A controlled register-based study of 460 neurofibromatosis 1 patients: increased fracture risk in children and adults over 41 years of age.

Neurofibromatosis 1 (NF1, von Recklinghausen's disease) is an autosomal dominant neurocutaneous-skeletal syndrome in which low bone mineral density (BMD) and osteoporosis are common. Low BMD is, however, not the sole component of fracture risk. In the current study, 460 Finnish patients with NF1 were identified from the hospital medical records and their fracture risk was evaluated. The control population included 3988 appendectomy patients whose age and gender distribution was similar to that of the NF1 patients. Medical records of NF1 and control cohorts were screened for fractures according to the International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) between January 2000 and October 2011. The results show that patients with NF1 had increased age-dependent fracture risk compared to controls. Specifically, patients with NF1 aged 41 years and older had a risk ratio of ×5.2 for fractures compared to controls, and children with NF1 had a ×3.4 risk ratio for fractures compared to children without NF1. In contrast, the fracture risk was not increased in NF1 patients aged 17 to 40 years. When fractures not traditionally related to osteoporosis such as fractures of fingers, toes, and skull were excluded, the results were essentially the same. No gender related differences were observed. In conclusion, patients with NF1 have increased fracture risk depending on age. We recommend considering prophylactic measures, such as lifestyle advice, to prevent fractures from occurring.