Estimating alcohol-attributable liver disease mortality: A comparison of methods

Abstract

Introduction: Alcohol is a leading contributor to liver disease, however, estimating the proportion of liver disease deaths attributable to alcohol use can be methodologically challenging.

Methods: We compared three approaches for estimating alcohol-attributable liver disease deaths (AALDD), using the USA as an example. One involved summing deaths from alcoholic liver disease and a proportion from unspecified cirrhosis (direct method); two used population attributable fraction (PAF) methodology, including one that adjusted for per capita alcohol sales. For PAFs, the 2011-2015 Behavioral Risk Factor Surveillance System and per capita sales from the Alcohol Epidemiologic Data System were used to derive alcohol consumption prevalence estimates at various levels (excessive alcohol use was defined by medium and high consumption levels). Prevalence estimates were used with relative risks from two meta-analyses, and PAFs were applied to the 2011-2015 average annual number of deaths from alcoholic cirrhosis and unspecified cirrhosis (using National Vital Statistics System data) to estimate AALDD.

Results: The number of AALDD was higher using the direct method (28 345 annually) than the PAF methods, but similar when alcohol prevalence was adjusted using per capita sales and all alcohol consumption levels were considered (e.g. 25 145 AALDD). Using the PAF method, disaggregating non-drinkers into lifetime abstainers and former drinkers to incorporate relative risks for former drinkers yielded higher AALDD estimates (e.g. 27 686) than methods with all non-drinkers combined.

Discussion and conclusions: Using PAF methods that adjust for per capita sales and model risks for former drinkers yield more complete and possibly more valid AALDD estimates.

Keywords: alcohol; alcoholic liver disease mortality; cirrhosis; population attributable fractions.

Figure 1.

Proportion of alcohol-attributable deaths relative to total deaths from assessed types of liver disease^a from all levels of alcohol consumption, by sex and method,^b U.S. population, 2011–2015 ^a To calculate the proportion of liver deaths due to alcohol, the denominator (i.e., total deaths from liver disease) was based on the same ICD-10 codes as used to determine the numerator (i.e., deaths that were alcohol-attributable.) ^b Method 1 involves summing all deaths from alcoholic cirrhosis and 40% of deaths from unspecified cirrhosis; the current approach used in the Centers for Disease Control Prevention Alcohol-Related Disease Impact application. Method 2 adjusts average daily consumption by indexing the number of drinks consumed during binge drinking occasions, if those quantities exceed usual consumption on days when alcohol is consumed (16). Method 3 adjusts the self-reported alcohol consumption to account for 73% of per capita alcohol sales (17). Method 3 accounting for former drinkers is the same as method 3, except non-drinkers were divided into lifetime abstainers and never drinkers, and relative risk estimates for former drinkers were also incorporated in estimates of deaths.