by Ryan Basen
Staff Writer, MedPage Today
November 17, 2016

WASHINGTON — Most people with knee osteoarthritis (OA) were able to walk the 6,000 daily steps they needed to improve their condition and prevent disability, according to researchers here.

In a prospective observational study, nearly half of the 1,790 knee OA patients (or high-risk knee OA patients) walked more than 6,000 steps daily. They performed the sit-to-stand test (repeating five times) in a mean 10.2 seconds, walked 400 m in just over 5 minutes, and walked 20 m at a clip of 1.3 m/sec, reported Hiral Master, PT, MPH, CPH, of the University of Delaware in Newark, and colleagues.

They also pinpointed benchmarks patients need to meet to reach the daily steps, they reported at the American College of Rheumatology annual meeting.

They recommended that clinicians encourage knee OA patients to meet the physical function thresholds of sit-to-stand >14 sec, gait speed <1.26 m/sec, and 400 m walk >350 sec or >5.5 minutes.

Taking longer than 12 seconds to perform the standing test is associated with fall risk for older adults, while walking slower than 1.2 m/sec makes it difficult to walk in the community, and taking longer than 365 seconds to walk 400 meters is a risk factor for death in older adults.

“Now that we have an idea of how much ability is necessary to be active, we can better develop intervention strategies that are personalized to patients’ individualized needs so we can get them to be more active,” said co-author and presenter Daniel K. White, PT, ScD, also at the Delaware institution.

Performing below these thresholds on the tests above may mean knee OA patients are not getting the appropriate amount of activity to prevent functional knee limitation White added. In a previous paper, White and colleagues determined that to be 6,000 steps daily.

They analyzed data from patients at the 48-month follow-up visit enrolled in the Osteoarthritis Initiative (OAI). Included patients had to wear a monitor for at least 10 hours daily over at least 4 days. Participants had a mean age of and 55% were female. The mean body mass index was 28.4 kg/m².

The study showed that daily steps had a positive correlation with walking speed (r=0.4, P<0.001), but a negative correlation with the standing test (r=- 0.2, P<0.001) and 400-m walk (r=-0.4, P<0.001).

Thresholds of high specificity (80%-95%) of physical performance (the 6,000 steps) ranged from 11-14 seconds for the standing test, 315-350 seconds for the 400-m walk, and 1.10-1.25 m/sec on the 20-m walk.

The results need to be validated in other cohorts, but “we have the preliminary numbers to rely on. We have confidence we’re on the right track,” White told MedPage Today.

Study limitations included testing for only one cutoff for physical activity (6,000 steps) and using daily steps as a physical activity marker, without taking into consideration other physical activity with few or no steps, such as bike riding.