Relevance of patient-centered actigraphy measures in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a qualitative interview study

Background: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are severe, progressive diseases characterized by key symptoms such as dyspnea and fatigue. These symptoms impair physical functioning, with patients struggling to perform their daily activities. One traditional measure of physical functioning and exercise capacity is the 6-minute walk test (6MWT). Actigraphy represents a promising tool to complement the 6MWT and provide a holistic picture of physical performance in patients with PAH or CTEPH. However, the current literature holds limited evidence on content validity of actigraphy in these populations, as reported by patients themselves. The primary objective of this study was to understand which physical functioning concepts are most meaningful to patients with PAH or CTEPH and identify relevant actigraphy variables and appropriate timeframes for their measurement.

Methods: This was a cross-sectional, qualitative study in adults with a confirmed diagnosis of PAH or CTEPH. Participants from the UK and USA were interviewed one-on-one via a web-based platform, with interviewers using a semi-structured discussion guide that included concept elicitation and cognitive debriefing sections. Data within the anonymized interview transcripts were coded and thematically analyzed.

Results: Concept elicitation identified the physical functioning concepts most meaningful to patients with PAH or CTEPH and generated a combined conceptual model of physical functioning, which strongly aligned with previous literature. During cognitive debriefing, of the four actigraphy variables debriefed in relation to these physical functioning concepts, study participants highly valued time spent in non-sedentary physical activity and time spent in moderate to vigorous activity, while step count and walking speed emerged as less relevant. Participants indicated four alternative variables as relevant: walking distance, walking up hills or inclines, duration of continuous walking bouts, and time spent walking. Regardless of the variable, participants suggested a timeframe of approximately 10 or 12 h/day over a minimum of 14 days for measuring physical functioning.

Conclusions: By demonstrating the content validity of actigraphy measures of physical functioning, this qualitative study begins to address the evidence gaps identified by the regulatory requirements for using actigraphy endpoints in future PAH and CTEPH clinical trials.