OBJECTIVES: To evaluate whether the content of QoL-B RSS (items 29-37) relates to patients’ experiences of symptoms included in the dose-finding study for tobramycin inhalation powder in non-CF BE, iBEST-1 (NCT02712983).

METHODS: Qualitative, semi-structured, open-ended telephone interviews were conducted with a subsample of patients completing the study at four sites in the United Kingdom. Patients were asked to describe the symptoms they experienced and their feedback was collected on the understandability, meaning, relevance of the items and response options contained within the RSS.

RESULTS: Seven patients comprising four females were interviewed with age range 40-72 years, disease duration 4-60 years and a median baseline QoL-B RSS score of 55.6 (range 40.7-77.8). The items of the RSS were found to be highly relevant to patients’ experiences of BE symptoms (sputum, cough, breathlessness, chest pain, wheezing, and chest congestion). However, some patients conflated the concepts of congestion and chest tightness. While four patients reported that they had experienced all colors of sputum listed under response options of item 32, three patients reported experiencing a non-listed color. Patients were able to relate the changes in sputum color to changes in symptoms with darker colors corresponding to a deterioration in symptoms. Response scales were considered distinct, appropriate, easy to use and representing the full range of severity or frequency levels of the changes experienced. Patients reported that any change would be positive and noticeable but for a change on the RSS to be considered as meaningful, an improvement of at least 1-point would need to occur in several respiratory symptoms.

CONCLUSIONS: Although based on only seven interviews, these results provide supportive evidence for the content validity of the QOL-B RSS. Further confirmation is warranted through additional interviews.

This study has received support from the EU/EFPIA IMI-JU iABC grant agreement n° 115721.