Low mortality risk but high loss to follow-up among patients in the Tanzanian national HIV care and treatment programme G. Somi 1 , S. C. Keogh 2 , J. Todd 3,4 , B. Kilama 1 , A. Wringe 3 , J. van den Hombergh 5 , K. Malima 6 , R. Josiah 1 , M. Urassa 7 , R. Swai 1 and B. Zaba 3 1 Epidemiology Unit, National AIDS Control Programme, Dar-es-Salaam, Tanzania 2 University College London, UK 3 Population Studies Department, London School and Hygiene and Tropical Medicine, UK 4 TAZAMA Project, National Institute for Medical Research, Mwanza, Tanzania 5 PharmAccess International, Dar-es-Salaam, Tanzania 6 Faculty of Nursing, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania 7 National Institute for Medical Research (NIMR), Mwanza, Tanzania Abstract objective To analyse survival and retention rates of the Tanzanian care and treatment programme. methods Routine patient-level data were available from 101 of 909 clinics. Kaplan–Meier probabil- ities of mortality and attrition after ART initiation were calculated. Mortality risks were corrected for biases from loss to follow-up using Egger’s nomogram. Smoothed hazard rates showed mortality and attrition peaks. Cox regression identified factors associated with death and attrition. Median CD4 counts were calculated at 6 month intervals. results In 88,875 adults, 18% were lost to follow up 12 months after treatment initiation, and 36% after 36 months. Cumulative mortality reached 10% by 12 months (15% after correcting for loss to follow-up) and 14% by 36 months. Mortality and attrition rates both peaked within the first six months, and were higher among males, those under 45 kg and those with CD4 counts below 50 cells / ll at ART initiation. In the first year on ART, median CD4 count increased by 126 cells / ll, with similar changes in both sexes. conclusion Earlier diagnoses through expanded HIV testing may reduce high mortality and attrition rates if combined with better patient tracing systems. Further research is needed to explore reasons for attrition. keywords HIV infections, antiretroviral therapy, national health programs, Tanzania, mortality, lost to follow-up Introduction HIV care and treatment programmes have scaled up rapidly over the past 5 years in sub-Saharan Africa, with large increases in numbers initiating treatment, and substantial mortality declines in the HIV infected popula- tion (UNAIDS 2010; WHO 2010). Estimated ART cover- age in the region increased from 28% to 37% from December 2008 to December 2009 (WHO 2010). However, increases in ART uptake have been accom- panied by rising attrition in national programmes (Brinkhof et al. 2008; Cornell et al. 2010; WHO 2010). Meta-analyses of sub-Saharan African ART programmes have yielded cumulative retention figures of 75–80% after 12 months on treatment and 67–77% at 24 months (Fox & Rosen 2010; Tassie et al. 2010). High attrition leads to underestimates of mortality on ART as patients lost to follow-up experience higher mortality than those remain- ing in programmes (Brinkhof et al. 2009b). Rigorous monitoring systems are needed to ensure accurate estimates of programme performance indicators such as attrition, mortality and treatment outcomes. Country-level analyses of routinely collected patient data in national programmes are important for evaluating programme performance over time. Despite numerous studies of ART patient outcomes in sub-Saharan Africa, few countries have presented national-level data from multiple sites incorporated into their ART programmes. Cohort analyses of patients in national programmes are often restricted to sub-regions (Boulle et al. 2008), or small sample sizes (Bussmann et al. 2008; Lowrance et al. 2009; Cornell et al. 2010). This paper is the first to report detailed national estimates of retention, mortality and treatment outcomes and their determinants in the Tropical Medicine and International Health doi:10.1111/j.1365-3156.2011.02952.x volume 17 no 4 pp 497–506 april 2012 ª 2012 Blackwell Publishing Ltd 497