Prevalence and Risk Factors of Cognitive Impairment in COPD: A Systematic Review and Meta‐Analysis
Authors: Zhang Ziwei , Yang Pengyu , Xiao Gui , Li Bei , He Mingxin , Yang Yuhan , Yang Yalou 
Published: January 2025

ABSTRACTAimThe aim of this systematic review is to present the pooled estimated prevalence and risk factors for cognitive impairment (CI) in patients with chronic obstructive pulmonary disease (COPD).BackgroundPatients with COPD suffer from progressive and irreversible airflow limitation, resulting in continuous impairment of lung function, which in addition to causing lesions in the lungs, often accrues to other organs as well. In recent years, a growing number of cross‐sectional and longitudinal studies have shown that hypoxia is an important factor in causing CI and that there is an important link between them, but the assessment of co‐morbid neurocognitive impairment and dysfunction is often overlooked. Some studies suggest that the diagnosis of mild cognitive impairment (MCI) is considered a precursor to dementia symptoms, with an annual conversion rate of 5%–10%, and it has been suggested that MCI is a potentially reversible state that can be used as a window for intervention. There is a lack of evidence on the prevalence and influencing factors of CI and its MCI.DesignA systematic review and meta‐analysis.MethodsPubMed, Web of Science, the Cochrane Library, Ovid, Wiley, and Scopus were searched for cohort, case‐control, and cross‐sectional studies investigating the prevalence and risk factors of CI and MCI in COPD to June 2023 from building. Meta‐analyses were performed to identify CI and MCI prevalence and risk factors using a random‐effects model. The methodological quality assessment was conducted by the modified Newcastle‐Ottawa Scale (NOS) and Agency for Healthcare Research and Quality (AHRQ). This study was registered on PROSPERO (CRD42021254124).ResultsIn total, 41 studies (21 cohort studies, 7 case‐control studies, and 13 cross‐sectional studies) involving 138,030 participants were eligible for inclusion. Current evidence suggests that the average prevalence of CI and MCI in COPD was 20%–30% (95% CI, 0.17–0.28) and 24% (95% CI, 0.17–0.32), respectively. Significant heterogeneity existed both in CI and MCI (I2 = 99.76%, 91.40%, p < 0.001). Mata‐regression analysis showed that different region could be the source of heterogeneity in the pooled results. Cough, FEV1, PaO2, age, education, depression, and BODE index are influential factors in the development of CI in COPD.ConclusionIntegrated epidemiological evidence supports the hypothesis that the prevalence of CI in the COPD population has shown an increasing trend, with differences by region and by instrument. Cough, FEV1, PaO2, age, education, depression, and BODE index are influential factors in the development of cognitive impairment in COPD patients. We should promote early screening and management of COPD patients and take targeted measures to prevent and reduce the incidence of CI.Implications for PracticeThis systematic evaluation and meta‐analysis identifies seven important risk factors for the development of CI among COPD patients and exposes their current epidemiological findings to provide a theoretical basis for public health administrators and healthcare professionals to effectively increase the screening rate of cognitive impairment in patients with COPD as well as to carry out early intervention.Trial RegistrationPROSPERO).crd. york.ac.uk