The relationship between anxiety, depression and treatment adherence in chronic obstructive pulmonary disease: A systematic review

Background: Almost half of the people with chronic obstructive pulmonary disease (COPD) do not adhere to the prescribed treatments and report anxiety and depression as comorbidities, resulting in higher rates of exacerbations, hospitalizations, and worse clinical outcomes. Objective: This systematic review provided a synthesis of studies about the relationships between anxiety, depression, and adherence in people affected by COPD. Methods: English language publications were searched in the PUBMED, SCOPUS, PsycInfo, Web of Science, PsycArticles, and Cochrane Library databases from December 2020 to March 2021, following PRISMA guidelines. The reference lists of eligible studies and other relevant systematic reviews were also searched. Data extraction and critical appraisal were undertaken by two reviewers working independently. The reference lists of eligible studies and other relevant systematic reviews were also searched. Data extraction and critical appraisal were undertaken by two reviewers working independently. Results: A total of 34 studies (23 quantitative and 2 qualitative studies, 9 reviews) were included. The relationship between depression and treatment adherence was significant and negative. Adherence to both rehabilitation, psychological, and antidepressant pharmacological treatments in depressed patients was linked to a decreased risk of hospitalization. Moreover, depressed patients compliant with an antidepressant were more likely to adherent to COPD maintenance inhalers. On the other hand, the associations between anxiety and adherence were poorly investigated and high heterogeneity characterized the studies, leading to a weak and variable relationship as well as too few interventions. Conclusion: The systematic review highlights the variability in estimates of the relationship between depression, anxiety, and treatment adherence in COPD. It could be explained by meth-odological differences across the included studies. This suggests that standardization is critical to improving the precision of the estimates. Recommendations for future research include attention to causal inferences, an exploration of mechanisms to explain the relationships between both anxiety and depression and adherence in COPD, and a comprehensive, systematic approach.