应用Schwartz公式和^(99)Tc^m-DTPA肾动态显像评估肾小球滤过率的一致性研究

Comparison and analysis of Schwartz formula appraisal of glomerular filtration rate and ^(99)Tc^m-DTPA clearance

目的评价应用Schwartz公式评估肾小球滤过率(GFR)的准确性,为儿科临床准确和便捷地评估GFR提供参考。方法选择2002年4月至2006年12月在复旦大学附属儿科医院肾病科诊断为慢性肾脏病(CKD)的患儿为研究对象。患儿于入院后第2日早晨空腹采血,以碱性苦味酸法测定血肌酐(SCr)水平,测量身高,采用Schwartz公式计算GFR(eGFR)。入院后第2或3日行99Tcm-DTPA肾动态显像,获得GFR(mGFR)。采用NKF-K/DOQI推荐的CKD分期标准,依据mGFR分为CKD 1~5期。mGFR与eGFR的相关性采用Pearson相关分析;eGFR估算mGFR的准确性采用相对预测误差(MPE)和绝对预测误差(MAE)表示,eGFR和mGFR的一致性采用Bland-Altman检验。结果170例CKD患儿进入分析,其中男100例,女70例;年龄2.3~17.8(9.3±3.9)岁。肾病综合征75例,肾小球肾炎28例,泌尿道感染49例,急性肾功能衰竭10例和慢性肾功能衰竭8例。CKD 1期80例,2期40例,3期27例,4期17例,5期6例。①eGFR和mGFR总体上有显著相关性(r=0.871);CKD 1期患儿的eGFR和mGFR呈显著弱相关性,CKD 2~4期患儿eGFR和mGFR无显著相关性。②eGFR预测mGFR的MPE和MAE随肾功能损害程度的加重呈增高趋势,CKD 1期79/80例(98.8%)、CKD 2期32/40例(80.0%)患儿eGFR预测mGFR的MPE均落在±30%内;CKD 3~5期患儿eGFR预测mGFR的准确性较差。③Bland-Altman检验结果提示,eGFR和mGFR的一致性CKD 1和2期患儿较好,CKD 3和4期患儿较差。结论Schwartz公式对于肾功能损害较轻的CKD 1和2期患儿预测mGFR的准确性较高,CKD 3~5期患儿的准确性较差。对于CKD 3~5期患儿仍应行99Tcm-DTPA肾动态显像以获得准确的GFR。

Objective The reliable measurement of glomerular filtration rate（GFR） is of great importance in clinical practice and research.The usage of radionuclides has offered an alternative method of estimating GFR that avoids some of the practical disadvantages of inulin clearance.But radioisotopic method has the disadvantage of precautions being required in handling and disposing of radioactive materials and is also expensive.To circumvent the practical difficulties of formal measurement of clearance,several prediction formulas have been published.The most common usage in children and adolescents is the Schwartz formula based on the serum creatinine level.The aim of this study was to identify an adequate measurement of GFR in pediatric clinical practice.Methods Children with chronic kidney disease from Children′s Hospital of Fudan University from April 2002 to December 2006 were collected.99Tcm-DTPA clearance（mGFR） was measured as GFR marker in patients with different kidney disease.At the same time estimated GFR（eGFR） was calculated via the equation developed from Schwartz formula according to serum creatinine level.eGFRs were compared with measured GFRs.The agreements between them were evaluated by B kappa statistics.The precision was evaluated by R2 from linear regression.The accuracy was measured by the percentage of GFR estimate within ±30%of the measured GFR（P30）.Results 170 patients with CKD（100 boys and 70 girls） were enrolled into the study.The mGFR was（73.3±26.8） mL·min-1·1.73 m-2.The eGFR from Schwartz formula was（74.2 ±27.9） mL·min-1·1.73 m-2.Pearson correlation analysis showed good correlation between mGFR and eGFR（r=0.871,P 0.05）.The concordance study using the Bland-Altman method showed that there was better consistency between eGFR and mGFR in CKD stage 1 to stage 2 than that in CKD stage 3 to stage 5.The over estimate of the Schwartz formula increased with GFR decreasing.Conclusions Compared with the reference standard,the Schwartz formula shows a certain degree of accuracy.In non-examination condition situation,the Schwartz formula is suitable for estimating GFR of children and adolescents.The formula remains useful for following changes of renal function in patients.