Objective: To analyze the occurring rules of human immunodeficiency virus (HIV) drug resistance under an unique therapy model among HIV-1 infected individuals on antiretroviral therapy (ART) in rural areas of Henan, China.
Methods: A cohort of 75 individuals on an ART regimen of zidovudine (ZDV), dideoxyinosine (ddI) and nevirapine (NVP) was established in March 2003. A total of 12 surveillance were conducted and 788 person-times were studied until 2010. The parameters of CD4 cell count and viral load (VL) were tested in each survey. And genotypic resistance testing was performed in patients with a failure of viral suppression. Survival analysis was used to estimate the occurrence time of resistance.
Results: The cumulative mortality rate was 16% (12/75) in the cohort. And the cumulative resistance rate was 88% (66/75) from 2004 to 2010. The rate of resistance reached 54.7% and the probability from susceptibility to drugs developing resistance decreased drastically from 100% to 45.3% within the first 1 year of initiation. The occurrence time of resistance for half of individuals in the cohort was at 12.0 months (95%CI 8.6 - 17.0) after initiation, 25.1 months (95%CI 19.0 - 33.3) in those whose VL was less than 4.0 lgU/ml and 4.8 months (95%CI 4.1 - 5.6) at VL > 4.0 lgU/ml during the first investigation. The individuals with an early occurrence of resistance within 12 months carried high risks for a failure of viral suppression and a decrease of CD4 counts.
Conclusion: The occurrence of resistance rises with the course of therapy. And the greatest probability for resistance is within the first 1 year of initial therapy. A high level of VL has a significant impact on the development of resistance. Preventing the occurrence of resistance during the initial therapy remains a key goal.