On the Estimation of Survival of HIV/AIDS Patients on Antiretroviral Therapy Using NPMLE Method: An Application to Interval Censored Data

The main objective of this paper is to estimate the survival of HIV/AIDS patients who are undergoing Antiretroviral Therapy in an ART centre, Delh i. Non Parametric Maximum Likelihood Estimation NPMLE (E-M) for interval censoring and KM survival plot for left, right and mid-point imputation have been used to estimate the survival of these patients. It has been observed that the mid-point imputed survival p lot has a very similar and consistent pattern as obtained by NPMLE (E-M) method. Considering these mid-point imputed value as right censored data, Cox PH model and Accelerated Failure t ime Model (AFTM) have been applied to identify the effects of prognostic factors like age, sex, mode of transmission, baseline CD4 cell count, hemoglobin, baseline weight and s moking habits on survival o f the patients. The Akaike Information Criterion (AIC) has been employed to compare the efficiency of these models and Cox-Snell residual is used to test the proportionality assumption.