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Reducing social isolation and loneliness in older people: a systematic review protocol
  1. Filipa Landeiro,
  2. Paige Barrows,
  3. Ellen Nuttall Musson,
  4. Alastair M Gray,
  5. José Leal
  1. Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, UK
  1. Correspondence to Miss Filipa Landeiro; filipa.landeiro{at}


Introduction Social isolation and loneliness affect approximately one-third to one-half of the elderly population and have a negative impact on their physical and mental health. Group-based interventions where facilitators are well trained and where the elderly are actively engaged in their development seem to be more effective, but conclusions have been limited by weak study designs. We aim to conduct a systematic review to assess the effectiveness of health promotion interventions on social isolation or loneliness in older people.

Methods and analysis A systematic review was conducted in Medline, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Applied Social Sciences Index and Abstracts, LILACS, OpenGrey and the Cochrane Library on peer-reviewed studies and doctoral theses published between 1995 and 2016 evaluating the impact of health promotion interventions on social isolation and/or loneliness for individuals aged 60 and over. Two reviewers will independently assess each study for inclusion and disagreements will be resolved by a third reviewer. Data will be extracted using a predefined pro forma following best practice. Study quality will be assessed with the Effective Public Health Practice Project quality assessment tool. A narrative synthesis of all studies will be presented by type of outcome (social isolation or loneliness) and type of intervention. If feasible, the effectiveness data will be synthesised using appropriate statistical techniques.

Ethics and dissemination This systematic review is exempt from ethics approval because the work is carried out on published documents. The findings of the review will be disseminated in a related peer-reviewed journal and presented at conferences. They will also contribute to a DPhil thesis.

Trial registration number CRD42016039650

  • social isolation
  • loneliness
  • intervention
  • systematic review
  • older
  • elderly

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Strengths and limitations of this study

  • This systematic review of interventions to alleviate social isolation or loneliness was based on a detailed search strategy including studies from any country published in any language.

  • The review followed robust guidelines and the quality of the papers included was assessed using a validated tool.

  • The heterogeneity of the interventions and of the tools used to measure social isolation or loneliness may not allow for direct comparisons between studies.


Worldwide, the population is ageing as a result of decreasing mortality and fertility.1 The global share of individuals aged 60 years or over represented 11.7% of the world population in 2013 and is expected to reach 21.1% by 2050.2 Up to 50% of those aged over 60 are at risk of social isolation3 and approximately one-third of older people will experience some degree of loneliness later in life.4 5

Social isolation has detrimental effects on health,6 7 having been identified as a risk factor for all-cause morbidity and mortality8 with outcomes comparable to smoking, obesity, lack of exercise and high blood pressure.9 It has also been associated with decreased resistance to infection,10 11 cognitive decline and mental health conditions such as depression and dementia9 and with increased emergency admission to hospital,12 longer length of stay and delayed discharges.13

The literature identifies two main types of interventions aiming to reduce social isolation and loneliness: group-based interventions (ie, support groups,14 15 reminiscence therapy,16 17 videoconferencing,18) and one-to-one interventions (ie, computer use training,19 animal companionship,20 21 visitor volunteers,22 etc). These types of interventions can be implemented in the community (ie, in a centralised location, such as centres for adult education or at the participant’s home) or in a supported living facility (ie, nursing or residential homes, warden-controlled flats, etc). These interventions can focus on: social skills training (ie, educational course on friendship,23 strategies to develop social behaviours,24 etc); enhanced social support (ie, befriending volunteer programme,22 support groups following bereavement,15 etc); increased opportunity for social interaction (ie, through the provision of services such as transport,25 home-delivered meals26 and use of technology such as internet and interactive games or activities,27–30 etc); and social cognitive training (ie, self-management group sessions,31 etc). Furthermore, these interventions can either be technology assisted or not.

