NEW YORK (Reuters Health) – A single test of either walking speed or the Short Physical Performance Battery (SPPB) can reliably predict future problems with mobility or activities of daily living (ADL), a new prospective study suggests.
Lower extremity physical performance measured at one point in time is a powerful predictor of future disability, the authors wrote online November 23 in the Journal of Gerontology.
“No matter how good or bad your physical functioning has been, current fitness is more important than history in predicting future functional decline and increased risk of disability and dependence,” said principal investigator Dr. Sari Stenholm, senior researcher in the Department of Public Health of the University of Turku, Finland.
“The person’s history of physical functioning doesn’t matter in terms of the future disability risk,” she said.
Dr. Stenholm and her colleagues conducted the InCHIANTI study of factors contributing to loss of mobility in late life in two Italian towns located in the Chianti area of Italy. They followed a random sample of community-dwelling seniors, all at least 65 years old, who were without ADL disability at baseline and at the three-year follow-up.
The researchers tested walking speed and the SPPB at baseline and three years later, which they called “zero-time,” and they used logistic regression to examine the associations between physical performance measures and mobility and ADL disability at the six-year and nine-year follow-ups.
Of the 1,155 people who agreed to enroll in the study, 977 took the physical performance measurement tests at baseline and at the three-year follow-up.
To measure walking speed, participants were asked to walk four meters along a corridor at their usual pace as if they were walking down the street, starting from a standing position, using a cane or walker if needed.
The SPPB involved three lower-extremity performance tests: walking speed involved two four-meter walks at usual pace along a corridor, ability to stand from a chair involved standing up and siting down as quickly as possible five times with their hands folded across their chest, and standing balance involved standing in three progressively more difficult positions.
Walking speed and SPPB score at zero-time strongly predicted mobility disability three and six years later, independent of age, sex, education, lifestyle factors, chronic diseases, and walking speed and SPPB score three years earlier.
At six years, 194 (22%) people had been lost to follow-up. This group was older and more sedentary, with more hypertension, coronary heart disease, peripheral arterial disease, knee osteoarthritis and depression than those who remained in the study (p<0.05 for all). This group also had lower walking speed and SPPB score than those who remained in the study (p<0.001 for all).
The odds ratios for three- and six-year incident mobility disability were 0.63 and 0.75, for an increment of 0.1 meters/second in walking speed, and 0.60 and 0.68, for an increment of one SPPB point score. The predictors of ADL disability were similar.
“We may be conflicted between using performance assessed at the time of screening or following potential participants over time, enrolling them when their performance declines a certain amount. This study shows that the first strategy is enough and the second, which is more complicated and expensive, offers no advantage,” said co-author Dr. Luigi Ferrucci, geriatrician, epidemiologist, and scientific director of the National Institute on Aging in Bethesda, MD, in an email.
“Measuring performance is easy, inexpensive and very informative. Although many physicians are initially skeptical, when they try they continue this practice forever,” he said.
Dr. Stenholm added in an email, “This doesn’t mean that we should not follow older people’s physical functioning. On the contrary, we need to monitor them regularly, so that we can notice possible declines at early phases.”
Melissa Bloom, a board-certified neurologic physical therapist at Physiotherapy Associates in Tucker, Georgia, who was not involved in the study, commented by email that “while the study did not show more significant results with repeated measures over time, by taking measures at regular intervals, clinically, you can catch declines as soon as they begin, at which time appropriate physical therapy could be initiated, further disability avoided and independence improved. Physical therapy treatments can often help address the limitations found in the study population,” she said.
J Gerontol A Biol Sci Med Sci 2013.