Factors Contributing to Health Deterioration in the Japanese Long-Term Care Insurance System in Terms of Instrumental Activities of Daily Living

Abstract

This study aimed to determine which instrumental activities of daily living (IADL) are associated with health deterioration from the “support level” to the “care level” among users of the long-term care insurance system in Japan. From April 2017 to March 2020, we conducted a retrospective follow-up survey on 178 Japanese community-dwelling older adults (64 men, 114 women) newly certified as support level. Independent variable was 8 IADL items and the outcome defined as the “support level maintenance time.” Cox models were used to assess the risk of health deterioration, with adjustments for age group, family composition, dementia status, and frailty status by gender. Dependence on 5 items, “laundry” (hazard ratio [HR] =2.5; 95% confidence interval [CI]: 1.1-5.8), “cooking” (HR = 3.7; 95% CI: 1.1-12.2), “telephone use” (HR = 2.4; 95% CI: 1.2-4.7), “financial management” (HR = 2.5; 95% CI: 1.2-5.0), and “medication management” (HR = 2.4; 95% CI: 1.2-4.8), was independently associated with a worse outcome among men, whereas dependence on “financial management” (HR = 2.6; 95% CI: 1.5-4.7) and “medication management” (HR = 2.0; 95% CI: 1.1-3.5) was independently associated with a worse outcome among women. These findings suggest that difficulties in “financial management” and “medication management” are common factors associated with health deterioration from the support to the care level among both genders. An association with household tasks was also seen among men, indicating that a paradigm shift is needed to increase the participation of men in household tasks.

Keywords

older adults long-term care insurance instrumental activities of daily living preventive care dementia household task

Introduction

Functional decline in older adults is generally preceded by a decreased ability to carry out instrumental activities of daily living (IADL) before a subsequent decline in the ability to carry out basic activities of daily living (BADL).¹ BADL include self-maintenance abilities such as dressing, eating, bathing, and toileting, whereas IADL include more complex and higher functional abilities such as using public transportation, shopping, preparing meals, and financial management.¹ IADL require more advanced abilities, but both BADL and IADL share common associations with lower limb function^1-3 and cognitive function.⁴

As of 2020, more than36 million residents of Japan were aged ≥ 65 years (aging rate = 29.2%), and the Organisation for Economic Co-operation and Development member countries are closely monitoring Japanese policy on welfare systems for older people.⁵ Japan’s long-term care insurance (LTCI) system was introduced in 2000 to provide care for older individuals with disabilities. Since 2006, Japan’s LTCI system has shifted toward a preventive focus and categorized individuals into 2 levels: “support level (1 and 2)” and “care level (1 to 5).”⁶ In the LTCI certification, status of BADL, IADL, behavioral problems, rehabilitation, and medical treatments are evaluated and scored into “standard care time.” A care need level is assigned 7 levels based on the estimated “standard care time,” reflecting the caregiver’s time and efforts in caring for the individuals.⁷ The “support level” refers to individuals who are primarily somewhat independent in basic activities like walking and transferring, as well as in BADL such as eating, dressing, and toileting. However, they rely on family members or caregivers for assistance with some IADL like financial management, shopping, and cooking.⁷ In contrast, those requiring care level typically need partial or full assistance with BADL, and most IADL require support.⁷ In other words, individuals at the support level are typically independent in BADL but require assistance in some aspects of IADL.^6,8 In Japan, older adults (age ≥ 65 years) at the support level are coordinated to receive preventive care services by preventive care managers at the Community Comprehensive Support Center (CCSC).^8,9 Preventive care services include various in-home services such as day care, home help, and home renovation.^8,9 When the health of an individual deteriorates from the support to the care level, a corresponding decrease in quality of life is seen, accompanied by an increase in the caregiver burden. Additionally, the financial burden on the LTCI system becomes heavier as the number of older people requiring care increases.^10,11

Previous studies have reported that the prevalence of IADL limitations is 19% to 32% in community-dwelling older adults aged ≥ 65 years.¹² Various IADL assessment tools have been used, including the Lawton and Brody Scale,¹³ Frenchay Activities Index,¹⁴ Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC),¹⁵ and Kihon Checklist (KCL).¹⁶

Recent studies suggest that the decline in IADL among the older people has slowed over the past 2 decades.^1,11 However, financial and medication management are known to deteriorate earlier within IADL.¹⁷ Previous research on individuals at “support level 1” indicated a higher risk of health deterioration leading to care level when not performing “use of public transportation” and “telephone use” in the IADL items of the KCL.⁶ However, to our knowledge, few studies examined the risk of dependence on independence for as many IADL items as Lawton’s items specifically for the support level participants. Japan’s LTCI system consists of 3 basic concepts: user-centered, social insurance, and support for independence.¹⁶ On the other hand, previous study reported that older adults may not engage in activities they are capable of performing in IADL.¹⁸ Considering that the support level is designated for individuals with mild conditions,¹⁶ it is important to examine the IADL status and identify which specific IADL items are associated with the duration of maintaining the support level, as it is expected to maintain or improve functional ability.

