New estimates of global under-5 mortality – Authors' reply
Authors: Christopher JL Murray, Thomas Laakso, Kenji Shibuya, Kenneth Hill, Alan D Lopez
Journal: The Lancet (2007)

Efforts to estimate key health indicators to guide development strategies should draw on all available expertise, data, and statistical acumen. Child mortality is no exception. Recent advances have been made to harmonise the work of identifying past trends and generating current estimates through the Interagency Child Mortality Estimation Group (IACMEG), including UNICEF, WHO, and other partners.1Child Mortality Coordination GroupTracking progress towards the Millennium Development Goals: reaching consensus on child mortality levels and trends.Bull World Health Organ. 2006; 84: 225-232Crossref PubMed Scopus (29) Google Scholar Despite these welcome advances, key challenges remain. In our paper,2Murray CJ Laakso T Shibuya K Hill K Lopez AD Can we achieve Millennium Development Goal 4? New analysis of country trends and forecasts of under-5 mortality to 2015.Lancet. 2007; 370: 1040-1054Summary Full Text Full Text PDF PubMed Scopus (201) Google Scholar we tried to analyse systematically all internationally available data on child mortality and to introduce new methods to estimate trends and uncertainty in the risk of child death worldwide. These methods and preliminary results were in fact presented to IACMEG in July, 2007, at their invitation, by two of our authors who are also members of IACMEG (KS and KH). In that meeting, IACMEG agreed to assess the advantages and disadvantages of the new approach. We have also proposed a formal method to estimate uncertainty in our estimates, even those based on surveys done within the last year or so. We recognise that further work on the estimation of uncertainty intervals is needed; however, opinions about what uncertainty levels might, or should, be do not constitute a scientific, replicable approach. We applaud IACMEG's intention to give greater attention to completeness of datasets, including vital registration data in their estimation strategies. These statistics have not been fully exploited by IACMEG in the past, and the fact that at the time of submission we were able to identify vital registration data on child deaths that were not included in their database for quite a few of the 60 countries they mention suggests that this aspect be given greater priority. There is much information content in a critical appraisal and prudent use of vital registration data, even incomplete, as shown in our paper. Although we have acknowledged that IACMEG does indeed distinguish between primary measurements in surveys and censuses and estimated values, as they should, they do not distinguish between the fitted values and out-of-sample projections. For example, there is no way to know which figures for 2005 that they produce are forecasted out of sample and which are not.3United Nations Children's FundThe state of the world's children 2007. UNICEF, New York2007Google Scholar, 4WHOWorld health statistics 2007. World Health Organization, Geneva2007Google Scholar Such a distinction is critical to guide those who use the projections to use them with greater understanding and confidence.5Murray CJ Towards good practice for health statistics: lessons from the Millennium Development Goal health indicators.Lancet. 2007; 369: 862-873Summary Full Text Full Text PDF PubMed Scopus (92) Google Scholar IACMEG notes that their overestimation of mortality in some sub-Saharan African countries compared with the available datasets is due to the addition of modelled estimates of child HIV deaths that are added to figures based on empirical measurements. We believe that monitoring of child mortality should be based on empirical measurements, not on a hybrid of empirical measurements plus model predictions for HIV. UNICEF has played a critical role along with USAID in funding data collection on child mortality in developing countries through the Multiple Indicator Cluster Surveys (MICS). The third round of these surveys was planned for 2005 and 2006. UNICEF leadership in the area of enhanced primary data collection should be applauded by all. As these new datasets become available in the public domain, we will have more clear understanding of child mortality levels, trends, and forecasts. The new method which we proposed in our paper is fully automated and reproducible and enables users to update them whenever new data become available, as opposed to an annual update by IACMEG. We also believe that assessing validity and the potential causes of the changes in child mortality is critical, not only for monitoring child health, but also for assessing the effect of various global strategies and initiatives. Greater efforts by the scientific community to develop and rely on reproducible methods, to share and incorporate all available data sources, and to adhere to best practices of transparency and data identification will better serve policy needs. We believe that our paper is an important contribution to this key aspect of the global health policy arena. New estimates of global under-5 mortalityChristopher Murray and colleagues (Sept 22, p 1040)1 publish the results of an analysis of under-5 mortality data. They note several issues they believe limit the quality and usefulness of evidence on child mortality estimates produced by the Inter-agency Child Mortality Estimation Group (IACMEG), which includes WHO, UNICEF, the World Bank, the UN Population Division, Harvard University, the US Bureau of the Census, and others. Full-Text PDF