The share of overall mortality attributable to alcohol is higher in Europe than elsewhere in the world because of the high prevalence of alcohol consumption. There are, however, substantial differences across countries and between the sexes in levels of alcohol-related mortality.
In a new study published in Addiction, Sergi Trias-Llimós, Maarten J. Bijlsma and Fanny Janssen show that to better understand these differences, it is necessary to not only look at mortality changes over calendar time, but to also examine the role of birth cohorts. Individuals who were born in the same period – and thus belong to the same birth cohort – have similar experiences at the same age, and are likely to adopt similar behaviours. Restrictions, prices and advertisements related to alcohol influence drinking behaviour directly at younger ages, which tends to predict patterns of alcohol use during the life course. Therefore, when studying trends in alcohol prevalence and subsequent mortality, it is necessary to not only look at age effects (increasing mortality with age) and period effects (mortality change over subsequent years), but to also examine cohort effects which refer to differences in mortality between generations, for example between individuals born in 1950 and those born in 1960.
The authors explored the country specific role of birth cohorts by using data about liver cirrhosis mortality from the World Health Organization (WHO) Mortality Database from 1950 to 2011. The analysis included national populations between the ages of 15-94 from eight European countries belonging to different regions and that have different alcohol consumption levels, patterns and trends: Austria, Finland, Hungary, Italy, the Netherlands, Poland, Spain and Sweden. On a descriptive level, the data exhibit higher liver cirrhosis mortality rates for men than for women, as well as different levels and different patterns over time across the countries. In Austria, Italy, Spain and Sweden the decline in liver cirrhosis mortality rates started around 1975, whereas in Hungary it began in the 1990s and only started to decline very recently in Finland.
The formal age-period-cohort analysis showed that the inclusion of the birth cohort dimension significantly contributes to the ability to describe and understand alcohol-attributable mortality trends in all analysed populations: The authors found clear differences across countries and between the sexes in the effects of birth cohorts on liver cirrhosis mortality trends, which could be linked to the differences in the abruptness of changes in alcohol consumption over time. The birth cohorts at higher risk of liver cirrhosis mortality were born during 1935–49 in Sweden and Finland, around 1950 in Austria and the Netherlands, and in 1960 or later in Hungary, Italy, Poland and Spain. These differences seem to be very much in line with the assumption that economic progress led to contextual changes, especially for young people. Indeed, positive changes in alcohol policies and increased social awareness of alcohol-related damage generally occurred earlier in more economically advanced countries than in less economically advanced countries.
The authors stress that the cohort dimension should also be included in future studies because of its high policy relevance, which was also emphasized in a commentary to the article in the same journal issue: The cohort dimension can provide information for health policy makers about the age-specific impact of their health policies and other contextual changes. Furthermore, it provides information about which birth cohorts have an elevated risk of alcohol-attributable mortality, and will therefore affect future mortality levels.