Previous reviews of health promotion interventions aimed at reducing social isolation in the elderly suggest that interventions with group-based formats and where individuals are required to actively participate were more effective than one-to-one interventions.32 33 Also, involving the study participants in the planning, implementation and evaluation of policies,34 high-quality training of facilitators32 and interventions based on existing community resources seem to produce more successful outcomes.4 34 The individuality of the experience of loneliness is an important issue which has also been highlighted in the literature, as this may cause difficulty in the delivery of standardised interventions: it has been suggested that programmes which are tailored to meet individual needs may be more appropriate and successful.4 But previous reviews were restricted to studies published in English language33–38 and up to 2013. Furthermore, statistical synthesis of effectiveness data has been largely lacking,33 34 36 38 39 as well as the assessment of the quality of the studies included using a validated tool.34–36 39 Previous systematic reviews that assessed the quality of the studies suggest that the literature investigating the effectiveness of interventions aiming to reduce social isolation or loneliness is of poor methodological quality and, although conclusions have been drawn, further investigation is required.32 The aim of this review is therefore to identify health promotion interventions aiming to alleviate social isolation or loneliness in older people and to assess their effectiveness.

Methods and analysis

Protocol and registration

We followed the reporting guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for Protocols 2015 (PRISMA-P).40 The completed PRISMA-P checklist is provided in online supplementary file 2. The protocol is registered with the PROSPERO international prospective register of systematic reviews (registration number CRD42016039650). The final review will be reported following the PRISMA statement.41–43 Important amendments to this protocol will be reported and published with the results of the review.

Supplementary Material

Supplementary data

Study selection criteria

Type of participants

Studies will be included if the full or part of the study population is older persons. The agreed United Nations cut-off age of 60 years will define the older population.1

Type of studies

This systematic review will include studies published in a peer-reviewed journal or doctoral thesis using a randomised control trial (RCT), non-randomised controlled trial (NRCT), controlled before-and-after (CBA) or uncontrolled before-and-after (BA) study design.

Type of outcome measure

The outcome of interest is social isolation or loneliness measured using appropriate instruments. Both validated (eg, Lubben Social Network Scale44 and Duke Social Support Index45 46 to measure social isolation and De Jong Gierveld Scale47 and UCLA Loneliness Scale48 to measure loneliness) and non-validated outcome instruments of social isolation or loneliness will be considered. To be included, studies must report a quantitative measure of the effect of the health promotion intervention on social isolation or loneliness.

Type of intervention

Studies will only be included if the health promotion intervention under analysis was designed specifically to alleviate or prevent social isolation or loneliness.

Search strategy

Electronic databases

The selection of electronic databases and the search strategy were developed in conjunction with an information specialist and were based on previous literature reviews’ search strategies.33 39 49 The following electronic databases were searched from 1995 until the end of 2015: Medline, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Applied Social Sciences Index and Abstracts, LILACS, OpenGrey and the Cochrane Library. No language or geography restrictions were applied to the search. The exact search terms used in all databases are described in  online supplementary file 1.

Supplementary Material

Supplementary data

Manual searches

The reference list of the studies included in this review, as well as those of previous literature reviews on health promotion interventions to reduce social isolation or loneliness, will be searched to identify additional potentially relevant studies.

Study selection

ENDNOTE X7, Thomson Reuters, will be used to manage the references. Duplicates will be removed by one reviewer (FL). Two reviewers (FL and PB) will then independently assess each abstract to determine whether full-text review is needed. Any disagreement between the two reviewers will be resolved by a third reviewer (JL). Full text of potentially eligible studies will be retrieved and reviewed and assessed for final inclusion by two reviewers (FL and PB) again with a third reviewer (JL) being consulted if necessary. Following PRISMA guidelines,41 a flow diagram will be created to illustrate the selection process.

Data extraction

Data extraction will be conducted independently by two authors (FL and PB) and disagreements will be solved as described above. Non-English references will be reviewed by two native or fluent speakers. The following information will be extracted using a data extraction form based on ‘The Cochrane Group Data collection form for intervention reviews’.50 Data extracted will cover the following points (see online supplementary file 3):

  • Study details: title, author, publication details, location, language (if not English);

  • Study design: type of study, duration, outcomes measured;

  • Participant demographics: setting, inclusion and exclusion criteria, population size and demographics;

  • Intervention characteristics: duration, type and mode of intervention;

  • Outcomes: measure of outcome used, any other outcomes analysed;

  • Results: raw data and effect size for social isolation or loneliness as main outcome as well as secondary outcomes;

  • Conclusions: author and reviewer conclusions.

