In the June 1st issue of the Journal of the Acquired Immunodeficiency Syndrome, Dr. Felipe Garcia and colleagues at the University of Barcelona in Spain report on the influence of baseline CD4+ T cell count, viral load, and age on immunologic outcome in 861 naïve patients with HIV infection treated with at least three highly active antiretroviral drugs.

The investigators classified patients into quartiles according to baseline CD4+ T cell count. For each patient, they analyzed baseline and "last" CD4+ T cell count, using a linear regression model to account for the fact that individual patients had varying intervals between their first and last measurements.

After a median follow-up of 173 weeks, the relative risk of having a last determination of CD4+ T counts less than 200 cells per microliter was 1.0 for patients counts of 350-499 cells per microliter, 0.92 for patients with 200-349 cells per microliter, and 0.79 for patients with less than 200 cells per microliter at baseline.

On the other hand, the relative risks of having a CD4+ T cell count above 500 cells per microliter at the final determination were 0.32, 0.69, and 0.94, respectively, for patients with baseline counts of less than 200, 200-349, and 350-499 cells per microliter.

"The increase in CD4+ T cells from baseline…was maintained for up to 4years of follow-up," the authors said. "This increase seemed to slow down after approximately 3 years [and] plateau after 4-5 years…even in patients who achieved and maintained viral suppression."

The investigators found no significant differences among the three higher baseline-count groups in the proportion of patients who progressed to AIDS or died. Similarly, baseline age above or below 40 years had no significant effect on progression to AIDS or death.

The authors note that CD4+ T cell counts in their patients never returned to normal. Still, they conclude their findings suggest there is no "point of no return" in CD4+ T cell counts, beneath which HAART should not be initiated.

"Long-term immune recovery is possible regardless of baseline CD4+ T cell count," the researchers conclude. "However, patients who start therapy with a CD4+ T cell count below 200 cells per microliter have poorer immunologic outcome[s]."