Estimated creatinine excretion per day (CKD epidemiology collaboration)
This model estimates an individual's expected daily creatinine excretion. Knowledge of the normal rate of creatinine excretion can be applied to assess completeness of the 24 hr urine collection.
Research authors: Ix JH, Wassel CL, Stevens LA, Beck GJ, Froissart M, Navis G, Rodby R, Torres VE, Zang YL, Greene T, Levey AS.
Details Formula Study characteristics Files & References
★★★★
Model author
Model ID
592
Version
1.21
Revision date
2018-05-31
MeSH terms
  • Creatinine
  • Urine Collection
  • Renal Excretion
  • Model type
    Custom model (Calculation)
    Status
    public
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    Formula

    Additional information

    Study population: 
    A total of 2466 participants from three kidney disease trials were randomly allocated into equation development (N=1644) and internal validation (N=822) data sets. Creatinine excreation rate (CER) served as the dependent variable in linear regression to develop new equations. Their stability was assessed within the internal validation data set. Among 987 separate individuals from three additional studies the equations were externally validated and compared with existing equations.

    Model performance: 
    Age, sex, race, weight, and serum phosphorus improved model fit. Two equations were developed, with or without serum phosphorus. In external validation, the new equations showed little bias.

    Conclusions: 
    CER can be estimated with commonly available variables with little bias and moderate precision, which may facilitate assessment of accuracy of timed urine collections.

    Source: 
    Ix JH, Wassel CL, Stevens LA, et al. Equations to estimate creatinine excretion rate: the CKD epidemiology collaboration. Clin J Am Soc Nephrol. 2011;6(1):184-91.

    Study Population

    Total population size: 1644
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    Females: {{ model.numberOfFemales }}

    Continuous characteristics

    Name Mean SD Unit
    Weight 77 16 kg
    Height 171 10 cm
    Body mass index (BMI) 26.2 4.5 kg/m2
    Body surface area (BSA) 1.89 0.22 m2
    Name LL Q1 Median Q3 UL Unit
    Serum creatinine 1.0 1.4 2.1 mg/dl
    Glomular filtration rate 30 49 89 ml/min
    Albumin 3.8 4.0 4.2 g/dl
    Phosphorus 3.2 3.6 4.1 mg/dl
    Creatinine excretion rate (CER) 1080 1369 1724 mg/day

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Race Black 179
    Other 1465
    GFR categories ≥ 90 ml/min 407
    60-89 ml/min 246
    30-59 ml/min 574
    <30 ml/min 417

    Related files

    Estimated creatinine excretion (ECR):
    ...
    mg/day

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    Result
    Note
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    Estimated creatinine excretion (ECR): mg/day

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    Outcome stratification

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    Conditional information

    Result interpretation

    How this model should be used: 
    Creatinine excretion rate (CER) indicates timed urine collection accuracy. Although equations to estimate CER exist, their bias and precision are untested and none simultaneously include age, sex, race, and weight.

    Model limitations: 
    Caution should be used in using the equations in patients without kidney disease and in persons with muscle mass outside of population norms.

    Model performance upon internal validation: 
    Performance of the newly developed equation was assessed in internal (N=822) and external (N=987) validation data sets. Little bias (<1%) was observed in the internal validation data set. Precision was moderate (interquartile range around the percent difference was 26%). For accuracy, the measured CER was within 15% of the expected CER (P15) among 59% of individuals, and within 30% of  expected CER (P30) among 85% of individuals. 

    Source: 
    Ix JH, Wassel CL, Stevens LA, et al. Equations to estimate creatinine excretion rate: the CKD epidemiology collaboration. Clin J Am Soc Nephrol. 2011;6(1):184-91.

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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