Характеризация качества жизни и её полезность как показателя здоровья для людей с глубокими интеллектуальными и множественными нарушениями: обзор первичных исследований.

Introduction

Quality of Life

The World Health Organisation (World Health Organisation 2012 ) defines quality of life (QOL) as ‘an individual's perception of their position in life in the context of their culture and value systems in which they live and in relation to their goals, expectation, standards and concerns’. The World Health Organisation (WHO) recommended QOL measurement instrument is the WHOQOL, a 100‐question assessment, yielding scores across six domains of living. It is an inherently subjective evaluation of a person's physical, psychological, social, personal and environmental status, scored according to the self‐reported perceptions of the individual concerned. QOL and disability are social constructs, and as such are heavily influenced by culture, governing structures and ideologies, economies, health and social welfare systems (Das 2023 ). Whilst the WHOQOL has been rigorously tested across many cultures and languages, it does not address how it should be used/interpreted for people who cannot self‐report. Reliance on self‐reporting of QOL is problematic for people who have cognitive or communication impairments, giving rise to an emerging field of health research that aims to address QOL concepts for people who are unable to self‐report them.

Health research about QOL is generally divided into studies developing/validating a measure of QOL, or studies testing the effectiveness of an intervention aiming to improve QOL (Costa Daniel et al. 2021 ). In this context, definitions and understandings of QOL are extremely varied, from a single overarching concept to a multifaceted one, often driven by the choice of outcome measure where various aspects of well‐being are ‘scored’ (Costa Daniel et al. 2021 ). These types of measures require the person completing them to assign a numerical value to a series of particular characteristics or activities are known as rating scales. Generally, the rating (or score) indicates a higher or lower level of occurrence or expression for example, 1 = never 2 = sometimes, 3 = often 4 = routinely examples include the San Martin Scale (Verdugo et al. 2013 ) and the Spanish Personal Outcomes Score (Carbó‐Carreté et al. 2019 ).

Health‐related quality of life (HRQOL) is a more specific concept and is usually defined in terms of symptom burden/relief in relation to a specific disease or condition (e.g., Multiple Sclerosis Impact scale (Hobart 2001 )). As such, HRQOL is generally part of a wider assessment of overall QOL—both being relevant to evaluation of a person's perception of their wellbeing, recognising that a person's experiences are more than their disease or condition. As measures of effectiveness of health interventions, QOL rating scales are problematic as they inherently contain (or fail to account for) additional moderator variables (e.g., social, psychological and environmental determinants) that could influence the outcome (Kovach 2019 ).

Intellectual Disabilities and Health Inequality

People with intellectual disabilities experience poorer health outcomes, greater risk of dying from preventable causes and reduced access to safe, high‐quality healthcare than the general population, despite the introduction of legislation to promote equity (Ramsey et al. 2022 ).

People diagnosed with profound intellectual disabilities often experience additional physical disabilities, sensory or mental health difficulties, or behavioural challenges, referred to as ‘profound intellectual and multiple disabilities’ (Heslop et al. 2013 ; NHS England 2013 ). People with profound intellectual and multiple disabilities have greater health needs than the general population and those with less severe intellectual disabilities; common manifestations include epilepsy, respiratory, gastro‐intestinal, swallowing, and nutritional disorders, reduced bone density, and postural asymmetry (NHS England 2013 ; White et al. 2022 ).

Even with specialist individualised support, people with profound intellectual disabilities generally have an extremely impaired ability to understand, interpret, remember or express information. This means they often lack the mental capacity to make informed choices about their needs, or express whether or not these have been met to their satisfaction (Bellamy et al. 2010 ). Inevitably, these decisions are taken by others acting as proxies for example, families, carers, healthcare professionals. There is much discussion in the literature about the reliability of proxy reporting, with some studies demonstrating high levels of disagreement between represented persons and their proxies (Lyons et al. 2017 ). Legislation provides a framework for decisions to be made in the best interests of people who cannot do so for themselves, emphasising the need to consider the impact of a decision on the person's QOL (Guardian OotP 2005 ). However, defining and describing QOL for people with profound intellectual disabilities is still the subject of much debate.

In England, A key NHS recommendation for people with profound intellectual and multiple disabilities is that holistic care should include specialist physiotherapy to manage pain and distress, protect body shape, and promote of health and wellbeing (Mansell 2010 ; Doukas et al. 2017 ). Specialist Physiotherapists prescribe 24‐h postural care interventions and equipment that protect and maintain body shape, function and QOL (Bruce and Standley 2019 ). However, no guidance is provided about how to assess QOL, or how recommended postural care interventions should be evaluated in terms of effectiveness for promoting QOL.

