The Prevalence and Risk Factors of Diabetic Retinopathy: Screening and Prophylaxis Project in 6 Provinces of China

Figures & data

Table 1 Comparison of the Characteristics Between Subjects with or Without DR

Variable	DR Group (n=1536)	Non-DR Group (n=3925)	P value
Age (years)^b	57 (50, 65)	57 (48, 66)	0.931
Age subgroup
<30 years^a	25 (1.6)	165 (5.0)	<0.001
30–50 years^a	366 (23.8)	827 (25.1)
50–70 years^a	979 (63.7)	1797 (54.5)
>70 years^a	166 (10.8)	506 (15.4)
Duration of diabetes (years)^b	10 (4, 14)	6 (2, 12)	<0.001
<5 years^a	472 (31.3)	1456 (45.8)
5–10 years^a	340 (22.5)	742 (23.3)
10–15 years^a	379 (25.1)	513 (16.1)
15–20 years^a	187 (12.4)	254 (8.0)
>20 years^a	130 (8.6)	213 (6.7)
Male^a	823 (53.6)	1757 (53.3)	0.867
Female^a	713 (46.4)	1538 (46.7)
Rural^a	338 (22.0)	399 (12.1)	<0.001
Urban^a	1198 (78.0)	2896 (87.9)
Northern^a	1014 (66.0)	2109 (64.0)	0.174
Southern^a	522 (34.0)	1186 (36.0)
Occupation			<0.001
Worker^a	423 (27.5)	1194 (36.2)
Farmer^a	624 (40.6)	1061 (32.2)
Business \service\housework^a	306 (19.9)	479 (14.5)
Scientific\ military\civil servants \ public institutions^a	183 (11.9)	561 (17.0)
Past and current smoking^a	519 (33.8)	1046 (31.7)	0.157
Past and current drinking^a	494 (32.2)	987 (30.0)	0.121
Self – reported hypertension^a	414 (27)	676 (20.5)	<0.001
Presence of other complications of diabetes mellitus^a	362 (30.8)	457 (22.5)	<0.001
Insulin treatment^a	835 (54.4)	1512 (45.9)	<0.001
Weight (kg)^b	69 (60, 76)	70 (61, 79)	0.001
Height (cm)^b	165 (160, 172)	166 (160, 173)	0.045
BMI (kg/m^2)^a	24.8 (22.8, 27.2)	25.1 (23.0, 27.7)	0.005
BMI subgroup			0.021
BMI < 25kg/m^2	807 (52.5)	1614 (49.0)
BMI ≥ 25kg/m^2	729 (47.5)	1681 (51.0)
SBP (mmHg)^b	130 (122, 146)	130 (120, 140)	<0.001
DBP (mmHg)^b	80 (78, 90)	80 (75, 86)	<0.001
FPG (mmol/L)^b	9.0 (7.0, 12.0)	8.4 (7.0, 11.0)	<0.001
2hPG (mmol/L)^b	12.7 (10.0,16.1)	12 (9.7, 15.4)	<0.001
HbA1c (%)^b	8.8 (7.4, 10.2)	8.2 (6.9, 10.0)	<0.001
HbA1c subgroup			<0.001
HbA1c ≤ 7.0%^a	154 (21.2)	432 (28.8)
HbA1c > 7.0%^a	432 (78.8)	1067 (71.2)
TC (mmol/L)^b	4.6 (3.9, 5.3)	4.6 (3.9, 5.4)	0.241
TG (mmol/L)^b	1.6 (1.0, 2.4)	1.7 (1.1, 2.6)	0.024
LDL (mmol/L)^b	2.7 (2.0, 3.2)	2.7 (2.1, 3.3)	0.076
HDL (mmol/L)^b	1.0 (0.9, 1.2)	1.0 (0.9, 1.3)	0.037
Hyperlipidemia^a	528 (76.1)	1121 (79.1)	0.11

Notes: ^aNo (%); ^bMedian (25th percentile-75th percentile); DR group: the diabetic patients who was diagnosed as DR; Non-DR group: the diabetic patients who cannot be diagnosed as DR.

Abbreviations: BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, Fasting plasma glucose; 2hPG, 2 h postprandial plasma glucose; HbA1c, hemoglobin A1c; TG, triglycerides; TC, total cholesterol; HDL, high-density lipoprotein; LDL, low-density lipoprotein.

