Measuring coverage in MNCH: determining and interpreting inequalities in coverage of maternal, newborn, and child health interventions

Abstract

To monitor progress towards the Millennium Development Goals, it is essential to monitor the coverage of health interventions in subgroups of the population, because national averages can hide important inequalities. In this review, we provide a practical guide to measuring and interpreting inequalities based on surveys carried out in low- and middle-income countries, with a focus on the health of mothers and children. Relevant stratification variables include urban/rural residence, geographic region, and educational level, but breakdowns by wealth status are increasingly popular. For the latter, a classification based on an asset index is the most appropriate for national surveys. The measurement of intervention coverage can be made by single indicators, but the use of combined measures has important advantages, and we advocate two summary measures (the composite coverage index and the co-coverage indicator) for the study of time trends and for cross-country comparisons. We highlight the need for inequality measures that take the whole socioeconomic distribution into account, such as the relative concentration index and the slope index of inequality, although simpler measures such as the ratio and difference between the richest and poorest groups may also be presented for non-technical audiences. Finally, we present a framework for the analysis of time trends in inequalities, arguing that it is essential to study both absolute and relative indicators, and we provide guidance to the joint interpretation of these results.

Figure 1. Co-coverage of nine preventive interventions for Nigeria (DHS 2008), by wealth quintiles.

See Box 2 for more information on the interventions included.

Figure 2. Concentration curve for measles vaccination and underweight using data from the Nigeria 2008 DHS.

Conc. index, concentration index.

Figure 3. Linear, bottom, and top patterns of inequality for skilled birth attendance in Gambia, Bolivia, and Bangladesh, respectively.

See Box 3 for further discussion of patterns of inequality.

Figure 4. Different situations in relation to the time trend of the health indicator studied, and how changes are related to increased or decreased measures of inequality.

(A) Situation 1—increasing rates of a health indicator, typical of a preventive intervention, such as immunization, or a desirable behavior such as exclusive breastfeeding. (B) Situation 2—declining rates of a health indicator, typical of an ill-health indicator, such as undernutrition or mortality, or a risk factor, such as high parity. “d” indicates the difference in coverage between the top and bottom quintiles; “r” indicates the ratio of the coverage in the top and bottom quintiles.

Figure 5. Real example of a set of countries where skilled birth attendant coverage increased over time for the richest 20% of the population.

This example corresponds to situation 1 in Figure 4. CAR, Central African Republic.