Depression has an adverse effect on patients recovering from heart failure and cardiovascular problems, according to a new study.

In particular, moderate to severe depression was linked to a five-fold increase in mortality among heart failure patients — even when researchers removed the independent risk and severity of heart failure. Happiness seemed to protect other patients from mortality risk; those who weren’t depressed had an 80 percent lower mortality risk.

In the study, called OPERA-HF, researchers examined heart failure patients over 302 days; 103 patients weren’t depressed, 27 had mild depression, and 24 had moderate to severe depression. Depression was measured using the Hospital Anxiety and Depression Scale, which rates depression on a 0-21 scale. Over the course of 302 days, 27 of the patients died. It turned out that those with moderate to severe depression were five times more likely to die than patients with little to no depression.

“Our results show that depression is strongly associated with death during the year following discharge from hospital after an admission for the exacerbation of heart failure; we expect that the link persists beyond one year,” Professor John Cleland, lead author of the study and professor of cardiology at Imperial College London and the University of Hull in the UK, said in the press release. “The association was independent of the severity of heart failure or the presence of comorbidities.”

The researchers aimed to study heart failure in a more holistic fashion, which offered them clearer insights into mortality. “This included social, mental, and physical frailty, as well as comorbidities and the severity of heart failure,” Cleland said in the press release. “Depression has been reported to predict death in patients with heart failure, but until now it was thought that this could be because depressed patients have more severe heart failure and more comorbidities.”

Depression, the researchers note, is common in heart failure patients — up to 20 to 40 percent of them are affected by it. Depression is associated with sleep problems, a change in appetite, and either weight gain or weight loss; as well as lack of motivation to take care of yourself. This is possibly one of the reasons why there was an increased risk of mortality among heart failure patients who were depressed.

Ultimately, taking a holistic approach in treating heart failure patients (and hospital patients in general) might be the best way to alleviate symptoms and reduce mortality. More research is needed, however, for the researchers to move forward with appropriate treatment plans.

“Our research clearly shows a strong association between depression and risk of death in the year after discharge from hospital,” Cleland said in the press release. “Recognition and management of depression may reduce mortality for patients with heart failure.”

Source: Cleland J. et al. OPERA-HF. European Society of Cardiology. 2015.