A systematic review to identify assessment instruments for social isolation or loneliness in adults with heart failure

Heart failure is an enduring and debilitating syndrome, affecting 65 million people world-wide¹. The prognosis for heart failure is worse than many cancers². People living with heart failure experience symptoms such as breathlessness, limited exercise capacity, fatigue, edema, disrupted sleep patterns, which can contribute to poor quality of life³. The management of heart failure is complex, often punctuated by frequent hospitalization and emergency department visits. Further, coping and adjusting to living with heart failure can be challenging for the individual affected, but also family caregivers who provide care at home, or in the community. Multimorbidity, frailty, depression, anxiety, social isolation, and loneliness are commonly associated with heart failure, contributing to worse patient outcomes and increased costs^4,5,6. High quality social connections and community interactions are important to optimize the well-being of adults living with heart failure⁷.

Loneliness is a subjective experience and occurs when the social connections and individual needs in life are greater than the connections they have⁸. Social isolation does not discriminate, it is estimated to impact 1 in 4 older adults⁹. Recognized as a modern-day health crisis, it is associated with increased mortality and as a risk factor comparable to smoking, obesity, and physical activity⁹. Such concern is well founded given the links that social isolation and loneliness has to mental illness, emotional distress, suicide, the development of dementia, premature death, and poor health behaviors including smoking, physical inactivity, and poor sleep and can influence physiological outcomes including high blood pressure and impaired immune function¹⁰. The COVID-19 pandemic, generational shifts, a lack of social and community cohesion and housing shifts to apartment living are identified as a few contributing factors to the worsening impacts^11,12,13,14.

Social isolation is defined as the objective state of having a small network of kin and non-kin relationships and this few or infrequent social interactions¹⁵. Whereas loneliness is defined as a painful subjective feeling that results from a discrepancy between desired and actual social connections⁹. Social isolation has been reported as a strong determinant of health and predictor of mortality¹⁶. Social isolation and loneliness have increasingly been suggested as risk factors for cardiovascular disease¹⁷. A UK-based cohort study in 2023 involving 12,898 participants with heart failure, examined the relationship with loneliness and social isolation¹⁸. The study identified a significant association between the factors, with the impact of social isolation on heart failure potentially modified by loneliness status (P-interaction = 0.034)¹⁸. Interventions that focus on individual and communal experiences of social isolation and loneliness could indeed be measures for the maintenance of cardiovascular health¹⁸. The risk associated with social isolation are not restricted to certain areas, cultures or sociodemographic as this was shown in a recent systematic review outlining the high rates of loneliness across high, middle, and low-income countries¹⁹. Whilst often used interchangeably, social isolation and loneliness are conceptually different. Importantly, socially isolated people may not necessarily be lonely and vice versa. Therefore, assessing loneliness and social isolation is crucial in this context.

Social isolation and loneliness are social determinants that clinicians need to recognize and address as important components of patient centred health care¹⁷. Therefore, should be regularly evaluated for all patients particularly those with cardiometabolic disease who are at high risk of developing heart failure¹⁷. To date, it is unclear how social isolation and loneliness have been assessed in adults living with heart failure, this warrants further exploration.

The primary aim of this review was to identify patient reported assessment instruments used to access social isolation and loneliness in adults living with heart failure.

Design

A systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, see Supplementary Materials 1 and 2²⁰. The systematic review protocol was registered prospectively in PROSPERO on the 18^th, March 2024 RECORD ID: [CRD42024518571].

The participants, phenomena of interest, and the context (PICo) approach was used to guide formulation of the search strategy and research question for this systematic review²¹. Participants: adults living with heart failure, phenomena of interest: patient reported social isolation and/or loneliness, context: original research studies including a predominant population of adults living with heart failure using a patient reported assessment instruments to measure social isolation and/or loneliness.

This review included primary observational cohort studies, randomized controlled trials (RCT), quasi-experimental single group pre-/post- studies assessing loneliness and/or social isolation using a patient reported assessment instrument. Conference abstracts, reviews, editorials, and any publications not written in English or secondary analyses were excluded.

Eligibility criteria

Original studies that included adults with a primary or secondary diagnosis of heart failure, consistent with heart failure guidelines were included^22,23,24,25. Studies that did not investigate heart failure or did not include a predominant population living with heart failure (≥20%) were excluded.

