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

Authors

  • Carlos A. Vaz Fragoso MD,

    Corresponding author
    1. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
    • Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut
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  • John Concato MD,

    1. Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut
    2. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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  • Gail McAvay PhD,

    1. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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  • H. Klar Yaggi MD,

    1. Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut
    2. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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  • Peter H. Van Ness PhD,

    1. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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  • Thomas M. Gill MD

    1. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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Address correspondence to Carlos A. Vaz Fragoso, Clinical Epidemiology Research Center, VA Connecticut Healthcare System, 950 Campbell Ave., Mailcode 151B, West Haven, CT 06516. E-mail: carlos.fragoso@yale.edu

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.

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