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Table 2

Incidence of further three or more–step progression of retinopathy and new PDR between the end of the DCCT and after 18 years of the EDIC study overall and stratified by the level of retinopathy at the end of DCCT

Retinopathy levels at DCCT closeoutFurther ≥3-step progression
PDR
n at risk*No. with event (%)Adjusted risk reduction (%, CI)P valuen at riskNo. with event (%)Adjusted risk reduction (%, CI)P value
All levels 1,358  46 (36, 54) <0.0001 1,318  47 (30, 60) <0.0001 
 Intensive 684 267 (39.0%)   668 86 (12.9%)   
 Conventional 674 380 (56.4%)   650 172 (26.5%)   
Stratified by retinopathy levels at DCCT closeout         
 Stratum 1: no retinopathy   30 (5, 49) 0.021   8 (−186, 70) 0.89 
  Intensive 194 100 (51.6%)   194 8 (4.1%)   
  Conventional 123 74 (60.2%)   122 5 (4.1%)   
 Stratum 2: microaneurysm only   54 (38, 65) <0.0001   53 (19, 73) 0.007 
  Intensive 275 88 (32.0%) 274 23 (8.4%) 
  Conventional 220 112 (50.9%) 220 32 (14.6%) 
 Stratum 3: mild nonproliferative retinopathy   55 (33, 70) <0.0001   52 (23, 70) 0.002 
  Intensive 149 44 (29.5%) 149 31 (20.8%) 
  Conventional 200 101 (50.5%) 199 64 (32.2%) 
 Stratum 4: moderate or severe nonproliferative retinopathy   45 (17, 63) 0.004   44 (9, 65) 0.018 
  Intensive 65 35 (53.9%) 50 24 (48.0%) 
  Conventional 126 93 (73.8%) 104 71 (68.3%) 
Retinopathy levels at DCCT closeoutFurther ≥3-step progression
PDR
n at risk*No. with event (%)Adjusted risk reduction (%, CI)P valuen at riskNo. with event (%)Adjusted risk reduction (%, CI)P value
All levels 1,358  46 (36, 54) <0.0001 1,318  47 (30, 60) <0.0001 
 Intensive 684 267 (39.0%)   668 86 (12.9%)   
 Conventional 674 380 (56.4%)   650 172 (26.5%)   
Stratified by retinopathy levels at DCCT closeout         
 Stratum 1: no retinopathy   30 (5, 49) 0.021   8 (−186, 70) 0.89 
  Intensive 194 100 (51.6%)   194 8 (4.1%)   
  Conventional 123 74 (60.2%)   122 5 (4.1%)   
 Stratum 2: microaneurysm only   54 (38, 65) <0.0001   53 (19, 73) 0.007 
  Intensive 275 88 (32.0%) 274 23 (8.4%) 
  Conventional 220 112 (50.9%) 220 32 (14.6%) 
 Stratum 3: mild nonproliferative retinopathy   55 (33, 70) <0.0001   52 (23, 70) 0.002 
  Intensive 149 44 (29.5%) 149 31 (20.8%) 
  Conventional 200 101 (50.5%) 199 64 (32.2%) 
 Stratum 4: moderate or severe nonproliferative retinopathy   45 (17, 63) 0.004   44 (9, 65) 0.018 
  Intensive 65 35 (53.9%) 50 24 (48.0%) 
  Conventional 126 93 (73.8%) 104 71 (68.3%) 
*

Analysis includes all subjects who were free of scatter photocoagulation during DCCT, alive at the initiation of EDIC, and had at least one retinal evaluation in EDIC. The stratified analysis was limited to those with retinopathy measurements at DCCT closeout. Analyses were stratified by retinopathy severity at the end of DCCT, defined as no retinopathy (ETDRS grade 10/10), microaneurysms only (grade 20), mild nonproliferative diabetic retinopathy (NPDR) (grade 30), or greater or equal to moderate NPDR (≥grade 40 or scatter laser).

A separate Weibull model was performed for each strata and for all levels combined, after adjustment for primary/secondary cohort, HbA1c value at entry to the DCCT, and diabetes duration at DCCT baseline. Analysis of all levels combined was also adjusted for the level of retinopathy at the end of the DCCT. Risk reduction is for intensive therapy as compared with conventional therapy. The P value is obtained from a Wald test of the group coefficient in the model.

Analysis includes all subjects who were free of PDR during DCCT, alive at the initiation of EDIC, and either had an EDIC retinal assessment or reported pan-retinal laser treatment for retinopathy during EDIC.

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