However, to our knowledge, no studies have explored which IADL items are related to a deterioration in health from the support to the care level among preventive care users. Particularly, support for independence is emphasized for individuals with mild conditions (i.e., those at the support level).¹⁵ Therefore, the present study aimed to investigate the association between particular IADL dependencies among preventive care service users and health deterioration in Japan’s LTCI system.

Methods

Participants

A retrospective follow-up survey was conducted in the Yoshii-Sasebo CCSC area in Sasebo city, Nagasaki Prefecture, Japan, which encompasses 4 rural towns. As of October 2020, the combined population of these towns was 17,941, with 6890 individuals aged ≥ 65 years (aging rate = 38.4%).

Over a 3-year period from April 2017 to March 2020, we enrolled 248 individuals who were newly certified as support level and had received preventive care services until March 2023. After excluding 5 individuals aged < 65 years, 43 who used “day service type C” (limited to 3-6 months), 21 who underwent only housing renovations, and 1 because of missing data, we retained a final sample of 178 participants. All participants were followed up until March 2023, marking the end of the censoring period.

This study was approved by the Nagasaki University Graduate School of Biomedical Sciences (approval No.:23092001), and informed consent was obtained from all participants.

Procedures for Certifying the Need for Long-Term Care

Figure 1 shows the detailed process for certifying the care need level.⁷ The process of categorizing dependent older adults begins with a surveyor’s 74-item questionnaire that assesses current physical and mental conditions, including activities of daily living and IADL. The first decision is reached through a computerized algorithm, and the second by a “Long-Term Care Certification Board,” taking into account the initial computer decision, a doctor’s opinion, and a surveyor’s report containing specific remarks.^19,20 Finally, individuals certified as dependent older adults are categorized into 7 levels (ranging from support levels 1 and 2 to care levels 1-5) based on their condition. Support level 1 indicates the lowest degree of disability, whereas care level 5 corresponds to the highest level of disability.^19,20

Measures

Support level maintenance time

The duration of the support level was confirmed using each individual’s LTCI card. In addition to checking the validity date (validity period), gender and age were also confirmed from the LTCI card. The validity period for new LTCI certification was typically 6 months (range, 3-12 months), while sub-sequent updates had a validity period of 12 months (range, 3-36 months). Changes in the care need level classification could be applied at any time based on changes in the participant’s physical or mental condition that required consultation with a preventive care planner and family doctor. The validity period for certification in the case of a change in care level application was generally 6 months (range, 3-12 months).

The basic information

The basic information includes sex, age, family structure, and body mass index (BMI). Age categories were defined as “young–old” (65-75 years) and “old–old” (≥75 years). Individuals with a body mass index < 18.5 kg/m² were classified as “underweight.” Family structure was categorized as cohabiting or living alone.

Physical and mental condition

Confirmation of the main diseases related to the need for long-term care was conducted based on the attending primary doctor’s opinion. The presence or absence of disease such as stroke (e.g., cerebral infarction) and dementia (e.g., Alzheimer’s disease) was considered. Diseases such as dementia and stroke were categorized based on their presence or absence.

Additionally, we used the KCL^16,21 to assess physical frailty. The KCL is a 25-item yes/no questionnaire on physical and mental status and daily functioning. Based on the criteria established by Satake et al,²¹ for physical frailty, participants in this study were categorized into frailty (KCL score ≥ 8) and non-frailty (KCL score ≤ 7).

