The value of qualitative research in randomized controlled trials involving drugs and medical devices: a systematic mapping review

The use of qualitative research with randomized controlled trials (RCTs) has grown exponentially over the last decade, but little is known about how it is contributing to trial procedures and interventions. This review systematically mapped the value that qualitative research has had in RCTs of drugs and medical devices.

We searched five electronic databases (MEDLINE, EMBASE, PsycINFO, CINAHL, and ASSIA) and the NIHR Journals Library to identify original, peer-reviewed qualitative research conducted in the context of specific RCTs (pilot or full). Drawing on studies published between January 2019 and December 2020, we identified and classified examples illustrating how qualitative research had contributed to the trial. This created a list of questions qualitative methods can address in RCTs.

Of 207 included studies, only 22 percent explicitly articulated their value. Most frequently reported contributions included: (a) explaining trial findings; (b) ensuring that interventions meet the needs of key stakeholders; and (c) making the trial feasible and viable (e.g., through improved trial design and conduct). A total of 776 examples demonstrating how qualitative methods had enhanced the trial were classified into twenty-seven subcategories. A list of sixty potential questions was developed to assist future research design.

The value of qualitative research in trials is expanding. While qualitative methods have traditionally been associated with complex interventions, this review highlights their relevance to trials involving drugs and devices. Future trials could benefit from expanding the use of qualitative methods to deepen understanding of outcomes, strengthen measurement validity, and capture experiences of conditions.