The assessment of burden of COPD (ABC) tool: What counts most?

The ABC tool is an instrument to support shared decision making between patient and caregiver. It includes a colored balloon diagram to visualize patients9 scores on the subjective burden of COPD questionnaire and objective severity indicators. We determined the importance of each item of the burden of disease from a patient-perspective, in order to calculate a weighted index score that can be related to costs. We conducted a Discrete Choice Experiment (DCE) among COPD patients in a cluster-RCT of the ABC tool. Each COPD patient received 14 choice questions, in which he was asked which of two health states was more severe. States were described in terms of the 15 items of the ABC questionnaire: dyspnoea (at rest; during physical activity), coughing, sputum production, limitations (in strenuous physical; moderate physical; daily and social activities), feeling depressed, concern about breathing getting worse, worrying, listlessness, tension, fatigue and exacerbations. Each item had 3 levels. Weights for each item-level combination were derived statistically from the likelihood of each health state to be considered worse than the other. Weights were re-scaled to generate the ABC index score, ranging from 0 (best) to 100 (worst). 282 patients completed the DCE. The highest weights were assigned to dyspnoea at rest, limitations in moderate physical activities, daily and social activities, concern about breathing getting worse, fatigue, and exacerbations. Mild, moderate and severe burden of disease were defined as ABC index scores 40, respectively. This categorisation was most predictive of mean annual healthcare costs: €1200, €2500 and €9500, respectively.