Psychometric Validation of the German Translation of the Quality of Life Questionnaire-Bronchiectasis (QOL-B)-Data from the German Bronchiectasis Registry PROGNOSIS

Patients with bronchiectasis feature considerable symptom burden and reduced health-related quality of life (QOL). We provide the psychometric validation of the German translation of the disease-specific Quality of Life Questionnaire-Bronchiectasis (QOL-B), version 3.1, using baseline data of adults consecutively enrolled into the prospective German bronchiectasis registry PROGNOSIS. Overall, 904 patients with evaluable QOL-B scores were included. We observed no relevant floor or ceiling effects. Internal consistency was good to excellent (Cronbach's alpha >= 0.73 for each scale). QOL-B scales discriminated between patients based on prior pulmonary exacerbations and hospitalizations, breathlessness, bronchiectasis severity index, lung function, sputum volume, Pseudomonas aeruginosa status and the need for regular pharmacotherapy, except for Social Functioning, Vitality and Emotional Functioning scales. We observed moderate to strong convergence between several measures of disease severity and QOL-B scales, except for Social and Emotional Functioning. Two-week test-retest reliability was good, with intraclass correlation coefficients >= 0.84 for each scale. Minimal clinical important difference ranged between 8.5 for the Respiratory Symptoms and 14.1 points for the Social Functioning scale. Overall, the German translation of the QOL-B, version 3.1, has good validity and test-retest reliability among a nationally representative adult bronchiectasis cohort. However, responsiveness of QOL-B scales require further investigation during registry follow-up.