Mild to moderate chronic airways disease does not carry an excess risk of cognitive dysfunction

Whether chronic obstructive pulmonary disease (COPD) carries a risk of cognitive dysfunction prior to the onset of arterial hypoxemia is not known. Our objective was to assess both the prevalence and main correlates of subclinical cognitive dysfunction in older patients with non-hypoxemic COPD.

Home-dwelling non-demented subjects over 64 years of age consecutively attending 24 outpatient Departments of Respiratory Medicine or Geriatrics because of COPD (N = 233), asthma (N = 203), non-obstructive bronchitis (N = 92) or chronic non-respiratory and non-dementing diseases (controls, N = 1080) underwent a multidimensional assessment. Cognitive status was assessed by the Mini-Mental State Examination (MMSE). Independent correlates of MMSE < 24 were identified by logistic regression analysis. In order to limit the confounding effect of collinearity between COPD group membership and the 6' walked distance, a properly designed multivariate analysis was performed.

Prevalence of MMSE < 24 ranged from 16.7% (controls) to 21.9% (COPD). Education < 9 years (Odds Ratio = 1.56, Confidence Intervals = 1.22-1.98), a score > 6 on the 15-item Geriatric Depression Scale (OR = 1.37, CI = 1.16-1.62). a 6' walked distance < 242 m (OR = 1.22, CI = 1.02-1.45), a Barthel Index greater than 80 (OR = 1.48, CI = 1.03-2.14) and a Forced Vital Capacity inferior to 80% of the predicted value (OR = 1.17, CI = 1.09-1.38) qualified as independent correlates of MMSE < 24. The multivariate analysis confirmed that groups had comparable MMSE scores.

Non-hypoxemic COPD did not increase the risk of subclinical cognitive dysfunction in an older population.