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.