Staging the Severity of Chronic Obstructive Pulmonary Disease in Older Persons Based on Spirometric Z-Scores

• Autores: Carlos A. Vaz Fragoso, John Concato, Gail McAvay, H. Klar Yaggie, Peter H. Van Ness, Thomas M. Gill
• Localización: Journal of the American Geriatrics Society, ISSN 0002-8614, Vol. 59, Nº. 10, 2011, págs. 1847-1854
• Idioma: inglés
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• Resumen

  • 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.