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Gait Speed vs Functional Ability in the ‘Oldest Old’
GERIATRICS AND GERONTOLOGY SPECIAL SECTION EDITORIAL Michael W. Rich, MD, Section Editor
Gait Speed vs Functional Ability in the ‘Oldest Old’ SEE RELATED ARTICLE p. 1188
As the leading edge of the “aging tsunami” draws nearer, health professionals and health care systems seek ever more precise and practical indices of the health, health and social care needs, and expected longevity of older citizens at both the individual and population levels. This demographic imperative has generated an ever-increasing array of techniques and instruments to inform effective and cost-sensitive care of older persons. These efforts have recently focused on a landmark study by Studenski et al1 in 2011. This was a detailed metaanalysis of 9 previous longitudinal cohort studies reported between 1986 and 2000. In the aggregate these included approximately 35,000 community-dwelling adults aged 65 years or more (average age 73.5 years [including 5.1% ⬎ 85], 60% women and 80% white). All were followed for at least 5 years (with a mean of 12.2 years), during which 50.8% died, with 10-year survival rate of 59.7%. Of the many indices examined, a single one stood out: gait speed. Measured as meters per second over 4 m at a usual pace from a standing start, gait speed was the index most strongly and continuously correlated with survival, and a rate exceeding 0.8 m/s predicted longevity above the median for age and sex. This index (combined with age and sex) was as accurate as a complex combination of parameters (in addition to age and sex) that included the use of mobility aids and self-reported function, or the aggregate of chronic conditions, smoking history, blood pressure, body mass index, and hospitalization. Thus, with gait speed so easily, accurately, and economically measured, this single index of vitality and estimated survival has captured attention in both lay and scientific circles. However, confirmation of this finding remains essential in other populations, especially those who might comprise the clientele of geriatric practitioners, whose patients are often concentrated among “the oldest old,” those aged more than 85 years. Thus, “Predicting SurFunding: None. Conflicts of Interest: None. Authorship: The author is solely responsible for the content of this manuscript.
0002-9343/$ -see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjmed.2012.05.020
vival in Oldest Old People,” by Taekema et al,2 in this issue of The American Journal of Medicine, is of substantial and especially timely interest. By using the population-based Leiden 85-Plus Study, they report the survival rates of 599 citizens of Leiden, The Netherlands, who comprised 87% of its citizens celebrating their 85th birthdays in 1997-1999 and who were enrolled in a multidimensional assessment and longitudinal survival study. As in the study by Studenski et al,1 assessments included detailed information regarding demographic, health (including the Geriatric Depression Scale and the Mini Mental State Examination), chronic diseases and selfreported health, physical activity, functional status (Instrumental Activities of Daily Living [IADL] using the Groningen scale), and gait speed (m/s), all collected by research nurses in each subject’s living site. Although the study by Taekema et al2 generally confirms the important predictive value of gait speed in estimating survival among Dutch citizens after reaching 85 years of age, important differences emerged in this oldest old cohort. First, 12.2% did not complete the walking test, and this in itself was associated with diminished survival. Thus, not all persons, especially the oldest old (and notably those with cognitive or affective impairments), can effectively perform this key prognostic test. Second, although gait speed levels among Leiden subjects predicted higher survival among the participants in the highest, middle, and lowest tertiles, the cutoff rate of greater than 0.8 m/s that predicted greater than median survival in the study by Studenski et al1 was observed in only 9% of Leiden subjects, a discrepancy without clear explanation. Moreover, in 6 analytic models of increasing sophistication and complexity, further adjustment for chronic diseases, body mass index, smoking, systolic blood pressure, physical activity, and walking aid use attenuated the predictive power of gait speed to predict survival duration, as did the added measures of the Geriatric Depression Scale and Mini Mental State Examination. Thus, although gait speed may well serve as a single, simple, and easily measurable index of vulnera-
1150
The American Journal of Medicine, Vol 125, No 12, December 2012
bility to death in the oldest old, the mechanisms of that association and strategies to postpone that outcome are certain to prove complex and elusive. Finally, and perhaps most useful, the authors report the equal or superior utility of self-reported (or surrogatereported) IADL capability to predict survival compared with gait speed. In the Leiden cohort, the significant association between gait speed and mortality was lost when adjusted for IADL functional capability, whereas the opposite did not hold, that is, poor IADL ability was associated with poorer survival in both men and women in the fully adjusted model, which included gait speed, and only one quarter of those judged to have poor IADL ability survived for 5 years. So stay tuned! Much remains to be learned in gerontology and geriatrics, especially regarding our oldest old citi-
zens and patients. In the meantime, we are reminded that “slowing down” is a time-honored, visible index of declining vitality, whereas decreasing function is the common denominator of approaching dependency on the path to the end of life. William R. Hazzard, MD University of Washington Seattle
References 1. Studenski S, Perera S, Patel K, et al. Gait speed and survival in older adults. JAMA. 2011;305:50-58. 2. Taekema DG, Gussekloo J, Westendorp RGJ, de Craen AJM, Maier AB. Predicting survival in oldest old people. Am J Med. 2012; 125:1188-1194.
