Table 1.

Heart failure study descriptions

Study	Design	Sample	Measure
Three gramme sodium intake is associated with longer event-free survival only in patients with advanced heart failure (Lennie et al. 2011)	Prospective observational study measuring dietary sodium intake and 12-month event-free survival while controlling for other clinical variables. Patients were divided into two groups using a 3-g urine sodium cutpoint and stratified by NYHA Class (I/II vs. III/IV)	302 HF patients recruited from outpatient clinics associated with six large community hospitals and academic medical centres in Kentucky, Georgia, Indiana and Ohio	24-hour urine sodium to indicate sodium intake; event-free survival for 12 months as determined by patient or family interviews and medical record review. Differences in cardiac event-free survival determined by Kaplan–Meier survival curve with log-rank test and Cox hazard regression. Included questionnaires to assess HRQL, adherence, functional status and self-care
Cognitive deficits in chronic heart failure (Pressler et al. 2010)	Comparative design used to evaluate cognitive deficits among three groups (HF group, healthy participants group and other medical conditions group) and an explanatory correlational design to evaluate the relationships between HF severity, age, and comorbidity and cognitive deficits in the HF patients (Pressler et al. 2010)	414 total participants (249 HF patients, 63 healthy and 102 medical participants) recruited from HF clinics and a general medicine practice in Indiana	Series of neuropsychological tests administered to all participants designed to measure the following cognitive domains most likely to be impaired in vascular cognitive disorders: global cognitive function, premorbid intellect, language, working memory, verbal memory, visuospatial ability, psychomotor speed and executive function
Nurse-enhanced memory intervention in heart failure: the MEMOIR study (Pressler et al. 2011)	12-week randomised interventional study designed to determine efficacy of Brain Fitness, a computerised cognitive training intervention, for heart failure (HF) patients. Half the participants were randomly assigned to the Brain Fitness intervention group, and the other half was received a health education intervention	40 patients recruited from HF clinic in Michigan	Series of neuropsychological tests and questionnaires administered at baseline, 8, and 12 weeks to measure memory, working memory, psychomotor speed, executive function and performance of cognitive activities and instrumental activities of dialling living (IADLs)
Cognitive training to improve memory in heart failure (MEMOIR-2) (Pressler et al. 2015)	12-week randomised interventional study designed to build upon the MEMOIR-1 study by determining the efficacy of the Brain Fitness cognitive training intervention for HF patients. Half the participants were randomly assigned to the Brain Fitness intervention group, and the other half received a health education intervention	31 HF patients recruited from HF clinics in Michigan	Series of neuropsychological tests and questionnaires administered at baseline, 8, and 12 weeks to measure recall and working memory, psychomotor speed, executive function, IADL performance, HRQL, depressive symptoms, Timed Up and Go Test. Also measured gene and serum BDNF levels