Abstract
In this study we investigated the correlation between working capacity and APDL of middle-aged and elderly residents of welfare homes for the intellectually retarded. The subjects were 313 intellectually retarded people over 35 years old. The subjects were chosen from residents of four welfare institutions and job-placement centers for intellectually retarded people in Otaru, Hokkaido. Personal attributes, working capacity, and APDL were investigated in each subject. The items of personal attributes were: gender, chronological age, severity of intellectual impairment, and presence/absence of Down's syndrome. Working capacity was evaluated according to the 6 items. APDL was evaluated according to the 51 items. For statistical analysis of the working capacity of the subjects, the variables were summarized using principal component analysis and scored. Next, a search was made for the common factors in the 51 items of APDL using the principal component method. Finally, the correlation between working capacity and APDL was investigated by multiple regression analysis, with the obtained composite scores as dependent variables and the scores of APDL factors extracted by principal component analysis as independent variables. The following three factors were selected for the subjects: health management, outdoor movement and social activity. The multiple correlation coefficient using these three factors was R=0.63 (F=55.20, p<0.01). This indicates the necessity, from the viewpoints of prevention of senility, to focus not only on the decrease in working capacity of aging residents with intellectual impairment in welfare institutions but to establish various countermeasures based on the interrelationship between working capacity and APDL.
Keywords: intellectually retarded, working capacity, activities paralell to daily living
Welfare institutions for the intellectually retarded in Japan are developing into institutions of long-term residency as the severity of intellectual impairment among residents of such institutions continues to increase. The average age of residents in institutions for the intellectually retarded has also been increasing. With this continuing increase in both the severity of intellectual impairment and the age of residents in welfare homes, it is expected that additional caring services will be needed in the future. A decline in working capacity and maladjustment to work1), especially accompanying the aging of residents, have also been pointed out. From the viewpoint of improvement in QOL, an issue of major concern is how to maintain a working environment in which middle-aged and elderly residents of welfare homes for the intellectually retarded can operate with as much independence as possible. The degree of APDL and level of working capacity are closely interrelated, and both of these are thought to be involved in the improvement of QOL. However, there has been almost no research on the correlation between working capacity and basic disabilities in ADL and APDL.
Therefore, in this study we investigated how the degree of APDL affects the level of working capacity in middle-aged and elderly residents of welfare homes for the intellectually retarded. First, the variables for working capacity, defined as “the necessary physical capacity to perform task”2) were condensed using principle component analysis, and then the internal structures of 51 items of APDL, defined as “the physical capability to lead an independent life within the environment of one's home”3) were examined using factor analysis.
Methods
The subjects were 313 intellectually retarded people over 35 years old. The subjects were chosen from residents of four welfare institutions and job-placement centers for intellectually retarded people in Otaru, Hokkaido.
Personal attributes, working capacity, and APDL were investigated in each subject. The items of personal attributes were: gender, chronological age, severity of intellectual impairment, and presence/absence of Down's syndrome. Working capacity was evaluated according to the following 6 items based on the report of Tezuka4): “willingness to work”, “continuation of work”, “work safety”, “agility in work”, “reliability of work”, and “judgment during the execution of work”. Working capacity was divided into three groups: “absolutely no problem”, “no problem in general”, and“some problems”. These new evaluation criteria are based on the classification of expert skill disabilities in the International Classification of Impairments, Disabilities, and Handicaps5). “Working capacity” in this paper refers to the capacity needed to carry out tasks such as farming, carpentry, cement processing, printing, bookbinding, and laundering. For the evaluation of APDL, cooking and laundry activities were excluded in consideration of the limits to activities in the welfare institutions and of the difference between the roles of men and women. A total of 51 items of APDL, mainly concerning “physical stamina and exercise”, “use of public transport” and “walking around the town and shopping” were surveyed. Questions were asked on “use of public transport” using 2 choice method and on “walking around the town and shopping” using 5 choice method.
The survey was conducted by the detention method, and the data on each subject was obtained by evaluations made by the staff of the welfare institutions who were in charge of taking care of the subjects.
