Law 2008

Methods	Controlled ITS with quarterly data points
Participants	Intervention: West Virginia and Texas Medicaid programs; control: weighted average of 38 states with no PA
Interventions	PA policies for 2nd generation antipsychotics
Outcomes	Drug Use, drug costs
Notes	Assessed national trends in prescribing and utilization by calculating expenditures and dosing from 1991‐2005
Risk of bias
Bias	Authors' judgement	Support for judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	"we have some concerns about the data for total reimbursement in West Virginia. Figure 3 shows that despite a consistent trend, reported reimbursements varied significantly between quarters."
Selective reporting (reporting bias)	Low risk	All outcomes listed in the methods section are reported in the results section
Other bias	Low risk	"Texas and West Virginia may not be representative of the experience in other states and may differ in their authorization criteria, drugs covered, and implementation. However, given the broad geographic dispersion and differing population sizes, we feel that the consistency of results is important.Moreover, the drugs typically subject to PA in other state programs are similar to those in the study states."
Knowledge of allocated interventions adequately prevented during the study	Low risk	Outcomes are objective measures of healthcare utilization
Intervention independent of other changes	Unclear 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