In this section, we depicted the knowledge maps to identify hot topics and research frontiers in LTC research in the context of COVID-19 pandemic on the analyses of cited references and co-occurring keywords. The analyses were conducted as follows.
3.3.1. Document Co-Citation Network
We conducted document co-citation analysis to define the underlying intellectual structures of LTC domain in the context of COVID-19 pandemic. In this process, co-citation clusters were also identified, which could reflect the evolution process of scientific activity in this field. The following parameters in CiteSpace were used: (1) time slice from 2020 to 2022; (2) years per slice = 1; (3) term source = title/abstract/author keywords/keywords plus; (4) node type = reference; (5) pruning = none; (6) select the filtering condition G-index, k= 25. After running CiteSpace, a co-citation cluster network which contained 391 nodes and 1594 links was visualized. Each node represented a document in the field of LTC research and was labeled with the author’s name and the publication year, whereas each link between nodes reflected the co-citation relationship between the two corresponding documents. To produce this graph, a total of nine co-citation clusters were identified using the LLR algorithm, each of which was a group of tightly coupled references representing a thematic concentration in the bibliographic landscapes.
Generally, a highly cited article means a landmark of the domain. We summarized the top 18 most-cited references listed in
Table 4, from No. 1 to No. 18, assigned to seven clusters. Moreover, two references with high betweenness centrality, as indicated by purple rings in
Figure 5, were presented as Nos. 3–4. Ten references (i.e., No. 1, No. 7, No. 11, and Nos. 19–26) with the strongest bursts in the group of references that started to burst at the same time can be adopted to disclose the LTC research trends in the context of COVID-19 pandemic. Furthermore, we investigated the top five references in each cluster by cited counts.
Table 5 lists detailed descriptions of 49 representative references.
The first largest cluster (#0) contained 70 references labeled as “essential family caregiver”. Essential family caregivers are typically family members or friends who were a steady presence at a loved one’s facility, providing companionship and help with daily activities such as eating, bathing, and grooming. The outbreak of COVID-19 in LTC facilities resulted in severe impact on nursing home residents and staff, posing great challenges to the care of older people [
25,
31,
45,
46]. Additionally, the shortage of medical resources and staff [
25] made essential family caregivers critical to improving the safety, health, and well-being of older people in nursing homes in the wake of COVID-19 [
45]. A better balance between physical safety and well-being could be achieved through more sensible visitor policies during the pandemic, as social isolation is a serious health threat for older residents and increases the risk of mortality [
44].
Cluster #1 contained 65 references and was labeled as “COVID-19 pandemic”. COVID-19 pandemic rapidly affected mortality worldwide [
50], and most of those who died were older adults, especially those with underlying health problems [
47,
50]. In order to shield the vulnerable elderly, worldwide countries enforced lockdowns, curfews, and social isolation to mitigate the spread of the pandemic [
24,
47,
49]. Social isolation among older adults might reduce transmission, but it can have an impact on the mental health of the elderly and become a serious public health problem [
49]. At the same time, this pandemic highlighted the long-standing structural deficiencies affecting the nursing homes, which was an opportunity to provide some considerations for nursing home leaders and regulators to support the health and well-being of nursing home staff and residents [
48].
The third largest cluster (#2) had 55 members and was labeled as “COVID-19 cases”. Most references in this cluster focused on the statistical information of COVID-19 cases or deaths through publicly available data and found that larger facility size, urban location, greater percentage of African American residents, non-chain status, and state [
21], higher registered nurse staffing and quality ratings [
15], reducing overcrowding in nursing homes [
51], higher nurse aide hours, and total nursing hours [
52] might help contain the number of cases and deaths. Additionally, studies showed that nursing home staff were working under complex and stressful circumstances during the COVID-19 pandemic. These challenges added significant burden to an already strained and vulnerable workforce and are likely to contribute to increased burnout, turnover, and staff shortages in the long term, leading to increased COVID-19 cases and deaths [
32].
