Tools for Assessing Physical Function in the Geriatric Population
Self-Reported Physical Function
Geriatricians evaluate function by scoring the need for assistance with instrumental activities of daily living (IADLs) and basic activities of daily living (ADLs). IADLs encompass complex skills that are necessary for maintaining independence in the community, such as using the telephone; taking transportation; doing shopping, housework, and laundry; taking medications; and managing finances. ADLs encompass more basic functions required to maintain independence in the home, including bathing, dressing, toileting, feeding oneself, transferring from a bed or a chair, and maintaining continence (Table 1).
In the general geriatric population, requiring assistance with IADLs and ADLs has foreshadowed both further functional decline and mortality.[2,7] A study of community-dwelling older adults found that those who were impaired in one or more IADLs at the start of the study had almost sevenfold greater odds of being admitted to a nursing home within the next 6 years. However, if the respondents were dependent in one or two ADLs at the start of the study, they had almost 10-fold greater odds of being institutionalized.[8] In terms of mortality, community-dwelling older adults who were dependent in at least one IADL had almost a sevenfold greater risk of dying over the 6-year follow-up period compared with subjects who had no impairment.[8]
In older adults with cancer, independence in IADLs has been associated with improved treatment tolerance and improved survival. In a study of patients aged ≥ 70 years with advanced non–small-cell lung cancer receiving chemotherapy, independence in IADLs before starting treatment was associated with higher quality of life and improved overall survival.[9] In a smaller study of patients with ovarian cancer aged ≥70, functional dependence, defined as living at home with assistance or living in an assisted-care facility, independently predicted the risk of toxicity from chemotherapy.[6]
ADL dependence and how it affects outcomes has not been established in studies of outpatient cancer care for older adults, likely because most of this population does not require assistance with ADLs. However, the story for hospitalized older adults with cancer is more compelling. In a study of older adults with cancer admitted to an acute care for elders (ACE) unit, 45% required assistance in ADLs.[10] This has significant implications for these patients, as previous studies have demonstrated that the presence of impairment in ADLs increases the risk of mortality for hospitalized older adults.[7,11]
Performance-Based Measures of Physical Function
Older adults who are beginning to experience functional decline may not always detect and subsequently report early changes in function. Thus, while the IADL and ADL scales are convenient in a busy office setting because of their quick and easy administration, some studies have indicated that performance-based measures more accurately identify limitations in function than those relying on self-report.[12,13]
• Short Physical Performance Battery—A simple, standardized examination of physical function is the Short Physical Performance Battery (SPPB). It involves five directly observed tests that can be conducted by a member of the office staff (Table 2): walking 8 ft at the patient's usual walking speed; rising from a chair and returning to the seated position 5 times; and standing for 10 seconds with the feet together (in the side-by-side position), semitandem position (heel of one foot placed to the side of the first toe of the other foot), and tandem position (heel of one foot directly in front of the toes of the other foot).[13] Total scores range from 0 to 12, with higher scores indicating better function.
In a study of more that 5,000 subjects aged ≥ 71, increasing SPPB performance scores were associated with a stepwise decline in the mortality rate. Subjects who scored in the 25th percentile were more than twice as likely to die as those in the 75th percentile (a 5-point difference in scores). As decline in mobility has been correlated with progressive loss of other functions, it is particularly telling that low SPPB scores predict disability in ADLs at 1 and 4 years of follow-up.[14]
• Timed Up and Go Test—The Timed Up and Go (or Get Up and Go) test is a performance-based measure of functional mobility. To perform the test, the older adult sits in a chair with arms folded across the chest. While being timed with a stopwatch, the patient stands, walks forward 3 meters, turns, walks back to the chair, and sits, all the while without using the arms for support.
In a study of community-dwelling older adults ranging in age from 70 to 84 years, the mean time to complete the test was 8.5 seconds. Patients who were able to perform the test in less than 20 seconds tended to be independent in transfers. Older adults who required 30 or more seconds were more likely to require assistance with chair and toilet transfers, were at high risk for falls, and the majority could not climb stairs. The 25% of subjects who required between 20 and 29 seconds to complete the test varied widely in their balance, gait speed, and functional abilities. In this “grey zone” group, further individual assessment was needed to clarify functional ability. Scores on the Timed Up and Go correlated with measures of balance and gait speed.[15]
• Walking Speed—Several studies in the geriatric literature have indicated that gait speed is a valid functional indicator, and its simplicity is attractive for the clinical setting. An office staff member simply times patients walking at their usual speed for 4 meters marked on the floor with tape. In a prospective cohort study of 487 community-dwelling older adults, 41% of “slow walkers” (gait speed < 0.6 m/s) were admitted to the hospital at least once in the ensuing 12 months, compared with 26% of medium-speed walkers (0.6–1.0 m/s) and only 11% of “fast walkers” (> 1.0 m/s).[16] A decrease in walking speed by 0.1 m/s within 1 year is associated with a higher mortality rate at 5 years.[17] We found no studies of gait speed specific to the older adult cancer population; nevertheless, it provides a simple performance-based measure for the office setting, and merits further study.
