Sentinel surveillance and cross sectional survey on HIV infection prevalence: a comparative study

Abstract

Despite widespread use of sentinel surveillance systems in monitoring the magnitude of HIV-1 infection in populations, little is known of how the trends they produce compare with those of the larger populations which they support to represent. The objective of this study, therefore, was to assess how useful sentinel surveillance data on HIV-1 infection might be in estimating the magnitude of HIV-1 infection in the general population. To achieve this, results from a population based study on HIV-1 infection in Bukoba town were compared with those from antenatal mothers and blood donors, all from the same town. The studies were done during the period of 1987-90. The overall HIV-1 prevalence was highest in the general population sample at 24.2% (95% CI 20.6-27.8) followed by that in antenatal mothers at 22.4% (95% CI 20.6-25.2) and lowest in blood donors at 11.9% (95% CI 9.1-15.3). Seroprevalence among antenatal clinic attenders was significantly lower than that of females from the general population sample (p = 0.016). Prevalence among female blood donors did not differ significantly from that of females from the general population sample (p = 0.06). Blood donor males had a lower HIV-1 seroprevalence when compared to that from the general population males (p = 0.038). The age group 25-34 years had the highest prevalence of HIV-1 infection in all the three populations indicating that this group is at the highest risk of HIV infection and that the three populations show a similar trend of age specific prevalence. From these findings, it is noted that female blood donors as a sentinel population represents more closely estimates of HIV-1 seroprevalence of females in the general population than antenatal clinic attenders or male blood donors. Further studies are proposed in different settings in order to come up with guidelines on the methodology of using sentinel surveillance populations in monitoring HIV-1 infection.

PIP: Researchers compared the results of a sentinel surveillance study on HIV-1 infection in 1292 pregnant women 15-47 years old attending prenatal care and in 454 blood donors (mean age = 28.7 years) in Bukoba, Tanzania, in 1990 with those from a cross sectional population-based study on HIV-1 infection among 553 people 15-54 years old also conducted in Bukoba during August 1987 to April 1988 to determine which sentinel populations most closely represented the HIV-1 infection rate of the general population. The HIV-1 prevalence rate was 24.4% for the population-based sample, 22.4% for the pregnant women, and 11.6% for the blood donors. The general population females had the highest HIV-1 prevalence rate, while the male blood donors had the lowest rate (29.4% vs. 10.5%). Pregnant women had a significantly lower rate than general population females (22.4% vs. 29.4%; p = 0.016). The 25-34 year old age group had the highest prevalence of HIV-1 infection in all three populations, suggesting that this group faces the highest risk of HIV infection and that the three populations have a similar trend of age-specific prevalence. There were no significant differences between the HIV-1 prevalence rates among general population females and those among female blood donors, suggesting that female blood donors more closely represent the HIV-1 seroprevalence rate of general population females than pregnant women attending prenatal care or male blood donors. There is a need for additional studies in different settings in order to establish guidelines on the methodology of using sentinel surveillance studies in monitoring HIV-1 infection.