There are other clusters worth mentioning. References in cluster #3 had a common concern for the transmission, testing, infection control of SARS-CoV-2 [
19,
20,
22,
29,
42]. The most active citer to cluster #4 [
23,
30,
41,
53,
54] was McMicheal [
23], who suggested that implementation of public health measures targeting vulnerable populations such as residents of LTC facilities and health care personnel, providing information for patients and families as well as communicating more broadly to all stakeholders will be critical to manage the pandemic. Five references in cluster #5 were mainly about the safety and efficacy of SARS-CoV-2 Vaccine [
38,
39,
43,
55,
56]. References in cluster #6 reflected a common theme—the mortality and characteristics of patients dying in relation to COVID-19 [
28,
34,
36,
37,
57]. The common topic of cluster #7 and cluster 8 was the risks of COVID-19 to nursing homes [
6,
58,
59,
60,
61,
62,
63,
64]. Meanwhile, post-acute care for COVID-19 attracted much attention [
12].
Obviously, the COVID-19 epidemic had an impact on the cognition of the importance of LTC for the elderly and attracted more attention. In comparison with previous studies, we found that dementia care in nursing homes, quality of care, disease prevention and control, healthcare providers, and LTC facilities and residents were still the emphases of LTC research during the pandemic. However, studies before COVID-19 pandemic mainly concentrated on health status, mortality, database application, providing and paying for LTC, and frailty in elderly people [
5]. What made LTC research in the pandemic different was that the research paid more attention to the impact of the pandemic on LTC facilities and residents, including the effects on physical health, mental health, and human rights of older adults, how LTC facilities cope with COVID-19 epidemic and infection prevention and control strategies. In general, the focus shifted from the mental and physical health status of older adults in need of LTC to the impact of the pandemic on those of older adults in LTC facilities, from the prevention of general epidemics to the prevention and response of significant public health emergencies, from providing and paying for LTC to improving management and developing strategies for LTC facilities to improve the quality of LTC and well-being of their residents in the context of the pandemic.
In order to obtain an impression of evolution of research fronts in this research, we further focused on 11 burst references (i.e., Nos. 4–5, Nos. 8–9, No. 15, No. 17, No. 19, No. 27, and Nos. 35–38) in
Table 5. An article with citation burst means it received an increased attention in a certain period of time.
Figure 6 shows a timeline view of 11 burst references with their respective research foci. The LTC research trends at different times were revealed as three stages: in the early stage from January 2020 to December 2020, research focused on COVID-19 infection prevention and control strategies in LTC facilities; in the second stage from January 2021 to May 2021, focus shifted to COVID-19 cases and deaths in LTC facilities; in the third stage from June 2021 to December 2022, research of the COVID-19 virus, vaccine, and nursing homes received increased attention. In short, with the outbreak of COVID-19, research on LTC became more in-depth and diversified, mainly reflected in the significant increase in the proportion of database-based empirical research and survey research.
3.3.2. Keyword Co-Occurrence Network
An analysis of keywords can help us identify hot topics of LTC research in the context of COVID-19 pandemic.
Figure 7 shows the co-occurring keywords network produced by CiteSpace. The parameters in CiteSpace remained the same except the node type being changed from “reference” to “keyword”. The network contains 275 nodes and 1270 links in total from 2020 to 2022. In the figure, node size represents the frequency of the keyword in the record, and lines that connect nodes are co-occurred links. Furthermore, we merged the similar keywords that are in fact variants of the same entity, for example, “nursing hm” was merged into “nursing home”, “long term care” was merged into “long-term care”.
In particular, high-frequency keywords can reflect the research heat and keywords with high centrality represent major intellectual turning points and connecting more other keywords. Therefore, we identified 26 representative keywords in terms of the counts and betweenness centralities in
Table 6. The top 25 keywords from No. 1 to No. 25 had a co-occurrence frequency over 25. Additionally, one keyword No. 26 had high centrality.
The top two on the list in terms of co-occurrence frequency were “long-term care” (299) and “nursing home” (230). The outbreak of COVID-19 in nursing homes resulted in a high mortality rate and had a significant impact on the daily management of nursing homes, making it a hot topic for LTC research in the pandemic. Keywords with high centrality were observed in “nursing home residents”, which represented major intellectual turning points linking different keywords with significantly influenced LTC research development.
