IntroductionClinical outcome is an important determinant of programme success. This study aims to evaluate patients’ baseline characteristics as well as level of care associated with lost to follow-up (LTFU) and mortality of patients on antiretroviral treatment (ART).MethodsRetrospective cohort study using routine service data of adult patients initiated on ART in 2007 in 10 selected hospitals in Nigeria. We captured data using an electronic medical record system and analyzed using Stata. Outcome measures were probability of being alive and retained in care at 12, 24 and 36 months on ART. Potential predictors associated with time to mortality and time to LTFU were assessed using competing risks regression models.ResultsAfter 12 months on therapy, 85% of patients were alive and on ART. Survival decreased to 81.2% and 76.1% at 24 and 36 months, respectively. Median CD4 count for patients at ART start, 12, 18 and 24 months were 152 (interquartile range, IQR: 75 to 242), 312 (IQR: 194 to 450), 344 (IQR: 227 to 501) and 372 (IQR: 246 to 517) cells/µl, respectively. Competing risk regression showed that patients’ baseline characteristics significantly associated with LTFU were male (adjusted sub-hazard ratio, sHR=1.24 [95% CI: 1.08 to 1.42]), ambulatory functional status (adjusted sHR=1.25 [95% CI: 1.01 to 1.54]), World Health Organization (WHO) clinical Stage II (adjusted sHR=1.31 [95% CI: 1.08 to 1.59]) and care in a secondary site (adjusted sHR=0.76 [95% CI: 0.66 to 0.87]). Those associated with mortality include CD4 count <50 cells/µl (adjusted sHR=2.84 [95% CI: 1.20 to 6.71]), WHO clinical Stage III (adjusted sHR=2.67 [95% CI: 1.26 to 5.65]) and Stage IV (adjusted sHR=5.04 [95% CI: 1.93 to 13.16]) and care in a secondary site (adjusted sHR=2.21 [95% CI: 1.30 to 3.77]).ConclusionsMortality was associated with advanced HIV disease and care in secondary facilities. Earlier initiation of therapy and strengthening systems in secondary level facilities may improve retention and ultimately contribute to better clinical outcomes.