In performance-based tests, which objectively assess various aspects of physical functioning, an individual typically performs a task in a standardized manner and performance is measured with predetermined, objective criteria, often including time to completion or counting of repetitions. In recent years, these measures have been increasingly employed in studies of functional status and disability in old age. In older persons, performance measures provide information that complements what can be learned from a clinician's physical examination (Tinetti and Ginter, 1988) and from traditional, questionnaire-based approaches that assess disability through proxy or self-report (Guralnik et al., 1989, 1994; Reuben et al., 1992, 1995).
The Women's Health and Aging Study (WHAS) included physical performance measures because they offer objective and detailed information about functional capacity and therefore provide valuable information for understanding the causal pathway from diseases to disability. The specific performance tests selected assess a spectrum of functioning, from basic abilities such as balance to complex activities such as putting on a blouse. These measures also quantify physical function along a continuous scale, ranging from very poor to excellent. They are therefore expected to be particularly valuable in detecting change in function over time.
A variety of performance tests have been developed for use in institutions (Gerety et al., 1993; Winograd et al., 1994) and among community-dwelling older persons (Guralnik et al., 1994; Harding et al., 1994; Reuben and Siu, 1990; Tinetti, 1986; Tinetti and Ginter, 1988; Weiner et al., 1992; Williams and Hornberger, 1984; Williams et al., 1990). In general, these tests may be categorized by either the domain of functioning they assess (e.g., upper extremity versus lower extremity) or the complexity of the functioning they assess (more basic physiologic abilities, such as grip strength, versus more complex tasks, such as putting on a blouse).
The first part of this chapter groups the results of performance-based tests assessing basic physical abilities according to lower extremity and upper extremity function. Performance of more complex tasks that mimic activities in daily life are reported later in the chapter. The performance tests were administered in the participant's home by a nurse, with the exception of functional reach, dialing the telephone, putting on a blouse, and opening a lock with a key, which were administered by an interviewer.
The tables also provide information on subjects with missing values and, in particular, the percentage who could not complete the tests because of physical limitations. Identifying inability to perform a test provides meaningful information about individual functioning. In addition, completion rates for these tests may be important to other investigators as they estimate the proportion of the disabled population that can be evaluated using each specific instrument.
Good lower extremity function is necessary for mobility and is thus a critical element for independence in the community. Measures of gait, balance, and ability to rise from a chair have been found to predict mortality and nursing home admission in representative samples of older adults (Guralnik et al., 1994) and incident disability in nondisabled persons over age 70 years (Guralnik et al., 1995). Measurements of hip flexor and knee extensor muscle strength are presented in Chapter 12 (see Table 12.7).
The ability to walk is essential for many tasks of daily life. It requires the coordinated function of a number of subsystems, including muscular strength, joint mobility, coordination, proprioception, reflex control, and balance.
In the WHAS, the participant was asked to walk over a 4-meter course. For a small group of women, adequate space was not available in the home and a 3-meter course was used. Participants were instructed to stand with both feet at the starting line and to start walking after a specific verbal command. Timing began when the command was given. In this test, the subject could use a cane, a walker, or other walking aid, but not the aid of another person. The times to complete the first meter and the entire path were recorded. The test was repeated three times, twice at the woman's usual pace and once at her fastest possible pace. The speed of the faster of the two usual-pace walks is presented. The length of the walk expressed in meters divided by the time in seconds was used to calculate average walking speed.
Table 4.1 shows the results for the measured walks. The percent of participants unable to do the usual-pace walk increased with increasing severity of disability but not with age. This lack of an age association was unexpected. One possible explanation is that a high proportion of the oldest disabled women who cannot walk a short distance reside in long-term care facilities and were therefore excluded from this study of community-dwelling women. The percent unable to do the fast-pace walk was higher than for the usual-pace walk and increased with increasing age and disability.
Walking speed was inversely related to age and level of disability in both the usual-pace and fast-pace tests. It has been demonstrated that usual walking speed of less than 0.6 meters/ second is associated with increased risk of falls (Nevitt et al., 1989). In the WHAS population, the percent of subjects under this threshold ranged from 50 percent to over 75 percent, depending on age and level of disability (Table 4.1).
The difference between mean gait speed in the fast-pace versus the usual-pace walk becomes smaller with increasing level of disability, specifically 0.4, 0.3, and 0.2 in the moderate, ADL difficulty receives no help, and ADL difficulty and receives help groups, respectively (Table 4.1). This result should be interpreted with caution, however, since the results for the fast-pace walk include a somewhat smaller subset of subjects (women who were slower in the normal-pace walk were more likely not to perform the fast-pace walk).
A series of performance tests in the WHAS explore the integrity of physiological systems involved in the maintenance of static and dynamic balance.
Static balance is evaluated in three different, progressively more difficult stances (Buchner et al., 1993; Guralnik et al., 1994): (1) side-by-side: feet side by side, touching; (2) semi-tandem: side of the heel of one foot touching the big toe of the other; (3) tandem: heel of one foot directly in front of and touching the toes of the other foot. Each stance is progressively more difficult to hold. Women unable to hold a position for 10 seconds were not asked to attempt further stands.
