Our primary exposure was benzodiazepine prescriptions, ascertained through pharmacy files. A person is assumed to be exposed if they were covered by a prescription for a drug on a given day. We characterized initial benzodiazepine, Z drug, and buprenorphine prescription in terms of strength, quantity dispensed, and days’ supply. To standardize daily dosage, we calculated each benzodiazepine or Z drug’s strength in terms of total diazepam equivalent milligrams(29) using known pharmacologic conversion factors (eTable 2).(30–32) We calculated a daily diazepam equivalent dose by multiplying number supplied by strength (in diazepam equivalent milligrams) and dividing by days’ supply. Benzodiazepine dosage was stratified into high dose (diazepam equivalent mg dose > 30 mg) and low dose (≤ 30 mg) based on established thresholds.(33) Benzodiazepine exposure was categorized based on duration of action, namely short-acting (half-life ≤24 hours) or long-acting (half-life >24 hours), guided by established classifications.(6) Specific classifications of benzodiazepine agents and Z drugs, based on previously published definitions, are shown in eTable 2.(34, 35) Furthermore, we collected data on age, sex, relationship of patient to the primary beneficiary, and insurance status.