Table 2 Univariate and Multivariate Analyses of Factors Associated with DR in Patients with Diabetes

Variable	DR Group (n)	Non-DR Group (n)	Crude Model		Adjust Model
			OR (95% CI)	P value	OR (95% CI)	P value
Gender (male)	823	1757	1.01 (0.90, 1.14)	0.87	1.35 (1.06, 1.75)	0.015
Age <30 years	25	165	Ref		Ref
30–50 years	366	827	2.92 (1.88, 4.53)	<0.001	3.20 (1.32, 7.70)	0.01
50–70 years	979	1797	3.60 (2.34, 5.52)	<0.001	2.86 (1.20, 6.87)	0.018
>70 years	166	506	2.17 (1.37, 3.42)	<0.001	1.02 (0.39, 270)	0.96
SBP			1.01 (1.00, 1.01)	<0.001	1.01 (0.99, 1.01)	0.36
DBP			1.01 (1.00, 1.02)	<0.001	1.01 (0.99, 1.02)	0.54
Rural region	338	399	2.05 (1.75, 2.40)	<0.001	5.93 (3.10, 11.35)	<0.001
Northern region	1014	2109	2.29 (1.85, 2.83)	<0.001	1.78 (1.20, 2.66)	0.005
Self – reported hypertension	1122	2619	1.42 (1.23, 1.63)	<0.001	0.85 (0.61, 1.19)	0.36
Presence of other diabetic complications	362	467	1.54 (1.31, 1.81)	<0.001	2.01 (1.32, 3.06)	0.001
Workers	423	1197	Ref		Ref
Farmer	624	1061	1.66 (1.43, 1.93)	<0.001	1.39 (1.00, 1.92)	0.049
Business\service\housework	306	479	1.33 (1.50, 2.16)	<0.001	1.32 (0.91, 1.91)	0.14
Scientific\military\civil servants\public institutions	183	561	0.92 (0.75, 1.13)	0.42	1.04 (0.70, 1.55)	0.85
Not treating with insulin	701	1783	Ref		Ref
Insulin treatment	835	1512	1.41 (1.24, 1.59)	<0.001	1.61 (1.25, 2.06)	<0.001
FPG			1.05 (1.03, 1.07)	<0.001	1.04 (1.00, 1.09)	0.059
HbA1c			1.08 (1.04, 1.13)	<0.001	1.11 (1.04, 1.18)	0.002
HbA1c ≤ 7.0%	154	432	Ref		Ref
HbA1c > 7.0%	572	1067	1.50 (1.22,1.86)	<0.001	1.61 (1.17, 2.22)	0.003
BMI			0.98 (0.96, 0.99)	0.003	0.99 (0.96, 1.03)	0.84
BMI < 25 kg/m^2	807	1614	Ref		Ref
BMI ≥ 25 kg/m^2	729	1681	0.87 (0.77, 0.98)	0.021	0.88 (0.73, 1.06)	0.23
Duration of diabetes (years)			1.04 (1.03, 1.05)	<0.001	1.05 (1.02, 1.07)	0.001
< 5 years	472	1456	Ref		Ref
5 ≤ duration < 10	340	742	1.41 (1.20, 1.67)	<0.001	1.37 (0.99, 1.88)	0.054
10 ≤ duration < 15	379	513	2.28 (1.93, 2.70)	<0.001	2.29 (1.63, 3.21)	<0.001
15 ≤ duration < 20	187	254	2.27 (1.83, 2.82)	<0.001	1.60 (1.01, 2.53)	0.044
Duration ≥ 20	130	213	1.88 (1.48, 2.40)	<0.001	2.07 (1.24, 3.48)	0.006
Number of other complications comdiabetic omplications			1.20 (1.11, 1.31)	<0.001	0.94 (0.76, 1.16)	0.54

Notes: Crude model: adjusted no factors. Adjust-Model: adjustment for gender, SBP, DBP, FPG, 2hPG, TG, HDL, HbA1c, age, duration of diabetes, BMI, history of hypertension, insulin treatment, presence of other diabetic complications, number of other diabetic complications, region (rural, urban), occupation.

Table 3 Multivariate Analyses of Factors Associated with DR in Subgroup According to HbA1c Level

Variable	Adjust-Model
	OR (95% CI)	P value
HbA1c<7.0%
BMI<25 kg/m^2	Ref
BMI≥25 kg/m^2	1.28 (0.75, 2.16)	0.36
Urban region	Ref
Rural region	12.53 (4.65, 33.75)	<0.001
Not treating with insulin	Ref
Treating with insulin	2.34 (1.37, 3.98)	0.002
No other diabetic complication	Ref
Presence of other diabetic complication	1.36 (0.77, 2.39)	0.34
Duration<5 years	Ref
5 ≤ Duration < 10 years	1.31 (0.66, 2.60)	0.45
10 ≤ Duration <15 years	2.98 (1.46, 6.06)	0.003
15 ≤ Duration < 20 years	1.20 (0.40, 3.61)	0.75
Duration ≥ 20 years	2.58 (0.92, 7.22)	0.07
HbA1c ≥ 7.0%
BMI < 25 kg/m^2	Ref
BMI ≥ 25 kg/m^2	0.76 (0.59, 0.99)	0.04
Urban region	Ref
Rural region	3.49 (1.53, 7.96)	0.003
Not treating with insulin	Ref
Insulin treatment	1.47 (1.13, 1.91)	0.004
No other diabetic complication	Ref
Presence of other diabetic complication	2.19 (1.66, 2.88)	<0.001
Duration < 5 years	Ref
5 ≤ Duration < 10 years	1.45 (1.03, 2.05)	0.32
10 ≤ Duration < 15 years	2.05 (1.43, 2.94)	<0.001
15 ≤ Duration < 20 years	1.89 (1.19, 2.98)	0.007
Duration ≥ 20 years	1.63 (0.97, 2.74)	0.063