As for these 26 high-frequency keywords, according to previous scientometric studies, they can be directly regarded as LTC research hotspots. To focus on the major issues, we identified the hot research topics by integrating 26 high-frequency keywords and considering the co-occurring keywords shown in
Figure 7. The resulting four main hot spots were as follows:
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Nursing homes and residents was extracted using keywords “nursing home”, “long-term care”, “long-term care facility”, “resident”, “impact”, “facility”, “United States”, and “nursing home residents”. At the first outbreak of COVID-19, nursing homes became the hotbed for it [
6]. According to the data, more than one-third of COVID-19 death happened at nursing homes in the United States, even in some states, the proportion is more than one-half [
54]. Viral infection and COVID-19 disease are prevalent among nursing home residents [
29], due to their congregant living environments, greater likelihood of being exposed to asymptomatic and pre-symptomatic care providers, and difficulty in effectively implementing infection prevention and control practices [
22]. This pandemic had put both nursing homes and residents at acute risk highlighting the limited resources many facilities had in dealing with crises of this magnitude [
29].
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Older people in need of LTC in the pandemic was identified using nine keywords “long-term care”, “older adult”, “COVID-19”, “care”, “health”, “infection”, “risk”, “older people”, “mortality”, “dementia”, and “mental health”. Older people were the group of most susceptible to COVID-19, adding further difficulties to their LTC [
25,
45,
46]. This was mainly due to the higher incidence of immune dysfunction, chronic diseases, and disabilities in the elderly, which could develop a more severe form of the disease, and further lead to increasing mortality [
22,
25]. Furthermore, as for the individuals with Alzheimer’s disease and related dementia, the pandemic disrupted not only the basic routines, but also the LTC that promote their physical and mental health [
12]. However, it is particularly distressing that few care to frail and needy older people could be offered [
46]. Awareness of clinical differences of COVID-19 in this population, quickly initiating appropriate behaviors to care for the infected, and preventive interventions would help better LTC for the elderly in this crisis [
25].
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Infection prevention and control strategies was extracted using the keywords “COVID-19”, “infection”, “outbreak”, “prevalence”, and “public health”. There was a consensus that all patients involved in LTC should take proactive steps to prevent the epidemic [
20,
22]. To begin with, for residents of LTC facilities, frequent hand washing, universal use of face masks, and reducing contact were effective ways to control the spread of the epidemic [
22,
58,
59]. For all facilities providing LTC, strategies include restricting nonessential personnel from entering the facility [
20,
22]; additional prevention measures for asymptomatic or pre-symptomatic [
30,
54]; increasing in payments to direct caregivers [
29]; and continuous communication with residents and family members [
12,
45]. Government departments and national health departments might need to enhance the infection control capacity [
12], invest in public health infrastructure [
29], improve international surveillance, cooperation, coordination, and communication, as well as be better prepared to respond to future new public health threats [
33].
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Social isolation and loneliness comprised eight representative keywords “COVID-19”, “infection”, “risk”, “quality”, “social isolation”, “loneliness”, “mental health”, and “home”. Social isolation and loneliness caused by quarantine policies adopted to prevent the spread of the epidemic take a serious toll on the physical and mental health of older people in need of LTC [
34,
49]. Personal interactions were meaningful activities and are crucial to improve the quality of LTC [
30]. Many older people in need of LTC were socially isolated and lonely, depending on frequent visits from family and friends to socialize with them [
34]. However, quarantine policies during the pandemic prevented these visits, making older people feel increasingly lonely, abandoned, and despondent [
34]. At the same time, it could also cause anxiety and emotional trauma to families and others who could not visit their loved ones [
29]. Therefore, it is important to recognize the role that family members play as partners in LTC of the elderly and develop visitor policies in LTC facilities during the pandemic [
30].
On the whole, the change of research hotspots identified by keywords after the outbreak of the pandemic is similar to the trend shown by cited references. According to previous study [
5], the hot topics of LTC research mainly included dementia, quality of care, prevalence, and risk factors and mortality. While, after the outbreak of the pandemic, the hot topics of the research became the impact of the pandemic on LTC including the crisis of limited resources in nursing homes, the harm to the physical and mental health of the elderly, the increasing need for LTC among the elderly, the lack of effective infection prevention and control strategies, as well as the loneliness caused by policy of social isolation. In general, the pandemic made scholars more focused on the health services and right to survival and development of the elderly. Improving LTC in the context of the pandemic will help improve the health of older people and contribute to the prevention and treatment of COVID-19 in the elderly.