Hogg 2008

Methods	Purpose: to compare a comprehensive preventive intervention programme to no intervention Design: cluster‐RCT, match‐paired; "The unit of randomization and analysis was the practice; the unit of observation was the patient." Duration of study: 11.5 months Interval between intervention and when outcome was measured: "The intervention lasted 11.5 months." "Data were collected ... up to 2 months after the intervention."  Power computation: 24 practices were needed to detect a mean difference of 0.07 in the primary outcome between intervention and control groups ("The delta selected (0.07) approximates the 10% change in care frequently associated with care improvement interventions"), SD = 0.083, α = 0.05, β = 0.83, and 27 practices were recruited to allow for 15% attrition Statistics: Chi2, paired t‐tests
Participants	Country: Canada Setting: 2 letters and brochure to 351 primary care practices in eastern Ontario; 54 practices participated Eligible participants: (health status): ≥ 65 Age: ≥ 65 Gender: not stated
Interventions	Intervention 1: comprehensive preventive intervention programme; facilitators were assigned 13 to 14 practices and visited them monthly, average duration of visit 46 minutes; facilitators encouraged 26 preventive manoeuvres; with baseline audit, feedback and consensus building, and periodic follow‐up and consensus building Control: no intervention
Outcomes	Outcome measured: % influenza vaccination for each practice Time points from the study that are considered in the review or measured or reported in the study: "The intervention lasted 11.5 months." "Data were collected ... up to 2 months after the intervention."  % vaccinated by: "up to 2 months after the intervention"
Notes	Funding: Canadian Institutes of Health Research
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Practices were matched on solo versus group practice, presence of nursing staff and location (rural or urban) and each pair member was randomly assigned using the Statistical Analysis software package."
Allocation concealment (selection bias)	Low risk	"The allocation sequence was kept locked and unavailable to the administrative staff until the time of assignment."
Blinding (performance bias and detection bias) All outcomes	Low risk	"Physicians and facilitators were blinded to the actual manoeuvres that would be included in the preventive performance index."
Incomplete outcome data (attrition bias) All outcomes	Low risk	54 practices randomised, data from 54 analysed (27 intervention, 27 control practices)
Selective reporting (reporting bias)	Low risk	No selective reporting