Process Evaluation of a Double-Blind Randomized Controlled Trial to Assess the Efficacy and Safety of a Quadruple Ultra-Low-Dose Treatment for Hypertension Within a Federally Qualified Health Center Network (QUARTET USA)

BACKGROUND: This convergent parallel-design mixed-methods process evaluation of the QUARTET USA (Quadruple UltraLow-Dose Treatment for Hypertension USA) clinical trial (NCT03640312) explores patient and health care professional perceptions about the use of low-dose quadruple therapy (LDQT) as a novel strategy for hypertension management. METHODS AND RESULTS: A survey of all 62 patients enrolled in the QUARTET USA trial was conducted. A subsample of 13 patients and 11 health care professionals, recruited via purposive sampling, took part in semistructured interviews. At enrollment, 68% of participants (mean [SD] age, 51.7 [11.5] years; 56% self-identified as Hispanic: Mexican ethnicity, 16% as Hispanic: other ethnicity, 16% as Black race, 8% as White race, and 1.6% as South Asian race) reported that their current health depended on blood pressure medications, and 48% were concerned about blood pressure medications. At trial completion, 80% were satisfied with LDQT, 96% were certain the benefits of taking LDQT outweighed the disadvantages, and 96% reported that LDQT was convenient to take. Both patients and health care professionals found LDQT acceptable because it reduced patients’ perceived pill burden and facilitated medication adherence. Health care professionals stated that a perceived limitation of LDQT was the inability to titrate doses. Steps to facilitate LDQT implementation include introducing stepped-care combinations and treatment protocols, inclusion in clinical practice guidelines, and eliminating patient cost barriers. CONCLUSIONS: LDQT was an acceptable strategy for hypertension treatment among patients and health care professionals involved in the QUARTET USA clinical trial. Although LDQT was generally perceived as beneficial for maintaining patients’ blood pressure control and facilitating adherence, some clinicians perceived limitations in titration inflexibility, adverse effects, and costs.