Characterisation of paediatric pulmonary hypertensive vascular disease from the PPHNet Registry

Background There are limited data about the range of diseases, natural history, age-appropriate end-points and optimal care for children with pulmonary hypertension (PH), including the need for developing high-quality patient registries of children with diverse forms of PH to enhance care and research. Our objective was to characterise the distribution and clinical features of diseases associated with paediatric PH, including natural history, evaluation, therapeutic interventions and outcomes, as defined by the World Symposium on Pulmonary Hypertension (WSPH) classification. Methods 1475 patients were enrolled into a multisite registry across the Pediatric Pulmonary Hypertension Network (PPHNet), comprised of eight interdisciplinary PH programmes. Results WSPH Groups 1 (pulmonary arterial hypertension (PAH)) and 3 (lung or hypoxia-related PH) were the most common primary classifications (45% and 49% of subjects, respectively). The most common Group 3 conditions were bronchopulmonary dysplasia and congenital diaphragmatic hernia. Group 1 disease was predominantly associated with congenital heart disease (60% of Group 1 cases) and idiopathic PAH (23% of Group 1 cases). In comparison with Group 1, Group 3 subjects had better disease resolution (hazard ratio 3.1; p<0.001), tended to he younger at diagnosis (median (interquartile range) age 0.3 (0.0-0.6) versus 1.6 (0.1-6.9) years; p<0.001) and were more often male (57% versus 45%; p<0.001). Down syndrome, the most common genetic syndrome in the PPHNet Registry, constituted 11% of the entire PH cohort. Conclusions We find a striking proportion of paediatric PH patients with Group 3 disorders, reflecting the growing recognition of PH in diverse developmental lung diseases. Greater precision of clinical phenotyping based on disease-specific characterisation may further enhance care and research of paediatric PH.