Importance of age at diagnosis of pulmonary hypertension in children living at high altitude: Longitudinal follow-up of 86 patients.

Pulmonary hypertension (PH) at high altitudes presents unique characteristics due to hypobaric hypoxia. We aimed to evaluate the association between early diagnosis and clinical outcomes among children with severe PH living at high altitudes. A retrospective analysis was conducted on 86 children, divided into three age groups at the time of diagnosis: ≤3, 3-10, and ≥10 years. The median age at diagnosis was 4 years, with 48% of patients under 3 years old. Over a median follow-up of 6 years (interquartile ranges 2.5-8), 10% had a follow-up exceeding 15 years. Mortality rates were lowest in those diagnosed before age 3 (22% vs. 48% vs. 25%, p = 0.06). Responders to the prolonged hyperoxia test (PHT) were younger and had a significantly lower mortality hazard ratio (0.23, 95% confidence interval 0.08-0.70; p = 0.01). Early detection of PH in children living at high altitudes is associated with a higher likelihood of having a positive response to the PHT and subsequently, lower mortality rates. These findings underscore the importance of early diagnosis in improving long-term outcomes for this population.