Introduction
Loneliness is an unpleasant subjective experience that results from a perceived discrepancy between one’s desired and actual levels of satisfying social relationships [
1] and serves as a signal of unmet human need [
2], evoking craving responses for social interactions similar to those for hunger [
3]. While loneliness is a common experience, prolonged and problematic levels of loneliness are not equally distributed in the population [
4]. A recent conceptual model of loneliness by Lim and colleagues [
5] proposes that loneliness occurs when a trigger, such as a significant life event or life stage transition, interacts with various underlying risk factors including socio-demographic factors (e.g., age, gender, marital status, migration status, living status, socio-economic status), personal health (e.g., physical, mental, cognitive), and socio-environmental factors (e.g., workplace, digital communication). Experiencing loneliness can be distressing and cause considerable suffering [
6], however increasing evidence indicates that being lonely is also associated with poor health outcomes including increased mortality, increased risk of cardiovascular disease and metabolic syndrome, and poorer mental and emotional health [
7‐
10]. The significant health issues associated with loneliness, together with the social factors that underpin it, mean that addressing loneliness requires a public health approach to understand the distribution of loneliness in the population and its impact on population health [
4,
5,
8,
9,
11,
12].
One population group that experiences many of the risk factors for loneliness is people with disability. Many of these risk factors are structural in nature. For example, people with disability are more likely than people without disability to have lower education, lower income, be unemployed or underemployed, and live in vulnerable housing or within care homes or institutions, which lead to barriers to participation in various life domains [
13‐
15]. People with disability also experience poorer health outcomes than people without disability [
13,
15,
16], increasing their risk of loneliness. Furthermore, people with disability have less social support and are more socially isolated than people without disability [
17,
18], which reduces their access to potential solutions that may attenuate loneliness, including relationships and community support [
5]. It is therefore not surprising that people with disability are more likely to experience loneliness than people without disability [
17,
19‐
23].
Although we know that people with disability experience inequalities in loneliness relative to people without disability, we do not know if the magnitude of inequality has changed over time. This evidence gap can be closed by tracking disability-related inequalities in loneliness over the last two decades using longitudinal population survey data. This knowledge is important given that loneliness is associated with poorer health outcomes [
7‐
10]. Since people with disability have considerable health inequalities relative to people without disability [
15,
16], and both loneliness and health inequalities are at least in part driven by the social determinants of health (e.g., employment, education) [
5,
15], a clear understanding of the extent of inequalities in loneliness experienced by people with disability relative to people without disability is needed, as well as how the inequalities have changed in recent years. This evidence may lead to the development of policy solutions to address this issue and reduce the impact that inequalities in loneliness may have on the health inequalities experienced by people with disability relative to people without disability.
Disability is a complex biopsychosocial phenomenon resulting from dynamic interaction between biological, personal, and environmental factors, which together affect accessibility and participation within society [
24]. The diverse nature of disability means that while it is important to examine changes in loneliness prevalence for people with disability compared to people without disability, it is also necessary to consider changes in loneliness prevalence for subgroups of people with disability. For instance, stratifying analyses by factors such as age, sex, and disability group (based on type of impairment, i.e., sensory or speech, physical, intellectual or learning, psychological, brain injury or stroke, other), allows examination of inequalities in loneliness in subgroups of the population of people with disability.
Therefore, this study investigated the prevalence of loneliness for people with disability in Australia and examined whether inequalities in loneliness for people with disability have changed over time. We used data from the longitudinal Household, Income and Labour Dynamics in Australia (HILDA) Survey to examine population-level changes in annual prevalence of loneliness for people with and without disability between 2003 and 2020 and further stratified the analysis by age, sex, and disability group.
Discussion
This study found that for every year during the 18-year period from 2003 to 2020, the prevalence of loneliness was greater for people with disability, such that people with disability were 1.5 to 1.9 times more likely to experience loneliness than people without disability. These substantial and persistent inequalities in loneliness occurred regardless of sex, age or disability group. These sustained inequalities are of particular concern given that, although the prevalence of loneliness decreased for people without disability between 2003 and 2020, the prevalence of loneliness did not decrease for people with disability during this same period. Furthermore, inequalities in loneliness were more substantial for people with intellectual or learning disabilities, psychological disability, and brain injury or stroke, indicating that people in certain disability groups were more likely to experience loneliness.
Our findings that people with disability have increased risk of loneliness reinforce those from previous reports [
17,
19‐
23] and adds to the existing evidence by demonstrating that inequalities in loneliness have persisted for decades without improvement. Loneliness is known to be associated with poorer physical and mental health outcomes [
7‐
10] and is considered to be a public health concern in the general population [
4,
5,
8,
9,
11,
12]; given this, the consistently higher levels of loneliness observed for people with disability may contribute to the considerable health inequalities experienced by this population [
13,
15,
16]. In contrast, for people without disability loneliness prevalence decreased over the 18 years, mostly occurring between 2003 and 2009; yet there was no downward trend for people with disability over the same period. This difference in trends suggests potential differences in the drivers of loneliness, and their trends over time, between people with and without disability, which we did not examine in this study and requires further investigation.
