A Multicenter Evaluation of Variables Affecting the Predictability of Creatinine Clearance

Abstract

Data from 722 urine collections (627 patients) from 14 medical facilities were used to compare measured creatinine clearance values with clearance estimates calculated using three "urine-free' mathematical formulas. The influence of two patient weight variables (actual weight, lean body weight) and the level of renal function on clearance prediction was assessed. In addition, site parameters (region, facility), time parameters (month, day, day of the week), and patient parameters (age, sex, height, weight, diagnoses) were evaluated for their statistical influence on the relationship between measured clearance and estimates calculated with one of the methods. Strong, statistically significant correlations were observed between clearance values estimated with each prediction method and measured clearances. Although statistical differences were noticed between mean values predicted with each method, these differences were clinically insignificant. Use of lean body weight for calculation of creatinine excretion produced clearance estimates that were significantly lower than those obtained with actual weight and substantially closer to measured clearance values. Among patient variables, age and two specific diagnoses (congestive heart failure and pregnancy), were statistically associated with variability in the relationship between measured and predicted clearance. Interregional and interfacility differences in the measured-predicted clearance relationship, variability associated with the day of the week of collection, and tendency of the urine-free formulas to over-predict clearance support potential inaccuracy of measured clearance determination. The results suggest that inaccuracies in clearance determination, rather than inadequacies of urine-free prediction methods, account for the majority of the observed variability in the relationship.

Predicting Glomerular Function from Adjusted Serum Creatinine

“…Others have found good agreement between predicted C-CR for men and women with the values calculated for females using a 15% factor [5,10], Also, sex had no statistically significant influence on predicted C-CR in 627 patients using the 15% reduction for women [5]. I n our present study in transplants, the mean predicted C-CR reduced by 15% in females was 63.2 ml/min, compared with the 62.8 for males.…”

“…Improved correlation coefficients have been reported with the use of lean body weight in our formula [5]. This modification is most useful in the obese.…”

Prediction of creatinine clearance from plasma creatinine: comparison of five formulae.

“…The formulae of Cockcroft & Gault (1976) is the one most often quoted and has been evaluated by many investigators (Durakovic', 1986;Gates, 1985;Hallynck et al, 1981;Hull et al, 1981;Salazar & Corcoran, 1988;Sawyer et al, 1982). Good correlations between measured GFR and predicted CLcr [from the formula of Cockcroft & Gault (1976)] have been reported (r = 0.858, Durakovic', 1986) (r2 = 0.91, Hallynck et al, 1981.…”

“…For this purpose several formulae have been described to estimate creatinine clearance from plasma creatinine concentration (Beranek & Gabriel, 1985;Cockcroft & Gault, 1976;Gates, 1985;Hull et al, 1981;Jelliffe, 1973;Mawer et al, 1972), and Smith (1988) recommends that clinical laboratories should report calculated creatinine clearance whenever serum creatinine is reported. There have been some attempts to compare the effectiveness of these formulae (Durakovic', 1986;Gates, 1985;Hallynck et al, 1981;Rhodes et al, 1987;Sawyer et al, 1982;Sinton et al, 1986) but very few studies have compared several formulae (Rhodes et al, 1987). In this study we have compared the effectiveness of estimated creatinine clearance using five different formulae in a Chinese population.…”

Standardization of p‐creatinine assays and use of lean body mass allow improved prediction of calculated glomerular filtration rate in adults: A new equation

“…Accordingly, several alternative weight measures have been proposed that give a more accurate indication of muscular mass; these include lean body mass (LBM), ideal body weight (IBW) and adjusted body weight (ABW, the lowest weight of LBM or IBW and TBW) [13][14][15][16], though this approach has not been generally adopted.…”