BRIGHTON, ENGLAND – The gait of patients with rheumatoid arthritis undergoes significant variation throughout the day, judging from findings from the DIVIGN study.
There was a 54% improvement in gait velocity overall from the start to the end of a 12-hour assessment period. The mean improvement ranged from -41% to +397%.
The findings suggest that gait velocity should be measured at the same time of day in each patient when used as an outcome measure in clinical practice or in research.
"We all know about morning stiffness and how frequently patients report this, but this is really the first attempt to quantify the effects of early morning stiffness on gait," Michael Backhouse, a podiatrist and Arthritis Research UK doctoral student at the University of Leeds, England, said at the annual meeting of the British Society for Rheumatology.
Mr. Backhouse explained that patients with rheumatoid arthritis (RA) are known to have marked gait abnormalities. This includes decreased gait velocity, reduced stride length, and more time spent in a walking phase called double support where both feet are on the ground before one or the other leg swings forward to take the next step.
To quantify the diurnal variation in gait velocity, the investigators enrolled 31 patients with RA with a median age of 67 years and 10.5 years’ disease duration who were being treated as inpatients at the Chapel Allerton Hospital in Leeds. All patients reported morning stiffness for at least 30 minutes or more every day.
Each patient was asked to walk along a 5.2-m instrumented walkway (GAITRite, CIR Systems Inc.) at five time points throughout the study day; soon after waking (0 hour) at 7 am then at 1-, 3-, 6- and 12-hour intervals. Patients were asked to walk at a self-selected pace and were allowed to use walking sticks or other aids if required.
A visual analog scale was used to determine morning stiffness, and the Health Assessment Questionnaire (HAQ) and Disease Activity Score (DAS) 28 were used to see how changes in gait velocity might influence these disease outcome measures.
The sharpest increases in gait velocity were seen in the first hour of each patient assessment, with continued improvement throughout the day. At baseline, the mean gait velocity for all patients was 37.8 cm/sec., with values at 1, 3, 6, and 12 hours of 43.8 cm/sec., 45.5 cm/sec., 48.1 cm./sec., and 53 cm/sec. These translated into overall improvements of 20.4%, 32.9%, 37.8%, and 54.1% improvements, compared with baseline.
Although no control group of similarly aged individuals without RA was assessed, Mr. Backhouse observed that the expected gait velocity of healthy elderly individuals would be about 80-100 cm/sec.
In addition, stride length increased throughout the day, and patients were better able to steady themselves between steps (i.e., longer duration of the double support walking phase) before moving forward.
"When we looked at absolute gait velocity, that’s how fast patients were actually walking, we found that it did correlate with HAQ, that’s patient-reported physical function, at all time points, but it didn’t correlate at all with DAS28 or current disease activity," Mr. Backhouse reported.
"Gait velocity is perhaps one of the most widely used clinical outcome measure in studies of RA," Mr. Backhouse further observed. "This is probably because gait velocity can be so easily and objectively measured," he continued.
However, as the results of the DIVIGN study show, "there is marked diurnal variation of gait velocity ... and repeat measures should be made at the same time of day to exclude its effects," Mr. Backhouse concluded.
Arthritis Research UK and the National Institute for Health Research (London) funded the study. Mr. Backhouse said he had no conflicts of interest.