Estimation of HIV-1 Incidence Using a Testing History-Based Method; Analysis From the Population-Based HIV Impact Assessment Survey Data in 12 African Countries

BACKGROUND

Estimating HIV incidence is essential to monitoring progress in sub-Saharan African nations toward global epidemic control. One method for incidence estimation is to test nationally representative samples using laboratory-based incidence assays. An alternative method based on reported HIV testing history and the proportion of undiagnosed infections has recently been described.

METHODS

We applied an HIV incidence estimation method which uses history of testing to nationally representative cross-sectional survey data from 12 sub-Saharan African nations with varying country-specific HIV prevalence. We compared these estimates with those derived from laboratory-based incidence assays. Participants were tested for HIV using the national rapid test algorithm and asked about prior HIV testing, date and result of their most recent test, and date of antiretroviral therapy initiation.

RESULTS

The testing history-based method consistently produced results that are comparable and strongly correlated with estimates produced using a laboratory-based HIV incidence assay (ρ = 0.85). The testing history-based method produced incidence estimates that were more precise compared with the biomarker-based method. The testing history-based method identified sex-, age-, and geographic location-specific differences in incidence that were not detected using the biomarker-based method.

CONCLUSIONS

The testing history-based method estimates are more precise and can produce age-specific and sex-specific incidence estimates that are informative for programmatic decisions. The method also allows for comparisons of the HIV transmission rate and other components of HIV incidence among and within countries. The testing history-based method is a useful tool for estimating and validating HIV incidence from cross-sectional survey data.

Rapid reduction of maternal mortality in Uganda and Zambia through the saving mothers, giving life initiative: results of year 1 evaluation

Background

Achieving maternal mortality reduction as a development goal remains a major challenge in most low-resource countries. Saving Mothers, Giving Life (SMGL) is a multi-partner initiative designed to reduce maternal mortality rapidly in high mortality settings through community and facility evidence-based interventions and district-wide health systems strengthening that could reduce delays to appropriate obstetric care.

Methods

An evaluation employing multiple studies and data collection methods was used to compare baseline maternal outcomes to those during Year 1 in SMGL pilot districts in Uganda and Zambia. Studies include health facility assessments, pregnancy outcome monitoring, enhanced maternal mortality detection in facilities, and population-based investigation of community maternal deaths. Population-based evaluation used standard approaches and comparable indicators to measure outcome and impact, and to allow comparison of the SMGL implementation in unique country contexts.

Results

The evaluation found a 30% reduction in the population-based maternal mortality ratio (MMR) in Uganda during Year 1, from 452 to 316 per 100,000 live births. The MMR in health facilities declined by 35% in each country (from 534 to 345 in Uganda and from 310 to 202 in Zambia). The institutional delivery rate increased by 62% in Uganda and 35% in Zambia. The number of facilities providing emergency obstetric and newborn care (EmONC) rose from 10 to 25 in Uganda and from 7 to 11 in Zambia. Partial EmONC care became available in many more low and mid-level facilities. Cesarean section rates for all births increased by 23% in Uganda and 15% in Zambia. The proportion of women with childbirth complications delivered in EmONC facilities rose by 25% in Uganda and 23% in Zambia. Facility case fatality rates fell from 2.6 to 2.0% in Uganda and 3.1 to 2.0% in Zambia.

Conclusions

Maternal mortality ratios fell significantly in one year in Uganda and Zambia following the introduction of the SMGL model. This model employed a comprehensive district system strengthening approach. The lessons learned from SMGL can inform policymakers and program managers in other low and middle income settings where similar approaches could be utilized to rapidly reduce preventable maternal deaths.

Burden of diarrhea among children in Honduras, 2000-2004: estimates of the role of rotavirus

OBJECTIVES

To estimate the annual burden of diarrhea and of diarrhea that is associated with rotavirus (RV) in children who are treated at public clinics and hospitals in Honduras.

METHODS

Data were collected from computerized records of all children < 5 years old treated for diarrhea at clinics and hospitals operated by the Secretary of Health for the period of 2000 through 2004. A review of studies of RV in Honduras and neighboring countries provided estimates of detection rates of RV among children treated for acute diarrhea as outpatients or as inpatients. From these data, we estimated the annual number of cases of diarrhea and of rotavirus-related diarrhea in Honduras, the cumulative incidence of diarrhea and of rotavirus-related diarrhea for a child from birth to age 5 years, and the number of fatalities due to RV among children hospitalized for diarrhea.

RESULTS

From 2000 through 2004, a mean of 222,000 clinic visits, 4,390 hospitalizations, and 162 in-hospital deaths due to diarrhea were recorded annually among children < 5 years of age in the public health facilities in Honduras. From our review of scientific literature on Honduras and neighboring countries, an estimated 30% of outpatients and 43% of inpatients who were treated for diarrhea would be expected to have RV. Consequently, we estimated that 66,600 outpatient visits, 1,888 hospitalizations, and 70 in-hospital deaths among children < 5 years in Honduras could be attributed to RV each year. Therefore, a child in the first five years of life has a respective risk for consultation, hospitalization, and in-hospital death of 1:1, 1:46, and 1:1,235 for diarrhea. For an episode associated with RV, the respective risks are 1:3, 1:106, and 1:2,857. These values likely underestimate the true burden of diarrhea in Honduras, since some 51% of children with acute diarrhea do not receive formal care for the illness, 70% do not receive oral rehydration solution, and 80% of diarrheal deaths occur outside of hospitals.

