Table 1.

Variable definitions and units

Category	Variable name	Definition	Scale	Valid range/levels	Units
Main exposure variable	First PIP ever	Occurrence of the first PIP ever experienced by a patient during his/her study eligibility period	Dichotomous	Yes or no	1 if PIP 0 if no PIP
Secondary exposure variable	First criterion-specific PIP incidence density	Number of instances of first PIP for each criterion experienced by a patient during his/her eligibility period divided by the duration of the study eligibility period in years (will be calculated separately for STOPP/START and Beers’ criteria).	Continuous	0 to unlimited	Counts/year
Primary outcome variable	Time to any outcome	Time between first PIP and first of ER visit, hospitalisation or death, occurring within the time window for ‘PIP relevant outcomes’ (usually up to 3 months after an instance of PIP, but may be longer for some criteria—see text for examples)	Ordinal	0–90	Days
Secondary outcome variables	Time to ER visit	Time between first PIP and first ER visit	Ordinal	0–90	Days
	Time to hospitalisation	Time between first PIP and first hospitalisation	Ordinal	0–90	Days
	Time to ADE	Time to any diagnostic code for an ADE	Ordinal	0–90	Days
Covariates	Patient age	Patient's age at time of first PIP	Continuous	66–116	Years
	Patient sex	Patient's biological gender	Dichotomous	Male or female	Male or female
	Patient location	Type of setting a patient lives in at time of PIP	Dichotomous	Long-term care vs community setting	Long-term care vs community setting
	Number of prescribers	Number of prescribers who have issued prescriptions for a patient in year prior to the first PIP	Continuous	1 to unlimited	Count
	Number of dispensing pharmacists	Number of pharmacists from whom a patient obtained medication in the year prior to the first PIP	Continuous	1 to unlimited	Count
	Polypharmacy	Number of medications concurrently in use at time of prescription of a PIP	Continuous	1 to unlimited	Count
	SES	Socioeconomic quintile attributed to patient on the basis of his/her census data and postal code	Ordinal	Very low SES, low SES, middle SES, high SES, very high SES	Quintile
	Prior hospitalisations	Number of hospital admissions experienced by a patient in the 12 months preceding a PIP	Continuous	0 to unlimited	Count
	ER visit in past 6 months	Number of visits made to the emergency room by a patient in the 6 months preceding a PIP	Continuous	0 to unlimited	Count
	Comorbidities	Deyo modification of Charlson Comorbidity Index for a patient calculated at the time of first PIP, if patient was hospitalised in the year prior to the first PIP; for patients who were not hospitalised, we will use the Johns Hopkins ADG score	Continuous	0–32	NA
	Acuity of prior hospitalisations	Whether a hospitalisation occurring in the 12 months preceding a PIP was coded as ‘acute’ or not in the Discharge Abstract Database	Dichotomous	Acute vs other	1 if acute 0 if other
	Discharge diagnosis	Most responsible diagnosis for a hospitalisation occurring in the 12 months preceding a PIP as recorded in the Discharge Abstract Database	Categorical	ICD groups	Diagnostic groups
	Prescribing physician age	Physician age	Continuous	20 to ??	years
	Prescribing physician sex	Physician's biological gender	Dichotomous	Male or female	Male or female
	Prescribing physician year of graduation	Physician year of graduation	Ordinal	1945 to ??	Year (date)
	Prescribing physician location	Physician location of practice (rural vs urban)	Dichotomous	Rural vs urban	0 rural, 1 urban
	Type of prescribing physician	Type of physician prescribing a PIP for a given patient	Dichotomous	Specialist vs family physician	Specialist or family MD

ADE, adverse drug event; ADG, Aggregated Diagnostic Group; ER, emergency room; ICD, International Classification of Disease; NA, not available; PIP, potentially inappropriate prescribing; SES, socioeconomic status.