Association between Chronic Obstructive Pulmonary Disease and Dementia: Systematic Review and Meta-Analysis of Cohort Studies

Background: Chronic obstructive pulmonary disease (COPD) is a common disease among the elderly, which has been linked to cognitive decline. However, the relationship between COPD and dementia remains unclear. Summary: We conducted a systematic literature review by searching databases such as Pubmed, Embase, EBSCO, and Cochrane Library (from inception to April 18, 2018) for studies on COPD that also investigated the prevalence of dementia. We found 3 cohort studies including a total of 39,392 COPD patients. Then we applied the Newcastle-Ottawa Scale to evaluate the risk of bias. Key Messages: COPD patients faced a higher risk of dementia (HR 1.46; 95% CI 1.22-1.75; p < 0.001). Subgroup analysis on gender determined that the association between COPD and dementia was stronger in male patients (HR 1.49, 95% CI 1.20-1.86, p < 0.001) than in female patients (HR 1.41, 95% CI 1.27-1.57, p < 0.001). A subset study of patients aged >65 years revealed that the HR was greater for patients aged >= 75 years (HR 1.46, 95% CI 1.07-2.00, p = 0.02) than for those aged 65-74 years (HR 1.40, 95% CI 1.28-1.53, p < 0.001). The cohort studies included were from similar population-based databases, suggesting possible regional limitations and publication bias.