Fast GFR decline and progression to CKD among primary care patients with preserved GFR.

Background: Fast glomerular filtration rate (GFR) decline is associated with adverse outcomes, but the associated risk factors among patients without chronic kidney disease (CKD) are not well defined.

Methods: From a primary care registry of 37,796, we identified 2219 (6%) adults with at least three estimated (e)GFR values and a baseline eGFR between 60 and 119 ml/min/1.73 m2 during an observation period of 8 years. We defined fast GFR decline as > 5 ml/min/1.73 m2 per year. The outcome measure was incident CKD (eGFR < 60 ml/min/1.73 m2). Clinical and demographic characteristics were compared using Chi-square and independent-samples t tests.

Results: Older age, African-American race, unmarried status, hypertension and type 2 diabetes were more common in both fast decliners and those who developed incident CKD (p < 0.0001 to < 0.05). Lower neighborhood socioeconomic status, current smoking and baseline eGFR 90-119 ml/min/1.73 m2 were associated with fast decline (p < 0.01), while baseline eGFR 60-74 ml/min/1.73 m2 with incident CKD (p < 0.05). In multivariate regression models, among fast decliners with mildly reduced baseline eGFR (60-89 ml/min/1.73 m2), older age was significantly associated with incident CKD [odds ratio (OR) 1.04; 95% CI 1.01-1.08], and among those with normal baseline eGFR (≥ 90-119 ml/min/1.73 m2), type 2 diabetes was significantly associated with incident CKD (OR 3.83; 95% CI 1.35-10.89).

Conclusions: Among primary care patients without CKD, GFR is checked infrequently. We have identified patients at high risk of progressive CKD, in whom we suggest a closer monitoring of renal function.