Lee 1992.

Study characteristics
Methods	Study design: prospective cohort longitudinal Location: USA Time period: 1972 to 1990 Outcome: PDR Outcome measurement: cumulative incidence, means of progressors versus non‐progressors to PDR, and RR
Participants	Number of participants: 354 Diabetes type: T2D Inclusion criteria: NIDDM (no further description); Oklahoma Indians (understood to be Native Americans) examined at the Indian Health Service facilities in Oklahoma; fasting plasma glucose > 7.8 mmol (140 mg/dL) or a 2‐hour post‐load blood glucose level > 11.1 mmol (200 mg/dL); diagnoses of DM between 1937 and 1980   Exclusion criteria: PDR at baseline
Notes	Link to data extraction table, risk of bias assessment, and results: osf.io/by7rg/?view_only=efe5c7e01b0a4c2d8ab0a55cdc05fb08
Item	Authors' judgement	Support for judgement
Study participation	Unclear	See ‘Notes’ above for link to risk of bias assessment
Study attrition	Unclear	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	Yes	See ‘Notes’ above for link to risk of bias assessment
Adjustment for other prognostic factors	Unclear	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