For statistical analysis of the working capacity of the subjects, the variables were summarized using principal component analysis and scored. Next, a search was made for the common factors in the 51 items of APDL using the principal component method by orthogonal rotation. Chronbach's α coefficient of reliability was obtained, and the internal consistency was examined. Finally, the correlation between working capacity and APDL was investigated by multiple regression analysis, with the obtained composite scores (hereafter, “working capacity score”) as dependent variables and the scores of APDL factors extracted by principal component analysis as independent variables. The data of 30 of the 313 subjects who were diagnosed as having Down's syndrome were excluded from the analysis. Thus, data from a total of 283 subjects were used.
Results
1. Distribution of personal attributes
The subjects for analysis included 141 men (49.8%) and 142 women (50.2%). The mean age of the subjects was 48.3 years (S.D.=8.71, range: 35.0∼76.0 years). IQ scores were lower than 20 in 96 subjects (12.8%), 21∼35 in 90 subjects (32.0%), 36 ∼50 in 123 subjects (43.8%), and higher than 51 in 32 subjects (11.4%) (IQ scores for 2 subjects are unknown). A statistical difference in gender between age and IQ distribution was not found.
With regards to the items of work capacity, 79 subjects (28.6%) showed absolutely no problems in “willingness to work”, 138 (50.0%) showed no problems in general, and 59 (21.4%) showed problems. In “continuation of work”, 73 subjects (26.4%) showed absolutely no problems, 135 (48.9%) showed no problems in general, and 68 (24.6%) showed problems. In “work safety”, 56 subjects (20.3%) showed absolutely no problems, 155 (56.2%) showed no problems in general, and 65 (23.6%) showed problems. In “agility in work”, 41 subjects (14.9%) showed absolutely no problems, 145 (52.7%) showed no problems in general, and 89 (32.4%) showed problems. In “reliability of work”, 42 subjects (15.2%) showed absolutely no problems, 141 (51.1%) showed no problems in general, and 93 (33.7%) showed problems. In “judgment during the execution of work”, 33 subjects (12.0%) showed absolutely no problems, 131 (47.5%) showed no problems in general, and 112 (40.6%) showed problems.
The distribution of APDL is shown in Table 1. The items of physical stamina/exercise in which a high percentage of subjects experienced no problems were: walk without staggering (88.0%), stand up without staggering (87.6%), and sit on a chair without using a hand (85.6%). On the other hand, the items of physical stamina/exercise in which a low percentage of subjects experienced no problems were: run smoothly (65.6%), stumble or fall when running (70.5%), and stumble on rough surfaces and small stones while walking (74.2%). The items of “getting on and off buses and trains”, “walking around the town” and “shopping” in which the level of “independent” was high were: walk stably (40.3%), climb up steps (38.9%), climb down steps (38.9%), walk down a slope (37.5%), walk up a slope (36.7%), and walk long distance (34.3%). The items in which the level of “independent” was low were: use train accordingly (local, rapid, express) (1.8%); understand train fares (2.2%); judge the situation if a problem arises (2.2%); understand bus fares and bus tickets (2.6%); and use the correct manner when asking for and receiving assistance (2.9%).
Table 1. The distribution of APDL.
