Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Jul;5(2):179-84.
doi: 10.4103/0974-2069.99622.

The use of Z-scores in paediatric cardiology

Henry Chubb  1 , John M Simpson
Affiliations

The use of Z-scores in paediatric cardiology

Henry Chubb et al. Ann Pediatr Cardiol. 2012 Jul.

Abstract

Z-scores are a means of expressing the deviation of a given measurement from the size or age specific population mean. By taking account of growth or age, Z-scores are an excellent means of charting serial measurements in paediatric cardiological practice. They can be applied to echocardiographic measurements, blood pressure and patient growth, and thus may assist in clinical decision-making.

Keywords: Blood pressure; Z-score; cardio Z; echocardiography; paediatric cardiology.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest: HC and JMS are the joint authors of Cardio Z, an App developed for iPhone and available for purchase. Profits from the App are used to maintain future development and are donated to the Evelina Children's Hospital Appeal.

Figures

Figure 1
Figure 1
The relationship of Z-scores and centiles, assuming Normal distribution of the parameter. Note that the centile remains virtually constant at values distant from the mean (typically over 3 standard deviations from the mean), whilst the Z-score continues to be sensitive to changes in measurements
Figure 2
Figure 2
(a) demonstrates the relationship between mitral valve size in mm and the Z-score as derived by the three most commonly used algorithms. Values are calculated for a typical one year old male, weight 10kg, height 75 cm. The algorithms agree relatively closely around the mean (Z=0). (b) and (c). There is considerable discrepancy between the different algorithms, particularly at low Z-scores. Δ1 and Δ2 demonstrate the difference in magnitude of the change in Z-score, with a 1mm variation in measurement, at low and high Z-scores respectively
Figure 3
Figure 3
Main menu screenshot of the Cardio Z app showing the variables for which Z-scores can be calculated. The user can configure the reference data to be used and the formula to be used to calculate body surface area. The data can be stored as a “.pdf” document for emailing or storage
See this image and copyright information in PMC

References

    1. Huxley JS, Teissier G. Terminology of Relative Growth. Nature. 1936;137:780–1.
    1. McMahon T. Size and shape in biology. Science. 1973;179:1201–4. - PubMed
    1. Neilan TG, Pradhan AD, King ME, Weyman AE. Derivation of a size-independent variable for scaling of cardiac dimensions in a normal pediatric population. Eur J Echocardiogr. 2009;10:50–5. - PMC - PubMed
    1. Sluysmans T, Colan SD. Theoretical and empirical derivation of cardiovascular allometric relationships in children. J Appl Physiol. 2005;99:445–57. - PubMed
    1. Lopez L, Colan SD, Frommelt PC, Ensing GJ, Kendall K, Younoszai AK, et al. Recommendations for quantification methods during the performance of a pediatric echocardiogram: A report from the Pediatric Measurements Writing Group of the American Society of Echocardiography Pediatric and Congenital Heart Disease Council. J Am Soc Echocardiogr. 2010;23:465–95. quiz 576-7. - PubMed