Vitamin D levels in Irish children with fractures: A prospective case-control study with 5 year follow-up.

INTRODUCTION: Twenty-five-hydroxy-vitamin D3 (25-OH-vit D) is a prohormone that is essential for normal calcium homeostasis and bone metabolism. Understanding its role is an important component of the proper care of the pediatric orthopaedic patient. The aim of this study was to determine whether children in Ireland with fractures have increased prevalence of 25-OH-Vit D deficiency compared with age matched controls and to ascertain the relationship between a low 25-OH-vit D level and the incidence of fractures in Irish children. We hypothesised that children presenting to our centre following a fracture would have significantly lower 25-OH-vit D. METHODS: A prospective case-control study at a large urban tertiary referral academic hospital located in Dublin, Ireland was completed over a 14 month period from June 2014 to August 2015. A total of 116 subjects, distributed as cases (n = 58) and controls (n = 58) were included in this study. Whole blood (10 ml) was taken in two serum bottles from each patient. Serum 25-hydroxy-vitamin D3 levels were measured. An age matched control group was generated from other children attending the hospital, who also had vitamin D levels measured for different clinical reasons. We followed up both the fracture and control group for the next 5 years to assess the repeat fracture rate. RESULTS: Fifty-eight patients with a fracture requiring operative intervention, were included in the study. Statistical analysis was performed comparing to 58 age and sex-matched controls. The mean vitamin D level for the fracture group was 63.2 nmol/L (SD = 27.3), which was higher than the mean of the controls (62.5 nmol/L) (SD = 21.3) (p = 0.86), but this difference was found not to be statistically significant in unadjusted analysis. There was no statistically significant difference in the number of patients classified with low serum Vitamin D levels (<50 nmolL), with the fracture group consisting of 22 (37.9%) patients, and the control group of 17 patients (29.3%) (p = 0.33) with a level below 50 nmol/L. At five-year follow-up, 11 of the 58 patients (18.9%) in the fracture group went on to have a further fracture compared with eight patients (13.7%) from the control group. Out of these 11 from the fracture group five (45.45%) had been found to have a low serum 25-OH-Vit D level five years previously. Out of the eight controls that presented with a fracture within the five-year period, 3 (37.5%) had had a low vitamin D level at the origin of this study. CONCLUSION: The results of this study show that children presenting to our institution with low energy fractures have a prevalence of 38% 25-hydroxy-vitamin D deficiency. This study included children from age 1 to 16 primarily Caucasian encompassing all fracture types resulting from accidental trauma. Our findings suggest that in an Irish pediatric population vitamin D status may impact fracture risk with more than one-third being deficient in this review.