Researchers at Dana-Farber Cancer Institute and the VA Boston Healthcare System have uncovered a new vital sign for gauging survival and likelihood of having an unplanned hospitalization in older patients with blood cancers: the speed at which they can walk.
In a study published today in the journal Blood, the researchers report that for every 0.1 meter per second decrease in how fast patients walk four meters (about 13 feet), the risk of dying, unexpectedly going to the hospital, or using the emergency room increased by 22 percent, 33 percent, and 34 percent, respectively. The association was strongest in patients with non-Hodgkin lymphoma.
"The slower someone walks, the higher their risk of problems," said the study's senior author, Jane A. Driver, MD, MPH, co-director of the Older Adult Hematologic Malignancy (OHM) Program at Dana-Farber and associate director of the Geriatric Research Education and Clinical Center at VA Boston Healthcare System.
Measuring gait speed not only helps identify individuals who are frail and may have worse long-term outcomes, but it also can indicate those who are in better-than-expected shape based on their age. Researchers say the study results support efforts to integrate gait speed as a routine part of medical assessments for older patients with blood cancer, and that it should be measured over time to guide treatment plans.
"There is an unmet need for brief screening tests for frailty that can easily fit into clinic workflow and predict important clinical outcomes. This test can be done in less than a minute and takes no longer than measuring blood pressure or other vital signs," said Driver. "Based on our findings, it is as good as other commonly used methods which take considerably more time and resources and may not be practical for many oncology clinics."
The new study enrolled 448 adults ages 75 years and older who had hematologic cancers. Participants were 79.7 years old on average and completed several screenings for cognition, frailty, gait, and grip strength. Gait speed was measured using the National Institutes of Health 4-meter gait speed test. Patients were asked to walk at a normal pace for 4 meters and their speed was recorded in meters per second using a stopwatch.
The association between slower walking speed and poorer outcomes persisted even after adjusting for cancer type and aggressiveness, patient age and other demographic factors, as well as traditional measures of frailty and functional status. Gait speed remained an independent predictor of death even after accounting for standard measures of physical health.
Patients whose performance status - their general well-being and quality of life - was rated as very good or excellent by their physician were stratified into three groups by gait speed - those at risk or frail, pre-frail, or robust. Of the 314 patients in this group, nearly 20 percent had an unplanned hospital stay unrelated to elective or scheduled treatments, and 16.8 percent visited the emergency department.
"Our study reveals that the current standard of care for functional assessment in oncology--performance status--is not sufficient for elders with blood cancers. Gait speed appears to be much better at differentiating those patients at highest risk for poor outcomes," explained Gregory A. Abel, MD, MPH, director of the OHM clinic.
So much a part of everyday life that it's easily taken for granted, walking is a complex activity that involves multiple bodily systems, including the musculoskeletal, cardiovascular, and nervous systems, all of which must function properly together. Gait speed has been widely used as an assessment in rehabilitative and geriatric medicine. Measuring it doesn't require special equipment, is reasonably efficient, and has value even for patients who use a cane or a walker, Driver noted.
The first author of the study is Michael A. Liu, of Dana-Farber, Brigham and Women's Hospital (BWH), and the VA Boston Healthcare System. Co-authors are: Anays Murillo, MPH, Robert Soiffer, MD, Richard M. Stone, MD, and Gregory A. Abel, MD, MPH, of Dana-Farber; Clark DuMontier, MD, of Dana-Farber and Beth Israel Deaconess Medical Center; Tammy Hshieh, MD, MPH, of Dana-Farber and BWH; and Jonathan F. Bean, MD, of Spaulding Rehabilitation Hospital.
The study was supported in part by training grants from the National Heart, Lung, and Blood Institute (grant # HL007479) and the National Institute on Aging (AG000158); the Murphy Family Fund from Dana-Farber Cancer Institute; and a Clinical Research Scholar Award from the American Cancer Society. Driver is funded by a Veterans' Administration Merit Review Award.