This review included proportions of adults living with heart failure assessed for loneliness and/or social isolation using a patient reported assessment instrument. Studies that did not use a patient reported assessment instrument, i.e., electronic health record derived status as lived alone were excluded.

A search of three electronic bibliographic databases MEDLINE, CINAHL, and Scopus was conducted. Databases were searched from inception to 20^th March 2024. Only papers written in English language were included. The search strategy was reviewed by experts in the fields of heart failure and mental health. The detailed search strategy is provided in Table 1 in the appendix.

The search results were downloaded and uploaded to Covidence²⁶ for screening. Two reviewers independently conducted the title and abstract and full text, and data extraction. Conflicts were resolved by a third independent reviewer.

Potential overlaps between studies were identified at full text review to prevent double counting individual patients. This was done by comparing the study country, location, setting (hospital/community), and participant sample size. For instance, if two studies were from the same country, location, and used the same assessment instruments for social isolation and/or loneliness, only the study most recently published was included.

The following data were extracted using a standardized data extraction form on Covidence:

• Publication details: first author, journal, year, title, lead author contact details, country where study was conducted.

• Characteristics of included studies: methods, aim of study, study design, funding source, possible conflicts of interest.

• Participants: population description, inclusion criteria, exclusion criteria, prevalence of social isolation and loneliness, patient data, recruitment method.

• Patient reported assessment instruments: for social isolation and loneliness, type(s) of assessment instrument(s), if the study used a qualitative, quantitative, or mixed method assessment.

• Outcome data: mean scores or number of people and percentage of people with social isolation and/or loneliness, if reported.

Quality appraisal

Quality assessment was performed by two reviewers independently. The Joanna Briggs Institute (JBI) critical appraisal assessment instruments were adopted to assess the methodological quality and risk of bias using applicable scoring for the study types: RCT (0–13), cross sectional studies (0–8), cohort studies (0–11), and case control studies (0 to 10)^27,28,29. A score was assigned for each item from zero for “No” or “Unclear” responses and a score of one for a “Yes” response. The scores of the items for each study were summed to obtain a total quality score. Quality of the studies was then classified into three categories according to the JBI instrument used, these categories were low-quality (high risk of bias) when the quality appraisal score ranged from 0 to 4, moderate quality (moderate risk of bias) from 5 to 7, and high quality (low risk of bias) from eight and above. Studies having low and moderate risk of bias were included^30,31,32. All studies scored within the respective ranges for low and moderate risk of bias according to study type and therefore none were excluded at quality appraisal. Disagreements between reviewers were resolved through discussions or consultation with a third independent reviewer.

Analysis

There were no quantitative analyses performed. The results are presented as a narrative summary description of the individual studies and outcomes guided using the principles of the Cochrane framework for narrative data synthesis and analysis³³.

A total of 822 articles were retrieved from the three databases, of which 251 duplicates were removed. We screened 571 titles and abstracts and excluded 471 as irrelevant. Full text screening was conducted for 100 articles, of which 70 were excluded with reasons. Refer to Fig. 1 for the PRISMA diagram and the reasons for exclusion. In total, 30 studies were included for data extraction.

The Preferred Reporting Items for Systematic Reviews Meta-Analyses flow diagram.

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There was a total of 17 cohort studies, nine cross-sectional studies, two RCTs, and two case control studies included in this review. The total number of participants across the included studies was n = 529,665 mean age ranged from 52 to 83 years, 57% (n = 303,046) were women.

The studies originated from 15 countries (14 studies included participants from the United States, two from Sweden, two from Japan, two from the United Kingdom, one from Germany and Austria. The other remaining countries were single sites. Refer to Table 2 for the study characteristics and Table 3 for the outcomes.

The most commonly found measures to assess social isolation are listed here. Five studies used non-validated measurements of social network size and/or frequency of contacts within a specified period to quantify and assess either loneliness or social isolation risk^{34,35,36,37,38}. While six studies used either complete or modified versions of the Berkman-Syme Social Network Index and the Lubben Social Network Scale, which provide similar scoring systems to composite measures of network size and a contacts index^{18,39,40,41,42,43}. Overall, 11 studies assessed social isolation using network size and frequency of contacts as an index.

