Incidence of ICD-Based Diagnoses of Alcohol-Related Disorders and Diseases from Swedish Nationwide Registers and Suggestions for Coding.

AIM: To improve consistency between register studies in Sweden and ensure valid comparisons of possible changes in alcohol-related disorders and diseases (ARDDs) over time, we propose a definition of ARDDs. Based on this definition, we examined Sweden's incidence rates of ARDDs from 1970 to 2018 in non-primary healthcare settings (inpatient and outpatient). METHODS: Swedish Society of Epidemiology members were invited to give feedback on the International Classification of Disease (ICD) codes with a potential link to alcohol use. We then calculated age-standardised and age-specific incidence of ARDDs over time according to the National Patient Register, and the lifetime prevalence of ARDDs diagnosed in adults alive in Sweden on Dec 31, 2018. RESULTS: Sweden's estimated incidence of ARDDs increased substantially after introducing the new ICD-9 codes in 1987. In the past 10 years (2009-2018), the incidence of ARDDs has been stable (males: 110/100,000 person-years, females: 49/100,000 person-years). Requiring at least two ICD records for diagnosed ARDDs led to a somewhat lower incidence of ARDDs (males: 71 per 100,000 person-years, females: 29 per 100,000 person-years). In Sweden, the lifetime prevalence of diagnosed ARDDs in adults on Dec 31, 2018, was 1.9% (95% CI=1.9-1.9). CONCLUSION: In this nationwide study, we found an incidence of ARDDs of 50-100/100,000 person-years. In 2018, 1 in 52 adults in Sweden had been diagnosed with ARDDs in the National Patient Register.