Correlation between CD4 cell counts and the immune status among Critically ill HIV negative patients in intensive care units in Uganda

Abstract

Introduction: CD4 cells play a central role in regulation of adaptive cell mediated immune responses. Abnormal CD4 cells are usually reported in patients living with Human Immunodeficiency Virus (HIV), as a marker of their immune status, but not common practice among HIV negative patients. CD4 cell counts commonly fall low in HIV negative patients suffering from conditions such as viral illnesses, bacterial infections, sepsis, multiple organ system failure and trauma. In HIV negative individuals, a CD4 cell count provides a picture of the status of the adaptive immune system, with higher counts, typically signifying healthier immune systems. Use of CD4 cell counts as a measure of the immune status among critically ill HIV negative patients has not been established in Ugandan Intensive Care Units(ICUs), despite a high mortality of upto 40.1%, and yet CD4 is a single parameter that is simpler to perform . Objective: To assess the immune status of critically ill HIV negative patients admitted to ICUs in Kampala, using CD4 cell counts as a surrogate marker. Method: A multicentre prospective cohort study, conducted between 1st August 2017 to 1st March 2018 from four ICUs in Kampala. A sample size of 130 critically ill HIV negative patients were consecutively enrolled into the study. For each participant, we determined the HIV status, sociodemographics, clinical characteristics, CD4 cell counts, APACHE II score and found out a twenty eight day ICU mortality outcome. Data was collected using a standardized questionnaire by the principal investigator, and trained research assistants. It was double entered into EpiData 3.1 and exported to STATA 14 to apply bivariate and multivariate models for analysis. Descriptive and regression analysis for participant characteristics were presented as tables and figures. Results: After 28 day follow up, 71 [54.6%, 95% CI (45.9-63.3)] were low (less than 500 cells/mm³) CD4 counts and were not found to be significantly associated with 28-day mortality, OR (95%) 1 (0.4 – 2.4), p value = 0.093. CD4 Cell Count Receiver Operator Characteristic curve (ROC) area was 0.5195, comparable to APACHE II ROC area 0.5426 for predicting 24-hour mortality. Conclusion : CD4 cell counts were generally low among HIV negative critically ill patients. Low CD4 cells did not predict 28 day ICU mortality. CD4 cell counts were not found to be inferior to APACHE II score in predicitng 24 hour ICU mortality.