Depressive symptoms are mediating the relationship between non-cardiac comorbidities and self-care of heart failure

Type of funding sources: Other. Main funding source(s): Improving Self-Care Behavior and Outcomes in Rural Patients with Heart Failure; National Research Foundation of Korea grant funded by the Korea government (MEST)

Most patients with heart failure (HF) have multiple chronic comorbid conditions. For HF patients with non-cardiac conditions, adhering to recommended self-care regimens can be complicated because recommended regimens across those conditions can even conflict with each other. Our previous study has shown that the significant relationship between non-cardiac comorbidities and HF self-care disappeared after covariates were entered in the regression model. The lack of the direct effect of non-cardiac comorbidity on HF self-care may be due to the effects of a possible mediator. Depressive symptoms are highly prevalent to patients with heart failure and in those with multiple chronic conditions, and negatively affect patients’ adherence to self-care. Therefore, it is possible that depressive symptoms mediate the relationship between non-cardiac comorbidities and self-care.

To examine the mediating effect of depressive symptoms on the relationship between non-cardiac comorbidities and HF self-care in patients with HF.

A total of 590 patients with HF (66 years, 41% female, 35% New York Heart Association function class III/IV) were included in this study. The list of non-cardiac conditions was identified from the Charlson Comorbidity Index. Depressive symptoms were measured with the 9-item Patient Health Questionnaire (PHQ-9). Self-care was measured with the 9-item European HF self-care behavior scale (EHFScBS). The EHFScBS scores were standardized ranging from 0-100, with higher scores indicating better self-care. The mediation analysis was conducted using the PROCESS macro program in SPSS (version 3.5) with 5000 bootstrap samples.

Less than one-third of the patients (30.8%) had clinically significant depressive symptoms (PHQ-9 scores of 10 or greater). On average, patients had one non-cardiac comorbidity. The results of the mediation analysis were presented in the Figure. The total effect of the number of non-cardiac comorbidities on HF self-care was significant, after adjusting for covariates. The direct effect of the number of non-cardiac comorbidities on HF self-care was not significant, while the indirect effect mediated by depressive symptoms was significant. This indicate the mediation of depressive symptoms on the relationship between the number of non-cardiac comorbidities and HF self-care.

We found that the depressive symptoms are a mechanism linking non-cardiac comorbidities and HF self-care. This result indicates that depressive symptoms is a greater barrier to engaging in HF self-care than the complexity of managing non-cardiac comorbidities. Therefore, clinicians need to assess and manage depressive symptoms to improve HF self-care for HF patients with non-cardiac comorbidities.