Study design and participants
Sample size calculation for mean SWV’s based on a previous publication revealed a total of 30 patients to be enrolled (at least 15 healthy and 15 healthy controls). However, since we pre-planned to stratify DM-II patients in two groups, doubling of sample size of DM-II subjects was considered appropriate. The study was performed in our tertiary institution on a three consecutive months period. Overall 57 subjects including 40 outpatients with DM-II and 17 age and sex matched healthy controls were enrolled. DM-II patients were recruited from internal medicine or nephrology outpatient clinics and control subjects were asked to participate in the study by in-hospital advertisements.
Patients with DM-II were divided into two groups according to the presence of moderately elevated uACR [Groups with (Alb+) and without (Alb-) albuminuria]. During initial scanning of subjects with DM-II, those with more than mild reduction in eGFR (i.e. less than <60 ml/min/1.73 cm²), more than moderate proteinuria (urine ACR >300 mg/g) or already being treated for proteinuria, other confirmed diabetic organ complications, any systemic disease with a potential of renal involvement, history or symptoms of cardiovascular diseases, or common risk factors for vascular diseases (i.e. hypertension, smoking, dyslipidemia) were disqualified from the study. The uACR was measured from early morning urine samples, in at least 2 occasions of at least 3 months apart. The eGFR was calculated with 2009 CKD-EPI formula using serum creatinine value measured in at least 2 occasions of at least 3 months apart (16).
None of patients were not scheduled for elastography assessment by the clinician but were imaged for research purposes. Moreover, a scanning conventional kidney US was performed after initial recruitment and those with abnormal findings (renal tumor, hydronephrosis, congenital anomaly, signs of acquired renal disease) were excluded.