The association between mild cognitive impairment and self-care activity in community dwelling adult patients who have a diagnosis of chronic heart failure: a systematic review.

Review question/objective The objective of the review is to synthesise the best available evidence for an association between mild cognitive impairment and self-care activity in patients who have been diagnosed with chronic heart failure. The review question is: What is the evidence for an association between mild cognitive impairment and self-care activity, measured in one or more of the self-care domains related to heart failure in community dwelling adult patients who have a diagnosis of chronic heart failure? Background Heart failure Heart failure is a syndrome of reduced cardiac output, such that the heart cannot maintain adequate tissue perfusion.1 The severity of symptoms, systems affected, and causes can vary between patients. Quality of life for individuals affected by heart failure may be reduced by symptoms of breathlessness, limb oedema and fatigue, often resulting in disturbed sleep, reduced capacity for coping with normal daily activities or employment, and deteriorating mental well-being.2 The European Society of Cardiology suggests that the overall prevalence of heart failure is 2-3% of the population, but that increases significantly with age, rising sharply at around 75 years of age to 10-20% of 70-80 year olds.3 Hogg et al4 in a comprehensive literature review of international studies of patients with heart failure found reported prevalence of between 2.1% and 8.8%, although there was heterogeneity of age across the different papers. As the demographic characteristics of the population change in many countries, the burden of heart failure can be expected to increase.5 The link between self-care and heart failure management Whilst pharmacological advances have meant that the treatment of heart failure has improved significantly in recent years, there is growing recognition of the importance of effective self-care in the management of heart failure.3, 6 The inability to undertake self-care activities is well recognised as a contributing factor for increased hospital admission in patients with heart failure.7, 8 Self-care in this context has been described as a naturalistic decision-making process involving knowledge, experience, skill, and compatibility with personal values.9 Theoretically, the concept of self-care in heart failure has been explained in terms of three discrete yet overlapping components. These are self-care maintenance (involving activities associated with symptom monitoring and treatment adherence); self-care management (where patients recognise and respond to their symptoms by implementing self-care activities); and self-care confidence (acts as a mediator and moderator of the outcomes of the self-care process).9 Recommendations for patient behaviours or activities to promote self-care include advice regarding medication, fluid and sodium management, nutrition and weight management, smoking cessation, alcohol consumption, and physical activity,10 commonly described as the ‘domains’ of self-care in the context of heart failure. Self-care maintenance activities involves following these recommendations, whereas self-care management activity requires that patients recognise and evaluate a change in their symptoms, decide to take appropriate action and then evaluate their response to the intervention.9 Self-care confidence has not been presented as part of the self-care process per se, however, it has been shown to be an important factor in influencing the effectiveness of self-care.11 Specific tools have been developed and validated to measure self-care activity in patients with heart failure, related to the component stages and domains outlined above. The most commonly cited measurement tools are those developed in North America by Riegel11 and colleagues (The Self-Care of Heart Failure Index) and Jaarsma12 and colleagues in Europe (The European Heart Failure Self-Care Behaviour Scale). Both tools were developed based on an initial concept analysis to construct scale items and subsequent reliability and validity testing of internal consistency of the scales using pooled data drawn from multi-centre studies. It can be seen from the foregoing discussion that self-care activity in patients with heart failure involves a complex cognitive decision-making process; furthermore, the pathophysiology and symptoms associated with heart failure may have an adverse impact on cognitive functioning. Therefore, it is reasonable to consider the part that cognitive function may play in self-care activity in heart failure. Cognitive function and heart failure Cognition describes the intellectual functions required to manage independently within one's environment. These include memory, language, attention, visuospatial ability, behaviour, and executive functions.13 Cognition in aging persons follows along a spectrum ranging from normal function to severe impairment, known as dementia. Mild cognitive impairment is described as an intermediate step between normal cognitive function and dementia, and is described below. Mild Cognitive Impairment The term Mild Cognitive Impairment designates chronic cognitive deficits that make performance of some activities of daily living more difficult than usual (e.g. unable to organise medications or appointments without a memory aid or take care of finances), but are not severe enough to impair basic activities of daily living (e.g. dressing, eating, toileting).14 Formal diagnosis of Mild Cognitive Impairment requires evidence of abnormalities on neuropsychological testing (1.5 SD below age-standardised mean) in at least one