| Variable | Independent | Somehow Independent | Almost Independent | Dependent | Totally Dependent |
|---|---|---|---|---|---|
| Describe symptoms when feeling ill | 33 (11.7) | 95 (33.6) | 55 (19.4) | 59 (20.8) | 41 (14.5) |
| Treat small cuts | 23 ( 8.2) | 81 (28.7) | 57 (20.2) | 52 (18.4) | 69 (24.5) |
| Get up punctually | 81 (28.6) | 95 (33.6) | 53 (18.7) | 31 (11.0) | 23 ( 8.1) |
| Go to bed punctually | 78 (27.6) | 106 (37.5) | 53 (18.7) | 28 ( 9.9) | 18 ( 6.4) |
| Effectively use leisure time | 44 (15.5) | 95 (33.6) | 68 (24.0) | 41 (14.5) | 35 (12.4) |
| Count money | 20 ( 7.2) | 33 (11.9) | 32 (11.6) | 42 (15.2) | 150 (54.2) |
| Manage money | 23 ( 8.3) | 39 (14.1) | 36 (13.0) | 41 (14.8) | 138 (49.8) |
| Plan spending money | 17 ( 6.1) | 24 ( 8.7) | 35 (12.6) | 50 (18.1) | 151 (54.5) |
| Greet people appropriately | 52 (18.4) | 95 (33.6) | 59 (20.8) | 46 (16.3) | 31 (11.0) |
| Stand up without staggering | 248 (87.6) | — | — | — | 35 (12.4) |
| Walk without staggering | 249 (88.0) | — | — | — | 34 (12.0) |
| Stumble on rough surfaces and small stones while walking | 210 (74.2) | — | — | — | 73 (25.8) |
| Run smoothly | 185 (65.6) | — | — | — | 97 (34.4) |
| Stumble or fall when running | 198 (70.5) | — | — | — | 83 (29.5) |
| Sit on a chair without using a hand | 242 (85.8) | — | — | — | 40 (14.2) |
| Sit on the floor without using a hand | 235 (83.3) | — | — | — | 47 (16.7) |
| Walk stably | 114 (40.3) | 96 (33.9) | 28 ( 9.9) | 22 ( 7.8) | 23 ( 8.1) |
| Walk long distance | 97 (34.3) | 103 (36.4) | 30 (10.6) | 34 (12.0) | 19 ( 6.7) |
| Walk up a slope | 104 (36.7) | 100 (35.3) | 26 ( 9.2) | 31 (11.0) | 22 ( 7.8) |
| Walk down a slope | 106 (37.5) | 89 (31.4) | 31 (11.0) | 34 (12.0) | 23 ( 8.1) |
| Climb up steps | 110 (38.9) | 93 (32.9) | 32 (11.3) | 29 (10.2) | 19 ( 6.7) |
| Climb down steps | 110 (38.9) | 89 (31.4) | 30 (10.6) | 35 (12.4) | 19 ( 6.7) |
| Walk on the right side of a road with no sidewalk | 41 (14.5) | 76 (27.0) | 21 ( 7.4) | 97 (34.4) | 47 (16.7) |
| Understand traffic signals | 49 (17.4) | 71 (25.2) | 23 ( 8.2) | 67 (23.8) | 72 (25.5) |
| Cross the road safely | 38 (13.5) | 65 (23.0) | 27 ( 9.6) | 77 (27.3) | 75 (26.6) |
| Walk safely without bumping into other people | 38 (13.5) | 75 (26.7) | 25 ( 8.9) | 80 (28.5) | 63 (22.4) |
| Walk while carrying things | 85 (30.1) | 86 (30.5) | 26 ( 9.2) | 44 (15.6) | 41 (14.5) |
| Understand directions | 26 ( 9.3) | 74 (26.3) | 27 ( 9.6) | 83 (29.5) | 71 (25.3) |
| Ask for assistance when lost | 24 ( 8.5) | 60 (21.4) | 28 (10.0) | 84 (29.9) | 85 (30.2) |
| Understand the correct bus stop | 21 ( 7.7) | 52 (19.0) | 19 ( 7.0) | 72 (26.4) | 109 (39.9) |
| Understand bus timetables | 14 ( 5.1) | 36 (13.2) | 7 ( 2.6) | 48 (17.6) | 168 (61.5) |
| Get on a bus safely | 24 ( 8.8) | 63 (23.1) | 28 (10.3) | 68 (24.8) | 90 (33.0) |
| Understand bus fares and bus tickets | 7 ( 2.6) | 43 (15.8) | 14 ( 5.1) | 43 (15.8) | 165 (60.7) |
| Understand train fares | 6 ( 2.2) | 35 (12.9) | 14 ( 5.1) | 40 (14.7) | 177 (65.1) |
| Present train tickets | 8 ( 2.9) | 45 (16.5) | 19 ( 7.0) | 74 (27.2) | 126 (46.3) |
| Use train accordingly (local, rapid, and express) | 5 ( 1.8) | 26 ( 9.6) | 15 ( 5.5) | 42 (15.5) | 183 (67.5) |
| Get off a train safely | 20 ( 7.4) | 57 (21.0) | 26 ( 9.6) | 73 (26.8) | 96 (35.3) |
| Manage dress and facial appearance | 24 ( 8.5) | 78 (27.7) | 31 (11.0) | 84 (29.8) | 65 (23.0) |
| Prepare sufficient money for shopping | 19 ( 7.0) | 12 ( 4.4) | 160 (58.6) | 43 (15.8) | 39 (14.3) |
| Move smoothly with shopping bags | 60 (21.4) | 95 (33.8) | 23 ( 8.2) | 44 (15.7) | 59 (21.0) |
| Pass through the cash-register without any problems | 20 ( 7.3) | 47 (17.1) | 23 ( 8.4) | 56 (20.4) | 129 (46.9) |
| Use an elevator | 22 ( 7.9) | 38 (13.7) | 13 ( 4.7) | 81 (29.1) | 124 (44.6) |
| Plan a shopping list | 15 ( 5.5) | 35 (12.8) | 13 ( 4.8) | 65 (23.8) | 145 (53.1) |
