Kellerman 2000

Methods	Purpose: to compare a phone call reminder about influenza vaccination or no intervention Design: RCT, participants randomised Duration of study: 23 September to 23 October 1996 Interval between intervention and when outcome was measured: 1 month  Power computation: not performed Statistics: percentages, probabilities
Participants	Country: USA Setting: Smoky Hill Family Practice Center, Salina, Kansas Eligible participants: (health status): all 475 individuals ≥ 65 were sent a postcard reminder, eligibles are those who did not respond; exclusions = those resident in nursing homes Age: ≥ 65 Gender: not stated
Interventions	All 475 individuals ≥ 65 were sent a postcard reminding them about influenza vaccination; non‐respondents were then randomised to either: Intervention 1: 1 to 2 phone calls Control: no intervention
Outcomes	Outcome measured: % influenza vaccination Time points from the study that are considered in the review or measured or reported in the study: 23 September to 23 October 1996   % vaccinated by: 23 October 1996
Notes	Funding: no funding
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Alternate randomisation of alphabetised households
Allocation concealment (selection bias)	Unclear risk	No statement
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No statement
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Vaccination uptake for the whole practice for the 2 preceding years are provided, but not for the intervention and control groups. Not stated how immunisation data were recorded or whether the practice was computerised (however, participants were all ≥ 65 and thus Medicare beneficiaries so there was an incentive to record data to obtain payment) "For the purposes of this study, only immunizations administered at the Family Practice Center were considered in assessing the study's outcome. During the telephone intervention, Family Practice Center staff recorded any patient comments about prior immunization for that season or subsequent intentions for immunization."
Selective reporting (reporting bias)	Low risk	No selective reporting