From the Guidelines
CD4 counts in lab results are typically reported as the number of CD4 T-cells per cubic millimeter (cells/mm³) of blood, along with the CD4 percentage, which is the percentage of total lymphocytes that are CD4 cells, normally 30-60%. The lab report will usually include both the absolute CD4 count and the CD4 percentage, with the absolute count being more commonly used for clinical decision-making 1. According to the most recent guidelines, a CD4 cell count with percentage should be obtained upon initiation of care, as it provides valuable information for assessing immune function and determining the need for prophylaxis against opportunistic infections 1. It's also important to note that CD4 counts can fluctuate due to factors like time of day, concurrent infections, or recent vaccinations, so trends over time are more meaningful than single measurements. Some key points to consider when interpreting CD4 counts include:
- Total CD4 cell counts of 200 and 500 cells/µL generally correspond to CD4 cell percentages of 14% and 29%, respectively 1
- In children aged <5 years, there is more variability in the absolute CD4 count, so CD4 percentage is generally preferred for monitoring immune status 1
- CD4 counts may be affected by a variety of medications and intercurrent illnesses, so caution should be applied when interpreting CD4 cell counts during these situations 2, 1. For HIV management, CD4 counts are usually monitored every 3-6 months, with more frequent testing for those with low counts or recent treatment changes. Measurement of the CD8 cell count and the ratio of CD4 cells to CD8 cells is unnecessary, as the results are not used in clinical decision making 1.
From the FDA Drug Label
The mean baseline CD4+ cell count was 279 cells/mm3 (range 3–956) The mean baseline CD4+ cell count was 245 cells/mm3 (range 2–1191) The median change in CD4+ cell count from baseline was 80 cells per mm3 at Week 48 The median CD4 count (percent) increase from baseline to Week 24 was 105 cells per mm3 (5%) The median CD4 count (percent) increase from baseline to Week 48 was 141 cells per mm3 (7%)
CD4 cell count appears in laboratory results as a numerical value, typically reported in cells per cubic millimeter (cells/mm3) of blood, with a range of values.
- The mean baseline CD4+ cell count is reported as 279 cells/mm3 and 245 cells/mm3 in two different trials.
- The median change in CD4+ cell count from baseline is reported as 80 cells per mm3 at Week 48.
- The median CD4 count increase from baseline is reported as 105 cells per mm3 (5%) at Week 24 and 141 cells per mm3 (7%) at Week 48. 3 4
From the Research
CD4 Count Measurement
- CD4 count is typically measured in cells per cubic millimeter (mm^3) of blood 5, 6, 7, 8
- A CD4 count of less than 200 cells/mm^3 is considered a sign of advanced HIV disease 5, 6, 8
- CD4 count measurement is crucial for detecting advanced HIV disease and evaluating antiretroviral treatment (ART) programs 8
Distribution of CD4 Count at ART Initiation
- The prevalence of CD4 count less than 200 cells/µL at ART initiation has declined over time in all regions, but remains concerningly high at ≥30% 8
- CD4 measurement has declined sharply in recent years, especially in sub-Saharan Africa, with some regions experiencing a decline from over 50% to less than 20% 8
Factors Associated with CD4 Count
- Age and baseline CD4 count are associated with CD4 recovery in HIV-1-infected individuals receiving long-term suppressive combination antiretroviral therapy (cART) 7
- Exposure to different nucleoside reverse transcriptase inhibitors (NRTIs) in initial cART is not significantly associated with variable rises in CD4 cell count 7
- The presence of mucocutaneous manifestations, lower total lymphocyte count, lower total white blood cell count, and higher erythrocyte sedimentation rate are associated with a CD4 count less than 200 cells/mm^3 6