Notes: Adjust-Model: adjustment for gender, age, SBP, TG, HDL, BMI (<25kg/m², ≥25kg/m²), duration of diabetes (less than 5 years, 5–10 years, 10–15 years, 15–20 years and more than 20 years), insulin treatment (insulin treatment alone or combine with oral drugs, not treating with insulin), history of hypertension, presence of other diabetic complication (yes, no), region (rural, urban).

Table 4 Comparison of the Characteristics Between Referral Group and Non-Referral Group

Variable	Referral Group (n=319)	Non-Referral Group (n=4512)	P value
Age (years)	60 (53, 67)	57 (49, 66)	<0.001
Age subgroup
<30 years^a	2 (0.6)	188 (4.2)	<0.001
30–50 years^a	57 (17.9)	1136 (25.2)
50–70 years^a	214 (67.1)	2562 (56.8)
>70 years^a	46 (14.4)	626 (13.9)
Duration of diabetes (years)	11 (6, 18)	8.5 (2, 12)	<0.001
Duration subgroup			<0.001
<5 years^a	69 (21.9)	1859 (42.5)
5–10 years^a	64 (20.3)	1018 (23.3)
10–15 years^a	69 (21.9)	823 (18.8)
15–20 years^a	65 (20.6)	376 (8.6)
>20 years^a	48 (15.2)	295 (6.7)
Male^a	138 (43.3)	2399 (53.2)	0.22
Rural (versus urban)^a	82 (25.7)	655 (14.5)	<0.001
Occupation			<0.001
Worker^a	76 (34.2)	1541 (34.2)
Farmer^a	146 (45.8)	1539 (34.1)
Business/service/housework^a	66 (20.7)	719 (15.9)
Scientific /military/civil servants/public institutions^a	66 (20.7)	713 (15.8)
Past and current smoking^a	122 (38.2)	1443 (32.0)	0.02
Past and current drinking^a	108 (33.9)	1373 (30.4)	0.20
Self – reported hypertension^a	120 (37.6)	970 (21.5)	<0.001
Self – reported other complications of diabetes mellitus^a	159 (61.4)	719 (24.4)	<0.001
Insulin treatment^a	201 (63.0)	2146 (47.6)	<0.001
BMI (kg/m^2)	24.4 (22.1, 26.5)	25.0 (22.9, 27.6)	<0.001
BMI subgroup			0.002
BMI < 25kg/m^2	187 (58.6)	2234 (49.5)
BMI ≥ 25kg/m^2	132 (41.4)	2278 (50.5)
SBP (mmHg)^b	140 (129, 154)	130 (120, 140)	<0.001
DBP (mmHg)^b	80 (78, 90)	80 (75, 87)	0.003
FPG (mmol/L)^b	9.7 (7.5, 12.5)	8.5 (7.0, 11.1)	<0.001
2hPG (mmol/L)^b	13.0 (10.7, 16.8)	12.0 (9.8, 15.8)	0.004
HbA1c (%)^b	9.3 (8.1, 10.7)	8.3 (7.0, 10.0)	<0.001
HbA1c subgroup			<0.001
HbA1c ≤ 7.0%^a	16 (11.3)	570 (27.4)
HbA1c > 7.0%^a	126 (88.7)	1513 (72.6)
TC (mmol/L)^b	4.8 (3.9, 5.4)	4.6 (3.9, 5.4)	0.375
TG (mmol/L)^b	1.6 (1.1, 2.1)	1.7 (1.1, 2.6)	0.104
LDL (mmol/L)^b	2.8 (2.1, 3.3)	2.7 (2.1, 3.3)	0.415
HDL (mmol/L)^b	1.1 (0.9, 1.4)	1.0 (0.9, 1.2)	0.398

Notes: ^aNo (%); ^bMedian (25th percentile-75th percentile); Referral group: DR need for referral to ophthalmology. Non-Referral group: No DR or DR without need for referral to ophthalmology.

