Renal function preservation in type 2 diabetes mellitus patients with early nephropathy: a comparative prospective cohort study between primary health care doctors and a nephrologist.

BACKGROUND: Early referral of patients with end-stage renal disease to a nephrologist is associated with lower morbidity and mortality after initiating dialysis therapy; earlier referral may have better results. The aim of the study is to prospectively determine the impact of earlier referral to a nephrologist on renal damage progression of patients with type 2 diabetes mellitus (DM2) with early nephropathy.

METHODS: Fifty-two patients (27 patients, early nephropathy [EN]; 25 patients, overt nephropathy [ON]) from a primary health care unit were referred to a nephrologist (study cohort); 65 patients (34 patients, EN; 31 patients, ON) from another health care unit remained treated by only family doctors (control cohort). Both cohorts were followed up for 1 year.

RESULTS: Delta (final-baseline) in serum creatinine levels was maintained better by the nephrologist in the EN (study, 0.02 mg/dL versus control, 0.13 mg/dL [2 versus 11 micromol/L]; P = 0.02) than ON group (study, 0.15 mg/dL versus control, 0.25 mg/dL [13 versus 22 micromol/L]). In concordance, glomerular filtration rate was maintained better by the nephrologist in EN (study, 3.2 mL/min/1.73 m2 versus control, -13.3 mL/min/1.73 m2 [0.05 versus -0.22 mL/s/1.73 m2]; P = 0.01) than ON patients (study, -9.8 mL/min/1.73 m2 versus control, -10.9 mL/min/1.73 m2 [-0.16 versus -0.18 mL/s/1.73 m2]). Albuminuria increased more in patients treated by family doctors in the EN (study, 30 mg/d versus control, 116 mg/d; P < 0.05) and ON groups (study, 160 mg/d versus control, 623 mg/d). The nephrologist controlled systolic blood pressure better in both the EN (study, -3 mm Hg versus control, 2 mm Hg; P < 0.05) and ON groups (study, -19 mm Hg versus control, 5 mm Hg; P < 0.05); diastolic blood pressure had a similar pattern. The nephrologist significantly increased (P < 0.05) the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and statins and discontinued nonsteroidal anti-inflammatory drugs more than family doctors (study, 42%, 43%, 39%, and -11% versus control, 17%, 4%, -7%, and 27%, respectively). Glycemic and lipid control and stopping smoking were not attained by either the nephrologist or family doctors.

CONCLUSION: Earlier referral of patients with DM2 to a nephrologist was associated with better renal function preservation, which was significantly more evident in the EN than ON group. The nephrologist obtained better blood pressure control, more frequently used angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and statins; and discontinued nonsteroidal anti-inflammatory drugs more than family doctors. However, metabolic control and stopping smoking were not attained by either the nephrologist or family doctors.