Methods matter- construct validity of steps per day in patients with lumbar spinal stenosis

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Kinesiology

Background:

• Lumbar Spinal Stenosis (LSS) significantly impacts mobility and daily activity levels.
• Accurate measurement of walking in daily life is crucial for assessing functional status in LSS patients.
• Wearable accelerometers offer a promising method for objective mobility assessment.

Purpose of the Study:

• To evaluate the construct validity of a thigh-worn accelerometer for detecting walking in individuals with LSS.
• To test hypotheses regarding the agreement between thigh-worn accelerometer, a walking test, and an ankle-worn StepWatch for walking duration and daily steps.

Main Methods:

• Cross-sectional observational study involving 83 individuals with LSS.
• Participants wore a thigh-worn accelerometer for seven days and completed a walking test.
• A subset of 21 participants also simultaneously wore an ankle-worn StepWatch.

Main Results:

• The thigh-worn accelerometer showed significant agreement with the walking test for the longest walk duration (within 34% equivalence margin).
• The thigh-worn accelerometer recorded fewer daily steps than the ankle-worn StepWatch (mean difference -64%).
• Post hoc analysis revealed agreement in step count during continuous walking (mean difference -2.6%).

Conclusions:

• A thigh-worn accelerometer is suitable for monitoring continuous walking in daily life for LSS patients.
• Discrepancies in daily step counts between thigh-worn and ankle-worn devices necessitate careful consideration of device type and wear location.
• Objective mobility data from accelerometers can inform LSS management and rehabilitation strategies.