Abstract
Purpose: :
Identification of independent risk factors in the development of diabetic retinopathy requiring treatment
Methods: :
Data from 39,559 screening examinations, 265,600 measurements of HbA1c and 23,000 blood pressure measurements in 11.971 diabetic patients (2530 type 1 and 9366 type 2, five unknown) followed since 1994 were included in a decision model based on methods from survival analysis and logistic regression.
Results: :
For type 1 diabetic patients diastolic blood pressure was initially 77.4 [76.1;78.6] mmHg and systolic blood pressure 128.4 [126,2;130,5] mmHg. Diastolic blood pressure decreased -0.16mmHg/year (p=0.005) whereas systolic blood pressure increased 0.47mmHg/year (p<0,001). The initial value of HbA1c was 9.00 [8.9;9.1] % and declined significantly (-0,05%/year, p<0,001). In type 2 diabetic patients diastolic blood pressure was initially 84.7 [84.2;85.3] mmHg, systolic blood pressure initially 142.9 [141.7;144.1] mmHg, and HbA1c initially 8.8 [8.8;8.9] % and all three parameters declined significantly over time (-0,76 mmHg/year, p<0.001, -0.64 mmHg/year, p<0,001, and -0,12%/year, p<0,001). All the recorded risk factors at baseline differed significant between patients with the two diabetes types. Additionally, as compared to women, men had an age at diagnosis of the disease that was significantly lower in type 2 diabetic patients, a number of retinal haemorrhages and hard exudates, and a baseline and an average HbA1c that was significantly higher in patients with type 1 diabetic patients. Odds ratios for reaching a treatment end point of individual risk factors corrected for mutual interaction was calculated. It appears that the risk of reaching a treatment end point in both diabetes types was increased by increasing number of retinal haemorrhages and increasing HbA1c. Furthermore, in type 1 diabetic patients the risk of reaching a treatment end point was increased by increasing disease duration and by a recommended control interval of less than 3 months, whereas in type 2 diabetes this risk was increased by increasing age of diagnosis of the disease.
Conclusions: :
It is possible to develop an individualized screening system including other variables than diabetes type, duration and retinopathy grade. These models should take into account changes in risk factors occurring over time and differences in risk of developing retinopathy related to sex.
Keywords: diabetic retinopathy