TABLE 2.

Summary of the barriers to undertaking a clinical trial of primary prophylaxis in children

General barriers	Poor understanding of natural history and consequences of variceal hemorrhage
	Multiple etiologies of underlying portal hypertension in children
	Undertaking diagnostic endoscopy under sedation or anesthesia within a research protocol with uncertain benefits for the individual child
	No validation in children of scoring systems for the endoscopic appearance of varices
	Expected high dropout rate from research protocol
	Large sample size requirement
Barriers to a trial of β-blockers	Inadequate understanding of hemodynamic pathophysiology in children with portal hypertension
	Inadequate understanding of appropriate dosing of β-blockers in children with portal hypertension
	Drug toxicity
	Difficulty in maintaining double blinding
	Requirement for regulatory approval
	Funding from industry unlikely
Barriers to a trial of EVL	Poor acceptance of endoscopy by children and/or families, leading to low recruitment rate
	Poor compliance with repeat endoscopies
	Inadequate knowledge of optimal schedule for follow-up EVL in children
	Undertaking interventional endoscopy under sedation or anesthesia within a research protocol with uncertain benefits for the individual child
	Impossible to maintain double blinding

EVL = endoscopic variceal ligation.