Reference Intervals for Absolute and Percentage CD4(+) T Lymphocytes among an Apparently Healthy Population in Addis Ababa, Ethiopia

BACKGROUND: Reference intervals for clinical laboratory parameters differ based on several factors, including age, sex, genetic variation, and geographic location. This variation influences clinical decisions and treatment monitoring. Currently, Ethiopia has used adopted reference intervals from manufacturer values derived from non-Africans. Therefore, the aim this study was to determine reference intervals for absolute and percentage CD4(+) T cells for an apparently healthy population in Addis Ababa, Ethiopia. METHODS: A community-based cross-sectional study was conducted on 361 apparently healthy people in four subcities in Addis Ababa from January to June 2019. Sociodemographic and clinical data were collected using a structured questionnaire after informed consent had been obtained. Blood samples were collected and CD4(+) T-lymphocyte enumeration performed using a BD FACSPresto near-patient CD4 counter. Data were entered and analyzed using SPSS 20. Reference intervals were determined by a nonparametric test estimating percentiles 2.5 (lower limit) and 97.5 (upper limit) with 95% CIs. P<0.05 was considered statistically significant. RESULTS: A total of 337 (183 female and 154 male) healthy participants of median age 28 (IQR 17–35) years were included in the final analysis. Medians of absolute and percentage CD4(+) T-cell counts (932.0 and 42.9, respectively) of female participants were significantly higher than male participants (802.5 and 38.7, respectively; P<0.05). Reference intervals for absolute CD4(+) T-cell count and percentages in males were 483.8–1,310 cells/µL and 18.1–57.3 and in females 447.8–1,479.8 cells/µL and 25.6–58.9, respectively. CONCLUSION: The CD4(+) T-count reference intervals established in this study showed some inconsistency from the manufacturer’s provided values and other studies and also revealed sex differences, necessitating sex-specific locally established reference intervals.