The Multidimensional Scale of Perceived Social Support (MSPSS) was used by three studies^44,45,46. The Berkman-Syme Social Network Index was used by two studies^18,42, of which one used only three questions adapted from the Berkman-Syme¹⁸. The 6-item Lubben Social Network Scale (LSNS-6) was used by three studies of which one used the abbreviated version^39,40,4110-item version the of the Lubben Social Network Scale (LSNS-10)⁴³. The Patient-Reported Outcomes Measurement Information System Social Isolation Short Form 4a V2.0 (PROMIS) was used by two studies^47,48. One study assessed social isolation through a scoring system determined by asking the patient if they lived alone, were currently unmarried, and if they lacked a caregiver⁴⁹.

The Duke Social Support Index was used by two studies^45,50 of which one used only one item⁴⁵ while another used four items from this instrument⁵⁰. The Gijon Familial Evaluation was used by one study⁵¹ and another study used part of the Nottingham Health Profile Questionnaire to assess social isolation⁵². The Friendship Scale for Perceived Social Isolation was used by only one study⁵³. One study used the Social Limitations domain of the Kansas City Cardiomyopathy Questionnaire⁵⁴. This assessment instrument was specifically developed for the heart failure population⁵⁵. The UCLA Social Support Inventory (UCLA-SSI) was used by one study⁵⁶. One study used the interview schedule for social interaction which is a quantitative assessment instrument supplemented by qualitative responses⁵⁷. This study used a non-validated 15-item scale mentioned in a prior study to assess social support⁵⁸, alongside a contacts index³⁴. One study used a self-report four-point single item non-validated Likert-scale to assess perception of social isolation from 1 to 4⁵⁹.

The most commonly used validated instrument for loneliness was various versions of the University of California Loneliness Scale (UCLA-LS), used by seven studies^{18,39,47,48,60,61,62}. Two of these seven studies used an adapted version from the PROMIS database^47,48. A single item from The Centre for Epidemiologic Studies Depression Scale (CES-D) was used by one study⁶³. One study used a closed ended question of “are you lonely?” with a yes/no answer to assess loneliness⁴⁹ while another study used a multiple-choice question “does it happen that you feel lonely?” with the four possible answers of “Yes always”, “Yes often”, “No seldom” and “No never”⁵⁷. One study looked at family support constructs alongside a patient reported living alone status⁶⁴. A total of thirteen studies reported data on living alone status as either patient reported or collected through electronic medical records as part of baseline assessments^{18,35,37,39,40,42,44,45,49,50,57,62,64}.

Quality of the included studies

The quality appraisal result demonstrated that one of the RCT studies (Table 4), two of the cross-sectional studies (Table 5), and 14 of the cohort studies (Table 6), two case-control studies design (Table 7) had a high quality (low risk of bias). The rest of the studies in each study design demonstrated a moderate quality (moderate risk of bias).

This systematic review revealed that there are a range of instruments used to assess social isolation or loneliness of people with heart failure in research studies. A description of the most commonly used (defined as used by two or more included studies) assessment instruments from the included studies is provided below.

Multidimensional Scale of Perceived Social Support (MSPSS) was originally developed from a survey study using a cohort of undergraduate students by Zimet et al in 1988 to assess the perception of social support across the domains of family, friends, and significant other. The Cronbach alpha coefficient for significant other, family, and friends were 0.91, 0.87 and 0.85, respectively, indicating moderate to good internal consistency. The test retest for these respective domains and for the entire instrument was 0.72, 0.85, 0.75, and 0.88 which means moderate to good reliability⁶⁵. The assessment instrument was further tested in three groups (in pregnant women, adolescents living in Europe with their families, and pediatric physician residents in training) in 1990. The results demonstrated strong internal consistency with Cronbach alpha coefficients ranging from 0.81 to 0.98 across the subscales and between the study groups⁶⁶. In 2018, a psychometric evaluation of the MSPSS in people living with chronic diseases reported good internal consistency evidenced by a Cronbach coefficient alpha of 0.92 for the family domain, 0.96 for friends 0.93, for significant other and 0.91 for the entire assessment instrument⁶⁷.

