Health status and the spiral of decline.

COPD is complex and there are multiple determinants of poor health, so most studies of Chronic Obstructive Pulmonary Disease (COPD) now include health status, or health related quality of life measurement, along with FEV(1) as a primary endpoint. It is important to make a distinction between quality of life-which is unique to the individual, and health status measurement-which is standardized quantification of the impact of disease. Health status scores correlate weakly with FEV(1) but they are predictors of mortality independently of age and FEV(1). The determinants of impaired health status may change over time and the clinical consequences associated with a given change in score may change with disease progression. The largest study to date suggests that health status decline is linear over time, but longer-term studies are needed to confirm these findings. Inhaled corticosteroids have been shown to reduce the rate of decline of health status, possibly due to exacerbation prevention.