Background
In Europe, the number of people in need of long-term care (LTC) will increase dramatically by 2060 [
1]. This trend is caused by the demographic change, which leads to an aging population and is expected to increase the prevalence of disability and chronic conditions [
2].
To prepare the health care system for this urgent public health problem, it is important to understand the reasons for utilization and transitions of LTC over time. LTC can be defined as assistance with daily activities for people who are not fully capable of self-care on a long-term basis [
3]. Daily activities consist of activities of daily living (ADL), such as bathing or grooming, and instrumental activities of daily living (IADL), such as shopping or doing housework [
4]. LTC can be informal or formal. Informal LTC is defined as assistance from family members, friends or neighbors, whereas formal LTC encompasses institutional and home-based LTC provided by a skilled nurse or institution, as well as paid services for household support [
3].
In 2015, about 2.86 million people in Germany were in need of LTC. Of those, 72.6% received home-based LTC, whereas 27.4% received institutional LTC [
5]. To provide support for LTC services, Germany’s statutory nursing care insurance was introduced in 1995. People who apply for support are evaluated based on the amount of assistance they need for ADLs and IADLs. This is determined by a needs assessment, conducted by the statutory Health Insurance Medical Service (MDK) [
6,
7]. Based on the minimum time of assistance needed in minutes per day, one of the three care levels (I, II, III) is assigned to the person applying for support, according to legal guidelines from 2012 to 2016 [
8]. Further information on Germany’s nursing care insurance can be found in Additional file
1.
To detect determinants for the utilization of health care services, such as those received from physicians or hospitals, Andersen’s Behavioral Model of Health Services Use (ABMHS) [
9] has often been employed. ABMHS is also applicable for identifying determinants for the utilization of LTC [
10]. The model distinguishes predisposing, enabling and need factors. Predisposing factors represent demographic and social characteristics of individuals, such as age or education. Enabling factors consist of factors such as income or living arrangement and can either support or impede utilization of LTC. For example, living with a family member, a potential informal caregiver, can lead to the utilization of informal LTC. Need factors are defined as people’s physical and psychological health and functional status. If they deteriorate, they can support utilization of LTC [
9,
10]. To date, research has shown that older people’s utilization of LTC is associated with different factors, such as higher age [
11‐
14], female sex [
11,
14,
15] and impairments in daily activities due to chronic conditions [
11] or disability [
12‐
14,
16,
17]. Further differences could be found in the utilization of types of LTC. Older adults with higher income [
13,
18] and who live alone [
11‐
14,
17,
19] are more likely to receive formal than informal LTC. Studies have mainly focused on determinants for the utilization of institutional LTC, because this type of LTC causes high costs and thus is highly relevant for policy-makers to consider [
20,
21]. Another focus of research has been people with specific diseases, such as Parkinson disease [
22]. Less is known about the utilization of LTC by community-dwelling older adults without specific diseases and thus should to be investigated.
To prepare the health care system for future demands of LTC services, factors that determine the transitions of LTC (i. e. changes from no or one type of LTC to another) are even more important to identify. Therefore, longitudinal studies are necessary. To date, little is known about factors that determine transitions of LTC on an individual basis [
23].
The main objectives of this study are to identify relevant determinants for (1) utilization and (2) transitions of LTC over a time period of four years in adults older than 65 years in Germany. This approach allows a direct comparison of factors that are associated with current utilization of LTC and factors that might determine a transition to LTC over time. Furthermore, we would like to investigate the average amount of LTC received by individuals and the changes over four years. The results of this study may help to identify at-risk populations and plan future demands for LTC services.
Discussion
This study investigated the effects of predisposing, enabling and need factors as determinants for utilization and transitions of LTC in a population-based sample. To the knowledge of the authors, this is the first study to examine determinants for utilization, as well as for transitions of LTC, in older adults. The predisposing factors higher age and female sex, as well as the need factors higher multimorbidity and higher disability score, were determinants for both utilization and transitions of LTC. Living alone, higher income and higher disability score had a significant influence on the utilization of formal versus informal LTC. Overall, our findings are in line with other international studies that have identified determinants for utilization [
11‐
14] or transitions of LTC [
23,
44,
45].
