While there has been an increase in the number of studies that have explored the impact of loneliness and social isolation on HSU, findings to date have been inconsistent [12, 30]. Our study extends the existing evidence base by examining the relationship between HSU and loneliness as well as social isolation in the older adult population in Australia. To the best of our knowledge, this is the first study to investigate this association using a large longitudinal dataset in Australia. We hypothesized that older adults who experience loneliness and/or social isolation use more healthcare services compared to those who are neither lonely nor socially isolated. Our results partially support this hypothesis, although the findings varied across different types of healthcare services.
With regard to GP visits, among older adults who visited the GP, those who reported being lonely, socially isolated, or both lonely and socially isolated had higher frequencies of GP visits than those who were not lonely nor socially isolated. These findings are consistent with previous research demonstrating a positive association between loneliness and GP visits [13–15, 31–33]. Similarly, a study conducted in Europe found that socially isolated older adults had a higher frequency of GP visits, which is consistent with our findings [34]. These findings thus support the idea that loneliness and social isolation are important predictors of GP visits among older adults.
Many studies have supported the prevalence of a special doctor-patient relationship among older adults who are lonely and/or socially isolated [14–16]. Although the relationship is usually initiated due to formal health conditions, the nature of the relationship could then change to seeking a GP for social support or as a confidant rather than solely for medical treatment [15]. For lonely individuals, visiting a GP may be one of the few ways of connecting with another person, especially someone who is trusted to help [35]. Similarly, socially isolated older adults may also access medical doctors to fulfil a social role [14, 36]. Given that GPs are often the first point of contact for older adults, they play a crucial role in identifying loneliness and social isolation in their older patients. However, evidence suggests that GPs’ ability to identify patients who are lonely is limited [37]. To address this, GPs should be trained in screening patients for risk of loneliness and social isolation and refer them to appropriate services, which could involve linking them to community groups and activities, and voluntary services [38, 39], or more specific support groups and services, depending on the intensity of their social experience and context.
When examining the use of mental health services, we found that loneliness was associated with increased utilisation of mental health services, even after controlling for mental health conditions. However, it is important to note that our findings were limited by a small sample size of individuals reporting mental health service utilisation, as well as limited information about the types of mental health conditions reported. These findings are consistent with a recent study that demonstrated a strong association between loneliness and increased mental healthcare expenditure when using a fully adjusted model [40]. In our study, we found no significant association between social isolation and utilization of mental health services. This aligns with previous research which indicated that loneliness, has a stronger influence on mental health outcomes while social isolation is more strongly associated to physical health implications [41]. Furthermore, previous literature has explored how loneliness can worsen overall mental health in individuals with mental health conditions such as psychotic disorders, leading to increased healthcare service utilisation [42]. This implies that reducing loneliness may have the potential to reduce mental healthcare and associated healthcare costs [43]. Although our study highlights a connection between loneliness and increased use of mental health services, further research examining this relationship while adjusting for a wider range of mental health conditions is warranted.
Other specific health professional visits that we were able to explore included visits to the dentist, showing that older adults experiencing loneliness and social isolation in our study had lower use of dental health services. This finding is consistent with a previous study that used a loneliness index to measure perceived social isolation and also reported a lower likelihood of seeking dental care [44]. However, it is important to note that our study did not control for any dental health conditions due to the unavailability of data, which may have influenced our findings. Further research is needed to better understand the relationship between loneliness, social isolation, and dental care utilisation among older adults, including exploring potential barriers and facilitators to accessing dental services among this population.
Finally, with regard to hospital admissions, our findings suggest that loneliness is associated with an increase in hospital admissions, which is consistent with a study conducted in China by Zhang et al. (2018) that found higher rates of physician visits and annual hospitalisations among older adults [14]. However, this study relied on a simple binary outcome variable with no information on the number of hospitalisations, and previous longitudinal studies examining the general frequency of hospitalisation did not report such an association [15, 45]. Other studies have found that while loneliness may not be related to overall hospital admissions, it does increase the risk of being re-hospitalised once admitted [33], and is associated with unplanned emergency hospitalisations [18]. However, we were unable to determine whether the hospital visits in our sample were emergency or planned hospitalisations. Further research is needed to explore the relationship between loneliness and hospital admissions, including the types of hospitalisations and potential confounding factors that may affect this association.
According to the results of our study, despite frequent visits to GPs and mental health professionals, lonely individuals in our sample exhibited a higher rate of hospitalization. One possible explanation is that healthcare providers may prioritize the psycho-social well-being of lonely individuals, potentially overlooking their physical health needs [46]. This emphasis on mental health aspects could result in the neglect of certain physical health aspects, contributing to the increased hospitalization rates observed, leading to hospitalisation.
Older adults who reported being socially isolated also reported higher rates of hospitalisation. Although these results were not statistically significant in our study, previous studies found an association between social isolation and increased rates of hospitalisation in older adults [47, 48]. A qualitative study also repeatedly identified social isolation as an important contributing factor in frequent hospital admissions [36]. This was mainly explained through factors such feeling safe, seeking a support system, discussing fears and anxiety, adhering to health behaviours and being able to access health information and services.
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When looking at individuals who experienced both loneliness and social isolation, our study showed that these individuals had a higher rate of GP visits and hospitalisation compared to those who reported being lonely or socially isolated. Despite the small sample size in this group of individuals and the caution around interpreting these findings, a previous study has demonstrated the synergistic interaction of loneliness and social isolation on overall health [49]. This may explain the negative impact of experiencing both loneliness and social isolation on HSU. Future studies should include both loneliness and social isolation to further understand this combined effect. Given the lack of consistency in how loneliness and social isolation are defined and measured across studies, there is a need for standardized tools to measure these constructs separately [50].
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Strengths and limitations:
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Our study has several strengths. It is the first longitudinal analysis in Australia to investigate the association between loneliness and social isolation using a population-representative sample. By using repeated measures, we were able to thoroughly examine this association, providing further support for the findings of previous cross-sectional studies in this area [24]. Moreover, we separately examined loneliness and social isolation as two separate groups, as well as their combined impact, which adds to the existing literature on this topic.
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While this study provides valuable insights into the association between loneliness, social isolation, and healthcare utilisation, there are some limitations that should be considered. First, the self-reported nature of HSU data could potentially introduce recall bias, as individuals may not accurately remember the number of times they visited their GP or were hospitalised, thus underestimating the actual use of health services. Second, health conditions were also self-reported, no diagnostic tools were used in the survey. Thirdly, it may also be possible that other health indicators, not included in HILDA, may explain the association between loneliness and social isolation with HSU. Fourth, previous studies have reported a positive association between loneliness and emergency department visits, which our study was unable to capture due to the lack of information on emergency department visits in the HILDA [18, 51]. Fifth, the HILDA survey only includes community-dwelling individuals and does not include older adults living in institutional care, limiting the generalizability of our findings to this population. Lastly, the sample size of lonely and/or socially isolated older adults may have been limited by the fact that the SCQ was a mail-out survey, potentially leading to lower participation rates among this group compared to the overall sample. This may have resulted in reduced statistical power to detect significant differences between groups, thus limiting the generalizability of the findings.
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Conclusions: Given the limited evidence available on the impact of social relationships on HSU [23], our study provides valuable insights into the added burden of loneliness and social isolation on the HSU, as reflected in increased GP visits and hospitalisation. As the global population continues to age, there is an urgent need for further research to inform the development of effective programs and support services aimed at reducing loneliness and social isolation among older adults. Such interventions have the potential to not only improve the well-being of older adults, but also reduce the use of health care services and ultimately generate substantial healthcare cost savings.