The results of the balance tests are reported in Table 4.2. The proportion of women able to hold each stand decreased substantially with increasing age and level of disability. Almost 40 percent of women age 65 to 74 years maintained the tandem stand for the full 10 seconds in contrast to only 4 percent of the oldest women. Similarly, 35 percent of the moderately disabled women held the tandem stand for 10 seconds compared to 8 percent of the most disabled women. Progressively higher proportions of women were able to hold the semi-tandem and side-by-side stands, compared with the full tandem.
The functional reach test is a dynamic measure of the perceived limit of stability during a voluntary movement (Duncan et al., 1990; Weiner et al., 1992). For this test, the participant was instructed to stand with her right shoulder next to a wall, make a fist, fully extend her arm horizontally at the level of the shoulder, and then reach forward as far as possible without losing balance or changing the position of her feet. Functional reach is defined as the difference (in centimeters) between the initial and final position of the fist. The results shown in Table 4.3 are the best of three trials.
A relatively large percentage of the population did not perform the functional reach test. Participants were considered unable to do the test if they could not stand unassisted for 30 seconds, if there were concerns about safety, or if they attempted but could not complete the test. Excluded from Table 4.3 are the 10 percent of women whose homes had insufficient wall space to perform the test. As lack of sufficient wall space is unlikely to be associated with ability to perform the test, the data reported here should be considered representative of the entire WHAS sample.
The proportion unable to perform the test rose steeply with increasing age and level of disability. Among those who performed the test, the mean distance reached was shorter in women age 75 years and older compared with younger women, and shorter in those receiving help with ADLs compared with the remainder of the cohort. There was a wide spectrum of performance in the total population, ranging from 7.5 centimeters for those in the 5th percentile to 34.0 centimeters for those in the 95th percentile. Interestingly, this range was quite similar for all age and disability subgroups.
To test the ability to rise from a chair, participants were asked to sit with their arms folded across their chests in a straight-backed chair placed with its back against a wall, and then to stand up from the chair one time. If they were successful, they were asked to stand up and sit down as quickly as possible five times in a row. Timing commenced from the initial sitting position and ended at the final standing position at the end of the fifth stand.
The chair stand is a complex test in which several physiologic components, including muscular strength, balance, coordination, joint range of motion, and exercise tolerance, contribute to the overall performance. From the functional point of view, the task may be described as the ability to transfer the body from one posture to another, with the second posture requiring a higher level of energy and more effective functioning of the systems involved in maintaining balance.
Table 4.4 shows that the simple capacity to stand from a chair without using the arms is strongly associated with both age and level of disability. Table 4.5 shows the results for the repeated chair stands. It is interesting to note that the proportion of women who were unable to perform five chair stands was just slightly higher than the proportion who were unable to perform the single chair stand, as shown in Table 4.4. Among women who completed five stands, the mean time to completion increased with increasing age and severity of disability. There was, nonetheless, a wide range of performance in each age and disability subgroup. Evidence indicates that poor performance in chair stand tests is associated with adverse health outcomes in older persons (Cummings et al., 1995; Guralnik et al., 1994, 1995; Tinetti et al., 1995).
Performance on tests of upper extremity function is an important marker of functional dependency (Williams et al., 1990). Older individuals who perform poorly on tests of manual dexterity tend to use more health care resources (Scholer et al., 1990; Williams et al., 1982), including intermediate and long-term care (Williams and Hornberger, 1984; Williams, 1987).
In the WHAS, the following components of upper extremity function were assessed: grip and pinch strength, overhead lifting ability, shoulder range of motion, manual dexterity, and performance of selected tasks of daily living.
Table 4.6 and 4.7 report data on grip and pinch strength, which were obtained using a JAMAR hand dynamometer (Model #BK-7498, Fred Sammons, Inc., Burr Ridge, IL) and a standard 0-60 pound pinch gauge (Model #81441, Adaptability, Colchester, CT), respectively. Grip strength was performed three times with each hand. The best measure in the stronger hand is reported. For pinch strength, the best of two trials (one on the left side and one on the right side) is reported. For both strength measures, the percent of subjects who did not perform the tests increased with level of disability, while there was no clear association with age. Among those who were able to perform the tests, grip and pinch strength decreased with increasing age and level of disability.
To evaluate overhead lifting ability, another aspect of upper extremity strength, a water-filled plastic jug weighing 10 pounds was placed on the lap of the participant, who was then asked to lift the jug above her head using both arms. Nearly half the participants could lift the 10-pound jug over their heads and less than 8 percent could not lift it at all (Table 4.8). The percentage of women who could not lift the jug at least to eye level increased with increasing age and level of disability. The proportion of women who could lift the 10 pounds above their heads declined with increasing age and severity of disability, although the decline was more pronounced with increasing level of disability.
