.7% (n=529) were men and 9.9% (n=83) death occurrences were recorded. Sixty-five years of age was estimated as the effective changepoint that could change the cure rate of patients at the end of the follow-up times. Conclusion: The cure rate at any time during 30 and 180 follow-up days was noticeably higher in COVID-19 patients younger than 65 years who had cancer.