Health Problems in Aging Populations

The present paper addresses functional capacity as a reasonable proxy for health in the elderly. The conceptual framework and its relation to quality of life and productivity are stated. Distributions of functional capacity according to a scale from low to high levels of functioning are shown. Cross-cultural differences, regional differences, and predictors of functional capacity and active life expectancy are also described. J Epidemiol,1996; 6: S71-S78.

The World Health Organization (WHO) proposed autonomy in terms of functional capacity as a reasonable proxy for health in the elderly.Further, WHO emphasized that mortality and morbidity are useless for evaluating autonomy as a proxy for health1).
Functional capacity is not only of great predictive value for life expectancy2-4), but also salient as a basic component of quality of life (QOL) in the elderly5).QOL has been recently raised as a concept including subjective well-being of the elderly.
Functional capacity should be conceptually distinguished from productive ability).Productive ability subsumes paid employment, unpaid employment such as family farming, management of household affairs, voluntary organizational activity, mutual help, and self-care.Functional capacity may be regarded as the basis of productive ability.
The present paper addresses the conceptual framework, measures, and correlates of functional capacity as a reasonable proxy for health in the elderly.

CONCEPTUAL FRAMEWORK AND MEASURES OF FUNCTIONAL CAPACITY
Lawton developed a hierarchical model of competence comprising seven sublevels as follows7): The TMIG Index of Competence developed by us was devised to assess competence from the fifth to the seventh sublevels (Table 1)10).The indices mentioned above are selected   The response to each item is designed simply as 'yes' (able to do) or'no' (unable), and scored 1 for 'yes' and 0 for'no'.The total score is designed as the sum total of 13 items or the number of items answered with 'yes', in order that a higher score (full marks 13 points) could indicate higher competence of the elderly.
according to the purpose of observations or interventions.For evaluating the severity of the disabled elderly or setting goals for their rehabilitation, scales of ADL are relevant.On the other hand, the TMIG Index of Competence is the most useful scale for evaluating the level of competence in old people living in the community, because scales of ADL or IADL cannot detect the variety of competence in the elderly free from disabilities or frailty.Katz et.al proposed the concept "active life expectancy", meaning "the duration of functional well-being", as an index for measuring group levels of health").Both death and inability to perform specific tasks of a certain level of functional capacity are regarded as losing active (disability-free) life expectancy.There has been a wide variation in the definition of disability in preceding studies, such as disability in ADL, disability in IADL, and so forth.

DISTRIBUTION OF COMPETENCE ACCORDING TO THE SCALE12)
The proportion of the competent elderly varies according to the scale employed.Table 2 shows the rates of competence according to ADL in residents 65 years and over living in a rural community.We investigated this community as the baseline survey for a longitudinal interdisciplinary study").All residents were investigated as to functional capacity, including home visits to nonrespondents.Approximately 95 per cent of the elderly were found to be competent.Table 3 shows the rates of competence according to IADL in the same subjects as in Table 2.The proportion of the competent is lower than in Table 2.We found sex differences showing higher competence in terms of locomotion, paying bills, and handling their own money, and lower competence in preparing meals in men.Thus, the proportion of competence varied according to the index employed.The incompetent in terms of ADL are called the disabled.Old people who are competent in ADL but incompetent in IADL should be called frail elders or needy elderly.Intervention for the frail elderly is one of the most crucial issues for health care and rehabilitation medicine in aging societies.
Table 4 shows average scores of the TMIG Index of Competence (full marks=13) in the same subjects as in Tables 2.3.The validity of the Index and average scores in an urban area are given in another article10).This Index was not developed for detecting incompetent people, however, we empirically learned that the elderly with a score of less than five needed formal and informal supports.Thirty-five per cent of subjects received full-marks.
Competence as measured by the TMIG Index of Competence was higher in men than in women , and higher in urban areas than in rural areas.This competence is influenced by education, job history, and some other cultural differences .Consequently, there is a regional difference of levels14) .
Active life expectancy in Japan was calculated not only in local representative samples15), but also in a representative sample of the entire Japanese population16)