Gait Speed vs Functional Ability in the ‘Oldest Old’ SEE RELATED ARTICLE p. 1188
As the leading edge of the “aging tsunami” draws nearer, health professionals and health care systems seek ever more precise and practical indices of the health, health and social care needs, and expected longevity of older citizens at both the individual and population levels. This demographic imperative has generated an ever-increasing array of techniques and instruments to inform effective and cost-sensitive care of older persons. These efforts have recently focused on a landmark study by Studenski et al1 in 2011. This was a detailed metaanalysis of 9 previous longitudinal cohort studies reported between 1986 and 2000. In the aggregate these included approximately 35,000 community-dwelling adults aged 65 years or more (average age 73.5 years [including 5.1% ⬎ 85], 60% women and 80% white). All were followed for at least 5 years (with a mean of 12.2 years), during which 50.8% died, with 10-year survival rate of 59.7%. Of the many indices examined, a single one stood out: gait speed. Measured as meters per second over 4 m at a usual pace from a standing start, gait speed was the index most strongly and continuously correlated with survival, and a rate exceeding 0.8 m/s predicted longevity above the median for age and sex. This index (combined with age and sex) was as accurate as a complex combination of parameters (in addition to age and sex) that included the use of mobility aids and self-reported function, or the aggregate of chronic conditions, smoking history, blood pressure, body mass index, and hospitalization. Thus, with gait speed so easily, accurately, and economically measured, this single index of vitality and estimated survival has captured attention in both lay and scientific circles. However, confirmation of this finding remains essential in other populations, especially those who might comprise the clientele of geriatric practitioners, whose patients are often concentrated among “the oldest old,” those aged more than 85 years. Thus, “Predicting SurFunding: None. Conflicts of Interest: None. Authorship: The author is solely responsible for the content of this manuscript.
0002-9343/$ -see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjmed.2012.05.020
vival in Oldest Old People,” by Taekema et al,2 in this issue of The American Journal of Medicine, is of substantial and especially timely interest. By using the population-based Leiden 85-Plus Study, they report the survival rates of 599 citizens of Leiden, The Netherlands, who comprised 87% of its citizens celebrating their 85th birthdays in 1997-1999 and who were enrolled in a multidimensional assessment and longitudinal survival study. As in the study by Studenski et al,1 assessments included detailed information regarding demographic, health (including the Geriatric Depression Scale and the Mini Mental State Examination), chronic diseases and selfreported health, physical activity, functional status (Instrumental Activities of Daily Living [IADL] using the Groningen scale), and gait speed (m/s), all collected by research nurses in each subject’s living site. Although the study by Taekema et al2 generally confirms the important predictive value of gait speed in estimating survival among Dutch citizens after reaching 85 years of age, important differences emerged in this oldest old cohort. First, 12.2% did not complete the walking test, and this in itself was associated with diminished survival. Thus, not all persons, especially the oldest old (and notably those with cognitive or affective impairments), can effectively perform this key prognostic test. Second, although gait speed levels among Leiden subjects predicted higher survival among the participants in the highest, middle, and lowest tertiles, the cutoff rate of greater than 0.8 m/s that predicted greater than median survival in the study by Studenski et al1 was observed in only 9% of Leiden subjects, a discrepancy without clear explanation. Moreover, in 6 analytic models of increasing sophistication and complexity, further adjustment for chronic diseases, body mass index, smoking, systolic blood pressure, physical activity, and walking aid use attenuated the predictive power of gait speed to predict survival duration, as did the added measures of the Geriatric Depression Scale and Mini Mental State Examination. Thus, although gait speed may well serve as a single, simple, and easily measurable index of vulnera-
1150
The American Journal of Medicine, Vol 125, No 12, December 2012
bility to death in the oldest old, the mechanisms of that association and strategies to postpone that outcome are certain to prove complex and elusive. Finally, and perhaps most useful, the authors report the equal or superior utility of self-reported (or surrogatereported) IADL capability to predict survival compared with gait speed. In the Leiden cohort, the significant association between gait speed and mortality was lost when adjusted for IADL functional capability, whereas the opposite did not hold, that is, poor IADL ability was associated with poorer survival in both men and women in the fully adjusted model, which included gait speed, and only one quarter of those judged to have poor IADL ability survived for 5 years. So stay tuned! Much remains to be learned in gerontology and geriatrics, especially regarding our oldest old citi-
zens and patients. In the meantime, we are reminded that “slowing down” is a time-honored, visible index of declining vitality, whereas decreasing function is the common denominator of approaching dependency on the path to the end of life. William R. Hazzard, MD University of Washington Seattle
References 1. Studenski S, Perera S, Patel K, et al. Gait speed and survival in older adults. JAMA. 2011;305:50-58. 2. Taekema DG, Gussekloo J, Westendorp RGJ, de Craen AJM, Maier AB. Predicting survival in oldest old people. Am J Med. 2012; 125:1188-1194.