Background:  Collaborations to evaluate ART have been established in developing and developed countries:  Low Income Countries (ART-LINC) and ART Cohort Collaboration (ART-CC).
Methods:  We compared responses to highly active antiviral therapy (HAART) in 3048 patients from countries in low-income countries (Botswana, Brazil, Cameroon, Ivory Coast, India, Malawi, Morocco, Nigeria, Senegal, South Africa, Thailand, Uganda) with 12,574 patients followed in countries in developed countries (Canada, France, Germany, Italy, Netherlands, Switzerland, United Kingdom, United States, EuroSIDA). All subjects were ART-naïve and were started with > 3 drugs. We measured changes in CD4 counts and the proportion reaching undetectable viremia (< 500 copies/mL) during the first 6 months, and mortality from all causes in the first year.
Results:  Characteristics at start of HAART in the developing and developed countries, respectively, were as follows: Median age 36 vs 38 years; proportion female, 50% vs 21%; median (IQR) CD4 count 107 (34 to 214) vs 250 (100 to 402) cells/µl; dominant risk group heterosexual vs homosexual. CD4 count and viral load at 6 months were available in 53% and 42% of patients from developing countries compared to 84% and 81% in the developed countries. Median (IQR) number of CD4 cells gained from baseline to 6 months in developing and developed countries was 92 (23 to 167) vs 90 (19 to 180), and the proportion reaching undetectable viremia by 6 months was 71.4% to72.2%,  188 vs 344 deaths occurred during 4385 vs 24310 patient-years of follow up. KM plots of mortality by baseline CD4 count are shown in the figure. Probabilities of death (95% confidence interval CI at 1 year ranged from 1.5% (0.6 to 3.9) vs 0.4% (0.2 to 0.6) in patients with > 350 cells, to 11.9% (9.3 to 15.1) vs 3.9% (2.0 to 5.2) in patients with <25 cells.
Conclusions:  Immunologic and virologic response appear to be similar for HIV positive individuals in the two groups of countries. Compared to the pre-HAART era, mortality was reduced substantially both in developing and developing countries. For given baseline CD4 levels, mortality was higher in the developing countries. The difference in early mortality was most pronounced for patients with advanced disease, possibly because a larger proportion of patients in the developing countries presented with severe opportunistic infections.

Keywords: Developing countries; HAART; Mortality