Background: Gait speed is a simple physical function measure associated with key outcomes in the elderly population. Gait speed measurements may improve clinical care in patients with COPD. However, there is a knowledge gap about the reliability and variability of gait speed testing protocols in COPD. We evaluated established techniques of measuring gait speed in patients with COPD and assessed feasibility of implementing gait speed as a routine vital sign in an out-patient clinic.
Methods: The usual 4-meter gait speed (4MGS) ("walk at a comfortable/natural pace"), maximal 4MGS ("walk as fast as you can safely"), usual 10-meter gait speed (10MGS), and maximal 10MGS of subjects with stable COPD were measured. Walks were measured using a stopwatch and automated timing system. For the feasibility/implementation phase, patients from the entire spectrum of respiratory diseases completed acceptability surveys, and clinical assistants administered gait speed measurements using an automated timing system. Time to train and to administer the test and acceptability by the staff were evaluated.
Results: Seventy subjects enrolled; 60% were men, and the mean age ± SD was 69 ± 10 years. All methods showed excellent test-retest reliability (intraclass correlation coefficient of 0.95-0.97). The difference between the two timing systems did not exceed the suggested minimal clinically important difference of 0.1 m/s for the usual pace instructions but did exceed 0.1 m/s for maximal pace walks. The difference between 4MGS and 10MGS was 0.13 ± 0.10 m/s.
Feasibility: Most subjects reported that gait speed measurement prior to clinic appointment was very acceptable (66%) or acceptable (33%). Time added to clinic visit measuring 4MGS was 95 ± 20 seconds, and clinical assistants reported gait speed measurements as very acceptable (60%), acceptable (30%), and somewhat acceptable (10%).
Conclusions: Gait speed is a reliable measure in COPD, regardless of instructed pace, distance, or timing mechanism; however, adhering to one protocol is suggested. 4MGS was easily implemented into clinical practice with high acceptability by patients and clinic staff.
Keywords: ambulatory care facilities; chronic obstructive; feasibility studies; gait; methods; patient acceptance of health care; pulmonary disease.