Coding of Obesity-related Mortality Impacts Estimates of Obesity on U.S. Life Expectancy

BackgroundHigh levels of obesity remain an important population health problem in the U.S. and a possible contributor to stalling life expectancy. However, reliable estimates of the contribution of obesity to mortality in the U.S. are lacking, because of inconsistent coding of obesity-related causes of death. MethodsWe compare five International Classification of Diseases version 10 (ICD-10) coding schemes for obesity-related mortality used in the literature and examine how the magnitude of obesity-related mortality burdens varies across different schemes. We use U.S. multiple cause of death data and population estimates for the Black, white, and Latino population in the years 2010, 2015, and 2020. In sex- and race/ethnic-stratified analyses, we estimate the potential years of life expectancy gained if obesity-related mortality had not occurred as measured by each coding scheme. ResultsWe estimate that obesity-related mortality contributes to up to 78 months (6.5 years) of lost U.S. life expectancy, though estimates range from as low as 0 months, with a median contribution across ICD-10 coding schemes of about 20 months (1.7 years). Despite substantial variation across coding schemes, obesity-related mortality consistently contributes more to life expectancy deficits for Black Americans compared to white and Latino Americans. Across all ICD-10 coding schemes, the age pattern of obesity follows a J-shaped curve, suggesting exponential increases in obesity-related mortality after age 25. ConclusionsThe estimation of the burden of obesity-related mortality on life expectancy in the United States varies widely depending on the causes of death used in analyses. This inconsistency may obscure our understanding of the contribution of obesity-related mortality to trends in life expectancy. We propose a standardization of the coding of obesity-related mortality for future studies and outline which causes should be included.