| Find the needed products when shopping | 14 ( 5.0) | 35 (12.5) | 24 ( 8.6) | 74 (26.5) | 132 (47.3) |
| Select the shopping goods | 16 ( 5.7) | 47 (16.8) | 35 (12.5) | 83 (29.6) | 99 (35.4) |
| Give the correct money for the shopping goods | 18 ( 6.6) | 29 (10.7) | 23 ( 8.5) | 38 (14.0) | 164 (60.3) |
| Count the change returned | 17 ( 6.3) | 27 ( 9.9) | 16 ( 5.9) | 44 (16.2) | 168 (61.8) |
| Ask the store clerk for help if a problem arises | 9 ( 3.2) | 40 (14.4) | 28 (10.1) | 76 (27.4) | 124 (44.8) |
| Use the correct manner when asking for and receiving assistance | 8 ( 2.9) | 65 (23.6) | 27 ( 9.8) | 75 (27.3) | 100 (36.4) |
| Judge the situation if a problem arises | 6 ( 2.2) | 31 (11.3) | 32 (11.7) | 75 (27.4) | 130 (47.4) |
| Act smoothly according to the own judgement | 10 ( 3.6) | 33 (12.0) | 29 (10.5) | 83 (30.1) | 121 (43.8) |
2. Scoring working capacity by principal component analysis
The results of principal component analysis for scoring working capacity are shown in Table 2. One principal component with an eigenvalue above 1.0 was obtained: the value of the first component was 4.12, and the contribution was 68.7%. The factor loading of each item to the first principal component was in the range of 0.79∼0.85, indicating that every item belonged to the first principal component. The standard factor score was used for the working capacity score of each subject.
Table 2. The results of principal analysis for scoring working capacity.
 |
3. APDL structure and scoring using the principal factor method
For the 51 items of APDL, the refactoring method with the common initial values as SMC was applied, and a four-factor solution was judged to be appropriate for the APDL used in this study, based on the difference between the following factors and eigenvalues (Table 3). Furthermore, to make interpretation of the factors easier, the standard varimax rotation method of the orthogonal model was used. Four factors were obtained, and the following variables showed a large load in each of the factors: variables 1∼8 in the third factor, variables 9∼15 in the fourth factor, variables 16∼44 in the first factor, and variables 45∼51 in the second factor. The cumulative contribution up to the fourth factor was 73.4%.
Table 3. APDL structure using the principal factor method.
 |
Firstly, examining the factor loads in the first factor, the following items in the first factor showed high correlation coefficients (0.60∼0.92): understand bus fares and bus tickets; understand train fares; understand bus timetables; use train accordingly (local, rapid, express); present train tickets; manage money; plan spending money; count money; give the correct money for the shopping goods; count the change returned; prepare sufficient money for shopping; pass through the cash-register without any problems; use an elevator, plan a shopping list; find the needed products when shopping; judge the situation if a problem arises; act smoothly according to the own judgement; ask the store clerk for help if a problem arises; use the correct manner when asking for and receiving assistance; understand traffic signals; cross the road safely; walk safely without bumping into other people; walk on the right side of a road with no sidewalk; understand directions; ask for assistance when lost; get on a bus safely; get off a bus safely; and understand the correct bus stop. Thus, the first factor was considered to be related to social activity variables (hereafter called “social activity” factor).
Items with a high correlation (0.57∼0.78) in the second factor were: get up punctually; go to bed punctually; effectively use leisure time; greet people appropriately; describe symptoms when feeling ill; treat small cuts; and manage dress and facial appearance. Thus, the second factor was considered to be related to health variables (hereafter called “health management” factor).
