The following information will be noted: patient age, weight, gender, race/ethnicity, viral load, CD4 cell count, serum creatinine and other available laboratory data, start of HAART therapy (TDF - vs non-TDF-containing), changes in drug treatment, co-morbidities (hypertension, diabetes mellitus, anemia, hepatitis C virus or hepatitis B virus infection), drug treatment for co-morbidities and non-HIV-related illnesses, and adherence by prescription refill. The study endpoints will be: time from treatment initiation-to-event (GFR decrease >25% from BL) analysis between TDF-containing vs non-TDF-containing antiretroviral therapy; number of patients who convert from National Kidney Foundation-defined mild to moderate renal impairment or from moderate to severe renal impairment in the TDF vs non-TDF-treated patients; effect of co-morbidities and concomitant medications on time to GFR decrease >25% from BL.