Adult height improved over decades in patients with X-linked hypophosphatemia: a cohort study

Objectives The aim of this study is to analyze height after cessation of growth (final height [FH]) and its evolution over the last decades in X-linked hypophosphatemia (XLH) patients in France, as the data on natural history of FH in XLH are lacking.Design We performed a retrospective observational study in a large cohort of French XLH patients with available data on FH measurements.Materials and methods We divided patients into 3 groups according to their birth year: group 1 born between 1950 and 1974, group 2 born between 1975 and 2000, and group 3 born between 2001 and 2006, respectively, and compared their FHs.Results A total of 398 patients were included. Mean FHs were the following: for group 1, -2.31 +/- 1.11 standard deviation score (SDS) (n = 127), 156.3 +/- 9.7 cm in men and 148.6 +/- 6.5 cm in women; for group 2, -1.63 +/- 1.13 SDS (n = 193), 161.6 +/- 8.5 cm in men and 153.1 +/- 7.2 cm in women; and for group 3, -1.34 +/- 0.87 SDS (n = 78), 165.1 +/- 5.5 cm in men and 154.7 +/- 6 cm in women. We report a significant increase in mean FH SDS over 3 generations of patients, for both men and women (P < .001). Final height SDS in male (-2.08 +/- 1.18) was lower than in female (-1.70 +/- 1.12) (P = .002).Conclusion The FH of XLH patients in France increased significantly over the last decades. Even though men's FHs improved more than women's, men with XLH remain shorter reflecting a more severe disease phenotype. While the results are promising, most patients with XLH remain short leaving room for improvement.