Jackevicious 2008

Methods	ITS with monthly data points
Participants	N=6161 who received a PCI with coronary stenting during hospitalization in Ontario
Interventions	Change in a PA policy to a limited use policy allowing for use of clopidogrel for approved indicatons according to pre‐specified prescribing codes
Outcomes	Health: composite rate of readmission for myocardial infarction, death, repeat percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG) within 1 year of discharge, rates of death from any cause and major bleeding, drug use
Notes	Baseline characteristics differed: during the limited use period, patients had lower rates of aspirin use and higher rates of statin use (increase from 63% to 80% P<0.001)
Risk of bias
Bias	Authors' judgement	Support for judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Any undocumented difference in the proportion of missing data in the administrative datasets pre‐ and post‐intervention is unlikely to overturn study results
Selective reporting (reporting bias)	Low risk	All outcomes listed in the methods section are reported in the results section
Other bias	Low risk	No evidence of other risk of bias including seasonality.
Knowledge of allocated interventions adequately prevented during the study	Low risk	Outcomes are objective measures of healthcare utilization
Intervention independent of other changes	High risk	"There were some differences in baseline characteristics between patients in the prior‐authorization period and those in the limited‐use period. In particular, during the limited‐use period, patients had lower rates of aspirin use and higher rates of statin use"
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