Unveiling the hidden battle: Impact of Charlson comorbidities index on critical illness rate and mortality among hospitalized COVID-19 patients, comparing vaccinated and unvaccinated individuals in Kenya: A retrospective study

Abstract

Fatal outcomes were observed in hospitalized COVID-19 patients, particularly among those who were unvaccinated and had comorbidities. Robust research is needed to validate these findings in both vaccinated and unvaccinated groups. The study, involving 1792 COVID-19 patients, explored the links between comorbidities and fatal outcomes. This single-center retrospective cohort study employed Cox proportional hazard regression to analyze the impact of comorbidities on COVID-19 fatalities, adjusting for age, sex, smoking and vaccination status. Males experienced severe illness (75%) or mortality (76.8%). Notably, most people admitted to the ICU were over 31 years old (96.2%), with individuals over 60 years old facing the highest fatality rate (61.6%). The proportion of ICU admissions increased with the Charlson Comorbidities Index (CCI), with CCI 1-3 at 51.0% and CCI >4 at 52.6%. Mortality linked to CCI was 55.4% for CCI 1-3 and 52.6% for CCI >4. The risk of ICU admission and mortality both increased with higher CCIs. Common comorbidities such as obesity, cardiovascular diseases, diabetes, chronic liver disease, chronic pulmonary obstructive disease, cancer/malignancy, chronic kidney disease and hypertension predicted critical illness and mortality among COVID-19 patients. The area under the receiver operating characteristic curve (AUC-ROC) for predicting critical illness was 0.90 (95% CI: 0.89- 0.93), and for mortality, it was 0.90 (95% CI: 0.88-0.91). Additional factors, such as HIV and rheumatoid arthritis, independently predicted critical illness and mortality. The risk of critical illness and mortality showed an increase with the Charlson Comorbidities Index, both among vaccinated and unvaccinated individuals.