Risk of bias (quality) assessment

Two reviewers (FL and PB) will perform a quality appraisal of each study independently using the Effective Public Health Practice Project ‘Quality assessment tool for quantitative studies’51 recommended by the Cochrane Public Health Group as it is applicable to both experimental and quasiexperimental study designs.52 Non-English references will be reviewed by two native or fluent speakers for the quality assessment.

Description of studies and measurements of effect size

We expect to find a diverse range of study designs and heterogeneous interventions aimed at social isolation or loneliness. Hence, data will be divided by type of outcome: impact of interventions on social isolation and impact of interventions on loneliness. Social isolation and loneliness are intricately related but distinct concepts which are frequently used interchangeably.4 Social isolation is defined as a scarcity of contacts or social encounters of adequate quality or quantity, and is regarded as an objective measure of social interaction,6 39 53 54 whereas loneliness is described as the subjective counterpart of social isolation, where an individual’s perceived level of interaction with others does not fulfil their expectations, often resulting in an unpleasant emotional experience.4 6 55 56 Given that these two concepts have been used interchangeably and inconsistently in the literature, we will consider both collectively for search purposes but separately in terms of analysis. Similarities and differences found in the literature will be compared and discussed.

We will further divide the studies by type of study design (eg, RCT, NRCT, CBA and BA) and subdivide them by type of intervention (eg, group, one to one and other designs). A narrative synthesis of all relevant studies will be provided by type outcome, divided in terms of study design and subdivided by type of intervention, describing study and participants’ characteristics, interventions, outcomes, results and author’s conclusions.

The effectiveness of the health promotion interventions on alleviation or prevention of social isolation or loneliness will be presented in terms of mean effect size (eg, standardised mean difference) and respective CI. The rationale for these summary statistics is the expected variation in the instruments used to assess the same outcome. The effect size will be calculated using Hedges’ (adjusted) g, as it provides a superior estimate of the standardised mean difference (SMD) in studies with small samples.57

The primary effect size for each study will be calculated from the first available postintervention measurement time point. If a study has more than one intervention, the primary effect size will be calculated for the main intervention group targeting social isolation or loneliness or the group with the most robust design (eg, the intervention which yields the largest difference from the control group).35 If a study has more than one control group, the primary effect size will be calculated using the group which theoretically is expected to generate the greatest difference from the intervention group.35 In cases where there are more than two groups, we will first conduct pairwise comparisons and also explore more complex analysis, if appropriate, as suggested by Cochrane.58

The authors of the studies included in this review will be contacted with the aim to retrieve any missing data necessary for our analysis. We will attempt to calculate any missing SMDs for continuous measures from the reported statistics (eg,  CI and SEs) in the relevant paper.

If sufficient data are available, subgroup analysis (ie, type of intervention) will be conducted to account for heterogeneity. If there are sufficient numbers of comparisons for the same outcome and intervention across studies, the between-study heterogeneity will be quantified by calculating the χ2 test for heterogeneity (significance level p<0.1) and the I2 statistic. We will report the sum of the studies using both a fixed-effect and random-effects meta-analysis by type of study design and intervention.


This systematic review will be performed to compare the effectiveness of health promotion interventions in alleviating social isolation or loneliness in older persons. By grouping interventions, we will be able to determine which type of intervention is more likely to be effective and we will also assess the role technology plays in promoting social contacts. We will use a validated tool to assess the quality of evidence since previous reviews refer they were limited by the weak methodology of studies analysed, and we will synthesise the data using appropriate statistical methods, if feasible. Furthermore, we will include studies conducted in the last 20 years without any languages or any geographic restrictions. Previous reviews were restricted to studies published in English language and up to 2013.

Our review aims to address an increasingly relevant problem in terms of the impact it has on older people’s health and on health and social care systems worldwide. This review will therefore provide policy makers with a better insight on how to tackle social isolation and loneliness by identifying the type of interventions that alleviate or prevent social isolation or loneliness and under which circumstances.


The publication of this article was funded by the Open Access fund of the Nuffield Department of Population Health, University of Oxford. We would also like to thank our information specialists Eli Harriss and Nia Roberts for their help in developing the search strategy and selecting databases.


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  • Contributors FL conceived the initial idea for the study and is the guarantor of the review. FL and PB wrote the protocol. ENM, AMG and JL critically appraised the protocol and also contributed to its development by revising different versions. All authors read and approved the final version of the manuscript.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.