Cox regression analysis to explore the effect of year of T1DM diagnosis (categorical or continuous), gender, age at baseline (per year), duration of T1DM at baseline (per year), proteinuria and retinopathy at baseline, mean values of HbA1c (per %) and systolic BP (per mm Hg) during follow-up, and time-dependent variables of annual mean HbA1c (per %) and systolic BP (per mm Hg) at onset of ESRD
| Multivariate analysis | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Univariate analysis | Model A | Model B1 | Model B2 | Model C1 | ||||||
| HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | |
| Year of diagnosis | ||||||||||
| Categorical (B vs A) | 0.17 (0.07 to 0.40) | <0.001 | 0.26 (0.10 to 0.64) | <0.01 | 0.52 (0.19 to 1.40) | 0.19 | 0.61 (0.22 to 1.66) | 0.33 | ||
| Continuous per year | 0.91 (0.88 to 0.93) | <0.001 | 0.95 (0.92 to 0.99) | 0.02 | ||||||
| Male vs female | 0.75 (0.45 to 1.26) | 0.27 | 0.91 (0.54 to 1.52) | 0.71 | 0.59 (0.32 to 1.09) | 0.09 | 0.60 (0.33 to 1.12) | 0.04 | 0.53 (0.28 to 0.98) | 0.04 |
| Age at baseline | 1.09 (1.06 to 1.12) | <0.001 | 1.06 (1.03 to 1.09) | <0.001 | 1.05 (1.02 to 1.09) | <0.01 | 1.06 (1.02 to 1.08) | <0.01 | 1.02 (0.99 to 1.06) | 0.24 |
| Duration of diabetes | 1.13 (1.09 to 1.16) | <0.001 | 1.06 (1.01 to 1.10) | 0.01 | 0.95 (0.89 to 1.02) | 0.16 | 0.95 (0.89 to 1.01) | 0.11 | 0.97 (0.91 to 1.04) | 0.42 |
| Proteinuria | 22.5 (12.8 to 39.6) | <0.001 | 12.1 (6.0 to 24.3) | <0.001 | 12.1 (6.1 to 24.1) | <0.001 | 7.79 (3.89 to 15.6) | <0.001 | ||
| Retinopathy | 6.52 (3.7 to 11.41) | <0.001 | 2.44 (1.11 to 5.36) | 0.03 | 2.04 (0.91 to 4.58) | 0.08 | 2.15 (0.96 to 4.80) | 0.06 | ||
| Mean HbA1c | 1.81 (1.58 to 2.07) | <0.001 | ||||||||
| Mean systolic BP | 1.07 (1.05 to 1.10) | <0.001 | ||||||||
| HbA1c* | 1.13 (1.00 to 1.28) | 0.014 | 1.23 (1.04 to 1.46) | 0.01 | ||||||
| Systolic BP* | 1.07 (1.06 to 1.08) | <0.001 | 1.05 (1.03 to 1.07) | <0.001 | ||||||
| Model C2 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| HR (95% CI) | p Value | |||||||||
| Year of diagnosis | ||||||||||
| Continuous per year | 0.97 (0.93 to 1.01) | 0.09 | ||||||||
| Male vs female | 0.55 (0.30 to 1.03) | 0.06 | ||||||||
| Age at baseline | 1.02 (0.99 to 1.06) | 0.22 | ||||||||
| Duration of diabetes | 0.97 (0.90 to 1.04) | 0.32 | ||||||||
| Proteinuria | 7.65 (3.84 to 15.3) | <0.001 | ||||||||
| Retinopathy | 1.94 (0.86 to 4.39) | 0.11 | ||||||||
| HbA1c* | 1.21 (1.02 to 1.44) | 0.03 | ||||||||
| Systolic BP* | 1.05 (1.03 to 1.07) | <0.001 | ||||||||
*HbA1c and systolic BP values were analyzed as time-dependent variables.
Values entered in the multivariate analysis were as follows
BP, blood pressure; ESRD, end-stage renal disease; HbA1c, glycated haemoglobin; T1DM, type 1 diabetes mellitus.
Model A: year of diagnosis as a categorical variable, gender, age and duration of diabetes at baseline.
Model B: year of diagnosis as a categorical (B1) and continuous (B2) variable, gender, age, duration of diabetes and proteinuria and retinopathy at baseline.
Model C: year of diagnosis as a categorical (C1) and continuous (C2) variable, gender, age, duration of diabetes, proteinuria and retinopathy at baseline, and time-dependent variables of HbA1c and systolic BP.