Dietrich 1989
| Methods | Purpose: to compare effects of reminder letters and checklists to obtain influenza vaccination to no intervention Design: RCT, participants randomised Duration of study: enrolment during 3 months in "fall of 1984" Interval between intervention and when outcome was measured: 12 months before and after randomisation Power computation: not performed Statistics: t tests; Chi2 | |
| Participants | Country: USA Setting: community practice in New England with 5 family physicians and 1 internist Eligible participants: (health status) > 65 with office visits during 3‐month enrolment period in 1984; exclusions: no telephone, transient, blind, demented, terminally ill; 156 potential participants, 31 not eligible; 117 returned baseline questionnaire; 2 died and 1 moved during study Age: 74 Gender: 68% f | |
| Interventions | Intervention: mailed personal prevention checklists, letters encouraging use of checklists to keep track of preventive health care 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: 12 months before and after randomisation % vaccinated by 12 months after randomisation | |
| Notes | Funding: American Academy of Family Physicians and US Public Health Service | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "participants were assigned randomly" (no statement about method) |
| Allocation concealment (selection bias) | Unclear risk | No statement |
| Blinding (performance bias and detection bias) All outcomes | Low risk | No statement, chart audit for vaccinations (not stated who performed chart audit, but was retrospective), and questionnaires for vaccination received elsewhere |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All 114 recruited patients were followed to the end of the study; chart audit for vaccinations, and questionnaires for vaccination received elsewhere |
| Selective reporting (reporting bias) | Low risk | No selective reporting |