Mitchell 2012.

Study characteristics
Methods	Parallel RCT, Individuals randomised
Data	UK, primary care setting. The sample size was arbitrary in that it was limited to the numbers of host trial participants recruited at the two sites. Total n = 2704; Range age from 70 to 85 years old; 100% females.
Comparisons	Intervention group received a newsletter approximately 6 weeks before the follow‐up questionnaire Control group did not receive a newsletter.
Outcomes	Questionnaire return
Notes	Retention period: 24 months
Risk of bias
Item	Authors' judgement	Support for judgement
Allocation concealment?	Yes	The randomisation was undertaken by the York data manager who randomised to two equally sized groups in one single block allocation (the block was the size of all the potential participants).
Adequate sequence generation?	Yes	A computer program randomly divided the total numbers of participants into two equally.
Blinding of participants and personnel?	Yes	Not reported in the paper but unblinding not likely to impact objective outcome
Blinding of outcome assessment?	Yes	Not reported in the paper. However, objective outcome, staff have no plausible additional opportunity to influence postal response rate once questionnaires sent.
Incomplete outcome data addressed? All outcomes	Yes	No concerns raised.
Free of selective outcome reporting?	Yes	No concerns raised.
Other sources of bias	Yes	No further concerns raised.
Overall Risk of Bias	Unclear	Unclear