cognitive domain, with or without memory impairment.15 For the purposes of this review, Mild Cognitive Impairment will be defined as evidence of impairment on a validated screening tool or diagnostic battery in individuals who do not have cognitive impairment that is severe enough to interfere with their basic activities of daily living. The presence of cognitive impairment is well documented in patients with heart failure, with a prevalence ranging between 25% and 75%,16–19 depending on the definition used to define cognitive impairment and the cognitive domains being tested. The Mini Mental State Examination (MMSE)20 is a widely used instrument for cognitive testing in older persons, with or without heart failure.16, 21, 22 However, it is well documented that the MMSE is not sensitive for detecting Mild Cognitive Impairment and has limited sensitivity to executive functions.22,23 In other words, people with heart failure and Mild Cognitive Impairment will often score within the normal range on the MMSE and therefore the presence of Mild Cognitive Impairment is missed.21, 24, 25 The Montreal Cognitive Assessment (MoCA) is being used increasingly in heart failure patients, is recommended by the Canadian Stroke Network to assess for Mild Cognitive Impairment in patients with vascular disease,26 and is sensitive to cognitive deficits detected in older heart failure patients. Recent studies have reported a prevalence of Mild Cognitive Impairment, as defined by a total MoCA score <26, in 54-75% of older patients with heart failure.27–29 Difficulties with memory, attention, psychomotor speed, verbal learning, and executive functions are the most common types of cognitive deficits reported in heart failure patients.30, 31 It is often difficult to detect Mild Cognitive Impairment in a clinical setting without formal cognitive testing or specifically asking about signs of Mild Cognitive Impairment such as a decline in managing finances, organising medications, or performing other usual instrumental activities.14 Self-care management imposes a high cognitive demand on patients with heart failure. Patients may experience difficulty with self-care due to underlying cognitive impairment. In patients with severe cognitive impairment, such as dementia, difficulty with self-care is not unusual; however, emerging evidence suggests that patients with Mild Cognitive Impairment may also have difficulty with self-care.25, 32, 33 Nevertheless, the evidence base for this association is arguably limited; a preliminary literature search conducted for the development of this protocol identified several studies assessing cognitive function in heart failure and many studies investigating self-care activity in heart failure, yet very few studies were located that specifically investigated cognitive function and self-care activity in heart failure. Moreover, the sample size in those individual studies appears relatively small; therefore an opportunity to systematically review and synthesise existing data is warranted. Summary Heart failure presents a significant clinical, personal, social and economic burden. Self-care has been recognised as the cornerstone of effective heart failure management; however, given the established link between heart failure and deteriorating cognitive function, one may assume that self-care activity in patients with heart failure can be compromised by even mild cognitive impairment. A preliminary search of the literature identified isolated articles which indicate a relationship may exist between cognitive function and self-care activity in patients with heart failure7, 25, 32 however, in a search of the Cochrane Library, Joanna Briggs Institute (JBI) Library of Systematic Reviews, The University of York Centre for Reviews and Dissemination DARE database, and the National Institute of Health Research Health Technology Assessment programme (HTA) databases, no systematic review investigating an association between mild cognitive impairment and self-care activity in the context of heart failure was located. A search of Google Scholar identified one published systematic review34 that partially covered the area of interest, addressing our review question as part of its search strategy. However, this work was dissimilar from the review proposed here as it did not search for relevant grey literature, did not focus exclusively on the relationship between cognitive impairment and self care, and excluded articles where medication adherence was the only outcome measured. Therefore we believe that there are sufficient differences between the aim of that review and the work proposed here to merit further study. It is argued here that evaluation of the evidence base of such an association is important to inform clinical practice; identifying whether even mild cognitive impairment can affect specific domains or general aspects of self-care activity in patients with heart failure will enable clinicians who support patients in developing knowledge, skill and confidence in self-care to take account of the influence of cognitive function. Thus, synthesising the evidence of an association between mild cognitive impairment and self-care activity in the context of heart failure is the concern of the proposed review. Inclusion criteria Types of participants Studies will include community dwelling adult patients (18 years and above) who have a diagnosis of chronic heart failure, at any stage of the New York Heart Association (NYHA) Classification of Heart Failure.35 Patients will be included regardless of gender, age, ethnic origin or any co-morbidity. Focus of the Review: The focus of the review is the epidemiological association between mild cognitive impairment (considered