Immunological predictors of HIV-related survival

While the prognostic role of CD4 lymphocyte count is well established, little is known about how other immunological factors are associated with HIV-related survivorship. CD8 lymphocyte count is reported to inhibit growth of HIV in vitro and to deter the development of cytomeglovirus infections. Scarce information exists, however, on its association with HIV-related survivorship. The objective of the present study therefore was to assess whether survival estimation could be improved by including CD8 lymphocyte count as a prognostic factor. The study sample consisted of 904 adult HIV-infected patients who were treated between 1992 and 1997 at a large southwestern academic medical centre in the US. Survival analysis using proportional hazards modelling showed that baseline CD4 lymphocyte was highly and positively predictive of HIV-related survival. By contrast, baseline CD8 count was not predictive of survival in the study cohort. While the interaction between CD4 and CD8 was not statistically significant in the present study sample, decomposition of this effect indicates that these factors may operate synergistically to predict survival. In conclusion, these findings suggest that clinicians may improve their prognostic accuracy by relying on both CD4 and CD8 lymphocyte counts rather than relying exclusively on CD4 counts.