Zavrelova 2011.

Study characteristics
Methods	Study design: retrospective cohort longitudinal Location: the Netherlands Time period: 1998 to 2005 Outcome: PDR Outcome measurement: mean, median, and percentage difference
Participants	Number of participants: 3343 Diabetes type: T2D Inclusion criteria: T2D Exclusion criteria: T1D; no visit or one visit only for graded fundus photographs
Notes	Link to data extraction table, risk of bias assessment, and results: osf.io/srwv8/?view_only=e42486a93e6249f080791756a0a515e0
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

DM: diabetes mellitus; DBP: diastolic blood pressure; DR: diabetic retinopathy; HbA1c: glycated haemoglobin; HR: hazard ratio; IDDM: insulin‐dependent diabetes mellitus; NIDDM: non‐insulin‐dependent diabetes mellitus; NPDR: non‐proliferative diabetic retinopathy; OR: odds ratio; PDR: proliferative diabetic retinopathy; RR: risk ratio; T1D: type 1 diabetes; T2D: type 2 diabetes; WHO: World Health Organization