Measurement of GFR is considered the standard for estimating renal function. However, standardized accurate GFR methodology is expensive and cumbersome; therefore, estimates of GFR based on serum creatinine concentration have been employed. The purpose of the study presented here was to assess the accuracy and precision of using serum creatinine measurements to estimate GFR in the screenee cohort of The African-American Study of Kidney Disease and Hypertension (AASK) Pilot Study. GFR was estimated by four methods: 100/serum creatinine, Cockcroft-Gault equation, creatinine clearance from 24-h urine collection, and a new regression equation derived from the pilot study data. These methods were compared with renal clearance of 125I-iothalamate GFR (GFR1) in 193 hypertensive (diastolic blood pressure ≥95 mm Hg) African-American screenees (142 men, 51 women). A second GFR (GFR2) was performed in 98 screenees who were eligible (GFR1 25-70 mL/min per 1.73 m2) for the pilot study. Accuracy was assessed by the difference of 125I-iothalamate GFR-estimated GFR (Δ GFR), and precision was estimated from the combined root mean squared error (CRMSE) and the coefficient of determination (r2). The results for accuracy (± SD) and precision were as follows: (1)100/Scr, Δ GFR = -0.76 ± 16.5, CRMSE = 16.5, r2 = 0.69; (2) Cockcroft-Gault, Δ GFR = 9.56 ± 14.9, CRMSE = 17.7, r2 = 0.66; 3) 24-h creatinine clearance, Δ GFR = 0.79 ± 20.7, CRMSE = 20.7, r2 = 0.49; 4) New equation Δ GFR = -0.08 ± 12.8, CRMSE 12.7, r2 = 0.75. In comparison, a second GFR (GFR2, N = 98) had Δ GFR = 1.36 ± 8.48, CRMSE 8.6, r2 = 0.75. Estimates based on 100/SCr and the new equation were the most precise. It was concluded that GFR estimated by serum creatinine is superior to outpatient 24-h urine creatinine clearance in this population. Serum creatinine values can be used to provide a reasonably accurate estimate of GFR in hypertensive African Americans.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of the American Society of Nephrology|
|State||Published - Feb 1 1997|
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