We observed that the prevalence of loneliness and disability-related inequalities in loneliness were similar for males and females. We did however observe age differences in the prevalence of loneliness, such that younger people were more likely to experience loneliness than older people, particularly in the most recent survey years, with a possible increasing trend in prevalence developing for younger people (15–24 years) and a decreasing trend for older people (65+ years). This contrasts with the findings summarised in a recent meta-analysis of 57 studies between 2000 and 2019 suggesting that the prevalence of loneliness was higher in older adults than in young and middle aged adults; however, the authors of that meta-analysis also noted that the prevalence of loneliness varied considerably across countries and that the age pattern of loneliness may be context specific [
4]. To our knowledge, ours is the first study to have assessed the prevalence of loneliness across a sample with a broad age range, for people with and without disability, and across an extended period of years. Importantly, our findings demonstrate that people with disability have considerable inequalities in loneliness compared to those without disability, and that this inequality decreases in older age groups (75+ years). This suggests that there may be a difference in the drivers of loneliness for people with disability after age 75, given that many will have developed disability as they aged alongside their peers.
To account for the diverse nature of disability, we undertook sub-analyses to examine how inequalities in loneliness vary by disability grouping. We observed that the substantial inequalities in loneliness for all six disability groups were sustained over the 18 survey years, however the relative inequalities were more pronounced for people with intellectual or learning disabilities, psychological disability, and brain injury or stroke, who were 2.6 to 2.8 times more likely to experience loneliness than people without disability. Furthermore, the relative inequalities appeared to increase by about 75% between 2003 and 2020 for people with intellectual or learning disabilities, however there was a slight overlap in confidence intervals because of the relatively low sample size in this group. Given that the present study is the first to assess loneliness across a range of disability groups over an extended period, the reason for greater inequalities within certain disability groupings is not clear. People with intellectual or learning disabilities, psychological disability, and brain injury or stroke experience higher levels of socio-economic disadvantage than people in other disability groups [
14], which may explain their higher levels of loneliness given socio-economic disadvantage is a risk factor for loneliness [
5].
This study has several strengths. First, we used a large, nationally representative sample of the Australian population over an 18-year period. The sample population had age distributions for people with and without disability that were mostly consistent with those observed for people with and without disability aged 15+ years in Australia’s national survey of disability, the SDAC [
41]. Second, we employed direct age-standardisation using a reference population of people with disability, allowing us to address differences in age distribution between people with and without disability while ensuring that the prevalence of loneliness estimates reported reflect the reality for people with disability [
37,
38]. Finally, the structure of the HILDA Survey disability question allowed us to compare the effects of loneliness on different disability groupings rather than only on the presence or absence of disability.
There were also limitations. First, the HILDA Survey focusses on people living within the community, thus people with severe disability who are more likely to reside in care homes and institutions are underrepresented in the sample. Second, selection bias may have occurred due to missing data, however multiple imputation was used to decrease potential bias. Third, statistical power was limited for some of the disability groupings that had small sample sizes (e.g., intellectual or learning disability and brain injury or stroke) and this may have obscured some of the trends due to large confidence intervals. Fourth, reporting bias in the measure of disability may have occurred given that disability information was self-reported. Reporting bias may also have occurred with the direct measure of loneliness used in the HILDA Survey given that the potential stigma of admitting to being lonely can alter estimates of the prevalence of loneliness when compared to indirect multi-question measures of loneliness that do not use the term ‘lonely’ [
42,
43]. Nevertheless, the direct measure of loneliness used in this study has the advantage of solely assessing the subjective emotional experience of loneliness without being confounded by concepts associated with social isolation, support or trust that may be included in indirect multi-question measures. Fifth, we were unable to examine disability severity as a determinant of loneliness since the HILDA Survey only collects information on severity of disability and impact on daily activities every four waves. Sixth, the HILDA Survey is a panel survey, thus the outcome measure may be conditional on an individual’s experience in previous years; however, it is common for people to transition into and out of loneliness over the lifespan [
44], thus while a person may experience loneliness in one wave, they may not be experiencing loneliness in the following wave. Seventh, while intellectual disability and learning disability are different types of disability, we were unable to distinguish between them in this study because the question prompt used in the HILDA Survey was “difficulty learning or understanding things”. Finally, the last wave of data (2020) was collected between 3 August 2020 and 21 February 2021, predominantly by telephone due to government-mandated social distancing requirements because of COVID-19; thus, the 2020 estimates of loneliness may have been impacted by COVID-19. However, for most subgroups, the prevalence of loneliness observed in the 2020 wave was consistent with the trends observed in the previous waves for those subgroups.
Conclusions
Our findings indicate that addressing inequalities in loneliness for people with disability is a critical public health concern given that loneliness is not only a distressing experience that can cause considerable suffering [
6], but is associated with a wide range of poor physical and mental health outcomes [
7‐
10]. Loneliness is a multi-factorial societal problem thus interventions need to be disability inclusive and specifically address the loneliness experienced by people with disability. While population-level reductions in loneliness have been observed following whole-of-community interventions that build social connection [
45] and the use of green spaces and contact with nature [
46], solutions to reduce loneliness inequalities for people with disability need to directly address the disabling barriers that prevent people with disability from participating equally in society [e.g., 19] and their decreased social connectedness [
18]. There is an urgent need to understand the drivers of loneliness for people with disability, including socio-economic and geographic factors and how these may change during the life course, to develop tailored interventions to address the inequalities in loneliness for people with disability reported in this paper. The next phases in this program of research will seek to: (i) gain a better understanding of the drivers of loneliness in people with disability, including those that cause loneliness to persist; (ii) examine how the experience of loneliness affects health outcomes for people with disability; and (iii) co-design policy interventions to create more equitable and welcoming communities to ameliorate the loneliness currently experienced by people with disability.
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