The University of California Loneliness Scale (UCLA-LS) was originally developed in 1978 as a 20-item scale with high internal validity by Russell, Peplau and Ferguson at the University of California Los Angeles. This measure was developed due to a reported lack of simple and reliable assessment instruments to measure loneliness⁶⁸. The most commonly used version is version 3 developed in 1996 with good internal consistency (Cronbach coefficient alpha ranging from 0.89 to 0.94) and moderate reliability (test-retest reliability, r = 0.73)⁶⁹. A systematic review of the psychometric properties of UCLA-LS on adults in variation cross-cultural adaptations, including various short and long forms of the assessment instrument also showed moderate to good internal consistency (Cronbach alpha of 0.76–0.93). Although they found that UCLA-LS versions 4, 6, 7, and 10 had the better internal consistencies⁷⁰. Version 3 of this assessment measure was recently validated on 47 chronic obstructive pulmonary disease patients, demonstrating good validity and test-retest reliability⁷¹. The Patient-reported Outcomes Measurement Information System (PROMIS) Social Isolation Short Form 4a v2.0 is another abbreviated version of the UCLA, which uses only four items adapted from the UCLA Version 3 as part of the PROMIS database of patient reported outcome measurements^72,73,74.

Berkman-Syme Social Network Index was originally developed by Berkman and Syme in 1979 to measure social network indexes for comparison with health outcomes in the general adult population⁷⁵. This assessment instrument uses a scoring of frequency of contact with friends, family, neighbors, community and religious connections to quantify social isolation risk⁷⁵. The Lubben Social Network Scale 6 and 10 (LSNS-6 and LSNS-10) is an adaptation of the Berkman-Syme Social Network Index developed by James E. Lubben at UCLA to assess social networks in older adults. They reported an original Cronbach alpha of 0.70 in the 1980s. This was originally a 10-item scale and was developed incorporating the domains of family networks, friend networks, and interdependent networks to assess self-reported perceived support from social networks^76,77. The LSNS-6 abbreviated version was tested and developed by Lubben in three populations of older European communities, across the three sites of Hamburg, Solothurn, and Lonson. The Cronbach alpha coefficient was reported as 0.83 indicating good internal consistency⁷⁸.

The DUKE Social Support Index was originally developed as a 35-item scale in the 1980s by researcher at Duke University⁷⁹. This assessment instrument has further been abbreviated to a 23-item and an 11-item version for use in chronically ill aged populations⁸⁰. The 11-item Duke Social Support Index has been validated in older Australians with Cronbach alpha coefficients ranging from 0.6 to 0.8 indicating moderate internal consistency^81,82.

Kansas City Myocardiopathy Questionnaire was developed in 1996 by Spertus, Green, and colleagues to quantify health outcomes for adults living with congestive heart failure. Therefore, this assessment instrument was specifically validated in a cohort of adults living with heart failure. The (23-item) assessment instrument assessed seven domains of Physical limitation 0.90, Symptoms 0.88, Quality of Life 0.78, Social limitation 0.86, Self-efficacy 0.62, KCCQ functional status 0.93, KCCQ Clinical Summary 0.95 demonstrating good internal consistency in use with adults living with heart failure⁵⁵. This assessment instrument has a 2-week recall period and is commonly used by medical device and drug companies. There are 12-item and 23-item versions available for use⁸³.

Current widely accepted measures of loneliness include the variations of the UCLA Loneliness Scale. Social isolation is widely assessed using the various composite measures of social network size and frequency of contacts. It is recognized that while there are accepted assessment measurements of social isolation and loneliness, there are no “gold standard measurements”¹⁷. Researchers and clinicians, might use different assessment instruments and methods, leading to variations in how social isolation and loneliness are measured and reported. This can lead to challenges when developing and considering interventions for heart failure based on these factors. Additionally, loneliness can be perceived differently by different cultures and societies based on their collectivism/individualism scope. A recent study showed the Global Collectivism Index (GCI) across 188 nations globally to show that among the nations of the current study Turkey had the highest GCI accounting for 0.04 and Greece recording the least GCI of −0.062⁸⁴. With the globalization, societies have been shifting from collectivism to individualism leading to significant changes on the loneliness scores. This was reported in a study comparing Japan and London which showed that the rates of loneliness were much higher in Japan than in London while also increasing over a 6-year period⁸⁵. These rates, and changes, reflect a need for continuous assessment of the perceived loneliness rates among the older adult population, including those with heart failure. In addition to the evaluation of these rates on the outcomes of adults living with heart failure.

A recent systematic review on social isolation, loneliness and the impacts on cardiovascular disease outcomes found that diminished social relationships were associated with up to a 16% increased likelihood of experiencing a cardiovascular event⁸⁶, this is similar to previous research which linked social isolation as a risk factor for experiencing a cardiovascular event⁸⁷. There is consistent evidence that social isolation is a strong determinant of health¹⁶. Currently, there is a growing public health concern labeled the ‘loneliness epidemic’ notably affecting older adults demonstrating a cause-effect relationship on health outcomes¹¹, and also in the context of adults living with heart failure¹⁸.

