5561) and 80% (5134/6419) at phase I and 77% (3047/3958) and 80% (3972/4936) at phase II, respectively. Verbal autopsies were conducted for 94% of all deaths,9 with 53% of the verbal autopsy reports obtained from close relatives (spouse 19%, child 7%, parent 16% and sibling 10%). At each follow-up of the study, testing for the presence of HIV antibody was performed.13 The Kisesa HIV cohort is located in Magu District, Mwanza Region, in northwestern Tanzania. The cohort was established in 1994 (when baseline studies were conducted) and data collection is based on a biannual DSS that had conducted 14 phases by 2002 and sero-surveys repeated approximately every 3 years, with three testing surveys completed before 2002.10 14e17 The population in the DSS area grew from 19 354 in 1994 to 24 403 by 2002. Participation in the DSS is more than 98%, with proxy reporting accepted for absent household members. The average participation rate in sero-surveys was 72% in the ﬁrst three surveys. Deaths identiﬁed in the DSS are followed up with a verbal autopsy interview between 6 weeks and 6 months later, if a reliable informant can be identiﬁed who cared for the deceased during the ﬁnal illness. Verbal autopsy interviews were completed for 67% (420/629) of the adult male deaths and 64% (424/667) of the adult female deaths recorded in the DSS between 1994 and 2002; 94% of the verbal autopsy reports were obtained from close relatives (spouse 30%, child 28%, parent 21% and sibling 15%). The verbal autopsy tool The study teams identiﬁed deaths through the use of checklists of all individuals interviewed at the previous phase and discus- sions with village health workers, employers and surviving household members present at follow-up. Data were collected on the signs, symptoms and circumstances preceding death using a structured, closed, interviewer-led questionnaire. The verbal autopsy questionnaire was originally developed in Kisesa and contained speciﬁc questions related to symptoms of late-stage HIV and opportunistic infections14 and was used in that site from 1994 to 2002. A nearly identical questionnaire was adapted in Manicaland in both phase I and phase II. The questionnaires were administered in local languages (Shona, the predominant local language in Zimbabwe, and Swahili, in Tanzania). Interviewers were clinical ofﬁcers/certiﬁed nurses who received special training on how to administer the verbal autopsy questionnaire. Verbal autopsy informants were parents, spouse, other relatives or a neighbour (in rare circumstances when close relatives were not available). The interviews were conducted after the recognised mourning period, in a respectful and unhurried manner. In Kisesa, the interviewer gave a small, culturally appropriate gift (a bar of soap) to the person with whom the interview was conducted, as a token of appreciation of the time devoted to answering the lengthy questionnaire. Ethical approval for the DSS and all related procedures (such as the verbal autopsy interviews) was granted by the Tanzanian Medical Research Co-ordinating Committee for the Kisesa study and by the Zimbabwe Medical Research Council for the Manicaland Study. Research report Validation procedures We developed a computer algorithm that creates a set of criteria for classifying AIDS deaths based on verbal autopsy data.12 Seventy-ﬁve per cent of deaths from Manicaland phase I were randomly assigned to a training dataset. From this training dataset, all signs/symptoms with a likelihood ratio >1.92 in univariate analyses were considered as potential identiﬁers of AIDS death (as deﬁned below). Signs/symptoms were added to a list of criteria one at a time, based on the highest speciﬁcity. Verbal autopsy deaths with that sign/symptom were then removed from the dataset, and speciﬁcities of the remaining signs/symptoms were recalculated. Sensitivity was plotted against 1especiﬁcity in a receiver operator characteristic (ROC) plot. (The ROC is a tool used to select an optimum cut-off for a diagnostics test based on the trade-off of sensitivity and spec- iﬁcity.) These steps were repeated until the (equally weighted) sensitivity and speciﬁcity of the list of symptoms was maximised (ie, the point closest to the top left hand corner of the ROC plot). Deaths were classiﬁed as HIV/AIDS associated if the deceased had one or more of the criteria on the list. The sensitivity and speciﬁcity of the list was then tested on the Manicaland phase I test data (the remaining 25% of deaths), all phase II and all Kisesa data. AIDS death in the gold standard was deﬁned as an indi- vidual who was (a) HIV positive at baseline survey based on antibody testing; (b) was not reported to have suffered major injury from motor vehicle accident, self-inﬂicted (suicide), or accidentally (accident) or deliberately inﬂicted by another person (homicide) in the 2 weeks before death; and (c) did not die from direct obstetric causes (death during labour).12 Preliminary analyses highlighted that HIV prevalence among the deceased was markedly lower among the relatively older adults, so anal- yses were stratiﬁed at age 45 years. RESULTS There were a total of 376 and 219 deaths in phase I (1998e2003) and phase II (2003e2005), respectively, of the Manicaland study and 197 in Kisesa (1994e2002), among 19e59-year-olds for whom there was a verbal autopsy and a conclusive HIV test done within 3 years of death. A minority of deaths occurred in the 45e59-year age group (13%, 17% and 19%) in Manicaland phase I, phase II and Kisesa cohorts, respectively (table 1). In Manica- land, approximately 75% of deaths were caused by AIDS, compared with 51% in Kisesa 15e44-year-olds and 33% among Kisesa 45e59-year-olds. Herpes zoster, acute respiratory tract infections, abscesses and sores, acute diarrhoea and tuberculosis were all less commonly reported in Kisesa than in Manicaland (table 2). For deaths under the age of 45 years, weight loss, jaundice, tumours, respiratory tract infections and tuberculosis were less common among HIV-positive deaths in Kisesa compared with Manicaland. In applying the previously developed algorithm to Kisesa data, the sensitivity in classifying AIDS deaths was low (67%), mainly because of poor sensitivity (46%) in the 45e59-year age group. Table 1 Prevalence of AIDS mortality in Kisesa and Manicaland verbal autopsy subjects Age range (years) Total with HIV test and VA (n) AIDS deaths in gold standard (n (%)) VA, verbal autopsy. J Epidemiol Community Health 2010;64:330e334. doi:10.1136/jech.2008.081554 Manicaland Phase I train 15e44 237 173 (73%) Phase I test Phase I test Phase II test Phase II test 15e44 88 64 (73%) 45e59 51 40 (78%) 15e44 181 137 (76%) 45e59 38 28 (73%) Kisesa Test 15e44 158 81 (51%) Test 45e59 39 13 (33%) 331