Resources and Health Provision

The NHS has finite resources, with clinicians increasingly required to maximise health whilst minimising expenditure (Freudenberg 2021 ). Unsurprisingly, the most common reason for non‐provision of postural management equipment is lack of funding (Public Health England 2018 ), despite a legislative duty for free provision of specialist equipment by the NHS (Oliver 2006 ) and Local Authorities (Clements 2014 ). However, there is also legislative imperative to provide only the most cost‐effective option, and deciding what is cost effective in terms of QOL is difficult. Without sufficient research evidence or agreed QOL outcome criteria against which such provision can be measured, it is impossible to robustly demonstrate clinical and cost effectiveness. It is therefore inevitable that NHS and local authorities will use their ultimate discretion to prioritise lower‐cost interventions (Mandelstam 2016 ). Often, families and charities are compelled to make up the shortfall, or the person must endure without (NHS Improving Quality 2014 ). Thus, a dichotomy is created between the stated aims of NHS provision for people with profound intellectual and multiple disabilities, and what is actually provided.

Pragmatically, an agreed definition of what constitutes a positive health or QOL outcome for a person with profound intellectual disabilities is required before ways to demonstrate or predict such outcomes for specific interventions can be developed. Equally, definition and demonstration of outcomes is only useful if it works in practice to support such provision (Kovach 2019 ).

Aims

To identify and critically evaluate how QOL for adults with profound intellectual disabilities is characterised in the research literature.

To examine and describe methods used in contemporary research to measure QOL for adults with profound intellectual disabilities.

To explore how researchers use QOL measures to describe health and wellbeing outcomes for adults with profound intellectual disabilities.

To identify areas of strength and weakness in the research evidence, including areas of controversy and gaps in knowledge that may indicate the need for further research.

Method

This literature review was conducted following Arksey and O'Malley's framework (Arksey and O'Malley 2005 ), to identify and select relevant studies, chart, collate and report the results.

Identification and Eligibility of Sources

All types of primary quantitative, qualitative and mixed methods research were considered for inclusion in the review. Literature reviews, summaries, policy and opinion articles were not included since the full text of research included in these articles is not available for data extraction and critical evaluation. However, the reference lists of these articles were searched for further primary studies. 2010 was chosen as the earliest inclusion date to encompass research undertaken since (and immediately prior to) the publication of the CIPOLD report (2013) (Heslop et al. 2013 ), which provided accessible national data about the health and QOL inequalities experienced by people with profound intellectual disabilities for the first time.

Study Selection—Keywords and Search Terms

Research concerning QOL is often qualitative or part‐qualitative in nature, so keywords and their synonyms were identified using the SPIDER tool, as this captures qualitative literature more effectively than the PICO tool (Cooke et al. 2012 ; Methley et al. 2014 ). Medical subject headings (MESH) were searched in CINAHL and PUBMED databases to identify further synonyms and search phrases. Boolean operators and truncations were identified to create search strings. These were evaluated and refined using test searches. Key words and search terms are shown in Table 2 .

Searches were carried out iteratively, with the last search on 31/12/24 in the following databases: CINAHL, MEDLINE, APA PsycINFO, APA SocIndex, Education Source, PUBMED, Web of Science and Scopus. Hand searching through reference lists of returned articles was also undertaken.

Search Strategy

Searches were conducted iteratively combining search strings applied to ‘all fields’ or ‘all text’ depending on the database as shown in Table 3 .

A total of 2, 971 returned article titles and abstracts were screened for eligibility by the first author. Those which met the criteria (277) were screened for duplicates (110), which were then removed. The full texts of the remaining 167 articles were retrieved and assessed for eligibility against inclusion/exclusion criteria (Table 1 ).

Data Extraction and Critical Appraisal

All eligible articles were critically appraised using the Mixed Methods Appraisal Tool (MMAT) (Hong et al. 2018 ; Pace et al. 2012 ). and then their data systematically extracted into tables (Tables A1 and A2 ). A score was assigned to each study based on how well the MMAT quality criteria were met. Fully met criteria scored 2, partially met 1, and unmet 0. Scoring was used to indicate overall quality alongside narrative critical evaluation and is displayed alongside the extracted data. No articles were excluded on the basis of quality (Hong et al. 2018 ).

