Overhage 1996.

Methods	RCT Cluster Unit of randomization: services Unit of analysis: participants Study period: 1992 to 1993
Participants	USA 1 center Departments: medicine services Medical patients Inclusion criteria: patients admitted to general medicine ward during 6‐month study period for whom the computer generated at least 1 preventative care recommendation Exclusion criteria: patient was admitted before study began, patient was discharged after study ended, patient had already been hospitalized once during the study, patient remained in the hospital less than 18 hours N included: 801 (control), 821 (intervention) Age (mean (SD)): control = 51 (18), intervention = 51 (18) Male %: 50 (control), 50 (intervention) Control group: concurrent with intervention group. Control group observed for 6 months; same types of participants (department/hospital) as intervention group
Interventions	Aimed at doctors Use of reminders: electronic alert Computer reminder program analyzed electronic medical records, reminders appeared on printed daily reports and at work station when entering order, suggestions for orders provided Comparator: physicians who received the intervention (electronic alert) vs. controls (reminders were not printed or displayed)
Outcomes	Appropriateness of prophylaxis not assessed Received prophylaxis: 35.7% (control), 43.3% (intervention) PE/DVT occurrence not assessed
Notes	Funding sources: Quote: "This work was supported by grants HS 05626 and HS 07719‐013 from the Agency for Health Care Policy and Research, Rockville, Md."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Before each 6‐week rotation, the chief medical resident constructed teams of faculty, house staff and students bases on scheduling issues, clinical skills, and personalities. The study biostatistician then randomly assigned the teams to services. Patients were assigned intervention or control status based on the service to which they were admitted." (Page 1552, column 2, paragraph 2) They did not provide details on how the 6 services were randomized.
Allocation concealment (selection bias)	Unclear risk	There was no mention of allocation concealment in the text.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "In addition, to structuring call schedules to maintain 'blinding', the computer would not print or display reminders for control physicians at any time." (Page 1553, column 1, paragraph 5). There was no clear mention of blinding of all participants and personnel.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "The study biostatistician then randomly assigned the teams to services. Patients were assigned intervention or control status based on the service to which they were admitted." (Page 1552, column 2, paragraph 2)
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	There was no mention of the completeness of follow‐up or of incomplete outcome data.
Selective reporting (reporting bias)	Unclear risk	No clinical or safety outcomes reported
Other bias	Unclear risk	Low risk for baseline imbalances: Quote: "No differences were seen between the intervention and control patients for demographic characteristics or the most common primary admitting diagnoses (Table 2)." (Page 1552, column 1, paragraph 4) Unclear risk for incorrect analysis: clustering was taken into account in the analysis. But, there was no mention of sample size calculation. Quote: "Because compliance rates for different preventive care measures were correlated within each physician team, we analyzed the results for all preventive care measures combined and then for each measure separately using the Kleinman beta binomial model. For all comparisons, we defined a 2‐tailed P value of .05 or less as significant." (Page 1553, column 2, paragraph 4) Low risk of bias for other items listed as potential sources of bias