Keen 2001.

Study characteristics
Methods	Study design: prospective cohort longitudinal Location: multinational (10 centres) Time period: 1975 to 1978; follow‐up study conducted between 1983 and 1986 (in Oklahoma between 1988 and 1990) Outcome: PDR Outcome measurement: cumulative incidence and OR
Participants	Number of participants: 4483 Diabetes type: T1D and T2D Inclusion criteria: the study protocol required equal numbers of men and women with diabetes, sampled from three age bands within the range 35 to 54 years Exclusion criteria: not reported
Notes	Link to data extraction table, risk of bias assessment, and results: osf.io/mejrs/?view_only=7dda7dbbfcea4b78ac3bef421141ff80
Item	Authors' judgement	Support for judgement
Study participation	Unclear	See ‘Notes’ above for link to risk of bias assessment
Study attrition	No	See ‘Notes’ above for link to risk of bias assessment
Prognostic factor measurement	Unclear	See ‘Notes’ above for link to risk of bias assessment
Outcome measurement	Unclear	See ‘Notes’ above for link to risk of bias assessment
Adjustment for other prognostic factors	No	See ‘Notes’ above for link to risk of bias assessment
Statistical analysis and reporting	Unclear	See ‘Notes’ above for link to risk of bias assessment