1.6 The Global Burden of Disease (GBD) Study

To overcome the problem of poor comparability between studies, the GBD study, a global research programme involving hundreds of experts worldwide, has developed statistical methods (multi- state models implemented in the software program DisMod III) to model and calculate age-specific estimates of incidence, prevalence, mortality, and DALYs lost. While the study relies on some assumptions to deal with incomplete or low quality data, the estimates from GBD are widely used in stroke publications.

The latest edition was published as Global Burden of Disease  Study 2015 (GBD 2015)[74].

“The challenges [for stroke survivors and families in Greece] are day to day living …. But also, it is becoming a viable member of society again and I think that’s important worldwide, not only in [my country] Greece.”
(Stroke clinician and stroke support organisation volunteer, Greece)

 

Figure 2 shows GBD 2015 national estimates for incidence, prevalence, mortality and DALYs lost in 1995 and 2015.

Figure 2a: Number of new strokes and stroke survivors per 100,000 inhabitants in 1995 and 2015 (age- and sex-standardised to the world standard population, GBd 2015)

Figure 2b: Number of deaths due to stroke, and DALYs lost per 100,000 inhabitants in 1995 and 2015 (age- and sex-standardised to the world standard population, GBD 2015)

The GBD study shows large inequalities in the rate of strokes and mortality due to stroke across Europe, with higher rates and poorer outcomes being consistently found in Eastern European compared to Western European countries.

Across Europe the age-standardised rates of strokes, deaths from strokes, and people living with disability as a result of stroke have gone down. But relative improvements have been larger in Western European countries than in Eastern European countries.

The latest Eurostat (statistical office of the EU) cardiovascular disease statistics add further evidence (data extracted October 2016, http://ec.europa.eu/eurostat). The Eurostat stroke mortality figures show that the highest standardised death rates for stroke were reported for Bulgaria, Romania, Serbia, Latvia, Lithuania, Croatia, Hungary, and Slovakia, while the lowest rates were reported for France, Spain, Luxembourg, Austria, and Belgium. Mortality rates in Bulgaria (highest rate) were almost seven times as high as those recorded for France (lowest rate).

However, there are currently no Europewide standardised, nationally collected data on stroke, leading to a significant level of uncertainty due to poor or missing data in many parts of Europe, as seen by the widely differing estimates derived from population-based registers, hospital data sets, or GBD. For example, for the UK there is a large discrepancy between the number of strokes estimated for 2015 in the GBD study (43,000) and estimates based on the national stroke audit (110,000)[75]. This illustrates that estimates of the burden of stroke on a country level, comparisons between countries and healthcare systems, and future projections all have significant caveats at present.