Table 3 —

Probability of developing retinopathy in four fictitious type 1 diabetic patients under good (HbA1c ≤6.87%) or poor (HbA1c ≥9.49%) metabolic control, given HbA1c and BMI at baseline and for a duration period of 72 months

Mean HbA1c during 72 monthsRisk score*Probability of retinopathy
AbsencePresence
Patient I
 Baseline HbA1c = 8%≤6.87%17.092%8.0%
 Baseline BMI = 22 kg/m2≥9.49%19.060%40%
Patient II
 Baseline HbA1c = 8%≤6.87%17.290%10%
 Baseline BMI = 24 kg/m2≥9.49%19.255%45%
Patient III
 Baseline HbA1c = 11%≤6.87%17.982%18%
 Baseline BMI = 22 kg/m2≥9.49%19.938%62%
Patient IV
 Baseline HbA1c = 11%≤6.87%18.179%21%
 Baseline BMI = 24 kg/m2≥9.49%20.131%69%
  • *

    * Rf = 0.314 × HbA1c + 0.108 × BMI + 2.83 × log(duration) + 2.01 × metabolic control (metabolic control is coded 0 for good and 1 for poor);

  • probabilities (×100%) are obtained as follows: calculate Rf1 = 19.4 − Rf. Then, P(absence) = exp(Rf1)/{1 + exp(Rf1)} and P (presence) = 1 − P (absence).