Since 2003, there has been unprecedented global investment in delivering antiretroviral therapy (ART) for HIV infection to populations in resource-poor countries. The benefit of ART to an individual with advanced HIV infection is well established, (1-5) and programmes for its widespread introduction (6) can reduce the substantial increase in HIV-related adult mortality (7,8) that has occurred as the HIV pandemic has developed. The effect of ART roll-out can be measured in many ways--treatment coverage, behaviour change, the emergence of resistance, etc. (9,10)--but ultimately changes in population mortality are the most important measurable effect. In particular, national governments and international agencies faced with limited resources and competing demands need scientifically robust estimates of the potential effect at the population level of making a huge investment in ART roll-out. (11)
South Africa has over 5.5 million HIV-infected individuals and 14% of the world's HIV+ population. (8) The HIV pandemic is estimated to have reduced life expectancy in the country by about 13 years, from 64 in 1990 to 51 in 2005. (12) The northern province of KwaZulu-Natal carries the greatest burden of infection, with an estimated (12) 1.54 million HIV+ residents, which is more than the combined total of HIV+ people in Botswana and Uganda.
We composed an open cohort within an ongoing demographic surveillance system to investigate adult all-cause and HIV-related mortality trends in 2000-2006 in a population serviced by a well-functioning, public-sector ART programme initiated in 2004. (13)
Study area and population
The Africa Centre for Health and Population Studies hosts a demographic surveillance programme in the district of Umkhanyakude in the province of KwaZulu-Natal, South Africa. (13,14) Although it is largely rural, the demographic surveillance area (DSA), consisting of 435 square kilometres ([km.sup.2]), also includes a township and periurban informal settlements. Biannual surveillance visits to all homesteads within the DSA were performed by fieldwork teams to record births, deaths and any in- and out-migrations of household members. All household members reported during surveillance visits were followed up, whether or not they were residing in the homestead in subsequent visits. Thus, at each surveillance visit a key household informant is presented with a list of the household members recorded at the previous visit, and the residential and household membership status of each individual--i.e. whether or not he or she still lived in the homestead or had moved or died since the last visit--is recorded. The preferred key informant is the household head or a senior household member if the household head is absent. If by the fourth repeat visit to a homestead no suitable key informant is present, the case is referred to a tracking team that makes three more attempts, after hours or over weekends, to contact the key informant. The identity of the key informant is recorded and attempts are made to contact the same one for every visit. Household membership is self-defined on the basis of links to other household members. A resident is a member of a household who normally lives in the same homestead as the other members, whereas a non-resident household member normally lives elsewhere but retains links to the household. Individuals cease to be members of households when they terminate such links or die. Migrations to or from places outside the DSA (external migrations) were distinguished from those within the DSA (internal migrations). On average, 99.5% of all households participated in the biannual surveillance rounds, and the constant review of household members ensured high data quality and reduced the likelihood that any death would be missed.
Since the beginning of 2003, the HIV infection status of residents in the DSA aged 15-49 years (females) and 15-54 years (males) has been determined through separate annual sero-surveillance. …