Methods: Study design: Population-based cohorts for population-level DUS; New drug user cohort for patient-level DUS. Setting: European data sources with primary care and hospital records mapped to the OMOP common data model and onboarded as data partners in DARWIN EU. Source population: For population-level analyses (prevalence), the whole database population contributing follow-up time after typically 365 days of data visibility available before study start is included. Where needed, restriction to pre-specific subpopulations e.g. based on age, sex or history of diagnoses of interest can be applied. For calculation of incidence of drug use and patient-level analyses, prevalent users of the same drug are excluded. Outcomes measures and Statistical analyses: Population-level analyses: Incidence rates of drug use over calendar time, calculated as the number of new drug users, divided by the total population (person-years). Period or point prevalence calculated as the number of users in the source population at a time point or window. Analyses may be stratified by demographics or calendar period. Periods of calendar days, weeks, months or years can be defined as needed. Patient-level analyses comprise baseline characteristics of new drug users, with large-scale characterisation summarising patient-level features including socio-demographics, comorbidity, and comedication before/at/after treatment initiation. Indication for drug use and drug dose/strength at therapy initiation, treatment duration, as well as cumulative drug use and number of repeated prescriptions within a time period are provided.
