Patient-reported outcomes in coronary artery disease: the relationship between the standard, disease-specific set by the International Consortium for Health Outcomes Measurement (ICHOM) and the generic health-related quality of life instrument 15D.

BACKGROUND

Patient-reported outcome (PRO) instruments measure health gains, including changes in health-related quality of life (HRQoL). Previous studies have assessed the reliability and relationship of multiple HRQoL instruments in search of the optimal instrument for feasible measurement of PROs. Although the 15D instrument was shown to have the best sensitivity and construct validity among cardiac patients, it is unknown how well it captures relevant disease-specific information scores compared to instruments included in the International Consortium for Health Outcomes Measurement (ICHOM) standard set. The aim of this study was to investigate whether the disease-specific PRO instruments and a generic HRQoL instrument capture disease related symptoms in coronary artery disease (CAD) patients.

METHODS

Health status and HRQoL were assessed with the instruments included in the ICHOM standard set: Seattle Angina Questionnaire short-form (SAQ-7), Rose Dyspnea Scale (RDS), two-item Patient Health Questionnaire (PHQ-2), and with the 15D HRQoL instrument at baseline and 1 year from the treatment in a university hospital setting. Spearman correlation and explanatory factor analysis were used to assess the relationship of baseline scores and 1-year change in scores of 297 patients.

RESULTS

At baseline, the overall 15D score and SAQ-physical limitation (SAQ-PL), 15D "breathing" and SAQ-PL, as well as "breathing" and RDS showed moderately strong correlations. The factor interpreted to reflect "Breathing-related physical activity", based on high loadings of "breathing", RDS, SAQ-PL, "mobility", "vitality", and "usual activities", explained 19.2% of the total variance. Correlations between 1-year changes in scores were fair. The factor of "Breathing-related physical activity", with significant loading of RDS, SAQ-PL, "breathing, "usual activities", "vitality", "sexual activity", "mobility", and disease-specific quality of life explained 20.5% of the total variance in 1-year change in scores. The correlation of angina frequency measured by SAQ-7 and the 15D instrument was poor.

CONCLUSIONS

The 15D detects dyspnea and depression similarly to RDS and PHQ-2 but not angina similarly to the SAQ-7. This may call for supplementing the 15D instrument with a disease-specific instrument when studying CAD patients.