Children suffering from congenital heart disease worldwide are being let down by a paucity of research on their conditions, a review published in the European Journal of Cardio-Thoracic Surgery reports.

Though research exists on pediatric heart disease, applicable studies are few and far between, first author Nigel E. Drury, PhD, and co-authors wrote in the review. Drury and his U.K.-based team conducted an exhaustive review of medical databases in an effort to evaluate the state of research in the field—and they weren’t impressed with what they found.

“Randomized clinical trials represent the gold standard in evaluating healthcare interventions through rigorous testing of a predefined protocol with minimization of bias,” the researchers wrote. “However, much of modern pediatric cardiac surgical practice is based on expert opinion, institutional case series or experimental evidence derived from adults.”

Holding randomized clinical trials (RCT) accountable for the most accurate, useable information, Drury et al. searched the MEDLINE, CENTRAL and LILACS databases for all RCTs reporting the effect of any intervention on the conduct or outcomes of heart surgery in children since January 2000. The search was thorough, encompassing six continents and a handful of languages.

Drury and his team found 333 trials in all that pertained to their search; the studies randomized a total of 23,902 children and spanned 34 countries. Ninety-four percent of studies were early-phase and recruited a small cohort of patients, while just 11—3.3 percent—directly evaluated a surgical intervention.

Fifteen research projects in all made it to the late phases, the authors reported, accounting for 4.5 percent of the total. Late-phase trials yield the most telling results, offering a bleak outlook on the state of research in the field.

“Randomized controlled trials only represent the gold standard when appropriately designed, conducted and reported,” Drury and colleagues wrote. “Although phase II efficacy and safety trials have a role in determining whether potential treatments are worth pursuing, it is phase III clinical effectiveness trials that influence guidelines and change practice.”

The studies the researchers examined focused largely on single-center, phase II trials, according to the paper. Most of these cases recruited small patient groups, and reporting didn’t always adhere to international standards.

Drury et al. wrote their results were upsetting—but not surprising.

“Our findings are typical of the pediatric trials literature,” they said, noting recruitment for studies in the field isn’t lacking. An average of 90 percent of eligible patients are enrolled for these heart studies, and target sample size is achieved in 87 percent of cases. Still, scientists struggle to fill the existing research void.

“As a congenital heart disease community, we have the responsibility to provide scientific leadership and work together to conduct well-designed, rigorously conducted, multicenter trials with clearly defined, clinically relevant endpoints that answer important questions to improve the outcomes of surgery for our patients and their families,” Drury and co-authors wrote. “Our colleagues in other specialties, such as pediatric oncology, have made the opportunity to participate in late-phase clinical trials part of the routine care pathway and so must we—carpe diem."