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OBJECTIVE: To compare alternative methods to vital registration systems for estimating adult mortality, and describe patterns of mortality in Manicaland, Zimbabwe, which has been severely affected by HIV. METHODS: We compared estimates of adult mortality from (1) a single question on household mortality, (2) repeated household censuses, and (3) an adult cohort study with linked HIV testing from Manicaland, with a mathematical model fitted to local age-specific HIV prevalence (1998 -2000). FINDINGS: The crude death rate from the single question (29 per 1000 person-years) was roughly consistent with that from the mathematical model (22 -25 per 1000 person-years), but much higher than that from the household censuses (12 per 1000 person-years). Adult mortality in the household censuses (males 0.65; females 0.51) was lower than in the cohort study (males 0.77; females 0.57), while mathematical models gave a much higher estimate, especially for females (males 0.80 -0.83; females 0.75 -0.80). The population attributable fraction of adult deaths due to HIV was 0.61 for men and 0.70 for women, with life expectancy estimated to be 34.3 years for males and 38.2 years for females. CONCLUSION: Each method for estimating adult mortality had limitations in terms of loss to follow-up (cohort study), under-ascertainment (household censuses), transparency of underlying processes (single question), and sensitivity to parameterization (mathematical model). However, these analyses make clear the advantages of longitudinal cohort data, which provide more complete ascertainment than household censuses, highlight possible inaccuracies in model assumptions, and allow direct quantification of the impact of HIV.

Objectives: Reliable data on sexual behaviour trends are needed to evaluate HIV interventions in sub-Saharan Africa but are difficult to obtain due inter alia to social desirability bias. The objective of this paper is to assess whether the use of informal confidential voting interviews (ICVI) was associated with greater reporting of socially proscribed behavioural risk factors for HIV infection than were conventional interviewing methods. Methods: Comparison of changes in reports of risk behaviours for HIV infection in ICVI versus face to face interviews (FTFIs) between the first two rounds of a large scale, longitudinal, population based survey in Manicaland, Zimbabwe. Examination of factors that could contribute to observed changes in the effect of ICVI, including temporal changes in response error and social desirability, and factors affecting statistical power to detect differences between methods—that is, reductions in the prevalence of risk behaviours and sample size. Results: Enhanced reporting of HIV associated risk behaviours in ICVI interviews was not so apparent in the second round as in the first round of the survey, particularly for less frequently reported behaviours. Levels of reported HIV associated risk behaviour and sample sizes both declined between the two survey rounds. The level of response error was higher in ICVI interviews than in FTFI interviews but did not alter over time. Conclusion: ICVI interviews can reduce social desirability bias in data on HIV associated risk behaviours. The extent and direction of change in net reduction in bias over time remains uncertain and will depend on local circumstances.