Staging the severity of chronic obstructive pulmonary disease in older persons based on spirometric Z-scores.

Pubmed ID: 22091498

Pubmed Central ID: PMC3227010

Journal: Journal of the American Geriatrics Society

Publication Date: Oct. 1, 2011

MeSH Terms: Humans, Male, Female, Aged, Cohort Studies, Longitudinal Studies, Survival Analysis, Cause of Death, Severity of Illness Index, Health Surveys, Pulmonary Disease, Chronic Obstructive, Spirometry, Disability Evaluation, Geriatric Assessment, Connecticut

Grants: P30 AG021342, K24AG021507, R03 AG037051, R03AG037051, K24 AG021507, R03 AG037051-02, P30AG21342

Authors: McAvay G, Gill TM, Van Ness PH, Concato J, Yaggi HK, Fragoso CA

Cite As: Fragoso CA, Concato J, McAvay G, Yaggi HK, Van Ness PH, Gill TM. Staging the severity of chronic obstructive pulmonary disease in older persons based on spirometric Z-scores. J Am Geriatr Soc 2011 Oct;59(10):1847-54. Epub 2011 Sep 13.

Studies:

Abstract

OBJECTIVES: Among older persons, the use of spirometric Z-scores as calculated by the Lambda-Mu-Sigma (LMS) method has a strong scientific rationale for establishing a diagnosis of chronic obstructive pulmonary disease (COPD), but its clinical validity in staging COPD severity is not yet known. The current study has therefore evaluated the association between LMS-staged COPD and health outcomes, in two separate cohorts of older persons. DESIGN: Longitudinal cohort study. SETTING: The Cardiovascular Health Study (CHS, N = 3,248) and the Third National Health and Nutrition Examination Survey (NHANES-III, N = 1,354). PARTICIPANTS: Community-living white participants aged 65 to 80. MEASUREMENTS: Using spirometric data, COPD was staged as mild, moderate, or severe based on LMS-derived Z-scores. Clinical validity was then evaluated according to all-cause mortality, respiratory symptoms (chronic bronchitis, dyspnea, or wheezing), and moderate to severe dyspnea (available in CHS only). RESULTS: In CHS, the LMS staging of COPD as mild, moderate, and severe was associated with mortality (adjusted HR (aHR) = 1.50, 95% confidence interval (CI) = 1.15-1.94; aHR = 1.31, 95% CI = 1.03-1.67; and aHR = 2.00, 95% CI = 1.70-2.36, respectively) and with respiratory symptoms (adjusted OR (aOR)  = 1.69, 95% CI = 1.12-2.56; aOR = 1.87, 95% CI = 1.28-2.73; and aOR = 3.99, 95% CI = 2.91-5.48, respectively). Also in CHS, moderate and severe, but not mild, LMS-staged COPD was associated with moderate to severe dyspnea (aOR = 2.16, 95% CI = 1.24-3.75; aOR = 3.98, 95% CI = 2.77-5.74; and aOR = 0.84, 95% CI = 0.35-2.01, respectively). Similar associations were found for mortality and respiratory symptoms in NHANES-III, except mild severity was not associated with mortality (aHR = 0.93, 95% CI = 0.62-1.40). CONCLUSION: In white older persons, the spirometric staging of COPD severity based on LMS-derived Z-scores was associated with several clinically relevant health outcomes. These results support the use of the LMS method for staging the severity of COPD in older populations.