Regarding the utilization of LTC, we found that the predisposing factor higher age was an important determinant. A number of studies have found that utilization of LTC increases with higher age [
11‐
14], due to the higher care needs of this group [
11]. Our results showed that female sex also increased the probability to receive LTC, which is confirmed by previous research [
11,
14,
15]. This phenomenon might be related to females’ higher support-seeking attitude in health care services (e. g. physician visits, hospital stays), which has been identified to be independent of females’ health status [
46]. In our study, individuals with high education were more likely to receive LTC than those with low education. This is consistent with findings on utilization of health care services that show that individuals with higher education might be more aware of existing supports [
47,
48]. However, research on utilization of LTC shows that higher education is either associated with higher [
12,
13] or lower utilization of LTC [
49], or that it changes over time [
50]. One possible explanation for these inconsistencies is that education is often completed during young adulthood, years before people reach old age, when LTC is normally received. The study’s results indicated that living alone increased the probability to receive LTC. The enabling factor living arrangement is reportedly a significant determinant for utilization of LTC [
11,
12,
19,
51]. Much evidence shows that individuals living alone receive more frequently formal than informal LTC [
11‐
14,
17,
19]. Availability of a person in the same household may reduce the demand for formal LTC [
12,
13,
17]. We indicated that higher income was associated with the utilization of formal LTC, which is consistent with previous findings that higher income facilitates using paid LTC services [
13,
18].
Among the need factors, our results revealed that higher multimorbidity had a considerable impact on the utilization of LTC. Van den Bussche et al. [
52] have examined 46 chronic diseases and state that the need of LTC for adults older than 65 years in Germany increases with every disease. However, they have focused on the need of LTC, defined by having a care level. Our study emphasized that multimorbidity has an impact on the utilization of LTC in a study sample that includes also individuals who did not fulfil the prerequisites for receiving a care level. In a study which has examined the association of 23 chronic diseases with the utilization of LTC, more than 90% of the diseases had a significant influence on the outcome [
11]. These findings emphasize the importance of considering chronic diseases, especially multimorbidity, as determinants for utilization of LTC. An interesting result was that with a higher disability score, the odds of utilization of any LTC, as well as of formal LTC, increased dramatically. These findings are consistent with previous research, which equally has defined disability with impairments in ADLs and IADLs [
12‐
14,
16,
17]. According to literature, impairments in ADLs are one of the major determinants for utilization of LTC, especially for formal LTC [
16].
Regarding the average amount of LTC, our study showed that individuals receive more informal than formal LTC. Considering a similar definition of informal and formal LTC as our study, Wimo et al. [
53] and Katz et al. [
19] accord with our observations. Comparing the amount of LTC of our study with the amount of the two studies in minutes per day, it is notable that both other studies report higher values. This could be caused due to our healthier study sample, whereas Wimo et al. have focused on older people with dementia and Katz et al. on older people with disability. None of the studies have analyzed a change of the amount of LTC over time. In our study we could show that over a period of four years the amount of LTC increased. An explanation might be the higher disability with higher age, which increases the demand for LTC [
11‐
13] and can be seen in Additional file
3.
Regarding the determinants for a transition to LTC, our findings provide further evidence about determinants for transition from no LTC to LTC. Most studies in this field have mainly focused on determinants for transitions only to [
54,
55] and from [
56] skilled nursing facilities, and for individuals with specific diseases or restrictions, such as dementia [
57,
58] or palliative patients [
59,
60]. In contrast, determinants for transitions from no LTC to LTC, independent of the type of LTC, have been rarely investigated in a community-dwelling population [
23,
44,
61]. We found consistency in the determinants of utilization and transitions of LTC. Determinants for both were higher age and female sex, as well as higher multimorbidity and disability score. Higher age was a determinant for a transition from no LTC to LTC, as well as for the utilization of formal versus informal LTC. Geerlings et al. [
23] have analyzed determinants for transitions from no LTC to informal LTC and from no or informal LTC to formal LTC. In agreement with our results, they have found that higher age is a determinant for both transitions from no LTC to informal or formal LTC.
