McCaul 2002
| Methods | Purpose: to compare letter informing participants of importance of flu shot to reminder letter stating date and time of clinic Design: RCT, clustered by counties Duration of study: not reported Interval between intervention and when outcome was measured: not stated Power computation: not performed Statistics: t tests | |
| Participants | Country: USA Setting: 29 North Dakota counties Eligible participants: (health status): 6730 male and 9107 female Medicare recipients who had not submitted Medicare reimbursement requests for flu shots the previous year Age: ≥ 65 Gender: 57.5% f | |
| Interventions | Intervention 1: card reminding recipients of advantages of flu shots Intervention 2: letter reminding recipients of advantages of flu shots and stating time, date and place of flu shot clinics Control: no intervention | |
| Outcomes | Outcome measured: % vaccinated Time points from the study that are considered in the review or measured or reported in the study: not stated % vaccinated by: not stated |
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| Notes | Funding: Health Care Financing Administration | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "we randomly assigned counties to either the reminder letter (n = 17), action‐letter (n = 12), or no‐letter (n = 20) conditions. Within the reminder‐letter counties, we then randomly assigned individuals within each county to either the reminder‐only, reminder plus positive frame, or reminder plus negative frame conditions. Within the action‐letter counties, all individuals received the same action letter" (no statement about method of randomisation) |
| Allocation concealment (selection bias) | Unclear risk | No statement |
| Blinding (performance bias and detection bias) All outcomes | Low risk | No statement about blinding, but assessment based on Medicare reimbursement claims |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | E‐mail from author states "... subject loss was 6%, most of which was letters being returned." |
| Selective reporting (reporting bias) | Low risk | No selective reporting |