Assessment of endpoints in the pediatric population: congenital heart disease and idiopathic pulmonary arterial hypertension

PURPOSE OF REVIEW: Children with pulmonary arterial hypertension (PAH) are a distinct patient population, requiring a different approach to disease management and treatment. In developed countries, pulmonary hypertension is more common in children than adults. It is frequently associated with congenital heart disease. A smaller number of children have rapidly progressive idiopathic PAH. The natural history of PAH and the response to treatment can differ in children and adults. In idiopathic PAH, for example, infants and younger children may present with fatigue and impaired growth, as well as syncope, whereas teenagers may present with symptoms similar to those seen in adults. Aggressive therapy is usually required early in young children because the disease can progress more rapidly. RECENT FINDINGS: Thus far, no randomized trial of a pulmonary hypertension-specific drug in pediatric patients has been published. Trial methodology needs refining with selection of the most appropriate endpoints. Recent studies suggest that treatment with the dual endothelin receptor antagonist, bosentan, can benefit children. SUMMARY: Treatment response can be difficult to quantitate in children. There are challenges involved in performing and interpreting the traditional treatment endpoints used in adults: primarily exercise capacity, but also functional class and quality of life. It may be possible to overcome these problems in future pediatric trials by using a composite endpoint, time to clinical worsening, as in the adult PAH population. A composite endpoint uses parameters such as symptomatic progression and the need for additional therapy, hospitalization, transplantation, or death.