Data Coding and Analysis

The primary findings from each paper were coded (open coding) by SB according to their underlying concepts and synonyms, following the method established by (Coughlan and Cronin 2021 ) p115–116. Selected papers were read and coding samples were checked by HMC. Where quantitative scales were used, the actual numbers were rarely reported, so they were coded by researchers' interpretations. A total of 84 codes were assigned to concepts reflecting one aspect of QOL assessment for people with profound intellectual disabilities described in the studies. Themes were created by grouping codes with similar meanings and their associated texts then assigning headings to reflect the contents.

Labels were also assigned to each outcome tool/method of assessment to enable comparison between papers. Codes were then refined and arranged into themes (see Table A3 ) for overall analysis. Separately, codes were grouped by aligning them to each facet of the WHOQOL and arranged into the 6 corresponding domains (Table A4 ) for comparison and analysis. An Excel spreadsheet was used to generate charts and graphic representations of the data.

Results

A total of 2971 articles were screened for eligibility by title and abstract, with 167 articles meeting criteria for full text appraisal. 167 full text articles were retrieved and assessed for eligibility, with 31 articles being included in the review (see Figure 1 : PRISMA diagram). Articles were mostly excluded on the basis that they were secondary research or were not assessing QOL.

Study Design & Quality

18 studies were quantitative designs with observational and cross‐sectional study designs being the most prevalent. 8 studies were qualitative and 5 mixed methods, with semi‐structured interviews the dominant method of data collection. Overall quality of studies was moderate to good, with the lowest MMAT score being 5/10 (range 5–9). Strengths included appropriately sized, inclusive, representative samples in real‐life contexts. Limitations included insufficient justification for methods, inadequate explanation of confounding factors, and interpretations of findings that were only partially substantiated by the data.

Participant Characteristics

A total of 5716 participants were included in the review, of whom 3098 were adults with severe or profound intellectual disabilities aged 18–85 years (56% male, 45% female). A further 1312 people with an unclear age or level of intellectual disabilities were also included. The remaining 1306 participants were proxies, of whom 1018 (77.9%) were care staff, 237 (18.1%) family members, and 51 (3.9%) expert care professionals. Sample size ranged from 4 to 1770 participants.

People with intellectual disabilities participated exclusively in community settings. Studies conducted in academic or hospital settings were with expert professionals only. Participant characteristics by study are summarised in Table A1 .

Location

Two studies were conducted in Canada, with the remainder in Europe: Netherlands (Heslop et al. 2013 ), Spain (Carbó‐Carreté et al. 2019 ), Belgium (Carbó‐Carreté et al. 2019 ), Sweden (Costa Daniel et al. 2021 ), Italy (Das 2023 ), Denmark (World Health Organisation 2012 ), France (World Health Organisation 2012 ) and the UK (Costa Daniel et al. 2021 ). Studies completed within the same country tended to share one or more authors—meaning that there are few researchers working in this field. All included studies were conducted in ‘developed’ countries but varied considerably in terms of geopolitical, health, and social care structures and processes. It is accepted that these factors influence social constructs of disabilities, health, and QOL (Das 2023 ) meaning that direct comparison should be approached cautiously. Further, it reflects the dearth of research data in this field outside mainland Europe.

Theoretical Positionality

Most studies ( n = 22) collected quantitative data in the form of a ‘score’ or ‘rating’ defined by a specific tool, or observational data which was then coded/categorised and represented quantitatively. Some studies also collected qualitative data and then coded/categorised this in a quantitative way. Overall, a quantitative presentation of results was favoured in an attempt to represent a single reality of QOL for people with profound intellectual disabilities, consistent with post‐positivist ideology, despite 5 studies citing a pragmatist approach. Five studies employed interpretive phenomenology as their underpinning theoretical approach to explore the perceptions of: parents (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ); physicians (Nieuwenhuijse et al. 2020 ); professional caregivers (Nieuwenhuijse et al. 2022 ; Matérne and Holmefur 2022 ) and people with intellectual disabilities (Talman et al. 2019 ). One study (Talman et al. 2021 ) used descriptive phenomenology to explore the experiences of people with intellectual disabilities.

Ethics

All studies gained appropriate ethical approval according to local legislation and requirements. It is worth noting that practices described in some studies (such as parental consent for adult children) would not be permissible under UK law. There was acknowledgment that research activities could cause transient distress, particularly those observing responses to pain and unpleasant stimuli, and steps were taken to alleviate these where practicable (Enninga et al. 2023 ; Vos et al. 2013a , 2013b ).

Findings

The following themes and sub‐themes were found from the literature (Table 4 ).

