Delate 2005

Methods	ITS calculated on a per month per member basis
Participants	Plan members in medicaid program n=1,142,866 to n=1,324,643 during 24 month study period
Interventions	PPI PA program
Outcomes	Drug use, health services utilization, drug costs
Notes	Data collected 12 months prior and 12 months post‐implementation. Time series consisted of 24 PMPM (per member per month) for PPI and H2RA expenditures
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 Medicaid administrative datasets pre‐ and post‐intervention is unlikely to overturn study results
Selective reporting (reporting bias)	Unclear risk	It is not clear whether the restriction of the analysis to charges that were at lease partially reimbursed to the extent to which they were reimbursed introduced a selective reporting bias
Other bias	High risk	New claims for PPIs were not separated from renewals so the before‐after comparison is confounded by the indication.  New claims would be triggered by sickness just before.   The ratio of new to continuing users might differ between the 3 groups. People with Helicobacter infection were granted 1‐month of PPI. PPI users were more likely to have a gastro intestinal (GI) diagnosis and GI screening that H2RA users or non‐users
Knowledge of allocated interventions adequately prevented during the study	Low risk	Outcomes are objective measures of health care 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