Background: Poor functional status relating to heart failure (HF) negatively affects health-related quality of life (HRQOL). Patients with HF, especially those with New York Heart Association (NYHA) Class III or IV HF, often exhibit poor HRQOL because of physical limitations and HF-related symptoms. Although sense of coherence (SOC) has been reported to be a determinant of HRQOL, its role as a mediator between functional status and HRQOL remains unclear, and few studies have explored the prevalence of HF in patients in NYHA Classes I and II.

Purpose: This study was designed to investigate SOC as a mediator between different functional status classes and HRQOL in patients with HF.

Methods: A cross-sectional study was conducted on patients with HF recruited from a hospital in northern Taiwan from April 2020 to September 2020. The Minnesota Living with Heart Failure Questionnaire and a questionnaire on sociodemographic characteristics; functional classification in terms of NYHA Classes I, II, and III; and SOC were administered. The PROCESS v3.5 (by Andrew F. Hayes) macro was applied to analyze the effects, and Model 4 was used to examine the mediating role of SOC on the relationship between NYHA functional class and HRQOL.

Results: Of the 295 participants, SOC was found to mediate the effects of functional status on HRQOL more significantly in patients in Class II than those in Class III but not more significantly in patients in Class I than those in Class III. A weaker mediating effect of SOC was noted on the relationship between functional status and HRQOL in patients with HF in NYHA Class II than those in Class III.

Conclusions: In patients with HF, poor functional status often reduces HRQOL significantly. SOC mediates the relationship between functional status and HRQOL more significantly in those in NYHA Class II than those in Class III. Nursing staff should work to increase patients' SOC by strengthening their coping capacity and improving their functional status to improve their HRQOL.