Glassman 2020.

Study characteristics
Methods	Parallel RCT, individuals randomised
Data	USA, secondary care setting. All participants from the host trial. Total n = 305; median age from intervention group 53 (44–60) years, and in the control group 51 (45–59) years; 44.2% females; 52.4% Non‐Hispanic White; 25.5% Hispanic or Latino; 15% Non‐Hispanic Black or African American.
Comparisons	Intervention group received telephone calls at baseline, six months, and at annual visits after that (annual contact). Control group received a call at baseline only (baseline contact).
Outcomes	Visit completion rates.
Notes	Retention period: 24‐,36‐, 48‐ and 60‐months visits
Risk of bias
Item	Authors' judgement	Support for judgement
Allocation concealment?	Unclear	Not described in the paper
Adequate sequence generation?	Yes	Randomisation was stratified by treatment group and performed using study website using computer‐generated random numbers
Blinding of participants and personnel?	Unclear	Not described in the paper and telephone calls from staff may have potential to unblind participants or affect outcome.
Blinding of outcome assessment?	Yes	Not described 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 All outcomes	Unclear	The trial clearly reported why participants randomised where not included in the main analysis – withdrawn with reasons and death but this is at 5 years only
Free of selective outcome reporting?	Yes	All defined outcomes reported
Other sources of bias	Unclear	No further concerns raised.
Overall Risk of Bias	Unclear	Unclear