Introduction:
As the main cause of chronic kidney disease and end stage renal disease, diabetic kidney disease is a very serious condition. It has now become clear that the rate of kidney function decline shows a strong interindividual variability. A better characterization of this variability and identification of parameters associated with an accelerated kidney function decline are then of primary importance.
Methods:
In this observational study, we evaluated the kidney function decline in a cohort of 138 T2DM outpatients followed at CHUV (SWIDINEP cohort). The eGFR calculated using the CKD-EPI forumla was used as an indicator of kidney function. The eGFR decline was calculated through linear regression using every creatinine values available in the patients’ medical records from year 2000 to 2019. The slope of the linear regression line was used to calculate the yearly eGFR decline. Patients were then separated in quartiles according to their yearly eGFR decline. Patients enlisted in this cohort also underwent a complete clinical examination as well as blood sampling. Kidney ultrasonography and arterial waveform analysis (sphygmocor) were also performed.
Results:
The average yearly kidney function decline in the cohort was of -1.86 ml/min/1.73m2/year. The respective average annual eGFR changes were of -6.73±3.6 ml/min/1.73m2/year, -2.03±0.60 ml/min/1.73m2/year, -0.7±0.39 ml/min/1.73m2/year for quartiles 1 to 3 and of +2.12±3.39 ml/min/1.73m2/year for quartile 4 (p-value < 0.001). We found that urinary albumin-to-creatinine ratio as well as the presence of diabetic retinopathy was significantly higher in groups with a stronger decline. In addition, we found that peripheral and central systolic blood pressure and pulse pressure were higher in quartiles with a stronger decline. A faster eGFR decline correlated with carotid femoral pulse wave velocity especially among patients with an eGFR over 60ml/min/1.73m2/year (n=45) and was associated with higher renal resistance indexes.
Discussion:
This study confirms the strong variability in eGFR decline in our cohort. In addition, it indicates that several parameters associated with arterial stiffness were increased in groups showing the stronger decline.