CAPACITY
Making a valid cross-cultural comparison with regards to functional capacity is difficult.First, the scale employed should be completely standardized.It is of less bias to use measures for assessing low levels of functional capacity such as basic ADL.However, measures for assessing higher levels of functional capacity are influenced by cultural background.Therefore, a valid cross-cultural measure is difficult to develop.
Further, samples investigated, method of investigation, and response rates should be standardized in order to make a crosscultural comparison of functional capacity.Due to a lack of standaredization, successful cross-cultural comparisons have hitherto been rare.Even restricted findings, however, have revealed an interesting cross-cultural difference of functional capacity between western countries and Asian countries.Figure 1 shows a comparative prevalence of incompetence in any category among three categories of a Guttman Health Scale for the Aged17).This finding was obtained from the data of our cross-cultural longitudinal study between Michigan University and Tokyo Metropolitan Institute of Gerontology18).Both samples were representative (the sample of American Changing Lives Survey in USA; a two-stage random sample of the entire Japanese population), and the response rates were almost same, 67.0% and 66.9% in the USA and Japan, respectively.These comparative efforts thus were least biased by methodology.
We found another interesting cross-cultural difference with regards to functional capacity of the elderly between Florence, Italy and Beijing, China19).The cross-cultural comparison has shown a marked difference in the prevalence of incompetence as assessed by ADL and IADL, showing higher rates of incompetence in the Florence sample.A rate of incompetence in any one of the IADL items (mild) was found in 41 per cent of the Florence sample, and in eight per cent of the Beijing sample.A rate of disability in any one of the ADL items was found in 12 per cent of the Florence sample and in seven per cent of the Beijing sample.In particular, the Florence sample was more likely to be unable to perform heavy housework and to cut toe nails in IADL.What has brought about these crosscultural differences in functional capacity of the elderly should be explored in order to verify the etiology of disability and frailty.Cross-cultural differences should be considered in the context of cultural backgrounds.One possibility is that the elderly in western countries tend to rate themselves low as to abilities to perform some tasks.This influences the rating of functional capacity, because the investigation of abilities is based on self-report or self-rating.In addition, ability and actual activity (doing) are often confusing to examines, although they are conceptually distinguished.Virtually higher activities in daily life in IADL levels in oriental countries may enhance self-rated abilities of the examinees.
In any case, these cultural implications could not fully elucidate the relevant factors.A difference in lifestyles, a difference in diseases predisposing to disability, and other factors may contribute to the cross-cultural differences.Further investigation is warranted.

REGIONAL DIFFERENCES IN FUNCTIONAL CAPACITY IN JAPAN
We have carried out interdisciplinary longitudinal studies in several regions of different environments.Life expectancy in the elderly, functional capacity, and subjective well-being have been investigated in relation to geography, demography, and lifestyles including dietary patterns.
We found a marked difference in terms of functional capacity in elderly residents between a village in Akita Prefecture in the north and a village in Okinawa Prefecture in the south).Figure 2 shows the comparison of competence in ADL in women aged from 75 to 79 years between Akita and Okinawa.The elderly in Okinawa were significantly more competent.The same was found in every age category for both men and women, which difference in terms of ADL was compatible with difference in life expectancy at birth and 65 years between the two regions.Lower rate of cerebrovascular disease in Okinawa contributes to both higher life expectancy and a lower rate of disability.A 2-year longitudinal observation showed that declines in grip strength, serum albumin, and serum cholesterol were significantly lower in Okinawa than in Akita.This implies that the aging process was retarded in Okinawa20s.
We attempted to identify lifestyle factors relating to the difference in competence.First, food intake patterns were different, although total energy intake did not differ 21).In Okinawa, due to an absence of Buddhist influence, eating meat has not been stigmatized.Therefore, intake of animal protein and fats has been adequate.On the other hand, food intake patterns in Akita have been conventional: less intake of animal protein and fats, more intake of rice and salt.Intake of deep-coloured vegetables was also higher in the village of Okinawa.
The second possible factor relating to the difference in autonomy is daily physical activities.People in Okinawa enjoy year-round summer, whereas it snows heavily during winter in Akita.The difference in climate is not crucial, but the elderly in Akita are likely to be inactive during winter.Further, a difference in living arrangements is considered to influence the difference in competence.In the village of Akita, the elderly lived with other family members: three-generation families were common.On the other hand, the elderly lived only as a couple or lived alone in the village of Okinawa.In Japan, there ------Stepwise multiple regression analysis------Table 6. Significant baseline variables to the total score of the TMIG Index of Competence 5 years later in women aged 65 years and over in Nangai Village, Akita Prefecture.
------Stepwise multiple regression analysis------Table 7. A relationship of serum total cholesterol at baseline to the TMIG Index of Competence scores 2 years later.
Adjusted for age, education, self-rated health, chronic conditions and serum albumin.+p<.10 *p<05 **p<01 subscale:Instrumental self-maintenance comprises 1)-5), Intellectual activity comprises 6)-9), and Social role comprises 10)-13), out of the TMIG Index of Competence. the daily lives.The higher rate in employment and the higher participation in community activities found in Okinawa, especially among the very aged, are considered to reflect the attitude oriented toward autonomy in daily life.

