The diagnosis of a terminal or chronic illness can often result in family members being required to provide informal care to patients. Whereas this form of caregiving can have positive effects through benefit-finding and meaning assigned to caring [21–24] across a variety of diseases, it can also be associated with significant burden in physical and psychosocial domains. In the current study, significant burden was identified among individuals providing informal care for those diagnosed with AD or dementia. These findings are aligned with previous studies both in Japan and globally, suggesting that the burden experienced by caregivers extends across geographies, in spite of any influence of individual healthcare systems or cultural differences. Moreover, given little research in Japan investigating this form of burden or exploring its effects on health and economic outcomes, the current study identified potential impact of caregiving not only on quality of life, but also on comorbidities, productivity, and use of healthcare resources.
The caregivers recruited in the current study were on average 52.6 years old, somewhat younger than those involved in other studies of AD (e.g. 63.8 years [45]); however, as in the current study, the majority of caregivers in previous studies were female [45]. The age difference may be representative of the Internet-based format of this study, which may recruit younger individuals more comfortable with the online format.
The current study found that across a majority of health outcome measures, caregivers experienced significantly greater burden than did non-caregivers, even after matching them against non-caregivers with very similar baseline characteristics. Caregivers experienced greater frequency of comorbidities, including depression, insomnia, anxiety, and pain compared with non-caregivers.
Compared with non-caregivers, caregivers reported significantly lower health utilities, nearly reaching the MID for meaningfully poorer HRQoL, and they had significantly poorer physical and mental health status. Similar associations have been reported in the global literature, including among caregivers in the UK and Europe [62–64], thus reinforcing the critical importance of providing support to this vulnerable group.
Further, significant economic consequences were found among study caregivers compared with matched controls. These individuals reported significantly higher work productivity and activity impairment across all metrics. Finally, caregivers reported significantly greater resource use: i.e., more visits to the ER and healthcare providers in the previous six months and more frequent reports of any visit to the ER, hospital, or healthcare providers, further reinforcing the multifaceted economic impact of caregiver burden, as noted in previous studies outside of Japan [25]. With respect to baseline characteristics, caregivers had relatively poorer health and greater comorbid risk than (all, i.e., unmatched) non-caregivers, but they also had more financial resources at their disposal, lack of employment notwithstanding.
The current results align with previous global caregiver studies, including in particular a recent, similar analysis of burden among 209 caregivers of AD patients in NHWS Brazil [33]. For example, relative to their corresponding non-caregiver peers, the Japanese caregivers in the current study experienced health utilities impairments (−0.040 points) comparable to those of the Brazil caregivers (−0.024), as well as comparable impairments on PCS (−1.13 in Japan vs. -0.94 in Brazil) and MCS (−2.60 vs. -1.70, respectively), overall work impairment (26.5 % greater impairment in Japan vs. 35.9 % greater in Brazil), absenteeism (75.3 % vs. 59.6 % greater, respectively), presenteeism-related impairment (23.3 % vs. 32.7 % greater), activity impairment (16.6 % vs. 16.7 % greater), provider visits (43.9 % vs. 28.7 % greater), depression (odds ratio [OR] of 2.0 in Japan vs. 2.0 in Brazil), MDD (OR = 1.8 vs. 1.5, respectively), anxiety (OR = 4.8 vs. 1.7), insomnia (OR = 1.8 vs. 1.6), and pain (OR = 1.5 vs. 1.7).
The impairments found in the current study were also comparable to those reported by caregivers for adult relatives diagnosed with cancer in yet another NHWS-based study in the EU, where health utilities were 0.043 points lower for caregivers vs. non-caregivers (vs. 0.040 points lower for Japanese caregivers in the current study), PCS and MCS were 1.29 and 3.26 points lower, respectively (vs. 1.13 and 2.60 in the current study), overall work impairment, absenteeism, presenteeism-related impairment, and activity impairment were 46, 69, 45, and 32 % greater, respectively (vs. 26 %, 75 %, 23 %, and 17 % greater), provider visits were 33.2 % greater (vs. 43.9 %), and depression, anxiety, and insomnia had ORs = 1.5, 2.0, and 2.0, respectively (vs. 2.0, 4.8, and 1.8) [65].
In yet another NHWS-based study in the US, the burden of caregiving for patients with AD was compared with that for patients with multiple sclerosis (MS), finding that impairments did not differ significantly across the two conditions in terms of work productivity measures, HRQoL, or provider visits, although activity impairment, ER visits, and hospitalizations were significantly greater for caregivers of patients with MS [66].
