Developing and evaluating national severity distributions for use in Burden of Disease studies: a case study of cancers in Scotland

BackgroundIncreasingly Burden of Disease (BOD) measures are being used to influence policy decisions because they summarise health loss in an equitable manner. An important part of producing non-fatal BOD estimates are severity distributions (SDs). The Global Burden of Disease (GBD) study use the same SDs across countries due to a lack of available data. Aim To develop and assess the impact of national SDs compared with GBD worldwide severity distributions for 21 cancer types. MethodsPatient-level records from the Scottish Cancer Registry for 21 cancers were obtained and linked to death registrations. We estimated prevalent cancer cases for 2016 and assigned each case to one of four phases (diagnosis and treatment; controlled; metastatic; and terminal) using GBD 2016 study definitions. SDs were calculated by considering relative proportions. The impact of choice of SDs was evaluated by comparing relative differences between weighted-average disability weights (DW) derived using GBD 2016 worldwide SDs with those derived from Scottish SDs. ResultsFor the majority of cancers the most prevalent phase was the controlled phase, which contributed a higher proportion than the combined proportion from the other three phases across all cancers except mesothelioma. Differences in the composition of severity meant that most point-estimates of Scottish severity proportions were out-with the 95% uncertainty intervals. These differences resulted in overestimates of weighted-average DWs based on GBD 2016 worldwide SDs (17 out of 21 cancer types). The largest relative overestimates were for gallbladder and biliary tract cancer, oesophageal cancer and pancreatic cancer (71%, 32% and 31% higher respectively). ConclusionThese findings illustrate a systematic bias introduced by using worldwide SDs. Current non-fatal BOD estimates should not be interpreted too precisely when comparing populations when they rely on data inputs from other countries. It is essential to ensure that any estimates are based upon country-specific data as far as possible.

Download Full-text

The impact of worldwide, national and sub-national severity distributions in Burden of Disease studies: a case study of individual cancer types in Scotland

10.1101/654327 ◽

2019 ◽

Author(s):

Grant MA Wyper ◽

Ian Grant ◽

Eilidh Fletcher ◽

Gerry McCartney ◽

Diane L Stockton

Keyword(s):

Burden Of Disease ◽

Weighted Average ◽

Global Burden Of Disease ◽

Global Burden ◽

Cancer Type ◽

Point Estimates ◽

Disability Weights ◽

Cancer Types ◽

The Impact ◽

Deprived Areas

AbstractAimThe main aim of this study was to consider the extent to which the use of worldwide severity distributions in Burden of Disease studies are influencing cross-country comparisons, by comparing Global Burden of Disease distributions with nationally derived severity distributions in Scotland for cancer types.MethodsWe obtained individual records from the Scottish Cancer Registry for 21 cancer types and linked these to registered deaths. We estimated prevalent cancer cases for 2016 and assigned each case to sequelae using Global Burden of Disease (GBD) 2016 study definitions. We compared the impact of using severity distributions based on GBD 2016, a Scotland-wide distribution, and a distribution specific to deprivation strata in Scotland, on the weighted-average disability weights for each cancer type in Scotland.ResultsThe relative difference in point estimates of weighted-average disability weights based on GBD 2016 worldwide severity distributions compared with Scottish national severity distributions resulted in overestimates in the majority of cancers (17 out of 21 cancer types). The largest overestimates were for gallbladder and biliary tract cancer (70.8%), oesophageal cancer (31.6%) and pancreatic cancer (31.2%). Furthermore, the use of weighted-average disability weights based on Scottish national severity distributions rather than sub-national Scottish severity distributions stratified by deprivation quintile overestimated weighted-average disability weights in the least deprived areas (16 out of 18 cancer types), and underestimated in the most deprived areas (16 out of 18 cancer types).ConclusionOur findings illustrate a bias in point estimates of weighted-average disability weights created using worldwide severity distributions. This bias would have led to the misrepresentation of non-fatal estimates of the burden of individual cancers, and underestimated the scale of socioeconomic inequality in this non-fatal burden. This highlights the importance of not interpreting non-fatal estimates of burden of disease too precisely, especially for sub-national estimates and those comparing populations when relying on data inputs from other countries. It is essential to ensure that any estimates are based upon the best available country-specific data at the lowest granularity.

