Effectiveness of Antiretroviral Treatment on the Transition Probability of Immunological State of HIV/AIDS Patients: A Markov Chain Model on the Iranian “National Registry of HIV/AIDS Care” Database

Abstract

Antiretroviral therapy (ART) has improved survival and clinical course amongst HIV/AIDS patients. CD4 cell count is one of the most critical indicators of the disease progression. With respect to the dynamic nature of CD4 cell count during the clinical history of HIV/AIDS, modeling the CD4 cell count changes, which represents the likelihood of disease progression, is of interest to establish or revise treatment strategies and, specifically, to determine the stage at which giving ART is more clinically effective. In this historical cohort study on 917 HIV/AIDS patients in the Iranian “National Registry of HIV/AIDS Care” database, we used the Markov chain model to predict the effectiveness of the ART based on the transition probability of CD4 cell count, measured before and after initiating ART. We found that when the ART was initiated in the earlier stages of HIV infection, good prognosis might be more accessible; that is, after initiating ART at state$\text{CD}4\ge 500$, the probability of staying at this state was statistically increased than before the treatment ($P<0.001$). Also, it was found that initiating ART significantly decreased the probability of CD4 cell count transition to the lower counts ($P_{\text{CD}4\ge 500‐\text{to}‐350\le \text{CD}4<500}<0.001$,$P_{350\le \text{CD}4<500‐\text{to}‐200\le \text{CD}4<350}<0.001$, and$P_{200\le \text{CD}4<350‐\text{to}‐\text{CD}4<200}<0.001$). In addition, initiating ART showed a statistically significant increase in the probability of CD4 cell count transition from a lower state ($350\le \text{CD}4<500$) to a higher state ($\text{CD}4\ge 500$) ($P=0.009$). Furthermore, When CD4 count reaches under 200, even after the initiation of therapy, the probability of CD4 cell count transition to higher levels was not significant ($P>0.05$). In summary, these results have a message for primary healthcare organizations to extensively identify HIV patients and initiating ART as early as possible.