Tzamaloukas A H, Murata G H, Malhotra D, Fox L, Goldman R S, Avasthi P S
Medical Service, Veterans Affairs Medical Center. Albuquerque, New Mexico 87108 USA.
Perit Dial Int. 1996 Jan-Feb;16(1):41-7.
To identify the most advantageous formula for estimating creatinine clearance (CCr) and to establish a dose of dialysis that will ensure minimal acceptable levels of creatinine clearance in patients on continuous peritoneal dialysis (CPD).
Analysis of all CCr studies performed in CPD patients over 40 months.
All four dialysis units following CPD patients in one city. One dialysis unit is government-owned, one is university-affiliated, and two are community based.
One hundred and ninety-four patients representing almost the entire CPD population in Albuquerque.
Creatinine and urea clearance studies were performed in 24-hour urine and drained dialysate samples. Creatinine clearance (peritoneal plus urinary) was normalized to either 1.73 m2 body surface area (CCr) or body water estimated by the Watson formulas (KT/VCr). CCr and KT/VCr were either corrected by averaging urinary creatinine and urea clearances or were not corrected. Two dialysis units were designated as the training set (92 patients, 143 clearance studies) and the other two units as the validation set (102 patients, 181 clearance studies).
Minimal acceptable creatinine clearance levels were determined in the training set by computing the creatinine clearance value corresponding to 1.70 weekly KT/V urea by linear regression. Logistic regression models predicting low creatinine clearance were developed in the training set and were tested in the validation set.
The following weekly creatinine clearance values corresponded to 1.70 KT/V urea: corrected CCr 52.0 L/1.73 m2, uncorrected CCr 54.4 L/1.73 m2, corrected KT/VCr 1.46, uncorrected KT/VCr 1.53. Logistic regression identified as predictors of low creatinine clearance low daily urine volume (UV) and low daily dialysate drain volume/body water (DV/V) for all four creatinine clearance formulas, plus low/low-average peritoneal solute transport (only for uncorrected CCr) and serum creatinine (for both KT/VCr formulas). In the validation set, the predictive models produced an area under the receiver operating characteristic (ROC) curve between 0.835 and 0.919 indicating very good predictive accuracy. For corrected CCr and anuria, the regression model produced a minimal normalized drain volume (DV/V) value consistent with minimal acceptable CCr equal to 0.305 L/L per 24 hours. This DV/V cutoff detected low corrected CCR in validation set anuric subjects (n = 55) with a sensitivity of 85% and a specificity of 71%. For uncorrected CCR and anuria, DV/V cutoffs were 0.273 L/L per 24 hours (high/high-average peritoneal solute transport) and 0.420 L/L per 24 hours (low/low-average transport). Sensitivity and specificity of these cutoffs in validation set anuric subjects were 87% and 85%, plus 86% and 33%, respectively.
The uncorrected CCr appears to be the most advantageous creatinine clearance formula in CPD, because it allows the use of peritoneal solute transport type in the calculation of the minimal required normalized drain volume. The minimal acceptable uncorrected CCr is 54.4 L/1.73 m2 weekly. To achieve this uncorrected CCr in anuria, the required minimal normalized drain volume is 0.273 L per liter of body water daily if peritoneal solute transport is high or high-average and around 0.420 L per liter of body water daily if peritoneal solute transport is low or low-average. The required total daily drain volume is computed by multiplying the required normalized drain volume by body water.
确定估算肌酐清除率（CCr）的最有利公式，并确定能确保持续性腹膜透析（CPD）患者肌酐清除率达到最低可接受水平的透析剂量。
对40个月内CPD患者进行的所有CCr研究进行分析。
一个城市中跟踪CPD患者的所有四个透析单位。一个透析单位为政府所有，一个为大学附属，另外两个为社区型。
194名患者，几乎代表了阿尔伯克基市的全部CPD人群。
对24小时尿液和引流的透析液样本进行肌酐和尿素清除率研究。肌酐清除率（腹膜加尿液）根据1.73 m²体表面积（CCr）或通过沃森公式估算的身体水分（KT/VCr）进行标准化。CCr和KT/VCr通过平均尿液肌酐和尿素清除率进行校正或不进行校正。两个透析单位被指定为训练集（92名患者，143次清除率研究），另外两个单位为验证集（102名患者，181次清除率研究）。
通过线性回归计算与每周1.70 KT/V尿素对应的肌酐清除率值，在训练集中确定最低可接受的肌酐清除率水平。在训练集中建立预测低肌酐清除率的逻辑回归模型，并在验证集中进行测试。
以下每周肌酐清除率值对应于1.70 KT/V尿素：校正后的CCr为52.0 L/1.73 m²，未校正的CCr为54.4 L/1.73 m²，校正后的KT/VCr为1.46，未校正的KT/VCr为1.53。逻辑回归确定，对于所有四个肌酐清除率公式，低每日尿量（UV）和低每日透析液引流体积/身体水分（DV/V）是低肌酐清除率的预测指标，此外，低/低平均腹膜溶质转运（仅针对未校正的CCr）和血清肌酐（针对两个KT/VCr公式）也是预测指标。在验证集中，预测模型在接受者操作特征（ROC）曲线下的面积在0.835至0.919之间，表明预测准确性非常好。对于校正后的CCr和无尿情况，回归模型得出的最低标准化引流体积（DV/V）值与最低可接受的CCr一致，等于每24小时0.305 L/L。该DV/V临界值在验证集无尿受试者（n = 55）中检测到低校正CCR，灵敏度为85%，特异性为71%。对于未校正的CCR和无尿情况，DV/V临界值分别为每24小时0.273 L/L（高/高平均腹膜溶质转运）和0.420 L/L（低/低平均转运）。这些临界值在验证集无尿受试者中的灵敏度和特异性分别为87%和85%，以及86%和33%。
未校正CCr似乎是CPD中最有利的肌酐清除率公式，因为它允许在计算所需的最低标准化引流体积时使用腹膜溶质转运类型。最低可接受的未校正CCr为每周54.4 L/1.73 m²。对于无尿情况，若腹膜溶质转运为高或高平均水平，要达到此未校正CCr所需的最低标准化引流体积为每天每升身体水分0.273 L；若腹膜溶质转运为低或低平均水平，则约为每天每升身体水分0.420 L。所需的每日总引流体积通过将所需的标准化引流体积乘以身体水分来计算。