IADL assessment

We selected 8 IADL items from both the KCL and Sasebo city’s unique assessment sheet, using Lawton and Brody’s IADL scale¹³ as a reference. From the KCL,¹⁸ we included “use of public transportation,” “shopping,” and “telephone use,” with questions such as “Do you go out alone by bus or train?” (Yes/No), “Do you shop for daily necessities?” (Yes/No), and “Do you look up phone numbers and make phone calls by yourself?” (Yes/No). Those answering “Yes” were defined as having “Independence,” whereas those answering “No” were defined as having “Dependence.” From Sasebo city’s assessment sheet, we included “cleaning,” “laundry,” “cooking,” “financial management,” and “medication management.” Participants chose from options such as “independence,” “needs supervision,” “needs partial assistance,” and “needs full assistance” to best describe their daily life. Those selecting “independence” or “needs supervision” were defined as having “Independence,” whereas those selecting other options (“needs partial assistance” or “needs full assistance”) were defined as having “Dependence.” In the case of “medication management,” the participants could choose between “Self-managed without forgetting” and “Sometimes forgets to take medication.” Those self-managing without forgetting were defined as having “Independence,” whereas those who sometimes forgot were defined as having “Dependence.” The survey was conducted by the respondents themselves or their family members.

Outcome measures

In this study, the event was defined as new certification at care level 1 or higher in the LTCI during the follow-up period. The outcome of this study was defined as the duration from the support level to the care level, specifically, the period during which the support level was maintained.

Statistical Analysis

We recorded the age of the participants at the time of new support certification as the mean (standard deviation). Age categories were defined as “young–old” (65-75 years) and “old–old” (≥75 years). Individuals with a body mass index < 18.5 kg/m² were classified as “underweight.” Family structure was categorized as cohabiting or living alone. Diseases such as dementia and stroke were categorized based on their presence or absence. Qualitative data were presented as numbers and percentages.

Gender differences in the participants’ baseline characteristics were analyzed using the chi-square test. We compared the duration of support level maintenance between genders and other characteristics using log-rank tests with Kaplan–Meier curves. IADL items were also compared separately for men and women using log-rank tests. Support level maintenance time was calculated as the median and 95% confidence interval. Cases of censoring included “death,” “relocation”, “facility admission (e.g., small-scale multifunctional facilities),” and “cessation of service use.” Support level maintenance as of March 2023 was treated as censoring.

Adjusted hazard ratios (HRs) with 95% CIs for dependence on each IADL, predicting deterioration, were determined using Cox models with stepwise selection. Covariates included age group, family structure, presence of dementia, and frailty. EZR software²² was used for all statistical analyses.

Results

Table 1 summarizes the participants’ baseline characteristics. The mean age at new support level certification was 79.0 years for men and 81.8 years for women. Among old–old individuals, significantly more women were certified than men (87.7% vs70.3%, respectively; p = .004). The rates of living alone were 35.9% for men and 33.3% for women (p = .725). A significantly higher prevalence of stroke was seen among men than among women (34.4% vs 20.2%, respectively; p < .05).

Table 1.

Characteristics of the Study Participants (n = 178).

		Total (n = 178)		Male (n = 64)		Female (n = 114)		p
Variable		n	%	n	%	n	%	p
Age, years	Mean (SD)	80.8	(7.1)	79.0	(7.8)	81.8	(6.6)	.011^a
Age group	65-74 years	33	18.5	19	29.7	14	12.3	.004^b
Age group	≥75 years	145	81.5	45	70.3	100	87.7
Family structure	Cohabiting	117	65.7	41	64.1	76	66.7	.725^b
Family structure	Living alone	61	34.3	23	35.9	38	33.3
BMI, kg/m²	≥18.5	155	87.1	55	85.9	100	87.7	.734^b
BMI, kg/m²	<18.5	23	12.9	9	14.1	14	12.3
Dementia	Healthy	154	86.5	56	87.5	98	86.0	.774^b
Dementia	Presence	24	13.5	8	12.5	16	14.0
Stroke	Healthy	133	74.7	42	65.6	91	79.8	.036^b
Stroke	Presence	45	25.3	22	34.4	23	20.2
Frailty status	Non-frail	39	21.9	11	17.2	28	24.6	.254^b
Frailty status	Frail	139	78.1	53	82.8	86	75.4
Care need level	Support level 1	84	47.2	35	54.7	49	43.0	.133^b
Care need level	Support level 2	94	52.8	29	45.3	65	57.0

Note. SD = standard deviation; BMI = body mass index.

t-test.

chi-square test.

Figure 2 shows Kaplan–Meier curves for differences in the duration of support level maintenance between men and women. Men had a significantly shorter median duration than did women (36 vs 60 months, respectively; p = .041). Dementia was also associated with a significantly shorter duration of support level maintenance (p < .05). (Supplemental Figure 1).

