Satterthwaite 1997
| Methods | Purpose: compare personalised invitation recommending a visit to doctor to be vaccinated where patient required to pay for vaccination to personalised invitation to be provided with free vaccination to no intervention on influenza immunisation uptake Design: RCT Duration of study: not stated Interval between intervention and when outcome was measured: not stated Power computation: not stated Statistics: Chi2 statistic of significance adjusted for design effect of within practice clustering. Design effect for contrast of intervention 1 versus control was 1.09. Design effect of contrast for intervention 2 versus control was 4.05 | |
| Participants | Country: New Zealand Setting: 31 active general practitioners in the Auckland region randomly selected from the cervical screening program were invited to participate. Eligible practitioners were able to generate a list of names and addresses of all participants over 65 years of age, normally provided influenza vaccine to participants, worked at least 8/10 full time equivalent and did not currently have in place a postal reminder system for influenza vaccination for participants over 65 years. 8 doctors were not eligible, 7 were eligible but did not wish to participate and 16 were eligible and participated. Within each practice, up to 210 participants were randomly allocated to interventions Eligible participants: (health status) 2791 persons aged over 65 years Age: within each practice, participants aged over 65 years. Age distribution of participants not stated Gender: sex distribution of participants not stated No information provided on exclusion of participants | |
| Interventions | Intervention 1 (N = 931): personalised invitation sent to people (mail) recommending that they visit their general practitioner to receive a flu vaccination. Those who accepted the invitation would have had to pay about NZD 20 for vaccination Intervention 2 (N = 930): personalised invitation sent to people recommending that they visit their general practitioner to receive a flu vaccination at no charge Control (N = 930): no intervention. These persons would have had to pay about NZD 20 for vaccine | |
| Outcomes | Outcome measured: % participants vaccinated after intervention as recorded by practice staff, validated by authors only for participants who received intervention 2 Time points from the study that are considered in the review or measured or reported in the study: no information provided | |
| Notes | No information provided on year study was done. Internal evidence in the article suggested prior February 1997. Authors note that in 1997 flu season, government policy will change to make influenza vaccination free for persons over 65 years of age No information provided on vaccination status prior year Data are not presented by practice Funding: vaccine provided at no cost by Rhone Poulenc and distributed to practitioners by Ebos Group | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "The patients were randomly allocated" (no method stated) |
| Allocation concealment (selection bias) | Unclear risk | No information provided |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | No information provided |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | 930 in group 2 (invitation letter), 930 in group 3 (free vaccine letter) and 930 in group 1 (control); no data on attrition |
| Selective reporting (reporting bias) | Low risk | No selective reporting |