Summary of findings 1. Prognostic factors for the development and progression of PDR in people with diabetic retinopathy: demographic factors.

Population: people with diabetes  Outcome: progression to PDR
Prognostic factors	Study results: effect estimates (95% confidence interval (CI))	Certainty of evidence	Plain text summary
Gender (males versus females) (Refer to Table 2 for adjustment factors)	T1D and T2D (follow‐up 4 to 6 years)  Adjusted HR ranged from 0.92 (0.71 to 1.19) to 1.08 (0.94 to 1.22)   Data from 93,246 participants in 4 studies Adjusted RR 1.5 (0.70 to 3.40)  Data from 953 participants in 1 study	Moderatea	Gender is not likely to increase risk of developing PDR
Ethnicity (Refer to Table 3 for adjustment factors)	T1D (follow‐up 7 years) Adjusted OR 0.73 (0.30 to 1.78) (African American vs. White) Data from 312 participants in 1 study T2D (follow‐up 5 to 10 years) Adjusted HR 0.94 (0.89 to 1.00) (Non‐White vs. White ) Adjusted OR 4.4 (2.0 to 9.7) (Ashkenazi Jews vs. Non‐Ashkenazi Jews) Data from 32,883 participants in 2 studies Mixed T1D and T2D (follow‐up 5 years) Adjusted HR 1.29 (0.92 to 1.82; P > 0.05) (Black); 1.12 (0.76 to 1.65; P > 0.05) (Latino); 1.35 (0.73 to 2.49; P > 0.05) (Asian) Data from 4617 participants in 1 study	Very lowa,b,c	The evidence is very uncertain about the effect of ethnicity on risk of developing PDR
Age at diagnosis of DM (Refer to Table 4 for adjustment factors)	T1D (follow‐up 7 years) Adjusted standardised regression estimate 1.62 (1.06 to 2.48; P = 0.038) (< 12 years) Data from 2013 participants in 1 study T2D (follow‐up 5 years) Adjusted OR 0.46 (0.29 to 0.74) (18 to 34 years vs. 45 to 54 years); 1.25 (1.05 to 1.48) (55 to 64 vs. 45 to 54 years); 1.62 (1.28 to 2.03) (65 to 74 vs. 45 to 54 years); 1.30 (1.00 to 1.68) (≥ 75 vs. 45 to 54 years)	Lowa,b	Evidence from one study in T1D,  suggesting age of diagnosis < 12 years may be associated with progression to PDR in T1D   Evidence from one study in T2D, suggesting age of diagnosis between 18 to 34 vs. 45 to 54 years may decrease risk of progression to PDR, and age of diagnosis between 55 to 74 vs. 45 to 54 years may increase risk of progression to PDR
Duration of DM (Refer to Table 5 for adjustment factors)	T1Dand T2D (follow‐up 2 to 25 years) Adjusted OR ranged from 0.69 (0.35 to 1.36) to 1.20 (1.10 to 1.30). Data from 5591 participants in 4 studies Adjusted RR ranged from 1.03 (0.94 to 1.12) to 1.95 (1.58 to 2.39). Data from 4206 participants in 3 studies Adjusted HR 1.21 (1.10 to 1.79). Data from 452 participants in 1 study	Very lowa,b,c	Evidence is very uncertain about the effect of duration of DM on progression to PDR (duration of DM was not independently associated with development of PDR when correcting for other important risk factors, including HbA1C and DR severity at baseline)
Type of DM	T1D and T2D (follow‐up 5 to 8 years) Adjusted RR 0.62 (0.50 to 0.76) (T1D) 0.91 (0.72 to 1.13) (insulin‐treated T2D) Adjusted HR 0.86 (95% CI not reported; P value not statistically significant) (T1D)	Very lowa,b,c	Evidence is very uncertain about the effect of type of DM on progression to PDR, but T1D may have a protective effect
Socioeconomic status (Refer to Table 6 for adjustment factors)	T1D (follow‐up 4 years)  Adjusted OR 0.78 (0.52 to 1.18) (males, per 10‐point increase); 0.79 (0.46 to 1.37) (females, per 10‐point increase) Data from 996 participants in 1 study T2D (follow‐up 4 years)  Adjusted OR 0.84 (0.58 to 1.23) (males, per 10‐point increase); 0.88 (0.55 to 1.41) (females, per 10‐point increase). Data from 1370 participants in 1 study	Very lowa,b,c	Evidence is very uncertain about the effect of socioeconomic status on progression to PDR
Education level (Refer to Table 7 for adjustment factors)	T1D (follow‐up 4 years)  Adjusted OR 0.59 (0.20 to 1.78) (males, per 10‐point increase); 0.26 (0.07 to 0.99) (females, per 10‐point increase) Data from 996 participants in 1 study T2D (follow‐up 4 years)  Adjusted OR 0.50 (0.21 to 1.16) (males, per 10‐point increase); 0.90 (0.33 to 2.48) (females, per 10‐point increase) Data from 1370 participants in 1 study	Very lowa,b,c	Evidence is very uncertain about the effect of education level on progression to PDR

CI: confidence interval; DM: diabetes mellitus; HR: hazard ratio; OR: odds ratio; PDR: proliferative diabetic retinopathy; RR: risk ratio; T1D: type 1 diabetes; T2D: type 2 diabetes

^aDowngraded by one level for risk of bias: more than 80% of studies at high or unclear risk of bias
^bDowngraded by one level for inconsistency: significant differences in effect estimates reported by studies
^cDowngraded by one level for imprecision: wide 95% CIs