Table 3.
Dose–response relation for risk of NPDR among DM patients after propensity score matching.
| DM patients without taking metformin | ≤360 DDDs | 361–720 DDDs | 721–1080 DDDs | 1081–1440 DDDs | >1440 DDDs | |
|---|---|---|---|---|---|---|
| N | 5022 | 2295 | 1312 | 637 | 357 | 421 |
| NPDR (n, %) | 578 (11.51) | 262 (11.42) | 162 (12.35) | 70 (10.99) | 29 (8.12) | 32 (7.60) |
| NPDR onset time (years, mean ± SD) | 3.61 ± 2.35 | 3.79 ± 2.40 | 5.28 ± 2.22 | 6.60 ± 2.21 | 7.69 ± 2.11 | 8.37 ± 1.97 |
| Crude HR (95% CI) | Reference | 0.95 (0.82–1.09) | 0.73 (0.61–0.87) | 0.53 (0.42–0.68) | 0.33 (0.23–0.48) | 0.27 (0.19–0.39) |
| Adjusted HR (95% CI)∗ | Reference | 0.99 (0.84–1.17) | 0.77 (0.63–0.93) | 0.53 (0.40–0.69) | 0.33 (0.22–0.49) | 0.29 (0.19–0.43) |
| p value | 0.9115 | 0.0074 | <0.0001 | <0.0001 | <0.0001 | |
| p for trend | 0.0254§ | |||||
| 0.0096¶ |
∗Adjusted for gender, age, comorbidities, medications, aDCSI scores, DM duration, and other antidiabetic drugs use. §Dose–response relation among DM patients. ¶Dose–response relation among DM patients with taking metformin. NPDR: nonproliferative diabetic retinopathy; DDD: defined daily dose; aDCSI scores: adapted Diabetes Complications Severity Index scores; DM: diabetes mellitus; HR: hazard ratio.