Shoulder range of motion was tested using standardized voluntary movements. External rotation was assessed by having the participant put both hands behind her neck at the level of the ears. To evaluate internal rotation, the participant placed both hands behind her back at waist level with the fingers touching in the midline. These measures provide different information than traditional assessments in which the examiner manipulates the limbs to examine passive range of motion. Voluntary movements are influenced by the presence of pain and muscular weakness, as well as by the morphologic characteristics of the joints.
For external and internal rotation, performance was classified as "fully able" (test performed correctly), "partially able" (test performed partially; for example, forearm not parallel to the floor or hands not behind the neck for external rotation), or "unable" (no component of the movement could be performed), according to pre-established criteria.
The data on external shoulder rotation show reduced range of motion with increasing age and level of disability. The reduction in range of motion is particularly notable in association with disability level, declining from about 80 percent fully able among the moderately disabled to only half fully able among women who received help with ADLs. In contrast, problems with internal rotation were relatively rare, affecting less than 5 percent overall, with little association with age and an increase with increasing level of disability.
The Purdue Pegboard is a test of manual dexterity that involves two different abilities: gross movements of arms, hands, and fingers, and fine motor dexterity, also called "fingerprint" dexterity. The test consists of picking up small steel pegs from a well in the pegboard and placing them sequentially in 10 holes as quickly as possible.
Results are shown in Table 4.10 for the dominant and nondominant hands. There is a clear relationship of performance with age and disability level. With increasing age and severity of disability, the proportion who were unable to complete the test increased and, among those who completed the test, there was a decline in both the mean and median times. The strong association between manual dexterity and disability is noteworthy, as many ADLs do not depend on fine motor movements of the hand. Performance on the Purdue Pegboard test probably also reflects the central neurologic processing components of movement, such as coordination.
The performance-based assessment of upper extremity function ended with three timed tests that mimic common tasks performed in daily life -opening a lock with a key, putting on and buttoning a blouse, and finding a telephone number and dialing it. The capabilities explored by these performance tests differ from the functional abilities described above. These tests focus on the ability to reproduce complex, real-life tasks rather than on specific physiologic abilities. Thus, these measures are closer to the concept of disability than are the tests of more basic abilities.
For the task of opening a lock with a key, the participant was instructed to pick up a key from the table and open a lock mounted in a wooden block as quickly as possible. Time was recorded from the first movement of the participant's hand toward the key until the lock was opened. A maximum time of 1 minute was allowed. For the task of putting on and buttoning a blouse the participant was given a blouse of appropriate size and instructed to put it on and button it as fast as possible without mistakes (Cardiovascular Health Study, 1990). This task was performed in the standing position or, for women unable to stand unsupported, in the sitting position. Timing began when the participant touched the blouse and ended when the task was completed or after 4 minutes, whichever came first.
In general, the functional abilities of almost all participants could be evaluated with these tests, although many were unable to perform certain aspects of the tasks. All but 6 percent were able to open the lock and all but 5 percent were able to put on the blouse (Tables 4.11 and Tables 4.12). However, 19 percent of the women were unable to button the blouse. Poor performance in opening a lock and putting on a blouse was associated with level of disability, and the buttoning component of putting on the blouse was especially problematic for women who received help with ADLs. A major component of these tasks is manual dexterity. The association of performance on these tasks with level of disability is consistent with the results previously presented for tests investigating more basic physical abilities of the upper extremities, i.e., pinch and grip strength and Purdue Pegboard performance.
In the telephone use task, the participant was instructed to look up a specific telephone number on a mock telephone book page and to dial it on a standard Touch-Tone telephone. If the participant could not find the number, the examiner told her where on the page to look for it. If still unsuccessful, she was given the number on a piece of paper. Timing began when the participant started looking for the telephone number and was stopped when she had dialed the entire number. Tables 4.13 shows results separately for finding and for dialing the number, and gives the distribution of time to complete the entire task for those who found and dialed the correct number.
The ability to find and dial a telephone number is more dependent on cognition, vision, and ability to read than on motor ability. Women with severe cognitive impairment were excluded from this study population, so the role of cognition in task performance is probably less important than for the total older population. The ability to find the telephone number decreased markedly with increasing age and disability level. The need for prompting increased somewhat with age but not with disability level. The strong age and disability gradient was more related to visual problems and was noted through the need for a magnifier and inability to read print. Among those who found the correct telephone number or were given the number, 90 percent dialed the correct number. The percentage successful in this task declined with age and level of disability. However, the age gradient was associated with the increased percentage of the older subjects dialing the incorrect number, while the disability gradient was more related to actual inability to dial the number in those with the greatest disability. The total time required to perform the task, shown only for those who completed the entire sequence by themselves, was associated with both age and disability, although there was a large range of variability within each subgroup.
The physical performance tests described in this chapter provide comprehensive information on many aspects of the functional capabilities of moderately to severely disabled older women in the WHAS. The study provides valuable information on the proportion of women who can complete each task and the level of performance of those who do complete the task. Even in this cohort of women, selected for having disability, most women could complete most of the tasks. There was, however, a wide range of performance in each of the age and disability subgroups. Ultimately, improving our understanding of the factors that cause an older person's functional limitations and the impact these limitations have on an older person's ability to remain independent in the community is an important challenge for aging research.
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