PREDICTORS OF FUNCTIONAL CAPACITY
We carried out a 15-year longitudinal interdisciplinary study in the urban community elderly aged 69-71 years between 1976 and 1991.In that study, the contribution of baseline variables to disabilities in ADL, 10 years later was examined.
The low level of social activities in a broader sense contributed to decline in ADL for both sexes.History of hypertension and ECG abnormalities contributed to decline in ADL in men alone, while overweight and anxiety for health contributed to decline in women alone.The contribution of social activities persisted to the outcome of ADL 15 years later.
A relationship of baseline variables to longitudinal changes in the level of the TMIG Index of Competence was also investigated based on longitudinal interdisciplinary studies in the elderly living at home.
Predictors of functional capacity as assessed by the TMIG Index of Competence based on a 5-year longitudinal observation in a rural area were analyzed using stepwise multiple regression analysis (Table 5, 6).Although significant variables somewhat differed between men and women, the pattern in the relationship of locomotion, the score at baseline, self-rated health, age, and an association with friends were uniform.
As illustrated in Figure 3, a 2-year decline in the score of the TMIG Index of Competence tended to be more common in the lowest tertile of serum total cholesterol (TC) in urban community elders aged from 65-84 years13).Table 7 shows positive relationship of TC at baseline to the score of total and subscales of the TMIG Index of Competence when adjusted for confounding factors.In these community elders, active intake of animal protein and fats and oils was found to prevent the decline of the TMIG Index of Competence23).The present relationship of TC may be linked with the food intake pattern.Epidemiological studies in both observational and intervention studies have demonstrated positive association between low serum cholesterol and suicide24).That linkage may be mediated by depressive status.Morgan et.al25) have reported higher occurrence of depression and depressive status in the elderly with low TC based on a longitudinal observation.Engelberg26) suggests that a reduction in serum cholesterol may decrease brain-cell-membrane cholesterol, lower the lipid microviscosi- ty, and decrease the exposure of protein receptors on the membrane surface, resulting in poor uptake of serotonin from the blood and less serotonin entry into brain cells.Brain serotonin is considered to have a role in preventing suicide or violence in susceptible people.
The score of the TMIG Index of Competence is inversely associated with depressive status measured by the Geriatric Depression Scale").TC should be re-evaluated from the viewpoint of mental function in addition to all-cause mortality and specific diseases in the elderly.
Predictors of active life expectancy were examined based on a 7-year longitudinal observation of 1044 elders living at home in the town of Yuwa, Akita Prefecture28).Baseline survey was carried out in 1142 residents age 65 years and over living at home by door-to-door method in 1983 (participation rate=92.5 per cent).One thousand and twenty-four subjects who were independent in ADL at baseline were followed-up in 1990.Those who were completely independent for every item of ADL at the follow-up were regarded as being in active life.Inactive life was defined as status changed into categories of dependence in any item of ADL, admission to institutions or hospitals, and death.Relationship of variables at baseline to active life seven years later was analyzed with a logistic regression model.As shown in Table 8, self-rated health was the second strongest predictor to chronological age for maintaining active life, although the direction of the sign for each variable was opposite.In men alone, drinking (directly) and smoking (inversely) had significant effects on active life.Subjective health and some lifestyles are thus likely to relate to active life over time.
Self-rated health is shown to be a predictor of functional capacity as well as of mortality.The present study found that it contributes to both the change in the score of the TMIG Index of Competence (Table 5, 6) and active life expectancy (Table 8).Thus, psycho-sociological factors and lifestyle are important for prolongation of biological life and physical functions in the elderly.
In addition to looking into predictors of functional capacity based on observational studies, some intervention trials have been launched.The FICSIT Trials in the USA have succeeded in interventions of the frail elderly29).Henceforth, intervention trials for maintaining and promoting functional capacity in the competent community elderly are urgently needed30).

Figure 1 .Figure 2 .
Figure 1.Comparison of incompetence in any category among three categories of a Guttman Health Scale for the Aged* in the representative samples of the elderly between the United States of America and Japan 18)

Figure 3 .
Figure 3. Frequency in 2-year decline of the total score of the TMIG Index of Competence according to tertile of serum total cholesterol

Table
. Items of the TMIG Index of Competence10).

Table 2 .
Proportions of competence in ADL in residents aged 65 years and over in 1989 in Nangai Village,

Table 3 .
Proportions of competence in IADL in same subjects as in Table212).

Table 4 .
Means and standard deviations of the score of the TMIG Index of Competence (full marks=13) in same subjects as in Table2.

Table 8 .
Multivariate logistic regression analysis between active life and independent variables28) .