Interestingly, a study on transitions of LTC in twelve European countries (including Germany) which controlled for determinants similar to those we controlled, has shown that higher age is a significant determinant for transition from no or informal to formal LTC [
44]. These findings show that higher age has to be considered on country-level as a strong determinant for transition to LTC. We also identified female sex as a determinant for transition to LTC. This could be explained by evidence that women seek more support in health care services [
46]. Contrary to Pan et al. [
45], who have shown that income had no significant association with a transition to LTC, our findings state that having a higher income decreased the transition from no LTC to LTC. These results must be interpreted with caution. One possible explanation could be that income is not as important as wealth in retirement age [
45]. Because data on wealth was unavailable, this information could not be considered in the current study. It is notable that all need factors had a significant influence on transition to LTC, which is also shown by Geerlings et al. [
23]. Over a period of four-and-a-half years, Koller et al. [
62] have revealed that older adults in Germany with more than three chronic diseases had higher odds of transition to “need of LTC”, defined as receiving a care level. Despite analyzing the need, instead of utilization of LTC, this finding is consistent with our study. The influence of multimorbidity could already be shown in our study’s sample, which also included individuals who did not fulfil the prerequisites for receiving a care level. An international study [
61] shows that multimorbidity has an influence on transition from no or informal LTC to formal LTC in eight European countries, which confirms our results on a macro level and emphasizes the high importance to consider multimorbidity as a determinant for transition to LTC. Regarding disability, research indicates that this need factor is associated with transition to LTC [
23], especially to formal LTC [
63]. Impairments in ADL and IADL hinder self-care and likely decrease independence in daily life.
Strengths and limitations
Analyzing both outcomes utilization and transitions of LTC within the same study sample allowed us to show the relationships between determinants for utilization and transitions of LTC. As part of the KORA-studies, instruments were carefully chosen and standardized assessments were conducted. The GEE logistic model allowed to consider the longitudinal approach of this study and could clearly identify determinants for utilization of LTC. To date, this methodology could rarely be used to identify determinants for utilization of LTC, due to limitations of cross-sectional data, as presented in previous studies.
Some limitations of the present study have to be acknowledged. First, information based on self-reports and might be susceptible to information bias. However, previous studies have shown that self-reports are a valid method to collect data on utilization of health care services [
64].
In considering the generalizability of this study, it is essential to mention that our study sample was selected to explore the determinants for utilization and transitions of LTC in older adults. The oversampling of men and older adults thus allowed us to examine influential factors in a relatively large sample of older community-dwelling adults, not those of the general population. Although the city of Augsburg and its two surrounding counties are not representative for whole Germany, we could show that our determinants for utilization of LTC are similar to previous findings with larger sample sizes [
11,
12].
Furthermore, our study had dropouts due to death and refusals. The stratified analysis by dropout could show that dropouts had a higher utilization of LTC and a poorer health status at t1. As a result, the strength of the associations between determinants for utilization and transitions of LTC is likely to have been underestimated.
It has also to be acknowledged that this study did not identify significant determinants for transitions of LTC within formal versus informal LTC apart from age. This might have been due to the small sample size for this sub-analysis and has to be examined in future studies. Nevertheless, the majority of determinants of formal and informal LTC show similar trends as in previous findings [
23,
45].
Also, the GEE logistic model could only estimate population-, rather than subject-specific correlations [
35,
36]. To examine determinants for utilization of LTC on an individual or class basis, other models (e. g. mixed models) should be used in future studies.
It would also be interesting to look at other patterns, such as the transition from informal to formal LTC. These patterns should be analyzed in future studies with bigger sample sizes.
Due to limited data access, it was not possible to include information on multimorbidity at t
2 and on different stages of the included chronic diseases. This would have made our analysis more accurate [
52]. Research states that chronic diseases deteriorate over time [
62], which could lead to systematic underestimation of multimorbidity as a determinant for utilization of LTC. Future studies should examine transitions to LTC in larger samples over a longer time period, including stages rather than only the number of chronic diseases.