Theme 1: How QOL Is Characterised

Descriptors and Indicators in Relation to WHOQOL Domains

Overall, authors gave greatest prominence to the ‘physical’ (21 studies), ‘psychological’ (20 studies) and ‘social’ (17 studies) domains of WHOQOL. The most mentioned descriptors of QOL were ‘emotional wellbeing’ and ‘physical wellbeing’ (15 and 14 citations respectively), followed by ‘social interactions and belonging’ and ‘environmental’ indicators (13 citations). 10 studies cited ‘independence’. Least reported indicators were ‘sexual fulfilment’ (1 citation) and ‘values’ (2 citations).

Figures 2 , 3 , 4 , 5 , 6 show the number of papers that cited each concept, and how these align with the first 5 domains of the WHOQOL. The 6th domain (spiritual, religion, personal beliefs) is not shown graphically, as only 1 descriptor ‘values’ was cited in 2 papers by the same authors (Bertelli et al. 2011 , 2019 ).

The physical capacity domain is dominated by the concept of physical health, with relatively infrequent mention of pain and comfort, and other indicators (Figure 2 ).

Emotional state was the most reported concept allied to the psychological domain of the WHOQOL (Figure 3 ). Other factors such as being understood, body image, and happiness were each cited by only one paper.

Participation in activities of daily living was the most reported feature of the independence domain, including activities such as washing, dressing, eating and drinking. Being able to engage in meaningful activities outside of the necessities of daily living was cited by only one paper (Figure 4 ).

The closely related concepts of social interaction and interpersonal relationships were reported as being highly influential on a person's QOL (Figure 5 ), The facets of trust, rights, power relations and sexual fulfilment were rarely cited.

Having the facility to undertake personal development and growth, and material wellbeing were the most frequently cited environmental factors. Affecting QOL (Figure 6 ).

Numerical and Narrative Expressions

Only 7 studies (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ; Nieuwenhuijse et al. 2020 , 2022 ; Matérne and Holmefur 2022 ; Talman et al. 2019 , 2021 ; Bradshaw et al. 2024 ) allowed participants the freedom to describe QOL and its possible meanings for people with profound intellectual disabilities, without requiring a level of agreement with a pre‐existing scale/measure. These studies described ‘good/better’ and ‘poor/worse’ QOL in terms of emotional, physical, psychological, environmental, and care quality.

Good QOL was described in terms of: happiness; pleasure; enjoyment; relaxation; social contact and relationships; being understood; safety; absence of pain and illness; absence of seizure activity; absence of difficulty eating or breathing (Nieuwenhuijse et al. 2020 , 2022 ; Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ). Additional indicators of good QOL were being: listened to; supported to express views; able to participate in daily life; involved in decision making; communicated with effectively; enabled to share power and responsibility (Talman et al. 2019 , 2021 ). One study (Matérne and Holmefur 2022 ) described QOL as being directly linked to quality of care, asserting QOL is determined by the knowledge, skills, and availability of staff to advocate for and enable participation through individually tailored support, adaptation and responsiveness. Bradshaw et al. (Bradshaw et al. 2024 ) describe factors associated with ‘better’ QOL, including consistency, opportunities for social contact, access to health and social services and meaningful activities.

Poor QOL was generally described as the absence of factors required to be present, or presence of those required to be absent for good QOL. Additional indicators of excessive sleeping, suffering, tense muscles, choking, and burden too great for family were also described as contributing to poor QOL (Nieuwenhuijse et al. 2020 ; Olsman et al. 2021 ). (Bradshaw et al. 2024 ). specifically mention deterioration in body shape (linked to poor posture) as negatively affecting QOL. Institutionalisation was identified as a significant contributor to poor QOL by 2 studies (Cameranesi et al. 2022 ; Navas et al. 2024 ). There were suggestions that a person could have a good QOL if there were sufficient positive factors to balance the negative ones (Nieuwenhuijse et al. 2020 ; Vos et al. 2010a ).

Use of Language

Some measures were developed or used in a language other than English for example The Personal Outcome Scale (Carbó‐Carreté et al. 2019 ; Tatsuta et al. 2025 ; Neveu et al. 2025 ), so interpretation is subject to the quality of translation in cultural context. Additionally, some measures easily yield a Likert scale response (always, often, sometimes, never) for example, San Martin Scale (Verdugo et al. 2013 ) The language in other scales is more nuanced and person‐centred requiring evaluation in relation to the needs and abilities of the specific individual for example, QOL‐PMD (Palisano 1997 ) .

Theme 2: How QOL for People With Profound Intellectual and Multiple Disabilities Is Assessed/Measured

Methods of Assessment of QOL

In all, 31 different methods were employed broadly grouped into rating scales, physiological measures and others, each with different areas of focus (Table 5 ). 14 studies used a single rating scale or tool to assess QOL; the remaining studies used different combinations of tools and methods (see Table A5 and Figure A6 ).