Table 5 The Association Between the Prevalence of Advanced DR in Subjects with Diabetes Mellitus

Variable	Crude-Model		Adjust-Model
	OR (95% CI)	P value	OR (95% CI)	P value
Gender (male versus female)	1.16 (0.92, 1.45)	0.21	0.51 (0.73, 1.97)	0.47
Age subgroup
< 30 years	Ref		Ref
30–50 years	4.72 (1.14, 19.48)	0.032	1.86 (0.42, 8.32)	0.42
50–70 years	7.85 (1.93, 31.85)	0.004	1.21 (0.27, 5.37)	0.80
> 70 years	6.91 (1.66, 28.72)	0.008	0.64 (0.13, 3.23)	0.59
FPG	1.06 (1.03, 1.09)	<0.001	1.03 (0.98, 1.09)	0.24
SBP	1.02 (1.01, 1.03)	<0.001	1.00 (0.99, 1.02)	0.81
DBP	1.02 (1.01, 1.03)	<0.001	1.00 (0.98, 1.03)	0.70
Past and current smoking (vs no smoking)	1.32 (1.04, 1.67)	0.021	1.11 (0.68, 1.82)	0.68
Hypertension (yes versus no)	2.20 (1.74, 2.79)	<0.001	1.40 (0.84, 2.33)	0.19
HbA1c (≥7.0% versus < 7.0%)	2.97 (1.75, 5.04)	<0.001	2.58 (1.38, 4.85)	0.003
Occupation
Worker	Ref		Ref
Farmer	1.92 (1.45, 2.56)	<0.001	1.16 (0.70, 1.93)	0.57
Business/service/housework	1.86 (1.32, 2.62)	<0.001	0.73 (0.40, 1.33)	0.30
Scientific/military/civil servants/public institutions	0.88 (0.58, 1.35)	0.56	0.66 (0.33, 1.33)	0.25
Duration subgroup
< 5 years	Ref		Ref
5–10 years	1.69 (1.20, 2.40)	0.003	1.25 (0.70, 2.24)	0.46
10–15 years	2.26 (1.60, 3.19)	<0.001	1.32 (0.72, 2.42)	0.36
15–20 years	4.66 (3.26, 6.65)	<0.001	3.12 (1.66, 5.85)	<0.001
> 20 years	4.38 (2.97, 6.46)	<0.001	3.66 (1.80, 7.44)	<0.001
Rural region (versus urban)	2.00 (1.70, 2.35)	<0.001	4.84 (2.53, 9.24)	<0.001
Insulin treatment (yes versus no)	1.35 (1.20, 1.53)	<0.001	1.73 (1.13, 2.65)	0.012
BMI ≥ 25kg/m^2 (versus BMI < 25kg/m^2)	0.88 (0.78, 0.99)	0.043	0.61 (0.41, 0.92)	0.017
Presence of other diabetic complication (yes versus no)	1.49 (1.27, 1.76)	<0.001	2.36 (1.55, 3.61)	<0.001

Notes: Crude model: adjusted no factors. Adjust-Model: adjustment for gender, age (<30 years, 30–50 years, 50–70 years, >70 years), SBP, DBP, BMI (<25kg/m², ≥25kg/m²), FPG, HbA1c (≥7.0%, <7.0%), duration of diabetes (<5 years, 5–10 years, 10–15 years, 15–20 years, >20 years), personal history of smoking, history of hypertension, region (rural, urban), occupation, insulin treatment, presence of other diabetic complication.

Table 6 Comparison of the Fundus Features Between Referral and Non-Referral Group Within DR Patients

Fundus Features	Referral DRn=319	Non-Referral DRn=1217
Microaneurysm^a	65 (20.4)	481 (39.5)	<0.001
Spot hemorrhage^a	97 (30.4)	791 (65.0)	<0.001
Flaky hemorrhage^a	85 (26.6)	0 (0)	<0.001
Vitreous hemorrhage^a	2 (0.6)	0 (0)	0.006
Preretinal hemorrhage^a	10 (3.1)	0 (0)	<0.001
Hard exudates^a	73 (22.9)	60 (4.9)	<0.001
Cotton wool spots^a	25 (7.8)	31 (2.5)	<0.001
Macular edema^a	51 (16.0)	0 (0)	<0.001
Other proliferative manifestations	32 (10.0)	0 (0)	<0.001
Other microvascular abnormalities^a	20 (6.3)	0 (0)	<0.001

Notes: ^aNo (%); Other proliferative manifestations: including fibroplasia membrane, vitreous hemorrhage, anterior retinal membrane, epimacular membrane, patchy membrane; Other microvascular abnormalities: including microvascular abnormalities, neovascularization, vascular occlusion, venous beading.