CONCLUSIONS

Diarrhea is a major cause of illness among children < 5 years old in Honduras, and RV is likely the most common cause. Our preliminary estimates need to be refined so that health planners in Honduras can make decisions on the future use of rotavirus vaccines. A program of hospital-based surveillance for rotavirus in Honduras has been established to address this need.

Estimating intercensal age schedules by intracohort interpolation

"This paper describes a procedure for estimating intercensal age schedules of rates of occurrence of demographic events (birth, death, marriage) from tabulations at two points in time of a status of the population (average children ever born, persons surviving, proportion ever married) classified by age." The procedure is called iterative intracohort interpolation. The paper describes a more general version than that originally developed by Ansley J. Coale and provides a probabilistic interpretation of the age-specific rates estimated by the procedure.

The relationship of interpregnancy interval to infant birthweight and length of gestation among low-risk women, Georgia

To examine the association between interpregnancy interval and low birthweight (< 2500 g), preterm delivery (< 37 weeks' gestation), and inadequate fetal growth, we studied a population-based sample of 23,388 white and 4885 black women at low risk for adverse pregnancy outcomes who delivered their first and second infants in Georgia from 1980 to 1992. We used fetal death and livebirth certificates. The interpregnancy interval was the time from delivery to the woman's next conception. For each pregnancy outcome, we stratified by race and used logistic regression to assess the association between interpregnancy interval and outcome, while controlling for confounders. Intervals < 6 months were observed for 3.7% of white women and 7.0% of black women and intervals > or = 48 months were seen for 16.8% of white women and 24.8% of black women. Results from logistic regression showed that, for both races, interpregnancy interval was associated with low birthweight and preterm delivery. Nearly all of the increased risk occurred in intervals < 6 months or > or = 48 months. The magnitude of the increase in risk associated with these intervals ranged from modest to moderate and was similar for black and white women. Because short interpregnancy intervals are rare and are weak risk factors among low-risk women, efforts to lengthen interpregnancy intervals are unlikely to reduce substantially their rates of adverse pregnancy outcomes.

Estimates of net migration by age at migration from pairs of enumerations of the foreign born: United States, 1880-1930

"This paper describes a new method for indirectly estimating age schedules of net migration. The method is illustrated with historical data for the United States. The analysis employs a recently developed technique--iterative intracohort interpolation--to estimate age schedules of net migration from pairs of enumerations of the foreign born by age. The data required for this application are enumerations of the foreign born (or more generally of those born outside the enumeration area) by age in two successive censuses, a life table presumed to reflect the mortality experience of the foreign born during the intercensal period, and, optionally, data on variations in the overall level of migration during the intercensal period. The procedure provides estimates of the average annual number of foreign born net migrants during a decade by their age at the time of entry/exit." (SUMMARY IN ITA AND FRE)

Using parity-progression ratios to estimate the effect of female sterilization on fertility

In this article, a new methodology that employs parity-progression ratios to estimate the effect of female sterilization on fertility is described, and results using data from Ecuador are compared to those obtained using a previously existing approach that classifies women by marital duration. The methods differ in how they disaggregate marital fertility and in the assumption they make about what the subsequent fertility of sterilized women would have been if they had not been sterilized. The analysis of the Ecuadoran data shows that the estimate of births averted by sterilization has diminished over time, even as sterilization prevalence has been increasing. This situation is attributed to a decline in the fertility of nonsterilized women resulting from increased use of reversible methods of contraception.

Ethnicity and the use of health services in Belize

Data from the 1991 Belize Family Health Survey show differentials in the use of maternal and child health services between ethnic groups (Creole, Mestizo, Maya/Ketchi and Garifuna). Multivariate analysis is used to explore whether such differentials can truly be attributed to ethnicity or to other characteristics that distinguish the ethnic groups. Health services considered are: family planning, place of delivery (hospital/other), postpartum and newborn check-ups after a birth, and immunisations for children. The language usually spoken in the household is found to be important for interpreting ethnic differentials. Mayan-speaking Maya/Ketchis are significantly less likely to use family planning services or to give birth in a hospital. Spanish-speakers (Mestizos and Maya/Ketchis) are less likely to use newborn and postpartum check-ups, after controlling for other characteristics. There are no ethnic differentials for immunisations. Programmatic implications of these results are discussed.

Reproductive patterns and child mortality in guatemala

In this paper, we investigate the association of child mortality with maternal age, parity, birth spacing, and socioeconomic status, in a sample of Guatemalan children who were included in a public health intervention program. Our results indicate that maternal age, birth order, and the length of the previous and following birth intervals all have a significant impact on the risk of child mortality and that these associations cannot be accounted for by differences in breastfeeding, socioeconomic status, or the survival status of the previous child.