Figure 3 shows the proportions of independence and dependence in IADL status for both genders. Among men, the highest dependence rates were for “cleaning” (80%) and “cooking” (78%), whereas the lowest was for “telephone use” (33%). Among women, the highest dependence rates were for the “use of public transportation” (71%) and “cleaning” (65%), whereas the lowest was for “telephone use” (25%).

Table 2 shows the adjusted HRs and 95% CIs for dependence on each IADL item for men and women. Among men, significant HRs were observed for dependence on “laundry” (HR = 2.5; 95% CI: 1.1-5.8), “cooking” (HR = 3.7; 95% CI: 1.1-12.2), “telephone use” (HR = 2.4; 95% CI: 1.2-4.7), “financial management” (HR = 2.5; 95% CI: 1.2-5.0), and “medication management” (HR = 2.4; 95% CI: 1.2-4.8), whereas among women, significant HRs were observed for dependence on “financial management” (HR = 2.6; 95% CI: 1.5-4.7), and “medication management” (HR = 2.0; 95% CI: 1.1-3.5).

Table 2.

Factors Contributing to the Deterioration of Health From the Support Level to the Care Level in Terms of Instrumental Activities of Daily Living by Gender.

	Men (n = 64)					Women (n = 114)
	Log-rank test		Cox model			Log-rank test		Cox model
IADL items	n^a	p	HR	95% CI	p	n^a	p	HR	95% CI	p
Use of public transportation	48	.099	-			81	.250	-
Cleaning	51	.276	-			74	.555	-
Laundry	41	.015	2.5	1.1-5.8	.030	48	.292	-
Cooking	50	.038	3.7	1.1-12.2	.033	64	.155	-
Shopping	45	.625	-			57	.047	1.8	1.0-3.1	.052
Telephone use	21	.007	2.4	1.2-4.7	.009	28	.561	-
Financial management	29	.006	2.5	1.2-5.0	.011	29	.001	2.6	1.5-4.7	.001
Medication management	26	.007	2.4	1.2-4.8	.010	39	.033	2.0	1.1-3.5	.019

Note. The Cox model was adjusted for age group, family composition, dementia status, and frailty status. IADL = independent instrumental activities of daily living; CI = confidence interval; HR = hazard ratio.

Number dependent on item.

Discussion

In this study, we used Cox models to assess the IADL items linked to health deterioration from the support to the care level in the LTCI system for both genders. Our findings indicated significant HRs for specific IADL items, regardless of the covariates.

“Financial management” and “medication management” were identified as common factors linked to health deterioration in both genders. A previous study focusing on Japanese older adults at the support level who were exhibiting behavioral and psychological symptoms of dementia (BPSD) investigated factors contributing to the deterioration of care needs over a 2-year period.²³ That study utilized IADL assessments within an LTCI survey and identified significant odds ratios associated with dependence on “financial management” and “medication management.”²³ Additionally, prior research on community-dwelling older adults has indicated the presence of various BPSD, including sleep disturbance and irritability, even in individuals without dementia.²⁴ The present findings align with previous research,²³ suggesting that even without dementia, the presence of BPSD at the support level and challenges in financial and medication management within IADL may be associated with a deterioration in health, leading to the need for care. Moreover, our findings are consistent with those reported by Tabira et al,¹⁷ who found that the “financial management” and “medication management” items on Lawton’s IADL scale deteriorate earlier than the other scale items in patients with very mild Alzheimer’s disease (vmAD). Advanced cognitive functions, including prospective memory and executive function, as well as calculation skills, are needed for financial and medication management.¹⁷ These IADL tasks also require self-management skills for daily life.¹⁷ Notably, medication management is critical and necessitates precise adherence to dosages and usage because of the risk of potential adverse effects.²⁵ Therefore, emphasizing financial management guidance and proper medication instructions for individuals at the support level is crucial.

Furthermore, the present findings revealed that dependence on “telephone use,” “cooking,” and “laundry” was linked to worse outcomes in men. Notably, “telephone use” was the most independent IADL item for both genders, with approximately 72% of men being independent. Previous research on vmAD revealed a sharp decline in IADL impairment related to telephone use, dropping from around 90% independence in the mid-70s to about 50% independence around the mid-80s.¹⁷Another study by Ito et al⁶ reported that IADL dependence on “telephone use” and “use of public transportation” as assessed by the KCL was associated with health deterioration from the support level to care level 1 or higher within 6 months of certification. These prior findings^6,17 align with those from our study and suggest a strong connection between the rapid progression of IADL impairment in telephone use and declining health in older individuals. However, it is worth noting that in our study, IADL dependence on telephone use was associated with worse health only in men. It is possible that men may have a shorter life-span²⁶ and a higher rate of hearing loss compared with women,²⁷ which could lead to the loss of telephone contacts and reduced social interactions, potentially contributing to health deterioration. Other factors, such as hearing impairment, visual impairment, and frequency of social participation, may be involved, and this necessitates further investigation. Contrary to the findings of the previous study by Ito et al,⁶ in the present study, the IADL item “use of public transportation” did not show significant HRs for either men or women. Previous research targeting an urban area⁶ suggested the importance of public transportation. However, among the IADL items in the present study, which focused on rural areas with many mountainous regions, independence in the “use of public transportation” was relatively low, potentially indicating its lower importance. Further research on the association between the “use of public transportation” and health deterioration from the support to the care level is therefore warranted.

