Effect of coexisting chronic obstructive pulmonary disease and cognitive impairment on health outcomes in older adults

Abstract

Objectives: To determine the extent to which the co-occurrence of chronic obstructive pulmonary disease (COPD) and cognitive impairment affect adverse health outcomes in older adults.

Design: Multicenter longitudinal cohort study.

Setting: California, Pennsylvania, Maryland, and North Carolina.

Participants: Three thousand ninety-three community-dwelling adults aged 65 and older from the Cardiovascular Health Study. Four hundred thirty-one had chronic obstructive pulmonary disease (COPD) at study baseline.

Measurements: Follow-up began at the second CHS visit and continued for 3 years. Spirometric criteria for airflow limitation served to establish COPD using the Lambda-Mu-Sigma method, which accounts for age-related changes in lung function. Cognitive impairment was evaluated using the modified Mini-Mental State Examination and claims data. Outcomes were respiratory-related and all-cause hospitalizations and death.

Results: Participants with coexisting COPD and cognitive impairment had the highest rates of respiratory-related (adjusted hazard ratio (aHR) = 4.10, 95% confidence interval (CI) = 1.86-9.05) and all-cause hospitalizations (aHR = 1.34, 95% CI = 1.00-1.80) and death (aHR = 2.29, 95% CI = 1.18-4.45). In particular, individuals with both conditions had a 48% higher rate of all-cause hospitalizations (adjusted synergy index (aSI) = 1.48, 95% CI = 0.19-11.31) and a rate of death nearly three times as high (aSI = 2.74, 95% CI = 0.43-17.32) as the sum of risks for each respective outcome associated with having COPD or cognitive impairment alone. Nevertheless, tests for interaction were not statistically significant for the presence of synergism between the two conditions contributing to each of the outcomes. Therefore, it cannot be concluded that the combined effect of COPD and cognitive impairment is greater than additive.

Conclusion: Coexisting COPD and cognitive impairment have an additive effect on respiratory-related and all-cause hospitalizations and death. Optimizing outcomes in older adults with COPD and cognitive impairment will require that how to improve concurrent management of both conditions be determined.

Figure 1

Effect of chronic obstructive pulmonary disease and cognitive impairment on the risk of (A) respiratory-related and (B) all-cause hospitalizations. COPD indicates chronic obstructive pulmonary disease; Cog Impair, cognitive impairment. COPD and cognitive impairment additively increased the risk of respiratory-related and all-cause hospitalizations. The numbers above the bar graphs are the hazard ratios (HRs). Below these point estimates within parentheses are the 95% confidence intervals (CIs). Participants with neither COPD nor cognitive impairment were the reference group. HRs were adjusted for age, gender, education, smoking, and other comorbidities.

Figure 2

Effect of chronic obstructive pulmonary disease (COPD) and cognitive impairment on the risk of death. COPD indicates chronic obstructive pulmonary disease; Cog Impair, cognitive impairment. COPD and cognitive impairment additively increased the risk of death. The numbers above the bar graphs are the hazard ratios (HRs). Below these point estimates within parentheses are the 95% confidence intervals (CIs). Participants with neither COPD nor cognitive impairment were the reference group. HRs were adjusted for age, gender, education, smoking, and other comorbidities.