Abstract 12066: Integrating and Revealing the Structure of the Quality of Life Instruments for Stable Coronary Patients
Introduction Two multi-domain instruments, SAQ and RAND_36, were used to assess quality of life in the COURAGE, a randomized trial evaluating the outcomes of optimal medical therapy (OMT) with or without percutaneous coronary intervention (PCI) in a total of 2,287 patients with stable coronary disease. To date the health domains were examined separately and the coherent structure of these two widely used instruments has not been described.
Methods A general-specific factor model was developed to analyze the factor structure of SAQ and RAND_36 assessed at 12 months after randomization and to better describe patients’ experiences after treatment.
Results The analysis indicate that the hypothesized general-specific structure fit SAQ and RAND_36 adequately. A general factor, labeled the overall health, captured the commonality shared by SAQ and RAND_36. Two specific factors also emerged, as would be expected, that represented the unique variance of each instrument after partitioning out overall health (Figure). Domains in the RAND_36 loaded stronger on the overall health factor than did those of the SAQ. SAQ domains loaded stronger on an angina-specific factor than the overall health factor. Domains of emotional well-being and social functioning in the RAND_36 loaded strongly on a unique factor, suggesting that they are distinct from the overall health. The PCI group scored marginally higher on the overall health than the OMT group ( p = .06) and significantly higher (p<0.001) on the SAQ, but no group difference was found on the RAND_36.
Conclusions The general-specific factor model provides a systematic approach to define the underlying structure of health status, as captured common ground shared by the SAQ and RAND_36. The model offers a more comprehensive understanding of outcomes of quality of life. The SAQ is more effective in gauging angina-related health status and capturing the benefits of PCI, whereas the RAND_36 is more attuned to assessing overall health status.
- Cardiovascular disease
- Quality of life
- Health factors
- Percutaneous coronary intervention
- Health promotion
- © 2011 by American Heart Association, Inc.