Because it is an indicator of general health and a red flag for certain conditions, gait speed alone is proposed as a vital sign.
Cummings SR, Studenski S, Ferrucci L. A Diagnosis of Dismobility-Giving Mobility Clinical Visibility. A Mobility Working Group Recommendation. JAMA (2014) Published online April 24, 2014. doi:10.1001/jama.2014.3033
Simple gait speed should be used as a vital sign for the care of older patients, these authors propose.
A diagnosis of dismobility would be defined as a very slow gait speed of ≤0.6 meters per second. Below this level, disability and poor health increase rapidly. By this definition, the prevalence of dismobility at age 60-64 is 3.1% for men and 2.7% for women, and it increases sharply at older ages.
Slow gait is a predictor of all-cause mortality. It limits independence, decreases quality of life, and is associated with increased risk of disability, hospitalization, placement in long-term care, and progression of many chronic diseases.
Measuring gait speed is simple, quick, reproducible, inexpensive, and feasible in clinical settings, say these authors, suggesting a timed 4-meter walk. Patients with slow gait speeds should be assessed for treatable conditions such as peripheral vascular disease, vitamin D deficiency, and low testosterone levels, they suggest, and counseled about a program of regular exercise and physical therapy.
Dismobility is distinct from other measurements of poor mobility, because it is based on gait speed only. The Short Physical Performance Battery (SPPB), for example, also includes static balance and timed chair rises.