Non-Alcoholic Fatty Liver Disease Explains Chronic-Liver-Disease-Related Mortality

Alcoholic liver disease and nonalcoholic fatty liver disease (NAFLD) are the leading etiologies for chronic liver disease chronic-liver-disease-related deaths in the United States over the last decade, according to the results of a new study.

The prevalence of nonalcoholic fatty liver disease— a spectrum that includes bland steatosis, nonalcoholic steatohepatitis, cirrhosis (including crypto-genic cirrhosis), and hepatocellular carcinoma—is increasing in the United States and worldwide, alongside the epidemic of obesity and type 2 diabetes. Additionally, chronic liver disease stands as an important cause of mortality and morbidity in both the United States and around the world.

In an effort to analyze the relationship between NAFLD and chronic liver disease, investigators evaluated the mortality trends of chronic liver disease in US patients over the last decade using data from the National Vital Statistics System (NVSS) for 2007 through 2016. (More than 99% of deaths in the United States are recorded by NVSS database.)

The investigators studied ICD-10 diagnostic codes alcoholic liver disease, chronic hepatitis B and C (CH-B and CH-C), iron overload (IO), NAFLD, cirrhosis, and hepatocellular carcinoma, and mortality data for the most common causes of chronic liver disease were selected. Diagnoses were established if the NVSS multiple-cause-of-death files referenced a specific diagnostic category (per ICD-10 coding).

The presence of ICD-10 codes for NAFLD/NASH or ICD-10 codes for ‘cirrhosis of unknown etiology’ (cryptogenic cirrhosis) qualified the patient as having NAFLD. “Age-standardized death rates were adjusted to the census 2000 population and analyzed using joinpoint regression model,” according to the study abstract. After propensity score matching, predictors of chronic-liver-disease-related deaths were estimated by using logistic regression models.

In the United States, 714,903 chronic-liver-disease-related-related deaths were registered during the study period. Consistently increasing, the age-standardized death rate for chronic liver disease has increased from 18.6 deaths per 100,000 population in 2007, to 21.5 deaths per 100,000 population in 2016.

Similarities in increasing death rates were found between males (Average Annual Percentage Change [AAPC] = 1.5, 95% CI (1.5% to 1.9%)) and females (AAPC = 2.7%, 95% CI [2.4% to 3.1%]). Age correlated with an increase in chronic-liver-disease-related deaths and was found to be higher among age groups 55 to 64 years (AAPC = 3.4%, 95% CI: 3.0% to 3.9%) and 64 to 74 years (AAPC = 3.4%, 95% CI: 2.1% to 4.3%).

NAFLD (41%), followed by alcoholic liver disease (32%) and CHC (20%), was the most common diagnostic etiology among chronic-liver-disease-related-related deaths. “Over time, death rates (per 100,000 population) increased from 7.6 to 8.9 for NAFLD (AAPC = 2.2%, 95% CI: 1.8% to 2.6%) and from 5.1 to 7.3 for alcoholic liver disease (AAPC = 3.5%, 95% CI: 2.9 % to 4.2%),” study authors wrote.

Cardiovascular disease (odds ratio [OR] = 1.16, 95% CI: 1.14-1.18), and renal failure (OR = 1.08, 95% CI: 1.06-1.10) were found to be independently associated with increased risk of death in patients with NAFLD in a multivariate analysis presence of T2DM (OR = 1.15, 95% CI: 1.13-1.17).

From their results, the investigators concluded that the leading etiologies for chronic-liver-disease-related-deaths over the last decade can be chalked up to NAFLD and alcoholic liver disease.