Conventional Therapy in Adults With X-Linked Hypophosphatemia: Effects on Enthesopathy and Dental Disease

Context: Treatment of X-linked hypophosphatemia (XLH) with active vitamin D metabolites and phosphate can partially correct skeletal deformities. It is unclear whether therapy influences the occurrence of two major long-term morbidities in XLH: enthesopathy and dental disease. Objective: The objective of the study was to investigate the relationship between treatment and enthesopathy and dental disease in adult XLH patients. Design: The study was designed as observational and cross-sectional. Setting: The study was conducted at an academic medical center's hospital research unit. Participants: Fifty-two XLH patients aged 18 years or older at the time of the study participated in the study. Interventions: There were no interventions. Main Outcome Measures: The number of enthesopathy sites identified by radiographic skeletal survey and dental disease severity (more than five or five or fewer dental abscesses), identified historically, were measured. Methods: Associations between proportion of adult life and total life with treatment and number of enthesopathy sites were assessed using multiple linear regression, whereas associations between these exposure variables and dental disease severity were assessed using multiple logistic regression. All models were adjusted for confounding factors. Results: Neither proportion of adult nor total life with treatment was a significant predictor of extent of enthesopathy. In contrast, both of these treatment variables were significant predictors of dental disease severity (multivariate-adjusted global P = .0080 and P = .0010, respectively). Participants treated 0% of adulthood were more likely to have severe dental disease than those treated 100% of adulthood (adjusted odds ratio 25 [95% confidence interval 1.2–520]). As the proportion of adult life with treatment increased, the odds of having severe dental disease decreased (multivariate-adjusted P for trend = .015). Conclusions: Treatment in adulthood may not promote or prevent enthesopathy; however, it may be associated with a lower risk of experiencing severe dental disease.