How do world and European standard populations impact burden of disease studies? A case study of disability-adjusted life years (DALYs) in Scotland

Abstract

BackgroundDisability-Adjusted Life Years (DALYs) are an established method for quantifying population health needs and guiding prioritisation decisions. Global Burden of Disease (GBD) estimates aim to ensure comparability between countries and over time by using age-standardised rates (ASR) to account for differences in the age structure of different populations. Different standard populations are used for this purpose but it is not widely appreciated that the choice of standard may affect not only the resulting rates but also the rankings of causes of DALYs. We aimed to evaluate the impact of the choice of standard, using the example of Scotland.MethodsDALY estimates were derived from the 2016 Scottish Burden of Disease (SBoD) study for an abridged list of 68 causes of disease/injury, representing a three-year annual average across 2014–16. Crude DALY rates were calculated using Scottish national population estimates. DALY ASRs standardised using the GBD World Standard Population (GBD WSP) were compared to those using the 2013 European Standard Population (ESP2013). Differences in ASR and in rank order within the cause list were summarised for all-cause and for each individual cause.ResultsThe ranking of causes by DALYs were similar using crude rates or ASR (ESP2013). All-cause DALY rates using ASR (GBD WSP) were around 26% lower. Overall 58 out of 68 causes had a lower ASR using GBD WSP compared with ESP2013, with the largest falls occurring for leading causes of mortality observed in older ages. Gains in ASR were much smaller in absolute scale and largely affected causes that operated early in life. These differences were associated with a substantial change to the ranking of causes when GBD WSP was used compared with ESP2013.ConclusionDisease rankings based on DALY ASRs are strongly influenced by the choice of standard population. While GBD WSP offers international comparability, within-country analyses based on DALY ASRs should reflect local age structures. For European countries, including Scotland, ESP2013 may better guide local priority setting by avoiding large disparities occurring between crude and age-standardised results sets, which could potentially confuse non-technical audiences.

The Global Burden of Meningitis in Children: Challenges with Interpreting Global Health Estimates

“…Across models it was unclear from published methods exactly how neonatal meningitis as a cause was disaggregated from neonatal sepsis, and other infectious conditions of the newborn, when we know that the majority of the underlying input data does not distinguish between these two causes of death. Unless methods are made transparent, it is difficult for policy makers to understand, and therefore trust, model outputs [ 39 ].…”

Reflections on key methodological decisions in national burden of disease assessments

“…Between these two approaches, evidence has illustrated the impact of how rates of DALYs and ranks of causes are affected. This choice directly affects deaths and has large implications for how we value YLLs in relation to YLDs [ 37 ]. Aspirational or standard life tables are a good way to facilitate comparisons between countries, as they perform a similar function as to when rates are standardised.…”

“…To address this and also produce a comprehensive national BoD study, researchers are using the GBD framework but adjusting certain methodological aspects to tailor it to the needs of the specific country using counry specific sources e.g. use of country specific disease classification, use of disease prevalence data derived from administrative patient databases instead of survey-based disease incidence estimation and use of national disability weights in accordance with the contextualized disease classification [ 37 , 45 , 49 – 51 ].…”

“…The Eurostat task force’s revision of the 2013 ESP highlighted that the plausibility and validity of ASRs come into question when residential populations have excessively different age structures than proposed standard populations [ 95 ]. Recent evidence focusing on differences between ASRs constructed using the 2013 ESP and GBD WSP illustrated that they were not only different in scale, but due to the effects of differences in age-weightings between standard populations there were significant changes in the rank order of causes [ 37 ]. Since the GBD WSP is a younger population than the 2013 ESP, causes that operate early in the life course would be expected to see relative gains, with those causes operating later in the life course observing reductions in ASR.…”

Is Covid-19 lockdown related to an increase of accesses for seizures in the emergency department? An observational analysis of a paediatric cohort in the Southern Italy

“…In addition, the literature reports an increase in sleep disorders, depression and other psychiatric disorders in children, during pandemic [ 16 – 19 ]. Moreover, strong social restrictions allowed children to assume incorrect habits about food, physical activities or screen time [ 20 , 21 ]. Children, indeed, spent a lot of time at home using MMDs such as TV, smartphones, tablets and video consoles [ 22 ].…”