It is important to note that the comparisons of caregiver burden referenced above are with respect to general health outcomes domains: mental health-related comorbidities, overall mental and physical status, productivity impairments, and resource use. There may be other, more disease-specific variations in burden that were not captured in the current or comparable studies. For example, the specific needs and psychological experiences of caring for individuals with severe dementia or AD may differ from those of caregiving in other conditions, even as general health outcome impairments are similar in degree. Generally, with variations in terms of magnitude and significance of differences across health outcomes, the current study finds that caregivers for patients with AD in Japan experienced impairments comparable to those experienced by caregivers for patients with AD in other geographies (e.g., Brazil and US), as well as impairments experienced by caregivers for patients with other conditions (cancer, MS, and schizophrenia) across geographies [65–67].
Strengths and limitations
The online survey format provides certain sampling advantages, including a broad representation of the overall population (including alignment with census data for Japan) and wide variance in caregiver and non-caregiver characteristics, but it may under-represent caregivers without access to or comfort with online technology (i.e., those who are not “digitally literate”). This online format may also bias recruitment toward younger, wealthier segments of society. Despite this, the fact that significant impairment and burden was established even among this group of caregivers suggests that under-represented groups (older, resource poor) may experience even greater burden than what was found in the current study.
While this study provides important insight into the potential health and economic effects of caregiving in the context of AD, the cross-sectional study design precludes any definitive conclusions from being drawn about causal relationships. Moreover, the self-report nature of the NHWS provides the potential for recall and other reporting biases (e.g., imprecise or inaccurate estimates of time, past productivity, and past resource use).
The NHWS did not collect information regarding the relationship status between patients and their caregivers, nor did it collect information on the level or type of care being provided. Many caregivers may have been the offspring of patients, as suggested by the relatively young age of caregivers in the current study. To the extent that this was the case, AD may have a meaningful impact on the work productivity of younger caregivers in the working population. It should be noted that the caregiving relationship can be complex and shift over time, influenced by both patient and caregiver characteristics, external pressures, and the availability of financial and other resources. Future research should thus clarify caregiver-patient relationships and surrounding issues, further elucidating the role that family members assume in caring for those with AD, which can inform the provision of more effective supportive services.
Moreover, the NHWS did not provide data on the precise proportion of caregivers who cared for patients with DAT vs. other forms of dementia. While research suggests that AD composes a majority of dementia among patients, it is unclear how this translates into caregiving (e.g., whether caregiving is more prevalent among AD patients). Also, the NHWS did not provide data on patients’ disease progression and severity, and patients with more severe disease are expected to have correspondingly older caregivers and poorer patient outcomes [25, 45]. Therefore, future research should assess the specific contributions of different types of dementia or disease severity to types and degree of caregiver burden.
Finally, the NHWS did not provide detailed data on non-caregivers’ family relationships, meaning that the incremental burden observed in caregivers vs. non-caregivers may in some part have been caused by concerns relating merely to having an older relative with or without dementia, regardless of caregiving status. At the same time, the propensity matching employed in the study (especially controlling for variables such as age, employment and marital status, and children in the household) should have limited considerably the heterogeneity among non-caregivers and provided a relatively focused comparison against a pool of matched non-caregivers similar to the caregivers.
Additional studies are needed to better understand those who are non-caregivers, particularly for the subset of persons who have a relative with dementia but have not taken on caregiver responsibilities. This research may help elucidate how and why people become caregivers and the impact of not being able to fulfill the role of caregiver.
Implications
The current study reinforces understanding of the significant health-related burden that AD caregivers can experience, extending this research and quantifying the impact family caregiving can have not only on quality of life but also on comorbidities, work productivity, and healthcare resource use. Supportive care programs for caregivers often rely upon traditional counseling modalities, requiring time away from caregiving responsibilities and potentially hampered by stigma surrounding mental health. The potential for family caregiving to impair work productivity could therefore suggest innovative worksite-based interventions and provide a preliminary basis for gaining employer support. Such interventions could provide both instrumental (e.g., time to run errands) and emotional support in a less stigma-prone environment, while reducing time spent away from caregiving responsibilities and mitigating the negative impact of caregiving on work productivity. At the same time, interventions focused on screening and treatment of depressive symptoms may offer another modality via which to identify and reach out to caregivers, perhaps focusing on strengthening the positive aspects of caregiving to better address the unique needs of this population.