Griffin 2019.

Study characteristics
Methods	RCT, individuals randomised
Data	UK, primary care setting. All host trials participants included. Total n = 9375; mean age 77.9 (SD 5.8) years; 52.4% females; 61% married.
Comparisons	Participants were randomised allocated participants to receive prospective monthly falls diaries for one simultaneous 4‐month period: · Intervention group 1 received falls diaries from randomisation to 4 months follow‐up. · Intervention group 2 received falls diaries from 5 and 8 months. · Intervention group 3 received falls diaries from or between 9 and 12 months Furthermore, all trial participants received a postal questionnaire at baseline and at 4‐, 8‐, 12‐, and 18‐months post‐randomisation to evaluate data retrospectively.
Outcomes	Number of participants who provided falls data on a full set of diaries and on the questionnaire for the corresponding period
Notes	Retention period: up to 4 months. Data also available for 5‐8 months and 9‐12 months.
Risk of bias
Item	Authors' judgement	Support for judgement
Allocation concealment?	Unclear	This nested trial design used a separate randomisation strategy to allocate trial participants. However, allocation concealment unclear.
Adequate sequence generation?	Unclear	This nested trial mentions that the design used a different randomisation strategy to allocate trial participants. However, not reported the sequence generation. The number of people in the control arm was higher compared at the intervention arm.
Blinding of participants and personnel?	Yes	Not reported in the paper.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