This article presents baseline and retrospective data from the initial phase of the TAHOD cohort. Among patients not on antiretroviral treatment, there was a nonsignificant decrease in CD4 count of 0.9 cells/μL each month. Among patients who started HAART and had a baseline and 6-month CD4 count measurement, the mean 6-month CD4 count increase was 115 cells/μL. Among patients who started HAART and had a viral load assessment at 6 months, 69% of patients had an undetectable viral load.
A higher rate of AIDS-defining illnesses at study entry was found among the TAHOD patients (43% of patients) compared with that found in cohorts in Western countries (18%–19% in Australia4
and 21% in the Antiretroviral Cohort Collaboration5
). More importantly, tuberculosis was the most frequently reported AIDS-defining illness among the TAHOD patients compared with those in Western countries, where P. carinii
pneumonia and Kaposi’s sarcoma are most common.4,6
The rate of CD4 change among the TAHOD patients while not on antiretroviral treatment was similar to the rate found in Western countries whether the patients were homosexual men (+0.24 to −42.7 cells per month in the United States7
and −5.6 cells per month in the Netherlands8
) or injecting drug users (−3.2 cells per month in Baltimore, MD, USA9
Individuals treated with HAART experience reductions in viral load and restoration of CD4 cell counts. Smith et al10
observed a monthly increase of 11.6 cells/μL after an increase of 97.2 cells in the first month among treatment-naive patients whose viral loads remained below 500 copies/mL for prolonged periods. In the EuroSIDA study, Mocroft et al11
found that among 413 patients who received at least 3 drugs in which at least 1 new PI or NNRTI was included, 69% subsequently experienced at least a 1 log decline in viral load and 49% achieved a viral load <500 copies/mL. In the OzCombo trials,12,13
naive patients administered 2 NRTIs plus indinavir experienced a mean CD4 count increase of 125 to 150 cells/μL at 6 months and 58% had an HIV viral load <50 copies/mL at 12 months, whereas naive patients receiving 2 NRTIs plus nevirapine experienced a mean CD4 count increase of 100 to 150 cells/μL and 70% to 80% achieved a viral load <50 copies/mL. Using retrospective data from the TAHOD, patients starting HAART experienced a mean CD4 count increase of 115 cells/μL at 6 months, with 69% of patients achieving an undetectable viral load, which was comparable to results from other studies in Western countries.
In our analyses, patients receiving a HAART regimen containing an NRTI and NNRTI but excluding a PI had better responses at 6 months after starting treatment in terms of CD4 count increases and HIV viral load. Although similar findings have been reported in other cohort studies,14
this result may reflect selection biases to different treatment regimens at different sites within the TAHOD and should be interpreted cautiously. Our analyses also indicated that in terms of HIV viral load 6 months after starting HAART, patients infected with HIV through heterosexual contact seemed to respond more poorly than patients infected through homosexual contact. Unlike Galai et al,15
who followed their patients from seroconversion, most patients in the TAHOD did not have a clear seroconversion date and might be at various stages of disease progression. Analyses of prospective data from the TAHOD, as such data become available, should provide more robust assessments of the effect of these and other covariates on patients’ responses to HAART.
There are a number of limitations to be considered in relation to the findings. First, analysis of the rate of CD4 change and response to HAART in terms of CD4 cell count and viral load were based on retrospective data. With data transfer provided twice each year, prospective data will become available for further analyses. Second, the TAHOD patients, recruited based on clinicians’ judgment of good follow-up, cannot be seen as entirely representative of HIV patients in the Asia-Pacific region. However, studies on the natural history of HIV disease and responses to antiretroviral treatment can still be derived from a cohort of TAHOD patients with good follow-up, albeit with some limitation on generalizability of findings. Third, there were variations in terms of diagnostic criteria and clinical definitions as well as assay technique or reagents across the TAHOD participating sites. Standardized data collection forms and data management training for each site were used to try to maximize consistency.4
Analyses of retrospective data in the TAHOD suggest that the overall response to HAART in Asian patient populations is similar to that seen in Western countries. The TAHOD is expected to recruit more than 2000 patients when fully recruited. Potential sites in countries such as Indonesia and Viet Nam are likely to contribute data to the TAHOD in the near future. With prospective follow-up, the TAHOD should be able to assess the natural history of HIV disease and response to antiretroviral treatments in patients from the Asia and Pacific region. Future analyses based on prospective follow-up data include identifying predictors of short-term risk of clinical progression and the risk and predictors of mycobacterial tuberculosis among the TAHOD patients.