Fibroid interventions: reducing symptoms today and tomorrow: extending generalizability by using a comprehensive cohort design with a randomized controlled trial

Background Uterine fibroids are an important source of morbidity for reproductive-aged women. Despite an increasing number of alternatives, hysterectomies account for about 75% of all fibroid interventional treatments. Evidence is lacking to help women and their health care providers decide among alternatives to hysterectomy. Fibroid Interventions: Reducing Symptoms Today and Tomorrow ( NCT00995878 , clinicaltrials.gov ) is a randomized controlled trial to compare the safety, efficacy, and economics of 2 minimally invasive alternatives to hysterectomy: uterine artery embolization and magnetic resonance imaging–guided focused ultrasound surgery. Although randomized trials provide the highest level of evidence, they have been difficult to conduct in the United States for interventional fibroid treatments. Thus, contemporaneously recruiting women declining randomization may have value as an alternative strategy for comparative effectiveness research. Objective We sought to compare baseline characteristics of randomized participants with nonrandomized participants meeting the same enrollment criteria and to determine whether combining the 2 cohorts in a comprehensive cohort design would be useful for analysis. Study Design Premenopausal women with symptomatic uterine fibroids seeking interventional therapy at 3 US academic medical centers were randomized (1:1) in 2 strata based on calculated uterine volume (