A high prevalence of reduced GFR has been reported in Western populations. However, little is known about the real prevalence of chronic kidney disease (CKD) in Eastern Europe. Our aims were 1) to identify the true burden of CKD in a large adult population sample; 2) to compare the GFR estimates by the "classic" MDRD4 formula with the GFR derived from the formula proposed recently by Levey.

Methods: Data from 19.509 consecutive Caucasian adult ambulatory patients, referred to two laboratories affiliated to two regional referral centers in Romania, were recorded. Collected data were on age, gender, and serum creatinine (Scr). For one center, total cholesterol, LDL- and HDL-cholesterol, and Hb values were also available. GFR was determined by the classic four-variable MDRD formula (MDRD4) GFR1 = 186 x Scr(-1.154) X age(-0.203) (x 0.742 if female) and by the new MDRD formula (modMDRD4): GFR2 = 175 x corrected Scr(-1.154 x age(-0.203) (x 0.742 if female).

Results: 19394 patients (mean age 47.7 years, 39.1% males, mean Scr 0.9 mg/dL) were analyzed. The prevalence of CKD (defined as GFR < 60 ml/min/1.73 m2) was 8.8% (according to MDRD4), and 11.7% (modMDRD4). Therefore, 506 patients (5%) classified by the "classical" MDRD4 formula with a GFR1 of 60-89 mL/min/1.73 m2 have in fact CKD. Stage III CKD was present in 10.74% of patients (males 9.04%, females 11.82%), stage IV CKD in 0.57% (0.72%-0.47%), and stage V in 0.39% (0.29-0.45%). As expected, in the elderly population, the burden of CKD is much higher: 39.74%, with 9.30% of elderly having GFR severely reduced (< 45 ml/min). The prevalence of end-stage renal disease was at least double in the elderly compared to non-elderly. There was a linear relationship between anemia occurrence, lipid abnormalities, and GFR reduction.

Conclusion: The prevalence of chronic kidney disease in this large Eastern European unselected population is high (8.8-11.7%), similar to the NHANES III population. Almost 40% of elderly subjects have reduced GFR, with one in 10 patients having a severe reduction of renal function.