Overview of differences in modelling approach and data used by the UN IGME and the IHME for estimating the U5MR and the number of under-five deaths.

aThere are concerns about the incompleteness of early infant mortality data from civil registration in some European countries. The problem is not necessarily derived from a dysfunction of the civil registration system; it is often caused by different definitions being used for live births, which influences the counting of early infants. The UN IGME carried out an analysis of the ratio of early neonatal (under 7-d) deaths to total neonatal deaths. The average value of this ratio for Western European countries was 0.77, with few values below 0.7. A statistical analysis of this ratio for available country-years found that the ratio was significantly lower than the Western European average for the following countries: Belarus, Bulgaria, Czech Republic, Estonia, Greece, Hungary, Latvia, Lithuania, Romania, Russian Federation, Slovakia, and Spain. In only four countries did this ratio change significantly over time, and in all cases it was decreasing, not increasing. Based on this analysis, it was decided to apply a 10% upward adjustment to under-five mortality for Belarus, Hungary, and Lithuania, and a 20% adjustment for the other countries, including the Russian Federation. In all cases, a single country-specific correction factor was applied to the entire time series.