Having a sense of purpose, that is, feeling that one’s life is goal-oriented and driven, tends to be according to⁸⁸, protective for psychological health. Ma et al.⁸⁹ with their nationally representative longitudinal panel study of older adults in the United States with a working sample of 2649 concur. In fact, the research team found that purpose in life fully mediated the negative impact of loneliness on protective behaviors when measured cross-sectionally⁸⁹. Loneliness has a direct correlation with social connectedness and in this regard and of foci in this paper, there is a well-documented, strong association between social relationships and cardiometabolic disease^17,90. There could be justification in examining the roles of biomarkers as indicators of social isolation and/or loneliness in patients.

Social isolation and loneliness are different constructs and have a close relationship. However, they are often discussed together though it is important to note that socially isolated people are not necessarily lonely, and lonely people are not necessarily socially isolated in an objective sense⁹¹. Social isolation refers to the objective concerns and characteristics of a situation and refers to the absence of relationships with other people. It is the state of having few or no social relationships or infrequent social interactions. Loneliness though is a subjective feeling of being alone or disconnected, regardless of the actual amount of social contact. Given the differences the two constructs are measure differently. Social isolation is usually assessed numerically by the number of social contacts a person has, the frequency of social interactions, and the size of their social network. Loneliness, however, is most often assessed using self-report scales where the person rates their feelings of loneliness and perceived social support on validated assessment instruments such as those identified in this paper.

The role of proxy social isolation and loneliness measurements in the clinical setting needs further exploration. This could take the form of composite, validated, quality or single item patient reported assessment instruments. Is asking if somebody is feeling lonely an appropriate use of clinical resources, will the use of proxy measures in clinical practice provide adequate insights to predict patient outcomes?

Do validation measures have justification or is it justifiable to use non-validated measures specific to the context of a patient population? These could be number of interactions, how many visits, social network size, or simple questions such as “do you feel lonely?” or “are you socially isolated?” or “do you feel you receive sufficient social support?”.

Given the impact of social isolation and loneliness on individual and population mental health and wellbeing, any study that improves understanding and use of their measurement and assessment may inform better interventions and outcomes. Studies across decades have shown that adaptation to enduring cardiac disease and psychosocial recovery from acute cardiac events depends more on psychological than on physical factors^92,93,94. The importance of understanding the mind-heart-body connection through constructs such as loneliness and social isolation for clinicians is therefore imperative. Specifically, in the context of this study where the association between loneliness and social isolation and heart failure is recognized, an overview of measurements may inform better interventions and outcomes for people experiencing heart failure.

With the increasing recognition of the association between social isolation and loneliness and heart failure, it is a timely necessity to strengthen the evidence for population and individual health. Population-based decision-making regarding determinants of health relies on standardized and comparable health data to inform practice, guidelines, and recommendations. Individual patient care relies on standardized and quality assessment and measurement of determinants to plan and communicate interventions and evaluate outcomes. This overview of assessment instruments for measuring loneliness and social isolation, promoting standardization and quality assessment.

This study provides an overview of the assessment instruments currently used to measure loneliness and social isolation in people with heart failure. Heart failure is a significant global health concern and therefore warrants such focus. However, given that loneliness and social isolation are widely reported experiences, and are also increasingly identified as determinants of other ill health, this study could inform consideration of the use of measurements in other significant health contexts and chronic diseases such as cancer and diabetes.

One limitation of this review is the exclusion of studies published in languages other than English, so it is possible that some relevant publications were missed. Due to the heterogenous nature of the assessment instruments used to assess loneliness and social isolation across each included study, meta-analysis could not be performed which limits comparison of findings. To ensure a quick and contemporarily relevant review, only three bibliographic databases were searched in the conduct of this review.

To conclude, social isolation and loneliness exert deleterious effects on both mental and physical health, significantly diminishing life satisfaction. The UCLA Loneliness Scale was the most used instrument to assess loneliness and composite measures of network size and frequency of social contacts are most common to assess social isolation in adults living with heart failure. Social isolation and loneliness are established risk factors for elevated morbidity and mortality rates, substantially contributing to a decreased quality of life. Addressing these psychosocial factors is critical not only for improving individual health outcomes but also for reducing the broader societal and economic burdens associated with chronic disease.