Rodgers 2019.

Study characteristics
Methods	Factorial RCT, individuals randomised
Data	UK, primary care setting. Participants in the host trial who were due to be sent their 12‐month follow‐up questionnaire who had not withdrawn or requested not to be sent the 12‐month questionnaire. Total n = 826; mean age 77.5 (SD 7.0) years old; 61.6% females.
Comparisons	Participants were assigned to one of the following six groups: a) trial update newsletter plus handwritten Post‐it® note applied to the questionnaire b) newsletter plus printed Post‐it®; c) newsletter only d) handwritten Post‐it® note only e) printed Post‐it ® note only f) none
Outcomes	Return of questionnaire
Notes	Retention period: 12 months
Risk of bias
Item	Authors' judgement	Support for judgement
Allocation concealment?	Yes	An independent data manager who was not involved in the recruitment of participants generated the allocation sequence.
Adequate sequence generation?	Yes	Generated the allocation sequence by computer and allocated participants in a 1:1:1:1:1:1 ratio.
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	Unclear	Not reported in the paper.
Free of selective outcome reporting?	Unclear	Not reported in the paper.
Other sources of bias	Yes	No further concerns raised.
Overall Risk of Bias	Unclear	Unclear