Challenges for scaling up ART in a resource-limited setting: a retrospective study in Kibera, Kenya.

Objective: To determine levels of dropout and adherence in an antiretroviral treatment (ART) program in sub-Saharan Africa's largest urban informal settlement, Kibera, in Nairobi, Kenya.

Method: Retrospective cohort study.

Results: : Of 830 patients that started ART between January 2005 and September 2007, 29% dropped out of the program for more than 90 days at least once after the last prescribed dose.