PLoS ONE (Jan 2018)

A mathematical model for predicting the adult height of girls with idiopathic central precocious puberty: A European validation.

  • Pierre Lemaire,
  • Gwénaëlle Duhil de Bénazé,
  • Dick Mul,
  • Sabine Heger,
  • Wilma Oostdijk,
  • Raja Brauner

DOI
https://doi.org/10.1371/journal.pone.0205318
Journal volume & issue
Vol. 13, no. 10
p. e0205318

Abstract

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BACKGROUND:A previous single-center study established a mathematical model for predicting the adult height (AH) in girls with idiopathic central precocious puberty (CPP). OBJECTIVE:To perform internal and external validations by comparing the actual AH to the calculated AH established by this model and to update it. METHODS:The original formula, calculated AH (cm) = 2.21 (height at initial evaluation, SD) + 2.32 (target height, SD) - 1.83 (luteinizing hormone/follicle-stimulating hormone peaks ratio) + 159.68, was established in a sample of 134 girls (group 4) and was applied to additional girls with CPP seen in the same center (group 1, n = 35), in Germany (group 2, n = 43) and in the Netherlands (group 3, n = 72). This formula has been updated based on these extended data, and both versions are available at the following location: http://www.kamick.org/lemaire/med/girls-cpp15.html. RESULTS:Despite the differences among the 4 groups in terms of their characteristics at the initial evaluation and the percentages of patients treated with the gonadotropin-releasing hormone analogue, they have similar calculated and actual AHs. The actual AHs are 162.2±7.0, 163.0±7.6, 162.4±7.7 and 162.1±5.6 cm in groups 1 to 4, respectively. They are highly correlated with the AHs calculated by the formula established in the original group (group 4), with R at 0.84, 0.67 and 0.69 in groups 1 to 3, respectively. When the actual AHs and the AHs predicted by the Bayley and Pinneau method are compared, the R is 0.76, 0.51 and 0.64 in groups 1 to 3, respectively. The absolute differences between actual AHs and the calculated AHs are greater than 1 SD (5.6 cm) in 15%, 35% and 28% of the patients in groups 1 to 3, respectively. CONCLUSION:This study validates and updates the previously established formula for predicting AH in girls with CPP. This updated formula can help clinicians to make treatment decisions.