In the third factor, climb up steps; climb down steps; walk up a slope; walk down a slope; walking stably; walk long distance; walk while carrying things; and move smoothly with shopping bags showed correlation coefficients in the range of 0.50∼0.87, indicating that the third factor was related to outdoor movement. Thus, the third factor was named “outdoor movement” factor.
In the fourth factor, the following items showed correlation coefficients of 0.53∼0.74: sit on a chair without using a hand, sit on the floor without using a hand, stand up without staggering, walk without staggering, stumble on rough surfaces and small stones while walking, stumble or fall when running, and run smoothly. Thus, this factor was considered to be related to motor function variables (hereafter called “motor function” factor).
With regards to the reliability of the evaluation, Chronbach's α coefficient of reliability for the APDL structure of the subjects was 0.98, and the internal consistency for each factor was high: 0.99 (first factor), 0.92 (second factor), 0.97 (third factor) and 0.87 (fourth factor).
4. Correlation between working capacity and APDL
The correlation between working capacity and APDL was investigated in the male and female subjects by multiple regression using the stepwise forward regression with the working capacity scores (standard factor scores) as the dependent variables and the APDL scores (standard factor scores) as the independent variables. The following three factors were selected for the male subjects: social activity (standardized partial correlation coefficient = 0.48), health management (0.43) and outdoor movement (0.21). The multiple correlation coefficient using these three factors was R=0.70 (F=39.62, p<0.01). The same three factors were also selected for the female subjects, and the standardized partial correlation coefficients all showed positive contributions: outdoor movement (standardized partial correlation coefficient = 0.49), health management (0.37) and social activity (0.19). The multiple correlation coefficient using these three factors was R=0.62 (F=26.29, p<0.01).
When these three factors were treated together for both male and female subjects (Table 4), the standardized partial correlation coefficients all showed positive contributions in the order of: 0.41 for health management, 0.36 for outdoor movement, and 0.31 for social activity. The multiple correlation coefficient using these three factors was R=0.63 (F=55.20, p<0.01).
Table 4. Correlation between working capacity and APDL.
| Variable | Partial Reg Coeff | Stand Error | Stand Partial Reg Coeff | F-Value (Sig. T) | Partial Correla Coeff | |
|---|---|---|---|---|---|---|
| Health Management | − 0.430 | (0.052) | − 0.41 | 69.70 (0.000) | − 0.46 | |
| Outdoor Movement | − 0.382 | (0.051) | − 0.36 | 55.00 (0.000) | − 0.42 | |
| Social Activity | 0.315 | (0.049) | 0.31 | 40.79 (0.000) | 0.37 | |
| Constant | 0.008 | |||||
| R-Square | 0.63 | |||||
| F-Value | 55.20 (3, 253) Sig.(0.00000) | |||||
Discussion
In this study, the correlation between the working capacity and APDL of middle-aged and elderly people with intellectual impairment was investigated to obtain an index that can be used for the care of intellectually retarded residents of welfare institutions. The investigation focused on the correlation with APDL as a disability in the impairment, disability and ICIDH model. The reason why basic ADL as disabilities were excluded was simply because most of the actions such as eating, going to the toilet, dressing and undressing, and bathing were able to be conducted independently. Also, the reason why the correlation with intellectual disability was excluded was due to the difficulty of conducting a detailed and objective evaluation of the degree of intellectual disability in every subject in a short period of time.
The reason why only subjects over 35 years old were used in this study was because reports have shown that early symptoms of senility appear from about this age6). Subjects with Down's syndrome were also excluded from this study due to the small number of cases and due to the fact that there have been several studies already conducted on Down's syndrome cases7). Although there is no data available for a direct comparison with the distribution of personal attributes (e.g., gender, age, etc.) of the subjects used in this study, a comparison with past reports7)8) shows almost the same distribution, indicating that the selection of subjects was appropriate for the purpose of this study.
