Schneeweiss 2006

Methods	ITS with monthly data points
Participants	Senior beneficiaries in provincial drug benefit plan, British Columbia, Canada, N=501,104
Interventions	Restricted coverage to rabeparazole and required treatment failure with a H2RAs. Omeprazole, pantoprazole, and lansoprazole had to be paid for out‐of‐pocket unless physician requested exemption
Outcomes	Utilization of PPIs, drug discontinuation rates, gastrointestinal hemorrhage rates, drug expenditures
Notes	Introducton of a general 30% coinsurance requirement (Fair PharmaCare) 2.5 months earlier may have diminished some of the potential savings of the PPI restriction. Time series analysis between January2002 and June 2004.
Risk of bias
Bias	Authors' judgement	Support for judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	"The databases comprehensively covered all British Columbia seniors with the exception of a very small number of patients who left the province.This censoring is most likely random in a province that has net in‐migration of elderly persons.
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Low risk	"The design of our study implicitly controlled for many confounding factors including health status by adjusting for baseline time trends in utilization and health outcomes."
Knowledge of allocated interventions adequately prevented during the study	Low risk	Outcomes are objective measures of healthcare utilization
Intervention independent of other changes	Low risk	Known and unknown changes in the environment are unlikely to be responsible for sudden change and magnitude of effect size
The shape of intervention pre‐specified?	Low risk	The point of analysis is the point of intervention; ie, the date the policy intervention was implemented was used to delineate pre and post policy time periods with adequate data points to capture the shape of the pattern of intervention effect over time
Intervention unlikely to affect data collection?	Low risk	Sources and methods of data collection were the same before and after the intervention