Optimal Conditions for Obtaining Valid Step Count Measurements in Hospitalized Patients with Abnormal Gait.

Objective: This study investigated the optimum conditions for obtaining valid step-count measurements for patients with abnormal gait.

Methods: Subjects comprised 61 hospitalized patients with abnormal gait. Four different devices were tested: Active Style Pro (AS), Walking Style (WS), Lifecorder PLUS, and Steps. The same device type was attached to the waist on both the affected and the unaffected side. Patients then walked 25 m at a comfortable speed. This test was repeated four times, once for each device. The measurement error (ME) and walking parameters (gait velocity, step length, and cadence) were calculated from the test data. ME scores smaller than 3% and 10% were classified as valid: scores above these standards were classified as invalid. Walking parameter values that identified the invalid group with a specificity of 0.95 were set as the cut-off velocity (COV), the cut-off step length (COS), and the cut-off cadence. Sensitivity values >0.40 and positive predictive values >80% were then set as necessary conditions.

Results: COV values were 0.90 m/s (AS on the unaffected side at 3% ME and AS on the affected side or the unaffected side at 10% ME), 0.92 m/s (WS on the unaffected side at 10% ME), and 0.98 m/s (WS on the affected side at 3% ME). COS values were 0.50 m (AS on the affected side at 10% ME) and 0.52 m (AS on the unaffected side at 3% ME).

Conclusion: The most accurate measurements were obtained using AS attached to the unaffected side with a gait velocity of >0.90 m/s.