Decline of Health Status Sub-Domains by Exacerbations of Chronic Obstructive Pulmonary Disease: A Prospective Survey

Abstract

Background: Exacerbations of chronic obstructive pulmonary disease (COPD) are held responsible for a decline in health status (HS). This may not apply equally to all exacerbations, because different definitions are required for quite different illnesses. Selection of definitions and the sensitivity of the HS instrument may affect results regarding the impact of exacerbations. Sensitivity of a new HS instrument, which covers different and more aspects, has not yet been tested, with respect to exacerbations. Objectives: Confirmation of the negative HS effect of exacerbations by using a highly differentiated instrument, and to evaluate which aspects of HS are affected most. Methods: One hundred and sixty-eight ambulatory patients with COPD were evaluated prospectively with regard to a wide range of HS aspects, at the beginning and end of a 1-year follow-up. Recording of symptom changes and treatment on monthly diary cards resulted in the identification of event-based exacerbations. HS was assessed via a newly validated instrument integrating both physiological and non-physiological sub-domains. Parametric correlations were calculated between exacerbation frequency and HS scores at the end of the study. Partial corre-lations were then explored using HS scores at baseline to correct for prior HS levels. Results: Correlations between -exacerbation frequency and HS sub-domains were found to be frequent, predominantly in non-physiological sub--domains. After correction for HS scores at baseline, only 2 sub-domains (belonging to the main domain ‘Complaints') remained significantly but weakly correlated. Conclusion: Exacerbation frequency and HS show weak correlations after a year, but most of these disappear after correction for prior HS levels. In such exacerbations, aggravated HS probably takes much longer to manifest itself.