“Day 25”: a temporal indicator of stabilization of mortality risk among COVID-19 patients with high viral load

INTRODUCTION: The relationship between SARS-CoV-2 viral load and hospitalization and mortality among COVID-19 patients has been established. However, the estimation of the duration of time after which the risk of mortality of these patients stops escalating was not extensively discussed earlier. Stratifying patients according to their risk of mortality would optimize healthcare services and costs and reduce mortality. METHODOLOGY: In this retrospective observational study, hospital records were used to collect data of 519 COVID-19 patients from May through November 2020. Data included the clinical condition of patients, their viral loads, their admission chest computed tomography results (CO-RAD scale), and the duration of their hospitalization. A Kaplan–Meier analysis was constructed to estimate mortality risk concerning viral load. RESULTS: By the end of the study, 20.42% of patients were deceased. The cumulative mortality was: 36.1% (75/208) among patients with high viral load, 12.6% (28/222) in those with moderate viral load, and 3.4% (3/89) among those with low viral load. Predictors of mortality were: older age [adjusted hazard ratio (aHR) = 1.02, 95% CI: [1.00–1.03], (p = 0.05)], "being female" [aHR = 1.53 with 95% CI: [1.03–2.26], (p = 0.031), "high CO-RAD scale" [aHR = 1.32 (1.06–1.64), p = 0.013], "high viral load" [aHR = 4.59 (2.38–20.92), p = 0.017, ICU admission [aHR = 15.95; 95%CI:7.22–35.20, p < 0.001] and lymphocytosis [aHR = 1.89 45;95%CI:1.04–3.45, p = 0.036]. In the ICU-admitted patients, the median survival was 19 days and mortality stabilized at "day 25". For patients with high viral load, mortality rates stabilized at "day 25 post-admission" after which the risks of mortality did not change until day 40, while patients with low and moderate viral loads reached the peak and stabilized at day "20 post-admission". CONCLUSIONS: Initial high SARS-CoV-2 viral load might be used as an indicator of a delayed stabilization of mortality risk among COVID-19 patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41182-022-00483-8.