Qualitative and mixed methods provide unique contributions to outcomes research.

Outcomes research examines the effects of medical care interventions and policies on the health outcomes of individuals and society.1 Investigators conducting outcomes research seek to inform the development of clinical practice guidelines, to evaluate the quality of medical care, and to foster effective interventions to improve the quality of care.2 Outcomes research has traditionally used quantitative sciences to examine the utilization, cost, and clinical effectiveness of medical care through randomized and nonrandomized experimental designs. Quantitative methods are not as well suited to measure other complex aspects of the healthcare delivery system, such as organizational change, clinical leadership in implementing evidence-based guidelines, and patient perceptions of quality of care, which are also critical issues in outcomes research.3–7 These more nuanced aspects of healthcare delivery may be most appropriately examined with qualitative research methods.8–10 Qualitative approaches are becoming more common in clinical medicine and health services research.5,11–15 Federal encouragement of qualitative research is regularly reflected in funding program announcements issued by the National Institutes of Health.16 For more than a decade, federal agencies and foundations such as the National Science Foundation have demonstrated a commitment to supporting qualitative research through funding scientific conferences, workshops, and monographs on this field of inquiry.17–20 Despite this steady growth in qualitative research, outcomes investigators in cardiology have relatively little guidance on when and how best to implement these methods in their investigations. The purpose of the present report is to introduce qualitative methods as providing unique and critical contributions to outcomes research. This report will describe the situations in which qualitative approaches are most helpful; summarize the primary principles and practices in study design, sampling, data collection, and data analysis for qualitative studies; present representative examples of cardiovascular outcomes research that uses qualitative methods; and synthesize current standards for ensuring rigor and enhancing credibility of qualitative research. Defining Qualitative Research Qualitative research is a form of scientific inquiry that spans different disciplines, fields, and subject matter and comprises many varied approaches.21 Qualitative methods can be used to understand complex social processes, to capture essential aspects of a phenomenon from the perspective of study participants,5 and to uncover beliefs, values, and motivations that underlie individual health behaviors.22–24 Such research can also illuminate aspects of organizational context and healthcare delivery that influence organizational performance and quality of care.10,25 Qualitative studies are often exploratory in nature and seek to generate novel insights9,23,26,27 using inductive (starting with observations and developing hypotheses) rather than deductive (starting with extant hypotheses and testing them with observations) approaches. Qualitative research can be distinguished from quantitative research in several ways. First, whereas quantitative research counts occurrences (eg, estimates prevalence, frequency, magnitude, incidence), qualitative research describes the complexity, breadth, or range of occurrences or phenomena. Second, whereas quantitative research seeks to statistically test hypotheses, qualitative research seeks to generate hypotheses about a phenomenon, its precursors, and its consequences. Third, quantitative research is performed in randomized or nonrandomized experimental and natural settings and generates numeric data through standardized processes and instruments with predetermined response categories. Qualitative research occurs in natural (rather than experimental) settings and produces text-based data through open-ended discussions and observations. Mixed methods, in which quantitative and qualitative methods are combined, are increasingly recognized as valuable, because they can capitalize on the respective strengths of each approach.28 Pairing quantitative and qualitative components of a larger study can achieve various aims, including corroborating findings, generating more complete data, and using results from 1 method to enhance insights attained with the complementary method.29,30 Approaches to mixedmethods studies differ on the basis of the sequence in which the components occur and the emphasis given to each.29,30 The qualitative and quantitative components may be per-