Rating Scales

None of the rating scales used in these studies encompassed all 6 domains/24 facets of the WHOQOL. Only 2 had a concept pertinent to the spiritual/religion/personal beliefs domain, and none contributed to the facts of work capacity, physical environment/climate or transport. The scales that covered most facets of the WHOQOL were the QOL‐PMD (Doukas et al. 2017 ) and San Martin Scale (Lyons et al. 2017 ). Table A7 shows how different aspects of the rating scales used in the studies align with the WHOQOL domains and facets.

The WHOQOL domains most included in the rating scales were ‘participation in and opportunities for recreation/leisure activities’ (8 scales), ‘personal relationships’ (8 scales), and ‘activities of daily living’ (7 scales), consistent with the components of QOL described as most important in the qualitative studies (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ; Nieuwenhuijse et al. 2020 , 2022 ; Matérne and Holmefur 2022 ; Talman et al. 2019 , 2021 ).

Physiological Measures

Even where studies utilised similar measures, there was disagreement about how these should be interpreted. Bossink et al. (Bossink et al. 2017 ) considered QOL as being separate from physiological measures, noting that oxygen saturation improved post intervention, whereas QOL score (and other physiological measures) did not. By contrast, Vos et al. (Vos et al. 2013a , 2013b , 2010a , 2010b ) sought to use physiological measures as indicators of emotional wellbeing and QOL by demonstrating congruence between physiological responses and emotional behaviours.

The use of automated devices such as accelerometers (Vos et al. 2013a ) (detects movement), pulse oximeters (Vos et al. 2013a , 2010a ; Bossink et al. 2017 ) (measures heart rate and blood oxygen saturation), and skin conductance sensors (Vos et al. 2010b ) (measures electrical changes in the skin caused by sweat gland activity) was reliable but not always well tolerated by participants.

Proxies & Tacit Knowledge

All studies used proxies to assess QOL, some alongside persons with profound intellectual and multiple disabilities, and others without including them at all, even in a passive or observational capacity. The types of proxies involved in the studies are summarised in Figure 7 .

Most studies employed carer or family proxies, either directly involved in the person's care or with whom they had a close relationship. Congruence between carer/family proxy scores was variable (Bossink et al. 2017 ; de Geus‐Neelen et al. 2019 ), with some areas having greater agreement than others. The areas eliciting most disagreement concerned subjective wellbeing domains, such as ‘discomfort’ and ‘sexual fulfilment’.

Tacit knowledge (intuitive, unarticulated understanding gained through lived experience) was widely considered key to communication, being understood and ‘heard’, making needs known and met (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ; Nieuwenhuijse et al. 2022 ; Matérne and Holmefur 2022 ; Talman et al. 2021 ; Bradshaw et al. 2024 ; de Geus‐Neelen et al. 2019 ).

Caring personal relationships between proxies and the person with intellectual disabilities were reported to be crucial to developing tacit knowledge, enabling subjective judgements to be made on their behalf (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ; Matérne and Holmefur 2022 ; de Geus‐Neelen et al. 2019 ). However, close relationships sometimes made it harder to be objective, with parents struggling to differentiate their QOL from that of their child(ren) (Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ), and the QOL of people with profound intellectual disabilities being significantly correlated with that of their family (Bertelli et al. 2011 ) .

Care staff knowledge, competence, availability and skill to provide good active support were identified as key to the wellbeing of people with profound intellectual and multiple disabilities (Matérne and Holmefur 2022 ; Bradshaw et al. 2024 ; Beadle‐Brown et al. 2016 ). Carers are pivotal in: establishing good communication; delivering individually tailored, high quality care; setting goals for individual support plans; advocating for service users and ensuring their needs of daily living are met (Matérne and Holmefur 2022 ; Herps et al. 2016 ). Staff awareness of power relations between themselves and service users, and sensitivity to managing these was identified as a key part of enabling inclusion and choice (Talman et al. 2021 ).

Carers who knew the person really well tended to give higher QOL scores than health professionals who saw the person infrequently (Carbó‐Carreté et al. 2019 ; Nieuwenhuijse, Willems, van Goudoever, and Olsman 2023 ; Bertelli et al. 2019 ). In studies where researchers were proxies, QOL was generally reported to be poor (Talman et al. 2021 ; Vos et al. 2010a ; Beadle‐Brown et al. 2016 ).

