A paper published today in PLoS Medicine using CASCADE data has shown that there is no need to take into consideration the CD4 slope prior to the start of HIV therapy when deciding whether to initiate therapy.
The CASCADE Collaboration, is a large collaborative study of 25 cohorts of HIV patients with known date of seroconversion. Wolbers et al considered whether there was any evidence of an association between pre-therapy CD4 slope and the primary outcome (a first new AIDS-defining event or death).
A total of 2,820 HIV-positive patients initiating cART (combination antiretroviral therapy) were included in the study; the average pre-cART CD4 cell decline among them was 61 cells/ml/year. Of these, 255 experienced a new AIDS-related event or died after starting cART but the researchers found no evidence for an association between the primary outcome and the pre-cART CD4 slope or between survival and this slope. In addition, the rate of CD4 cell count decline was not significantly associated with progression to AIDS or death among 1,731 HIV-positive, symptom-free patients with CD4 cell counts above 350 cells/ml who were studied before cART was developed.
As well as showing that the rate of CD4 decline will not improve the prediction of clinical outcome, the findings also suggest that the rate of decline in individual patients is extremely variable over time. So, a rate measured at one time point cannot be used to predict the CD4 count in the future.
The findings of this study strongly suggest that knowledge of the current CD4 cell count and an assessment of other established risk factors for progression to AIDS are sufficient when deciding whether to initiate therapy in symptom-free HIV-positive patients.