Fischer 2004

Methods	Controlled ITS with quarterly data points
Participants	50 Medicaid programs in 22 states
Interventions	PA policy for COX‐2 inhibitors
Outcomes	Drug use and drug costs
Notes	Policies classified based on 5 cinical risk factors for gastrointestinal adverse effects: More strict ≥4 gastrointestinal complicatons, and patients have a history of GI complications from NSAIDS, Strict ≥4 gastrointestinal, all others defined as less restrictive
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	Unclear risk	"States with prior‐authorization programs may have differed systematically from states without such programs in ways not captured by our data, since states with these programs had slightly lower rates of coxib use before the programs were implemented. Patterns of NSAID prescribing for Medicaid beneficiaries appear to have similar variability, even independent of the effects of prior‐authorization programs, and should be a target of subsequent studies."
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