Methods |
Purpose: to compare personalised letter with no intervention Design: RCT, individuals randomised Duration of study: interval between intervention and when outcome was measured: "Kaiser Permanente ...operates seasonal influenza clinics." Power computation: not performed Statistics: percentages |
Participants |
Country: USA Setting: Kaiser Permanente Northeast Region HMO in Portland, Oregon/Vancouver and Washington metropolitan area Eligible participants: (health status): ≥ 65, discharged alive from hospital October 1983 to September 1984 with diagnoses of cardiovascular, pulmonary, renal, metabolic/nutritional, neurologic or malignant diseases Age: ≥ 65 Gender: intervention 48.1% f; control 52.7% f |
Interventions |
Intervention 1: personalised recommendation to obtain influenza vaccination, and information about where and when to obtain vaccination 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: not stated: "Kaiser Permanente ...operates seasonal influenza clinics." % vaccinated by; not stated |
Notes |
Funding: not stated; we e‐mailed the author for influenza vaccination uptake in the year before the intervention but no reply |
Risk of bias |
Bias |
Authors' judgement |
Support for judgement |
Random sequence generation (selection bias) |
Low risk |
"The study group population was randomised into intervention and control groups based on a pseudo random digit of the individual membership ID number." |
Allocation concealment (selection bias) |
Unclear risk |
No statement |
Blinding (performance bias and detection bias) All outcomes |
Unclear risk |
No statement: "Medical records were retrospectively reviewed at the end of the study period to ascertain whether subjects had received influenza vaccine" |
Incomplete outcome data (attrition bias) All outcomes |
Unclear risk |
"Medical records were retrospectively reviewed at the end of the study period to ascertain whether subjects had received influenza vaccine ..." |
Selective reporting (reporting bias) |
Low risk |
No selective reporting |