Children's bone age development is delayed with increasing altitude: a multicentre study.

Objectives: To investigate the bone age (BA) characteristics of children living in high-altitude regions and determine the impact of altitude on the development of BA.

Methods: From June 2014 to July 2022, 1318 children with left-hand-wrist radiographs were retrospectively enrolled from 3 different geographical altitudes (Beijing 43.5 m above sea level [asl], Lhasa 3650 m asl, and Nagqu 4500 m asl). The predicted age difference (PAD), defined as the difference between BA and chronologic age (CA), was considered the indicator for delayed or advanced growth. The PAD of children from the 3 regions in total and according to different age groups, genders, and ethnicities were compared. The linear regression model was used to assess the effect of altitude on PAD.

Results: A total of 1284 children (CA: 12.00 [6.45-15.72] years; male: 837/1284, 65.2%) were included in the study with 407 from Beijing, 491 from Lhasa, and 386 from Nagqu. The PAD for Beijing, Lhasa, and Nagqu were 0.1 [-0.30 to 0.65], -0.40 [-1.20 to 0.27], and -1.42 [-2.32 to -0.51] years, respectively. A linear regression analysis showed that altitude significantly contributed to PAD (compared to Beijing, Lhasa coefficient = -0.57, P < .001; Nagqu coefficient = -1.55, P < .001).

Conclusions: High altitude might be an independent contributor to the delayed BA development of children.

Advances in knowledge: The impact of altitude on BA development was revealed for the first time, highlighting the necessity of considering the altitude of the area when evaluating BA development for children residing in high-altitude regions.ke.