Himmelberg 1991.

Methods	STUDY DESIGN: ITS Risk of Bias: LOW
Participants	PROVIDERS: physicians in the hospital PARTICIPANTS: patients in the hospital CLINICAL PROBLEM: patients receiving restricted antibiotics SETTING: a tertiary‐care teaching hospital in the USA
Interventions	FORMAT: Interventions: restrictive, removal of restriction Intervention Functions: restriction DELIVERER: specialist physician COMPARISON: 6 months in the restriction period were compared with 6 months after restriction was lifted. DESIRED CHANGE: decrease excessive
Outcomes	PRESCRIBING: Choice: number of courses and cost of restricted drugs FINANCIAL: cost of drugs
Notes	FINANCIAL SUPPORT:Funding: commercial, Pfizer Roerig and the Upjohn companies. Competing Interests: no information ADDITIONAL DATA: no response from authors to request for additional data
Risk of bias
Bias	Authors' judgement	Support for judgement
Intervention independent (ITS) ?	Low risk	Data collected in same months in 2 consecutive years.
Analysed appropriately (ITS) ?	Low risk	Re‐analysed. Not done in original paper: comparison of means (uncontrolled before‐after) with t‐test.
Shape of effect pre‐specified (ITS) ?	Low risk	Done, intended effect was decrease in primary outcome, and point of analysis was point of intervention.
Unlikely to affect data collection (ITS) ?	Low risk	Done, data were from routine systems and unlikely to change over study period.
Knowledge of the allocation adequately prevented(ITS)?	Low risk	Done, data were from routine systems and unlikely to change over study period.
Incomplete outcome data addressed (ITS) ?	Low risk	Done, data were from routine systems and unlikely to change over study period.
Free of selected reporting (ITS) ?	Low risk	Done, data were from routine systems and unlikely to change over study period.
Free of other bias (ITS) ?	Low risk	No other apparent biases found.