Theme 3: Utility to Demonstrate Health/Wellbeing Outcomes

Validity, Reliability and Responsiveness

Three psychometric evaluation studies were included, which rigorously assessed statistical validity and reliability of the Personal Outcomes Scale (Tatsuta et al. 2025 ), San Martin Scale (Verdugo et al. 2014 ) and the CPADULT (Zalmstra et al. 2023 ). However, sensitivity to change and minimum clinically important difference (the smallest change deemed to be clinically significant, MCID) were either not mentioned (Tatsuta et al. 2025 ; Verdugo et al. 2014 ) or only fleetingly discussed (Zalmstra et al. 2023 ). Where MCID was considered, this was calculated statistically (0.5 × Standard Deviation of mean score) and not in relation to meaningful change for the individual (Zalmstra et al. 2023 ).

Quality of Life Outcomes/Thresholds

No studies evaluated QOL in relation to postural care. Only 1 study mentioned deteriorating posture and body shape as a negative influence on QOL (Bradshaw et al. 2024 ). 5 studies used QOL as an outcome measure following other health‐related interventions, and their results were varied. (Bossink et al. 2017 ). found no significant change in overall QOL following a power assisted exercise intervention, despite improvements in some domains. By contrast, both Cameranesi et al. (Cameranesi et al. 2022 ) and (Navas et al. 2024 , 2025 ) found significant positive changes across all domains of QOL following community transition from institutional life. However, Cameranesi et al. found a general decline in QOL back to pre‐transition levels in their follow up study (Cameranesi et al. 2025 ), noting that trajectories of QOL for individuals were highly variable.

Six studies evaluated proxy scored QOL in relation to level of intellectual disabilities. Some found that QOL score was rated lower for people with more severe/profound intellectual disabilities (Carbó‐Carreté et al. 2019 ; Vos et al. 2010a ; Baumstarck et al. 2025 ; Beadle‐Brown et al. 2016 ; Herps et al. 2016 ), whilst (Bertelli et al. 2019 ) found that people with intellectual disabilities had higher QOL than those without. (Carbó‐Carreté et al. 2019 ). noted that proxies who knew the person well scored QOL more highly than those who knew them remotely. Older people with profound intellectual and multiple disabilities were reported to experience worse QOL than younger people (Herps et al. 2016 ). None of the studies set thresholds for ‘good’ or ‘poor’ QOL, so participants scores were assessed relative to each other as ‘better’ or ‘worse’.

Discussion

Characterisation of QOL

QOL is inherently experienced subjectively and thus is a difficult concept to construct from outside the perspective of the person experiencing it. There is no single accepted definition or description of QOL for people with profound intellectual disabilities—definitions of QOL adopted by studies tended to be driven by the choice of outcome measure rather than the measure chosen to reflect a particular definition. This may reflect the limited choice of suitable outcome measures available, with researchers compelled to use the ‘best available fit’—even if the ‘fit’ is poor.

There is consensus in the literature that QOL is multifaceted, and comprises elements related to physical, psychological, social, and material wellbeing. Emphasis is given to social inclusion and participation, daily living activities, and interpersonal relationships. The language used to describe these elements is varied, and there is disagreement about how descriptors should be used. This reflects the inter‐relatedness of different aspects of wellbeing and highlights the difficulty of attempting to insert discrete categories into a broad concept that permeates all aspects of living.

The preference in the literature for quantitative rather than descriptive characterisation of QOL inevitably means that the meaning of QOL to individuals with profound intellectual disabilities is rarely explored. Measures based on observations of the person and their behaviour in their environment(s) do not necessarily reflect how that person is experiencing them. Further, studies rarely justify which components of QOL are assessed/included in terms of what is relevant or meaningful; rather, they tend to include what is feasible to observe or measure. Whilst this is often framed as a pragmatic decision, and the difficulty of exploring meanings for people unable to self‐report is cited, numbers without context are problematic. Attempting to quantitatively express a naturally qualitative and abstract concept will always be challenging. When a person cannot self‐report their experiences, alternative approaches are required.

Assessment and Measurement of QOL

It is widely accepted in the literature that using proxies is necessary when assessing QOL for people with profound intellectual disabilities, and general agreement that people who know them well are best placed to do this. The nature of the relationship between the proxies and the participants seems important—proxies in the Bertell et al. (Bertelli et al. 2019 ) study appraised QOL of people with intellectual disabilities that they knew well, and people without intellectual disabilities with whom they were only acquainted—possibly leading to an under‐estimation of those not so well known.

Additionally, outcomes appear more reflective of what proxies felt comfortable to comment upon, or was most practicable to observe than which areas were most important to the participants, with the least mentioned descriptors being the most subjective.

