Patients with chronic heart failure and high scores on a global self-care scale had similar rates of long-term, all-cause mortality compared with those with low scores, according to a secondary analysis from two observational prospective studies.

A post-hoc analysis found low self-reported sodium intake was associated with increased mortality. However, no other individual self-care behavior predicted all-cause mortality.

Lead researcher Dionne Kessing, MSc, of Tillburg University in the Netherlands, and colleagues published their results in the Journal of the American College of Cardiology: Heart Failure on March 1.

They defined self-care as the complex regimen patients with chronic heart failure undertake such as sodium and fluid restriction, weight monitoring and medication adherence.

In this study, the researchers examined 559 patients with chronic systolic heart failure who were 80 years old or younger, had left ventricular ejection fraction (LVEF) of 40 percent or lower, were stable after receiving oral heart failure medication for at least a month and did not have an MI or hospital admission in the month before enrollment. 

The mean age was 66.3 years old, and 78 percent of patients were men. They were recruited from three cardiology outpatient clinics in the Netherlands.

The researchers assessed heart failure self-care using the nine-item version of the European Heart Failure Self-care Behavior scale. Participants rated the items on a five-point Likert scale ranging from 1 (completely agree) to 5 (do not agree at all). Higher scores reflected worse self-care.

The nine items were whether patients weighed themselves every day; if they contacted their doctor or nurse if their shortness of breath increased; if they contacted their doctor or nurse if their feet or legs became more swollen than usual; if they contacted their doctor or nurse if they gained 2 kg in one week; if they limited their fluid intake to 1.5 to 2 liters per day; if they contacted their doctor or nurse if they had increased fatigue; if they ate a low salt diet; if they took their medication as prescribed; and if they exercise regularly.

After a median follow-up period of 5.5 years, 40 percent of patients died. Of the 221 deaths, 126 were classified as cardiac, heart failure related or multisystem failure and 95 were classified as non-heart failure related.

Patients who were deceased were older, more often male, unemployed and lower educated. They also had a lower LVEF, higher New York Heart Association functional class, a higher comorbidity score and lower levels of serum sodium.

The mortality rates were 40 percent in the high self-care group and 39 percent in the low self-care group. The mean survival was 6.7 years in the high self-care group and 6.9 years in the low self-care group.

The researchers said there were no differences in survival rates between the groups in self-reported daily weight monitoring, fluid restriction, consultation behavior, regular exercise and medication adherence. However, the mean survival time was 6.6 years in patients highly limiting their sodium intake and 7.2 years in patients who were low in limiting their sodium intake.

After controlling for demographic and clinical covariates, low sodium intake was associated with an increased risk for mortality.

Multivariable predictors of all-cause mortality were low sodium intake, male sex, New York Heart Association functional Class III to IV, Charlson comorbidity index and lack of a partner.

The researchers mentioned a few limitations of the study, including that they assessed self-care with a self-report measure, which may be subject to recall bias and under- or over-estimation. They also did not have information on rehospitalizations, which prevented them from secondary analyses on cardiac events and heart failure-related hospitalization.

“Based on our findings, more studies are needed to examine the correspondence between subjectively and objectively measured self-care, such as sodium intake, and its actual relationship with long-term prognosis,” the researchers wrote. “Large scale clinical trials of patients with newly diagnosed [heart failure] that are being followed over time in which subjective and objective measures of self-care are assessed would provide better insight into the long- term effects of self-care on prognosis.”