For the statistical analysis, the scores for the six items of working capacity were condensed into one score by variable elimination9) using principal component analysis. Next, in order to avoid multicollinearity9), which often occurs when using many variables in multiple regression, we reduced the number of variables by orthogonal rotation, which allows correlations between factors to be separated. Using this technique, we were able to reduce the number of variables by substituting the 51 items of APDL into 4 factors, and the scores were compressed into 4 factor scores. This procedure was considered to be appropriate in view of the large number of items of working capacity and APDL in the present study.
Thus, the results showed that: 1) the six items of working capacity of the subjects could be condensed into one factor structure, and 2) the 51 items of APDL could be condensed into four factor structures (social activity, health management, outdoor movement, motor function). 3) It was also found that the degree of working capacity is closely related to the three factors of APDL, i.e., health management, outdoor movement and social activity. This result shows that the degree of independence in the APDL of intellectually retarded residents of a welfare institution is closely related to the working capacity within the working environment of the institution, suggesting that the elevation and maintenance of the working capacity of intellectually retarded people can not be achieved unless some degree of independence in APDL is established and maintained.
Health management, outdoor movement and social activity were shown to be related to the degree of independence in APDL for both men and women. Of these three items, health management is especially important in the case of residents over 40 years old1). Proper health management naturally assumes regular self-management of health such as the maintenance of regular sleeping hours, the ability to know the degree of physical fatigue, awareness of the necessity of adequate rest, and ability to prevent and treat injuries. Lack of sleep can lead to dozing and distracted attention during work, which not only reduces work efficiency but may also lead to accidents. Also, paying proper attention to one's own physical cleanliness and appearance is important in order to have the right attitude towards tidiness and cleanliness in the workplace. Maintenance of clothes and ability to choose appropriate clothes to suit the temperature are also necessary. Checking the working clothes (shoelaces, cap, uniform, etc.) is very important for maintaining safety in the workplace. All of the above are important for maintaining good relationships among welfare institution residents, who share the same facilities. Also, in the case of elderly residents with intellectual impairment, as it has been shown that it is possible to minimize much of their loss in health management capacity by adjustments to their living environment10), necessary steps should be taken by the staff of welfare institutions to improve the residential and working environment for elderly residents.
With regards to outdoor movement, the most important movement for work inside the institution is the movement to and from the workplace. For intellectually retarded residents of a welfare institution, the workplace is usually the next most important base of institutional life to the living quarters, and it is therefore necessary to impress upon the residents the importance of their workplace. In this respect, movement disability is the first problem that must be considered before deciding on the type of work. Moreover, due to the limitations on activities in a welfare institution, the amount and type of activities conducted by intellectually handicapped residents becomes limited, and this may lead to a very limited daily life pattern. Especially for elderly residents with intellectual impairment, these restrictions are thought to cause a reduction in exercise and movement ability. In other words, since positive changes are possible through adjustments in life style and environment, making daily life as fulfilling as possible for the residents could lead to an increase in and maintenance of a high level of movement ability.
Social activity, which was shown to be one of the main factors in APDL, includes the elements of use of public transport, money management, shopping, self-judgment and safety control. Use of public transport assumes the knowledge of correct manners and customs required for using public transport. This is also related to the use of public facilities. Management of money requires the maintenance of a life style in which there is no unnecessary waste of money and an understanding of how to deal with money. The factor of shopping in APDL requires correct knowledge of types and prices of goods and the ability to buy daily necessities, as well as an interest in and understanding of basic economics in order to develop the ability to participate in society. Self-judgement requires the ability to ask for assistance when a problem arises11), the ability to judge circumstances, and the ability to act smoothly according to the judgement12). Safety control requires the knowledge of traffic rules and regulations, and the knowledge of basic customs necessary for life in society. In any case, in view of the decreasing ability of intellectually retarded people to adapt to society as they become older, appropriate assistance on an individual level is needed13) for them to continue activities in society.
This study has shown that the working capacity of intellectually retarded residents of welfare institutions is closely related to APDL, which is the basis of the individual's ability to perform activities. This indicates the necessity, from the viewpoints of prevention of senility, to focus not only on the decrease in working capacity of aging residents with intellectual impairment in welfare institutions but to establish various countermeasures based on the interrelationship between working capacity and APDL.
In this study, the work items investigated are not the same in each facility, and the evaluation criteria may vary. More detailed investigation using work items common to all facilities is being planned for a future study.
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