Development of a preference-based heart disease-specific health state classification system using MacNew heart disease-related quality of life instrument

Purpose: The MacNew Heart Disease Health-Related Quality of Life Instrument (MacNew) is a validated, clinically sensitive, 27-item disease-specific questionnaire. This study aimed to develop a new heart disease-specific classification system for the MacNew amenable for use in health state valuation. Methods: Patients with heart disease attending outpatient clinics and inpatient wards in Brisbane, Australia, completed MacNew. The development of the new disease-specific classification system included three stages. First, a principal component analysis (PCA) established dimensionality. Second, Rasch analysis was used to select items for each dimension. Third, Rasch analysis was used to explore response-level reduction. In addition, clinician and patient judgement informed item selection. Results: Participants included 685 patients (acute coronary 6%, stable coronary 41%, chronic heart failure 20%). The PCA identified 4 dimensions (restriction, emotion, perception of others, and symptoms). The restriction dimension was divided into physical and social dimensions. One item was selected from each to be included in the classification system. Three items from the emotional dimension and two symptom items were also selected. The final classification system had seven dimensions with four severity levels in each: physical restriction; excluded from doing things with other people; worn out or low in energy; frustrated, impatient or angry; unsure and lacking in self-confidence; shortness of breath; and chest pain. Conclusion: This study generated a brief heart disease-specific classification system, consisting of seven dimensions with four severity levels in each. The classification system is amenable to valuation to enable the generation of utility value sets to be developed for use in economic evaluation.