The use of diagnostic codes to record long-term excessive drinking and alcohol use disorder– a systematic review

Objectives Alcohol-related disease and mortality continue to rise globally, with hazardous drinking the third leading cause of premature death in the UK. Population studies are valuable for understanding excessive drinking patterns, but case-finding is limited by variability in Electronic Health Record (EHR) coding. This systematic review identified diagnostic codes used to define alcohol use. Methods Using PRISMA guidance, OVID (MEDLINE, PsychINFO, EMBASE), Pubmed and Web of Science were searched. Data were extracted on drinking-related codes and prevalence estimates. International Classification of Diseases (ICD) v10 and Read v2 studies were analysed using narrative synthesis, and risk of bias was assessed. Results Twelve studies were included from 16,913 records. Six of twelve studies were deemed to be at low risk of bias. No studies were deemed to be at high risk of bias. Two studies identified 18 shared Read v2 codes classifying drinking behaviour. Ten studies used ICD-10 codes; F10 and its subcategories were used consistently; additional codes improved episode-based case-finding but not identification of unique patients. Conclusion Coding heterogeneity complicates identification of excessive drinking. Although commonly used Read v2 and ICD-10 codes were identified, no standardised code set exists, highlighting the need for consensus to improve consistency in population-based alcohol research.