the presupposed risk factor) and self-care activity in the context of heart failure (considered the outcome). For the purposes of this review, mild cognitive impairment will be defined as evidence of impairment on a validated screening tool or diagnostic battery in individuals who do not have cognitive impairment that is severe enough to interfere with their basic activities of daily living. Studies that use validated instruments to measure cognitive function or impairment (as presupposed risk factor) will be considered for inclusion in this review. All included studies must also measure self-care capability or activities as outcomes of interest. This may be performed using validated tools, or more simple measures (such as percentage of missed medications). Self-care will include management of diet (including healthy diet, salt and fluid intake), medicines management, avoidance of risk factors for disease progression/deterioration, and symptom awareness and management. Types of study The review will include primary quantitative studies that formally measure both cognitive function and self-care activity and seek to describe the relationship between these factors. These may include any experimental design (including randomised controlled trials and quasi-experimental designs); analytical epidemiological designs, (including prospective and retrospective cohort and case control studies) and descriptive epidemiological studies (including case series studies and individual case reports and descriptive cross sectional studies). It is expected that there will be few, if any, experimental studies, as the research question does not lend itself to this type of trial. Search strategy The search strategy aims to find both published and unpublished (although indexed in the major databases) studies. Initial key words to be used will be: “Heart failure” “Cognitive” “Self care” These terms will be combined using the “AND” Boolean operator. Specialist advice from a librarian will be sought to further develop the specific search terms used within each database. A three-phase search strategy will be utilised in the review. An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. A second search using all identified keywords and index terms plus theoretically derived terms from the self-care literature will then be performed across all included databases. Thirdly, the reference list of all identified reports and articles will be searched for additional studies. As the concept of self-care in heart failure developed in the mid 1990's a date limit of 1995 is proposed for the database search. However, reviewing articles for the Background section of this review suggests that cognitive impairment in patients with heart failure has been recognised as a distinct problem since as early as 1977, and so no date of exclusion will be imposed on studies identified via reference lists from retrieved studies. Only articles with an English abstract will be included in the search. If papers with an English language abstract and foreign language body appear to answer the review question then translation expertise will be sought in the University or across the JBI collaborating network. Databases to be searched include: MEDLINE (In Process & Other Non-Indexed Citations) Medline, EMBASE, PsycINFO, CSA Sociological Abstracts, AARP Ageline, Academic Search Complete, CINAHL SocINDEX ISI Web of Science: Social Sciences Citation Index and Science Citation Index Expanded Ethos (The British Library database of doctoral theses) MedNar Google Scholar There will be no other attempt to identify grey literature or unpublished studies in the area of interest. Assessment criteria All citations located by the search will be assessed by two reviewers for relevance to the review based on the title/abstract using the specified inclusion criteria. If there is not enough information in the abstract to inform this decision, the full text of the article will be obtained. Assessment of methodological quality Quantitative papers selected for retrieval will be assessed by two independent reviewers for methodological validity prior to inclusion in the review using the relevant standardised critical appraisal instrument from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix I). Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer. Data extraction Quantitative data will be extracted from papers included in the review using the standardised data extraction tool from JBI-MAStARI (Appendix II). The data extracted will include details about the populations, study methods, exposures and outcomes. Data Synthesis Quantitative papers will, where possible, be pooled in statistical meta-analysis using JBI-MAStARI. All results will be subject to double data entry. Effect sizes expressed as relative risk for cohort studies and odds ratio for case control studies (for categorical data) and weighted mean differences (for continuous data) and their 95% confidence intervals will be calculated for analysis. A Random Effects model will be used and heterogeneity will be assessed statistically using the standard Chi-square. Where statistical pooling is not possible, the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate. Findings from descriptive studies will, where possible, be synthesised and presented in a tabular summary with the aid of narrative and figures where appropriate. Conflicts of interest None of the reviewers have any conflicts of interest associated with this study. Acknowledgements We would like to acknowledge the support of Glasgow Caledonian University and the Scottish Centre for Evidence Based Care of Older People in the conduct of this review.

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