Siriwardena 2002
| Methods | Purpose: to compare the effect of an educational outreach visit to primary healthcare teams on influenza and pneumococcal vaccination uptake to written feedback Design: stratified cluster‐RCT Duration of study: 8 months Interval between intervention and when outcome was measured: 6 months Power computation: based on vaccination rate per practice as primary outcome. Sample size was based upon attainment of an increase in vacation uptake of 20%. To detect a difference between control rates and the desired targets of at least 1 standard deviation, the Student's t‐test with power 0.8 and size 0.05 would require 17 practices per group or 9 per group to detect an effect of 1.5 standard deviations with same power Statistics: Poisson regression using population at risk as an offset and taking account of the stratification. Rates were expressed as mean vaccination rates, odds ratios and confidence intervals | |
| Participants | Country: UK Setting: 20 primary care practices in the West Lincolnshire Primary Care Trust and the 10 Trent Focus Collaborative Research Network Eligible participants: (health status) 30 practices had participants aged 65 years or older or who had coronary heart disease, diabetes or splenectomy on their registers. A total of 27,580 participants aged 65 years or older were included in the 30 practices Age: no information provided on age distribution of participants in practices Gender: no information provided on sex distribution of participants in practices | |
| Interventions | Intervention 1: 1‐hour educational outreach visit (based on principles of academic detailing) to practice teams; delivered by one of the research team that included feedback of practice vaccination uptake in relation to other practices in the study and national targets Control: written feedback on their vaccination uptake compared with other participating practices | |
| Outcomes | Outcome measured: mean vaccination uptake (adjusted for initial level and stratification) based upon practice records, for
Time points from the study that are considered in the review or measured or reported in the study: baseline data collection began in August 2000. Interventions delivered at the start of the annual influenza vaccination campaign of October 2000. Outcomes ascertained 6 months after the educational outreach visit, i.e. 8 months after baseline data collection |
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| Notes | Baseline data collection was in August 2000 and was done by practice staff The unit of cluster was the practice. However, because of ceiling effects (capacity to increase immunisation uptake depends on baseline, possibly easier to increase from low baseline), practices were stratified on baseline uptake of influenza vaccination for diabetics as this had been previously shown to be correlated with risk group. Within strata, practices were randomly allocated to intervention or control 20/39 practices in the West Lincolnshire Primary Trust participated as did 10/50 from the Trent Focus Collaborative Research Network Participating and non‐participating practices were similar in number of partners, list size, whether or not they were dispensing practices and rurally Funding: Trent Focus and West Lincolnshire Primary Care Trust | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "Fifteen practices were randomised to intervention and 15 to the control group after stratifying for baseline vaccination rate." |
| Allocation concealment (selection bias) | Unclear risk | No information provided |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | Not possible with this design |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | 13,633 in intervention group and 13,947 in control group, but no data on attrition; vaccination status assessed from clinic records |
| Selective reporting (reporting bias) | Low risk | No selective reporting |