Pulmonary hypertension trials: how can we do better?

Analysis of terminated pulmonary hypertension clinical trials. What are we doing wrong?

Despite significant interest in the diagnosis and treatment of pulmonary hypertension (PH) over the past two decades, there have been no notable advancements in reducing mortality. One contributing factor to this lack of progress is the insufficient number of well-designed and conducted trials. We aimed to evaluate factors associated with termination of PH clinical trials, to serve as a reference when designing future trials. We searched the ClinicalTrials.gov database for PH clinical trials conducted between January 1st 2000 to December 31st 2020. Information collected and analyzed included trial design, status, and publication status. Of the 240 analyzed clinical trials, 81% evaluated therapeutic interventions. Around 30.4% of the trials were terminated, most commonly due to recruitment issues. Terminated trials had a significantly lower number of enrolled patients when compared to trials that were completed (p= .017). Furthermore, there was an overall negative correlation between the year of trial initiation and the total number of enrolled patients (r= -0.18; p= .013). The likelihood of termination decreased by 1.9% for every additional enrolled patient. Ultimately, only 37.5% of the trials have been published. There was a significant positive correlation between number of patients enrolled and the journal's impact factor (r = 0.4, p < 0.05). Pharmaceutical companies sponsored the majority of the trials. The termination rate of PH trials is higher than other conditions. Factors such as recruitment contribute significantly to termination. Further studies are required to evaluate the challenges associated with recruiting this patient population.