Traditionally, laundry and cooking are not considered male roles and were not originally part of Lawton and Brody’s IADL items for men.¹³ Laundry, for instance, involves steps such as “starting the washing machine,” “using a dryer or alternative drying methods,” “folding the laundry,” and “storing clothes.”²⁸ Being independent in “laundry” requires cognitive abilities such as executive function, visuospatial cognition, and time orientation. A previous study linked laundry dependence in IADL to nighttime wakefulness and unfounded accusations in individuals with BPSD.²⁸ The act of doing laundry, including tasks such as hanging clothes in the morning and bringing them in the evening, might help regulate circadian rhythms and enhance mental well-being, which are particularly important in terms of sleep issues.

Similarly, independence in “cooking” among males might have a positive impact on delaying health deterioration. Cooking typically involves steps such as meal planning, food preparation (e.g., washing, cutting, heating), selecting seasonings, plating, and setting the table.²⁸ This IADL requires cognitive functions such as executive function, visuospatial cognition, memory, and precise upper extremity movements. Additionally, cooking dependence in IADL has been reported to be associated with nighttime wakefulness among individuals with BPSD.²⁸ Engaging in laundry and cooking activities may contribute to maintaining daily routines and averting cognitive decline, potentially reducing the risk of health deterioration in older men at the support level.

Limitations

This study has several limitations. First, due to the small sample size (n = 178), achieving a sufficiently high statistical power was challenging. A power analysis, assuming a 2-sided α error of 0.05 and a five-year survival rate of 30% for men and 50% for women, resulted in a detection power of 0.7. Second, we cannot rule out the possibility of selection bias. The study area consists of mainly rural mountainous regions with a considerably higher aging rate than the national average. As lifestyle differences between rural and urban areas could potentially impact the results, future studies should include urban areas to draw more conclusive findings. Third, the assessment of IADL is based on an original scale that may lack established reliability and validity. It would be desirable to use a reliable and validated assessment, such as Lawton’s IADL scale, in future research. Fourth, in the examination of causality, there is a possibility of other confounding factors. Adjustments may be necessary for factors such as education level, economic status, vision, and hearing, and larger sample sizes will be needed in future studies. Finally, this study did not consider combinations of different types of service utilization. Factors such as the presence or absence of daycare or home-visit care services could be confounding variables, so these should be considered in future studies.

Conclusions

In the present study, difficulties in “financial management” and “medication management” were identified as common factors associated with health deterioration from the “support level” to the “care level” in both men and women. Furthermore, among men, dependence on “telephone use,” “cooking,” and “laundry” were identified as factors contributing to health deterioration. These findings suggest that a paradigm shift is needed to expand the roles of older men within the household.

Supplemental Material

sj-docx-1-hhc-10.1177_10848223241242816 – Supplemental material for Factors Contributing to Health Deterioration in the Japanese Long-Term Care Insurance System in Terms of Instrumental Activities of Daily Living

Supplemental material, sj-docx-1-hhc-10.1177_10848223241242816 for Factors Contributing to Health Deterioration in the Japanese Long-Term Care Insurance System in Terms of Instrumental Activities of Daily Living by Takahiro Nishida, Yoshihiko Ide, Kenichiro Fukuda, Ayumi Honda and Sumihisa Honda in Home Health Care Management & Practice

Footnotes

Acknowledgements

We would like to thank Hitomi Yoshioka, chief care manager, Haruka Hino, public health nurse, Yuichi Suto, and Kazuto Yamaguchi, care planner for care prevention, for their assistance in the data collection. We would also like to express our sincere gratitude to Ms. Hiromi Abiru from the Sasebo Municipal Office for her cooperation in providing data on the LTCI system.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Supplemental Material

Supplemental material for this article is available online.

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