Photo Credit: iStock.com/Belitas

Given the rising prevalence of cognitive impairment in COPD, researchers have called for increased efforts to identify risk factors and intervene earlier.

Some experts suggest that COPD should no longer be defined as a single disease with various related comorbidities. Instead, it should be identified as part of a multimorbidity, allowing the various aspects of the disease presentation to be diagnosed and quantified. For example, airflow limitations, a primary characteristic of COPD, impair the respiratory system, which can lead to neurological damage. This impairment can, in turn, lead to cognitive impairment (CI).

Studies have examined the prevalence of CI in patients with COPD. However, no studies have focused on the factors contributing to this prevalence.

To address this knowledge gap, Ziwei Zhang and colleagues developed a systemic review and meta-analysis of studies examining the prevalence of CI and mild cognitive impairment (MCI) in patients with COPD to identify influencing factors. The results of the study were published in Public Health Nursing.

“Unspecified cognitive deficits in patients with COPD may have a serious impact on clinical management, leading to an inability to maintain functional independence, poor self-management, and greater withdrawal from pulmonary rehabilitation programs,” the authors said.

After applying exclusionary criteria, 41 studies, including 138,030 patients, were identified for inclusion in the meta-analysis. The cognitive assessment tools used in the studies varied, with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) most commonly applied.

Prevalence & Influencing Factors

Noting significant heterogeneity between the studies (I²=99.80%, P=0.00), researchers found that the overall incidence of CI in patients with COPD was 20% to 24%. Eight studies showed a combined MCI prevalence of 24% (95% CI, 0.17–0.32), with significant heterogeneity (I²=91.41%, P=0.00).

Geographical location was a compelling contributor to the heterogeneity in prevalence. The prevalence of CI in patients with COPD was 19% (95% CI, 0.12–0.27) in North America; 15% (95% CI, 0.11–0.19) in Europe; 34% (95% CI, 0.24–0.43) in Asia; 56% (95% CI, 0.37–0.75) in Oceana, which includes 14 countries such as Australia and Papua New Guinea; and 27% (95% CI, 0.17–0.37) in other regions.

CI assessment tools also contributed to the heterogeneity of documented prevalence. For example, when MMSE was used, the prevalence of CI was 21% (95% CI, 0.18–0.25), but when MoCA was used, the prevalence was 39% (95% CI, 0.25–0.52).

Given the high prevalence of CI in patients with COPD and indications that this correlation is trending higher, the researchers called for increased efforts to identify CI and public health policies to encourage screening and early intervention.

“Appropriate intervention strategies begin with the timely identification of cognitive dysfunction in patients with COPD,” Zhang and colleagues said.