It is clear that proxies are a potential confounding factor—seven studies have attempted to compensate for this by using more than one type of proxy (Baumstarck et al. 2025 ; Bossink et al. 2017 ; Beadle‐Brown et al. 2016 ; Verdugo et al. 2014 ; Dairo et al. 2017 ; Zalmstra et al. 2021 ). Since people with profound intellectual disabilities are unable to self‐report their QOL, and therefore cannot agree or challenge these findings, there is no basis for declaring any group of proxies in the literature as more or less accurate.

Proxy reporting by automated devices, may give the most objective data, but are not available in every setting and require training to set up, calibrate, operate and interpret, which all impact cost and time resources needed. Thus, these methods may lack feasibility in everyday practice. Further, physiological data are only helpful when interpreted in the context of environmental stimuli and tacit knowledge of the individuals concerned for example, a raised heart rate may reflect pain, excitement or distress depending on the context and meanings for that person.

Rating scales are the most commonly used measures of QOL for people with profound intellectual disabilities. Scales aiming to capture total QOL are too broad to be responsive enough to detect changes brought about by interventions that influence a single area. Similarly, scales that measure a single aspect of QOL (e.g., pain, activity), may be very responsive to that domain, but not reflective of total QOL. There is no consensus on how to effectively select, utilise or combine QOL tools to measure outcomes of health interventions for people with profound intellectual disabilities. There is also a lack of clarity about whether changes (or lack of change) in QOL scores should be interpreted as improvement, maintenance, slowed or accelerated deterioration.

Scoring systems tend to assume that either a particular score threshold is required to be ‘satisfactory’ or that a change between 2 consecutive scores is a positive outcome. The initial assumption is problematic, since there were no agreed definitions or thresholds for good, poor and meaningful changes to QOL for people with profound intellectual disabilities. In the latter case, the outcome can only be said to be ‘better’ or ‘worse’ than the initial measure, not ‘good’ or ‘poor’ in and of itself.

Most studies rated the QOL of people with profound intellectual disabilities as poor. Whilst the process(es) and reasoning for reaching these conclusions are unclear, it is consistent with the health and social inequalities experienced by people with intellectual disabilities and the lower value assigned to them by society. Poor QOL was associated with poor physical and mental health, but also acknowledgement that a person with profound intellectual disabilities may maintain a good QOL, even in the presence of significant illness or disability (Nieuwenhuijse et al. 2020 ; Vos et al. 2010a ).

Interpretation of the descriptors of QOL are subject to understanding of varied culturally and contextually derived uses of language making comparison a complex task. Even where the same words are used, meanings can be very different. As an example, take the term ‘material wellbeing’, which is used in SPOS, FQOL, San Martin Scale and QOL‐PMD measures. The San Martin Scale has 11 components relating to ‘material wellbeing’, which include aspects of physical safety of the person, environmental adaptations to meet their needs, personal space and belongings, technical aids and material goods (Verdugo et al. 2014 ; Gómez et al. 2015 ). The QOL‐PMD uses ‘material wellbeing’ to cover safety and accessibility of the environment and means of survival such as nutrition (Bossink et al. 2017 ; de Geus‐Neelen et al. 2019 ). SPOS and FQOL define it in terms of financial security (Carbó‐Carreté et al. 2019 ; Bertelli et al. 2011 ). Arguably, all are appropriate items to assess different aspects of material wellbeing, but it is possible to see that a person could be financially secure, but poorly nourished or well‐nourished but lacking physical safety. Thus, different scales rating ‘material wellbeing’ could give very different impressions of this aspect of QOL. Additionally, some terms such as ‘special attention’ and ‘optimal’ are highly subjective.

Use and Interpretation of QOL Measures

Bossink et al. (Bossink et al. 2017 ) interpreted a lack of change in QOL score to mean the intervention did not influence QOL; however, there are 2 alternative explanations—either the QOL instrument was not sensitive enough to detect change, or the intervention was instrumental in maintaining QOL. The community transition studies (Cameranesi et al. 2022 ; Navas et al. 2024 ) involved changes to the participants' whole way of living, so it is unsurprising that multiple areas of wellbeing would be affected. Dairo (Dairo et al. 2017 ) used a more specific tool to measure responses to their physical activity intervention (IPAQ). This was more sensitive to change, but less reflective of QOL as a whole. This serves to highlight the difficulties of using such a multifaceted concept as an outcome measure, due to the inherently high number of moderator variables.

