Parent cough-specific quality of life: Development and validation of a short form

Abstract

Cough is a distressing symptom and has a significant effect on many children and their families. Quality-of-life (QOL) measures provide important outcome indicators for clinicians and aid in evaluating the efficacy of interventions. The aim of this study was to develop and validate a short cough-specific QOL questionnaire for pediatric use. Two sources provided data to establish a shortened version of the Parent Cough-specific Quality of Life (PC-QOL) questionnaire. The first (n=240, 137 boys; median age, 29 months [interquartile range, 14-64 months]) was used for development and cross-validation. Stepwise regression was used to select the reduced set of items, and analyses of reliability, validity, and minimally important differences determined psychometric strength and sensitivity to change. The second independent dataset (n=320, 190 boys; median age, 39.5 months [interquartile range, 16-77 months]) was used as a confirmatory sample. Forward-step regression identified 8 items that accounted for 95% of the variance in the full-scale PC-QOL questionnaire. This shortened version (PC-QOL-8) was internally consistent (Cronbach α=0.84), had good test-retest reliability (intraclass correlation coefficient=0.66), and demonstrated strong validity (significant correlations with a cough verbal category descriptor score, cough visual analog scale, and subscales of the Short Form-12 General Health scale, the Pediatric Quality of Life Inventory, and the Depression, Anxiety, and Stress Scale). The reduced scale was responsive to change, and a minimally important difference of 0.9 was suggested. These findings were confirmed with the second dataset. The PC-QOL-8 questionnaire is a short, reliable, and valid instrument for assessing the effect of a child's chronic cough. It demonstrated sensitivity to change, and its length and psychometric properties should enhance its potential uptake and routine use in clinical practice and research.