Distribution of blood pressure and its positive association with body mass index standard deviation score in pediatric patients with X-linked hypophosphatemia: a sub-group analysis from the SUNFLOWER observational study.

Few studies have investigated the distribution of blood pressure (BP) and associated factors in pediatric patients with X-linked hypophosphatemic rickets (XLH). We analyzed snapshot baseline data from the SUNFLOWER study, a longitudinal observational cohort study of patients with XLH in Japan and South Korea (NCT03745521/UMIN000031605). We used data from pediatric participants aged 5-17 years who were 120-189.9 cm (males) and 120-179.9 cm (females) in height and had a history of conventional treatment. Systolic and diastolic BP (SBP and DBP, respectively) were categorized into percentile ranks based on age, sex, and height. Ordinal logistic regression analyses were performed to investigate the association between BP and exposure factors, including estimated glomerular filtration rate, serum intact parathyroid hormone levels, serum intact fibroblast growth factor 23 levels, urinary calcium/creatinine ratio, and body mass index standard deviation score (BMI-SDS). Forty-five participants were eligible for the subgroup analysis. Of these, 44 were evaluated after one patient with missing BP data was excluded. After height adjustment, three patients (6.8%) were at or above the 95th percentile for SBP, and five (11.4%) were at or above the 95th percentile for DBP. Regarding age adjustment, one patient (2.3%) was at or above the 95th percentile for SBP and three (6.8%) were at or above the 95th percentile for DBP. In the association analysis, age- and height-adjusted BP was positively correlated with BMI-SDS. These results suggest that some pediatric patients with XLH exhibit high BP and that a high BMI-SDS may be a risk factor.