From among a broad range of factors representing six domains considered central to walking ability, seven clinical measures were found to be independently associated with prevalent severe mobility difficulty in community-resident, functionally limited older women. These factors included feelings of helplessness and cognitive impairment, representing the central nervous system domain; knee pain on examination, representing the bone and joints domain; poor reported vision, representing the perceptual domain; and three measures probably representing multiple domains: inability to rise from a chair five times, inability to stand with feet side by side for 10 seconds, and reported balance problems while walking on a level surface or dressing. Twenty-two percent of those without severe mobility difficulty—having great difficulty or needing an aid to walk within one’s home or having a measured usual gait speed slower than 0.5 m/s—developed it within 1 year. The longitudinal analysis revealed that feelings of helplessness, inability to rise from a chair five times, knee pain on examination, poor reported vision, and cognitive impairment independently distinguished women at high risk of developing severe mobility difficulty.
Study findings provide evidence that, in functionally limited older women, deficits from multiple domains signal the transition to severe mobility difficulty. A brief clinical examination that encompasses five diverse measures that require little time, equipment, or training to acquire may bolster strategies to detect and prevent mobility dependence in disabled older women. Increased ability of clinicians to evaluate mobility status in older persons is important and significant, given the high personal and societal costs of mobility difficulty23–26
and evidence of the benefit of physical activity in older populations.27
Cognitive impairment was most strongly associated with incident severe mobility difficulty, consistent with previous findings of cognitive function predicting gait speed decline in initially well-functioning older adults.28
This suggests that cognitive impairment may be an important signal of the transition to severe mobility difficulty regardless of overall functioning and presence of other impairments (e.g., pain and vision). The MMSE requires little training to administer and is frequently used as a screening tool in clinical practice.
Inability to rise from a chair five times without use of arms was strongly associated with severe mobility difficulty at baseline and within 1 year. Although initially considered an indicator of lower extremity strength, particularly of the quadriceps muscles, it is now known that multiple factors, including back muscle composition and balance, pain, and “vitality” influence chair stand ability.29,30
Chair stand ability may be a robust indicator of severe mobility difficulty because it requires the integrated and coordinated action of factors similar to those needed for walking, including lower limb strength and balance. Together with findings that timed chair stands predict subsequent mobility difficulty in higher-functioning populations,3
these results suggest that the ability to perform repeated chair stands is an effective predictor across the spectrum of functional capacity.
Poor reported vision was predictive of severe mobility difficulty at 1 year, consistent with previous findings of its associated risk of functional decline.31,32
Although visual acuity is commonly assessed in clinical settings, a previous study33
found that nonstandard vision tests had higher failure rates with older age than standard high-contrast visual acuity and visual fields testing, which showed the lowest failure rates. To characterize vision in these analyses, a simple three-item question was selected for its efficiency and ease of use in screening. Poor self-reported vision may be predictive of severe mobility difficulty, because it captures problems with other aspects of vision important to mobility, such as contrast sensitivity and depth perception, in addition to visual acuity. It also reflects vision under “real world” conditions, such as poor lighting, that may reduce mobility. Additional longitudinal studies are needed to evaluate the ability of this three-item question, versus standard and nonstandard vision tests, to predict mobility difficulty.
In the clinical setting, helplessness is often considered a symptom of depression and, accordingly, is one component of the GDS. Although several longitudinal studies have shown that depressive symptoms predict physical decline,34,35
to the authors’ knowledge, no study has examined the role of sense of helplessness alone in predicting mobility difficulty. In univariate models, agreement with the statement, “I often feel helpless in dealing with the problems of life,” and mild depressive symptomatology, represented by a GDS score greater than 9, each predicted incident severe mobility difficulty. However, backward selection eliminated GDS scores from the final cross-sectional model. A possible explanation is that 64% of women with feelings of helplessness also had mild depressive symptom-atology and that helplessness and a GDS score greater than 9 were moderately correlated, with a Spearman correlation coefficient of 0.45. This suggests that the helplessness dimension of depression may play a significant role in the association between difficulty and depression or could be an outcome of this association. Further studies are needed to confirm whether the single statement assessing helplessness is as informative as the 30-item GDS in predicting mobility difficulty.
of the WHAS population examined three groups: one with emotional vitality, a four-item construct defined as high levels of happiness and personal mastery, as well as low levels of depressive symptomatology and anxiety; an intermediate group that failed to meet at least one of the four emotional vitality criteria; and a group with high depressive symptomatology. Personal mastery was partly defined as disagreement with the statement “I often feel helpless in dealing with the problems of life.” The authors found that the intermediate group tended toward poorer function and higher mortality than emotionally vital subjects. The current study suggests that feelings of helplessness may account for the greater risk of the intermediate group.
Knee tenderness on palpation or pain with passive motion detected by a trained examiner was also a significant independent predictor of severe mobility difficulty. This is often a clinical sign of knee osteoarthritis, a well-documented risk factor for decline in walking ability.38–40
In contrast, self-reported knee pain was not found to reliably predict onset of severe mobility difficulty. It may be that knee pain on examination was a more-robust predictor, because it may be a more-sensitive measure and less dependent on subject behavior and activity participation. Individuals with knee pain often avoid activity that generates pain, including walking, although such pain may underlie the impending development of severe mobility difficulty due to deconditioning and strength loss, among other factors.
A major difference between the cross-sectional and longitudinal models was the nonsignificance of the two balance-related measures in the latter. The inability to stand with feet side by side had a strong correlation with severe mobility difficulty and accordingly was rare in women without severe mobility difficulty at baseline, who constituted the longitudinal sample. Self-reported balance problems while dressing or walking on a level surface may not have been predictive because a substantial number of subjects with these difficulties at baseline reported none or less-frequent balance problems at 1 year. These results suggest that the inability to stand with feet side by side and self report of balance problems dressing or walking reflect balance incapacities whose presence is synonymous with severe mobility difficulty.
To test the statistical robustness of the predictive measures, the longitudinal model was repeated using each component of the composite measure of severe mobility difficulty separately—usual gait speed, self-reported difficulty walking across a small room, and dependence on an aid to walk 4 m. There were some differences in the combinations of significant clinical measures that emerged for each component. This suggests that use of a more-limited or -restrictive operational definition of severe mobility difficulty may miss important subgroups at risk and supports use of a composite assessment. Use of a composite assessment is consistent with clinical practice, in which evidence of pathology is frequently derived from several sources. Furthermore, self-report and performance-based measures are considered to provide complementary information.41–43
Several limitations should be considered. The general-izability of these results is limited to disabled community-resident women without severe cognitive impairment; thus, further studies are needed to determine applicability to men and those with severe dementia. In addition, the potential contribution of chronic diseases was not examined, because they were not included in the conceptual model used to select candidate measures, although impairments themselves are likely to reflect disease severity.5,26
In addition, clinical measures for some domains were limited in precision and scope, which therefore were not well represented in the analysis.
In summary, this study found a parsimonious set of clinical measures, drawn from a range of physiological domains, that identify older individuals at high risk of developing severe mobility difficulty. With a few brief questions and tests that require no special equipment and little training, clinicians and ancillary staff can identify those at risk of losing meaningful walking ability. Better recognition of threatened mobility independence enables clinicians to provide timely recommendations of appropriate interventions and anticipatory guidance on meeting future needs.