Hess 1990.

Methods	STUDY DESIGN: ITS Risk of Bias: MEDIUM
Participants	PROVIDERS: all physicians in the hospital PARTICIPANTS: all patients in the hospital CLINICAL PROBLEM: receiving cefazolin therapy SETTING: a 719‐bed tertiary‐care medical centre in the USA
Interventions	FORMAT: Interventions: dissemination of guideline; educational outreach by review and recommend change Intervention Functions: education, enablement, persuasion DELIVERER: pharmacist COMPARISON: usual care DESIRED CHANGE: decrease excessive
Outcomes	PRESCRIBING: Choice: cefazolin expenditure per patient day FINANCIAL: savings in drug costs
Notes	FINANCIAL SUPPORT: 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	12 months' data pre‐ and postintervention
Analysed appropriately (ITS) ?	Low risk	Re‐analysed. Not done in original paper, no statistical analysis, and only comparison was between mean (uncontrolled) before and after.
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) ?	Unclear risk	On page 588 the authors state that "a proportion of these savings can be attributed to a decrease in acquisition cost", but they do not say how much.