Download Full-text

Prioritising the development of severity distributions in burden of disease studies for countries in the European region

Archives of Public Health ◽

10.1186/s13690-019-0385-6 ◽

2020 ◽

Vol 78 (1) ◽

Cited By ~ 6

Author(s):

Grant M. A. Wyper ◽

Ian Grant ◽

Eilidh Fletcher ◽

Neil Chalmers ◽

Gerry McCartney ◽

...

Keyword(s):

Burden Of Disease ◽

Current Data ◽

Specific Data ◽

Health Loss ◽

Disease Occurrence ◽

Strategic Approach ◽

Disability Weights ◽

National Studies ◽

The Impact ◽

Country Specific

AbstractSeverity distributions are a means of summarising the range of health loss suffered to disease which enables estimates of disease occurrence to be paired with disability weights to estimate Years Lost to Disability (YLD) in burden of disease studies. There is a lack of current data exploring severity distributions, which has led to the Global Burden of Disease (GBD) study relying on using the same severity distributions across countries and regions across the world. This is also largely true for some national studies, although there are exceptions. Recent evidence has raised concerns that severity distributions are unlikely to be generalisable as major differences arise when using country-specific data to develop severity distributions. These issues raise uncertainties over interpreting YLD estimates, particularly if they are being used to develop and influence policies and to determine priorities across diseases and populations. It is clear that GBD researchers and those carrying out national studies need to work towards ensuring that estimates are based upon country-specific data, and, if possible, that the impact of assumptions are fully tested and understood. There is a lack of strategy about if, where, and how, this could be achieved, particularly around how efforts should be prioritised. This commentary advocates and presents a possible strategic approach to better understanding how efforts may be best placed.

Download Full-text

The impact of worldwide, national and sub-national severity distributions in Burden of Disease studies: A case study of cancers in Scotland

PLoS ONE ◽

10.1371/journal.pone.0221026 ◽

2019 ◽

Vol 14 (8) ◽

pp. e0221026 ◽

Cited By ~ 6

Author(s):

Grant M. A. Wyper ◽

Ian Grant ◽

Eilidh Fletcher ◽

Gerry McCartney ◽

Diane L. Stockton

Keyword(s):

Burden Of Disease ◽

The Impact

Download Full-text

The power of administrative data in national studies: experiences from the Scottish Burden of Disease study

European Journal of Public Health ◽

10.1093/eurpub/ckaa165.263 ◽

2020 ◽

Vol 30 (Supplement_5) ◽

Author(s):

I Grant ◽

G M A Wyper ◽

E Fletcher ◽

G McCartney ◽

D Stockton

Keyword(s):

Burden Of Disease ◽

Healthcare Services ◽

Disability Weights ◽

National Burden ◽

Causes Of Disease ◽

The Rich ◽

Disease Study ◽

Key Steps ◽

The Impact ◽

Burden Of Diseases

Abstract In 2013, the Scottish Burden of Disease Study (SBoD) study set out with an ambitious aim of comprehensively estimating the burden of 132 causes of ill-health and mortality. The study utilised the rich and widespread data which is recorded as a by-product of individual encounters across the universally available and free at point-of-contact healthcare services in Scotland, and other long-standing survey initiatives. It was carried out as an independent national burden of disease study, but used Global Burden of Disease methodology for disability weights. In 2017, our first report outlined the contribution of causes of disease and injury of DALYs. This was followed up in a 2018, with a further report highlighting the effect of socioeconomic inequalities in DALYs. In this presentation we will show the key steps involved in undertaking the SBoD study drawing on available data sources in Scotland. From the Scottish experience we will highlight important issues in knowledge translation for national burden of diseases studies to consider when specific choices are made on the methodological inputs into calculations for both YLL and YLD, specifically: (i) the differential impact between different life tables; (ii) the impact of differences in severity distributions; and (iii) the impact of using different standard populations when directly standardising rates.

Download Full-text