CD4 and AIDS: The studies of Mathieu et al. [68], Binquet et al. [69], and Shoko and Chikobvu [70] involved using the continuous-time Markov model constructed with clinical features, including the CD4 T cell count [68], viral load measurement [68], parameters associated with disease progression and immunological deterioration [69], and tuberculosis co-infection [69], allowing for the subsequent identification of potential predictor variables for HIV/acquired immunodeficiency syndrome (AIDS) progression in patients subjected to ART and immune deterioration.