MCID is based on the assumption that a measure or score should change in response to an intervention, and be unchanged without intervention, with the aim of intervention always being improvement (Kovach 2019 ; Abrams et al. 2006 ). In people who have progressive conditions and multi‐morbidity, this may not be realistic, with interventions directed more towards clinical stability and prevention or slowing of deterioration. In other words, if stability (i.e., no change in score) is the desired outcome (and therefore, clinically important), then there can be no minimum clinically important difference—a difference of 0, in this case, is a clinically important outcome.

These latter concepts are harder to demonstrate without comparison to data concerning the natural course/progression of the QOL of people with profound intellectual and multiple disabilities without interventions. Whilst developments such as the LeDeR project (annual report of causes of death in people with intellectual disabilities and/or autism) (NHS England 2023 ) have resulted in the availability of more mortality and morbidity data pertaining to profound intellectual disabilities, there is no way to know what health interventions those people received in relation to their QOL in the course of their lives. This is very different to more common conditions such as cancer, where symptom burden and health‐related quality of life is well documented across large populations, both with and without intervention (Nuffield Trust 2021 ).

Strengths and Limitations

The strengths of this review lie in the systematic approach to identifying, appraising and synthesising the data from current research literature, following an established process, the use of multiple databases and an internationally recognised QOL instrument as a basis for comparison.

One limitation is that a number of authors contributed to more than one research paper, meaning that the articles reviewed are attributable to a relatively small pool of researchers. This indicates the lack of contemporary research in this area, particularly in the UK where only 3 relevant studies have been published since 2010.

Conclusions

Establishing the effectiveness of postural care interventions to improve and maintain QOL is essential to providing evidence‐based care, achieving optimal outcomes and justifying expenditure on such provision for people with profound intellectual and multiple disabilities.

The emerging field of QOL research for people with profound intellectual disabilities is providing valuable insights into their experiences and interactions with their environments to support provision of high‐quality care. Acknowledging the breadth of the concept of QOL, researchers have been careful to include as many influencing factors as possible; however, this brings some limitations to their usage.

Current QOL scores cannot be interpreted to indicate a ‘good’, ‘acceptable’ or ‘poor’ QOL, instead providing a ‘snapshot’ assessment which must be repeated in order to establish if the situation is better, worse or the same as before. As a stand‐alone way of measuring QOL in relation to a health intervention, this is problematic for several reasons.

First, if the significance of change in score is calculated statistically, but is not related to any actual change (or lack thereof) in the person's experience, it lacks practical utility to determine meaningful improvement, stability or deterioration. Similarly, a person may perceive a large change in their QOL, but a rating scale may not be sensitive enough to reflect this.

Second, standardised ratings of QOL take no account of what type, rate and scale of change is meaningful or realistically achievable for the individual—whether the aim is improvement, stability, or slowed decline. Without this, interpretation of QOL scores is problematic.

Third, they cannot easily be used to show the benefits of a health intervention on QOL for people who by virtue of a progressive health condition or accelerated ageing process are anticipated to experience a decline in their wellbeing. The scores get worse with deterioration, but there is no way to show whether this deterioration has been slowed by the intervention.

Fourth, scores based on physical and mental health ignore the possibility that good QOL may still be achievable despite disability or poor physical and mental health.

There are currently no QOL measures that achieve the required balance between breadth of inclusion and specificity to enable responsiveness to change in relation to postural care interventions for people with profound intellectual disabilities. This represents a gap in the current knowledge base.

Recommendations

Evaluation of success in relation to postural care outcomes should include but not be restricted to mental and physical health outcomes, alongside QOL evaluation.

Where standardised QOL scores are used to evaluate health interventions, due consideration must be given to whether the tool is sensitive enough to reflect changes brought about by the intervention. If this is questionable, other ways of determining efficacy should be considered, which acknowledge the specific context for the individual with clear, realistic, person‐centred goals against which success can be benchmarked.

A new tool or system is needed that can assist families and carers to communicate meaningful information about the QOL of their family member/service user to those who hold decision‐making power. It is important that such tools are readily available, easy to use, unambiguous in their language and lead to shared understanding, as well as being flexible enough to reflect individual needs, values and goals.

Further research is required to explore the relationship between postural care and quality of life, and how this can be best demonstrated to support development of such tools and systems. These tools and systems can then be used to provide evidence for the clinical effectiveness of interventions and to support appropriate provision.

Funding

The authors have nothing to report.

Ethics Statement

Ethical approval for this research was obtained from the University of Chester research ethics committee—see enclosed letter dated 15th March 2024.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.

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Associated Data

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.