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Validation of the multiplier method for leg-length predictions on a large European cohort and an assessment of the effect of physiological age on predictions

View Article: PubMed Central - PubMed

ABSTRACT

Purpose: The Avon Longitudinal Study of Parents and Children (ALSPAC) prospective cohort was used to determine the accuracy of the Paley multiplier method for predicting leg length. Using menarche as a proxy, physiological age was then used to increase the accuracy of the multiplier.

Methods: Chronological age was corrected in female patients over the age of eight years with documented date of first menses. Final sub-ischial leg length and predicted final leg length were predicted for all data points.

Results: Good correlation was demonstrated between the Paley and ALSPAC data. The average error in prediction depended on the time of assessment, tending to improve as the child got older. It varied from 2.2 cm at the age of seven years to 1.8 cm at the age of 14 years. When chronological age was corrected, the accuracy of multiplier increased. Age correction of 50% improved multiplier predictions by up to 28%.

Conclusion: There appears to have been no significant change in growth trajectories of the two populations who were chronologically separated by 40 years. While the Paley data were based on extracting trends from averaged data, the ALSPAC dataset provides descriptive statistics from which it is possible to compare populations and assess the accuracy of the multiplier method. The data suggest that the accuracy improves as the patient gets close to the average skeletal maturity but that results need to be interpreted in conjunction with a radiological assessment of the growth plates. The magnitude of the errors in prediction suggest that when using the multiplier, the clinician must remain vigilant and prepared to perform a contralateral epiphyseodisis if the prediction proves to be wrong. The data suggest a relationship between the multiplier and menarche. There appears to be a factorisation and when accounting for physiological age, one needs to correct by 50% of the difference between chronological and physiological age.

No MeSH data available.


Details of the patient population and leg-length data analysis.
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Related In: Results  -  Collection

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Figure 1: Details of the patient population and leg-length data analysis.

Mentions: The ALSPAC study involved 15 247 pregnancies and 15 458 births, which were given a unique identification code on enrolment. (Data collection reduced after the age of 16 years and therefore data for boys who only reach skeletal maturity on average around the age of 16 years were not included in this study.) Of these, there were 7151 girls who were recorded as being alive at one year. The data were cleaned as shown in Figure 1.


Validation of the multiplier method for leg-length predictions on a large European cohort and an assessment of the effect of physiological age on predictions
Details of the patient population and leg-length data analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382340&req=5

Figure 1: Details of the patient population and leg-length data analysis.
Mentions: The ALSPAC study involved 15 247 pregnancies and 15 458 births, which were given a unique identification code on enrolment. (Data collection reduced after the age of 16 years and therefore data for boys who only reach skeletal maturity on average around the age of 16 years were not included in this study.) Of these, there were 7151 girls who were recorded as being alive at one year. The data were cleaned as shown in Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

Purpose: The Avon Longitudinal Study of Parents and Children (ALSPAC) prospective cohort was used to determine the accuracy of the Paley multiplier method for predicting leg length. Using menarche as a proxy, physiological age was then used to increase the accuracy of the multiplier.

Methods: Chronological age was corrected in female patients over the age of eight years with documented date of first menses. Final sub-ischial leg length and predicted final leg length were predicted for all data points.

Results: Good correlation was demonstrated between the Paley and ALSPAC data. The average error in prediction depended on the time of assessment, tending to improve as the child got older. It varied from 2.2 cm at the age of seven years to 1.8 cm at the age of 14 years. When chronological age was corrected, the accuracy of multiplier increased. Age correction of 50% improved multiplier predictions by up to 28%.

Conclusion: There appears to have been no significant change in growth trajectories of the two populations who were chronologically separated by 40 years. While the Paley data were based on extracting trends from averaged data, the ALSPAC dataset provides descriptive statistics from which it is possible to compare populations and assess the accuracy of the multiplier method. The data suggest that the accuracy improves as the patient gets close to the average skeletal maturity but that results need to be interpreted in conjunction with a radiological assessment of the growth plates. The magnitude of the errors in prediction suggest that when using the multiplier, the clinician must remain vigilant and prepared to perform a contralateral epiphyseodisis if the prediction proves to be wrong. The data suggest a relationship between the multiplier and menarche. There appears to be a factorisation and when accounting for physiological age, one needs to correct by 50% of the difference between chronological and physiological age.

No MeSH data available.