Conference Abstract | Volume 8, Abstract 7 | Published: 11 Jul 2025
Hellen Kaoma1,2,3,&, Oliver Mweso1, Dabwitso Banda1,2, Nyambe Sinyange1,2, Cephas Sialubanje3, Duncan Chanda4, William Malambo5
1Zambia Field Epidemiology Training Program, Lusaka, Zambia, 2Zambia National Public Health Institute, Lusaka, Zambia, 3Levy Mwanawasa Medical University, Lusaka, Zambia, 4Ministry of Health, Lusaka, Zambia, 5U.S. Centers for Disease Control and Prevention, Division of Global HIV/TB, Lusaka, Zambia
&Corresponding author: Hellen Kaoma, Zambia National Public Health Institute, Lusaka, Zambia, Email: biancakaoma@gmail.com
Received: 03 Jun 2024, Accepted: 11 Aug 2024, Published: 11 Jul 2025
This is part of the Proceedings of the Zambia Field Epidemiology Training Program Alumni Conference, September 11 – 13, 2024
Keywords: COVID-19, Hospital, Mortality, Survival Analysis, Zambia
©Hellen Kaoma et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Cite this article: Hellen Kaoma et al. Modelling in-hospital survival and associated factors among hospitalized patients with COVID-19, Zambia, March 2020 to December 2022: A retrospective cohort study. Journal of Interventional Epidemiology and Public Health. 2025;8(Conf Proc 4):7. https://doi.org/10.37432/JIEPH-CONFPRO4-00007
Numerous studies document the in-hospital survival time of COVID-19 patients, commonly reporting older, male gender, comorbidities, and compromised immune function. Yet few examined the variability of baseline mortality hazard. We estimated the median survival time for hospitalized COVID-19 patients, identified factors associated with in-hospital mortality, and assessed whether mortality risk changed over time.
We analysed routinely collected clinical information of patients admitted to COVID-19 treatment centres in five Zambian cities, these being Lusaka, Ndola, Living stone, Kabwe, and Kitwe between Mar-2020 and Dec-2022. Severe COVID-19 was defined as having oxygen saturation <90%, respiratory rate >30 breaths/minute, or oxygen therapy requirement. We fitted Kaplan-Meier, Cox proportional hazard and parametric survival models in R, and right censored patients discharged from the hospital.
Out of 3,921 patients, a minority (N=865, 22.6%) died with majority being male (65%). The median survival time was 25 days (IQR: 9-124) and mortality rate was 29.8 deaths per 1,000 persons per day. Factors associated with in-hospital time-to-mortality included: age ≥60 compared to <60 years (adjusted hazard ratio [aHR]: 2.90, 95% confidence interval [CI]: 1.78-4.74), having ≥3 comorbidities (aHR: 1.90; 95% CI: 1.23-2.92), COVID-19 severity (aHR: 4.52; 95% CI: 3.01-6.79) and ≥1 vaccine dose (aHR: 0.43; 95% CI: 0.27-0.69). The baseline mortality hazard was disproportional to time but increased for 5 days and then decreased over time. In the parametric accelerated failure time model, the effect of severe COVID-19 was to shorten (accelerate) the median time-to-mortality (adjusted time ratio [aTR]: 0.25; 95% CI: 0.18-0.36) while vaccinated patients had a longer (decelerated time-to-mortality) median survival time (aTR: 2.59; 95% CI: 1.63-4.09).
In-hospital mortality risk factors in Zambia reflect data reported in the Western world, including age, comorbidities, COVID-19 severity, and vaccination status. However, the increased and then decreased mortality risk over time would suggest that patients who died may have presented late to the hospital. Strengthening health systems and educating the public about early seeking and when to seek for care for COVID-19 may likely reduce in-hospital mortality in Zambia.
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