ssociation between drinking water hardness and incidence of hospitalization for childhood fracture: an ecological study of England

ABSTRACT Bone fracture during childhood is a very common injury, with rates in early adolescence equivalent to that of older age. Nutrition is profoundly important for healthy skeletal development, although data are scarce on the extent to which bone-forming minerals in drinking water might contribute to musculoskeletal health. The aim of this study was to describe the association between the hardness of local domestic drinking water across England with rates of hospitalization for childhood fracture, while adjusting for socio-demographic characteristics. Total water hardness (CaCO3), calcium and magnesium concentrations were obtained de novo from water companies. Counts of hospitalisations for fracture in patients aged under 18 years were extracted from the Hospital Episode Statistics database (1st April 2012 to 31st March 2020). Sex-specific Poisson regression was used to describe the association between water hardness and rates of fracture hospitalisations at neighbourhood-level (lower-level super output areas [LSOAs]), adjusted for age, deprivation, rurality and latitude. We included 29,776 LSOAs and identified 298,929 hospital admissions for fracture, at an estimated rate of 3.50/1,000 person years. Water hardness was associated with a significant reduction in fracture admissions: covariate adjusted incidence rate ratio (IRR) 0.87 (95% CI: 0.86 – 0.89) and 0.84 (0.82 – 0.86) comparing very hard to soft water areas, for boys and girls respectively. The reduction was consistent across commonly fractured skeletal sites and for secondary fractures within the same child. Likewise, concentrations of either calcium or magnesium were independently associated in a ‘dose-response’ manner with fewer hospital admissions for fracture. Future research is needed to confirm and further elucidate these findings, although they are suggestive that achieving adequate dietary intake of these bone-forming minerals may be especially important for children in areas with soft drinking water. We conclude that hospital admissions for childhood fracture are approximately 10-15% lower in hard water areas of England.