Study protocol for a matter of heart: a qualitative study of patient factors driving overuse of cardiac catheterisation.

INTRODUCTION: Overuse of cardiac catheterisation (CC) for stable coronary artery disease (CAD) is documented in Germany and other regions, although percutaneous coronary interventions do not provide a benefit over medical therapy for stable patients. Various studies investigated health system, physician and patient factors driving non-adherence to guidelines which recommend a stepwise approach with invasive procedures only in case of signs of ischaemia in non-invasive testing. In a larger-scale project, we aim to better understand the patients' perspective in order to develop an intervention that enhances patient's acceptance of this stepwise diagnostic approach for stable CAD. As a first step, this qualitative study aims to identify patient factors that prevent and promote the described overuse.

METHODS AND ANALYSIS: The exploratory qualitative interview study will include about 20 patients with stable CAD and a history of acute coronary syndrome from two German teaching practices. Narrative, structured interviews designed to last 30 to 90 min will be conducted. The interviews will be analysed using qualitative content analysis by Mayring. The analysis will address the following questions: (1) What are reasons for stable patients to undergo CC? (2) How do patients deal with their heart disease (secondary prevention)? (3) Which processes do patients describe regarding decision-making for non-invasive and invasive coronary procedures? (4) What information needs exist on behalf of patients to better understand the stepwise diagnostic approach outlined in guidelines and thereby avoid low-appropriate CCs? Based on these data, empirical typification will be conducted.

ETHICS AND DISSEMINATION: Ethical approval for the study was obtained. All participants will provide written informed consent. Data will be pseudonymised for analysis. The findings will contribute to the development of an appropriate intervention. Results will be disseminated by conference presentations and journal publications.