THEORY AND METHODS Infant mortality rate as an indicator of population health D D Reidpath, P Allotey ............................................................................................................................. J Epidemiol Community Health 2003;57:344–346 Background: The infant mortality rate (IMR) has been criticised as a measure of population health because it is narrowly based and likely to focus the attention of health policy on a small part of the population to the exclusion of the rest. More comprehensive measures such as disability adjusted life expectancy (DALE) have come into favour as alternatives. These more comprehensive measures of population health, however, are more complex, and for resource poor countries, this added burden could mean diverting funds from much needed programmes. Unfortunately, the conjecture, that DALE is a better measure of population health than IMR, has not been empirically tested. Methods: IMR and DALE data for 1997 were obtained from the World Bank and the World Health Organisation, respectively, for 180 countries. Findings: There is a strong (generally) linear association between DALE and IMR (r=0.91). Countries with low DALE tend to have a high IMR. The countries with the lowest IMRs had DALEs above that pre- dicted by the regression line. Interpretation: There is little evidence that the use of IMR as a measure of population health has a negative impact on older groups in the population. IMR remains an important indicator of health for whole populations, reflecting the intuition that structural factors affecting the health of entire populations have an impact on the mortality rate of infants. For countries with limited resources that require an eas- ily calculated, pithy measure of population health, IMR may remain a suitable choice. A general measure of population health is useful for com- paring the health status of a population over time, or between populations at a single point in time. It permits comparisons of health systems and programmes, and may highlight populations in need of particular attention from health services. 1 The infant mortality rate (IMR), defined as the number of deaths in children under 1 year of age per 1000 live births in the same year, has in the past been regarded as a highly sensi- tive (proxy) measure of population health. 2 This reflects the apparent association between the causes of infant mortality and other factors that are likely to influence the health status of whole populations such as their economic development, general living conditions, social well being, rates of illness, and the quality of the environment. More recently it has been argued that proxy measures of population health like IMR are problematic 3 ; and the past dec- ade has seen IMR fall out of favour. The World Health Report 2000, 4 for example, makes no reference to the measure. Despite starting as indicators of a whole population’s health, measures like IMR often, it is reasoned, become the principal focus of health policy such that health strategies and health priorities are formulated with the proxy outcome measure in mind. 3 As a consequence, health policies begin to target the chosen outcome measure, while ignoring the rest of the population for which the outcome measure was supposed to be an indicator. Thus, IMR may decrease, as infant mortality becomes the principal focus of health policy, but the whole population’s health may, unknown to the ministries of health, remain static or even degrade. This view has lead to the development of more comprehen- sive measures of population health; for example, the disability adjusted life expectancy (DALE). 5 Such measures are intended to (a) be sensitive to changes of health in the whole population, and (b) account for the morbidity associated with non-fatal health outcomes as well as mortality. 1 The argument about the dangers of using IMR as a measure of population health has intuitive appeal, highlighting the fact that it derives from a small, non-representative portion of the population and excludes any consideration of non-fatal health outcomes. In contrast, the DALE combines information about life expectancy with information about the prevalence of disabling sequelae at different ages, with a severity weight that reflects the impact of the disability. 5 If, however, ministries of health accept the argument against the use of IMR and choose to pursue an alternative measure of population health such as the DALE, they are faced with additional costs and complexity. In developed countries, the collection of the additional data may not be particularly onerous, and in some cases may already be collected. In those countries that are poorest, however, and have the worst popu- lation health, the cost of a more “comprehensive” measure may be prohibitive. Even if the cost were not prohibitive, the benefits of adopting a new measure would have to be signifi- cant. In the absence of data, the argument that IMR is a poor proxy measure of population health is mere conjecture. The aim of this study was to examine the relation between IMR and DALE to ascertain the robustness or otherwise of IMR as a measure of population health. METHODS The relation between IMR and DALE was examined in all 180 countries for which data were available. The DALE data for 1997/1999 for the total population at birth in each country were obtained from The World Health Report 2000 (annex table 5). 4 The IMR data for 1997 were obtained from the World Bank’s Development Indicators. 6 RESULTS The distribution of IMRs for the 180 countries was skewed with a long right tail. The median IMR was 29 (Vietnam) and ............................................................. Abbreviations: DALE, disability adjusted life expectancy; IMR, infant mortality rate See end of article for authors’ affiliations ....................... Correspondence to: Dr D D Reidpath, School of Health Sciences, Deakin University, 221 Burwood Highway, Burwood 3125, Australia; reidpath@deakin.edu.au Accepted for publication 7 May 2002 ....................... 344 www.jech.com