Measuring Under-Five Mortality: Validation of New Low-Cost Methods

n/aBackground: There has been increasing interest in measuring under-five mortality as a health indicator and as a critical measure of human development. In countries with complete vital registration systems that capture all births and deaths, under-five mortality can be directly calculated. In the absence of a complete vital registration system, however, child mortality must be estimated using surveys that ask women to report the births and deaths of their children. Two survey methods exist for capturing this information: summary birth histories and complete birth histories. A summary birth history requires a minimum of only two questions: how many live births has each mother had and how many of them have survived. Indirect methods are then applied using the information from these two questions and the age of the mother to estimate under-five mortality going back in time prior to the survey. Estimates generated from complete birth histories are viewed as the most accurate when surveys are required to estimate under-five mortality, especially for the most recent time periods. However, it is much more costly and labor intensive to collect these detailed data, especially for the purpose of generating small area estimates. As a result, there is a demand for improvement of the methods employing summary birth history data to produce more accurate as well as subnational estimates of child mortality. Methods and Findings: We used data from 166 Demographic and Health Surveys (DHS) to develop new empirically based methods of estimating under-five mortality using children ever born and children dead data. We then validated them using both in- and out-of-sample analyses. We developed a range of methods on the basis of three dimensions of the problem: (1) approximating the average length of exposure to mortality from a mother's set of children using either maternal age or time since first birth; (2) using cohort and period measures of the fraction of children ever born that are dead; and (3) capturing country and regional variation in the age pattern of fertility and mortality. We focused on improving estimates in the most recent time periods prior to a survey where the traditional indirect methods fail. In addition, all of our methods incorporated uncertainty. Validated against under-five estimates generated from complete birth histories, our methods outperformed the standard indirect method by an average of 43.7% (95% confidence interval [CI] 41.2–45.2). In the 5 y prior to the survey, the new methods resulted in a 53.3% (95% CI 51.3–55.2) improvement. To illustrate the value of this method for local area estimation, we applied our new methods to an analysis of summary birth histories in the 1990, 2000, and 2005 Mexican censuses, generating subnational estimates of under-five mortality for each of 233 jurisdictions. Conclusions: The new methods significantly improve the estimation of under-five mortality using summary birth history data. In areas without vital registration data, summary birth histories can provide accurate estimates of child mortality. Because only two questions are required of a female respondent to generate these data, they can easily be included in existing survey programs as well as routine censuses of the population. With the wider application of these methods to census data, countries now have the means to generate estimates for subnational areas and population subgroups, important for measuring and addressing health inequalities and developing local policy to improve child survival. : Please see later in the article for the Editors' Summary Background: Every year, more than 8 million children die before their fifth birthdays. Most of these deaths occur in developing countries, and most are the result of diseases or combinations of diseases that could have been prevented or treated. Measles, for example, is a major killer in low-income countries and undernutrition contributes to one-third of childhood deaths. Faced with this largely avoidable loss of young lives, in 1990, the United Nations' World Summit for Children pledged to improve the survival of children. Later, in 2000, world leaders set a target of reducing child mortality to one-third of its 1990 level by 2015 as Millennium Development Goal 4. This goal, together with seven others, is designed to alleviate extreme poverty by 2015. In 2006, for the first time since mortality records began, annual deaths among children under five fell below 10 million as a result of public-health programs such as the Measles Initiative, which has reduced global measles mortality by more than two-thirds by vaccinating 500 million children, and the Nothing but Nets campaign, which distributed insecticide-treated antimalaria nets in Africa. Why Was This Study Done?: Although global under-five mortality is declining, it is unlikely that Millennium Development Goal 4 will be reached by 2015. Indeed, in some countries, little or no progress is being made toward this goal. To improve progress and to monitor the effects of public-health interventions, accurate, up-to-date estimates of national and subnational child mortality rates are essential. In developed countries, vital registration systems—records of all births and deaths—mean that under-five mortality rates can be directly calculated. But many developing countries lack vital registration systems, and child mortality has to be estimated using data collected in surveys. In “complete birth history” surveys, mothers are asked numerous questions about each living child and each dead child. Such surveys can be used to estimate under-five mortality accurately for recent time periods but they are expensive and time-consuming. By contrast, in “summary birth history” surveys, each mother is simply asked how many live births she had and how many of her children have survived. Under-five mortality can be indirectly calculated from this information and the age of the mother, but the current methods for making this calculation cannot provide reliable estimates of under-five mortality more recently than 3 years before the survey. In this study, therefore, the researchers develop methods for estimating more recent under-five mortality rates from summary birth histories. What Did the Researchers Do and Find?: The researchers used data about all children born and dead children extracted from 169 Demographic and Health Surveys (DHS; a project started in 1984 to help developing countries collect data on health and population trends) covering 70 countries to develop four new methods to estimate under-five mortality. They tested these new methods and a method that combined all four approaches by comparing the estimates of under-five mortality provided by these methods and the standard indirect method to the estimates obtained from an analysis of the complete birth data in the DHS. The new methods all outperformed the standard indirect method, particularly for the most recent 5 years. The researchers also used their new methods to generate estimates of under-five mortality for each of the 233 jurisdictions in Mexico from summary birth histories collected in the 1990, 2000, and 2005 Mexico censuses. The overall trends of these subnational estimates, they report, mirrored those obtained from vital registration data. What Do These Findings Mean?: These findings suggest that application of the new methods developed by the researchers could significantly improve the accuracy of estimates of under-five mortality based on summary birth history data. The researchers warn that although their methods can provide accurate estimates of recent under-five mortality, they might not capture rapid fluctuations in mortality such as those that occur during wars. However, they suggest, the two questions needed to generate the data required to apply these new methods could easily be included in existing survey programs and in routine censuses. Consequently, systematic application of the methods proposed in this study should provide policy makers with the information about levels, recent trends, and inequalities in child mortality that they need to accelerate efforts to reduce the global toll of childhood deaths. Additional Information: Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000253.