Objective: To describe a population-based rural cohort of HIV-1-seropositive and seronegative individuals established in 1990 in south-west Uganda, and determine survival times in the cohort.
Design: Prospective cohort study.
Methods: Participants were recruited from a large population study, and invited to attend a clinic every 3 months. They were seen by clinicians who administered detailed medical questionnaires and undertook a physical examination.
Results: By the end of 1995, 390 (79%) of the 491 people asked to enrol in the natural history cohort (NHC) had done so. Ninety-three were prevalent cases of HIV infection detected during the initial survey round of the general population cohort in 1989/1990, 66 were subsequent incident cases, 177 were age-matched HIV-negative controls and 54 were HIV-negative spouses of HIV-positive individuals. Twenty participants seroconverted in the NHC. The age-standardized mortality rates per 1000 person-years for the prevalent, incident, and negative cases were 156.5 [95% confidence interval (CI), 115.8-211.4], 35.0 (95% CI, 16.4 75.0) and 13.5 (95% CI, 7.3-25.1), respectively. The median survival time from enrolment to death for the prevalent cases was 4.5 years (95% CI, 3.5- > 5.2); > 5.4 years from seroconversion for the incident cases; and > 5.2 years from enrolment for the HIV-negative cases. The 5-year cumulative survival for prevalents, incidents and HIV-negative participants was 46%, 83% and 94%, respectively.
Conclusions: We have described an NHC of HIV-positive and HIV-negative participants which is representative of the general population. The NHC was established over 5 years ago; it is continuing and we are maintaining good compliance rates. Survival probabilities in the cohort were lower than most other reported studies.
PIP: To enhance understanding of the natural history of HIV-1 infection among the general population in Africa, a population-based cohort of HIV-prevalent (n = 93) and HIV-incident (n = 66) cases, HIV-negative controls (n = 177), and seronegative partners of HIV-positive cases (n = 54) was recruited in rural southwest Uganda. Between 1990 and 1995, 1353 people-years (PY) of observation were achieved. There were 20 seroconversions during this period. The median duration from enrollment to seroconversion were 25 months for negative controls and 6 months for negative discordants. Of the 64 deaths over the 5-year study period, 54 involved HIV-infected subjects. The age-standardized mortality rates for the prevalent, incident, and negatives per 1000 PY of observation were 156.5 (95% confidence interval [CI], 115.8-211.4), 35.0 (95% CI, 17.4-75.0), and 13.5 (95% CI, 7.3-25.1), respectively. There were no significant differences in the gender-specific mortality rates per 1000 PY in males (48.9) and females (45.7). The median ages at death of prevalent, incident, and negative participants were 33, 53, and 53 years, respectively. The median survival times from enrollment to death were 4.5 years for prevalent cases, over 5.4 years for incident cases, and over 5.2 years for HIV-negative cases. At 5 years, the cumulative survival probabilities for prevalent, incident, and negative cases were 46%, 83%, and 94%, respectively, considerably lower than those reported in other studies. Follow-up of the cohort will continue, and future papers will address the clinical manifestations and other parameters of disease progression.