Step Activity Monitor: Accuracy and test-retest reliability in persons with incomplete spinal cord injury

Abstract

Abstract-Recovery of walking after incomplete spinal cord injury (iSCI) is a common focus of rehabilitation, but few measurement tools capture walking performance outside the clinic or laboratory. This study determined the accuracy and testretest reliability of the Step Activity Monitor (SAM), a microprocessor-driven accelerometer that measures walking activity. We evaluated 11 individuals with iSCI during replicate 6-minute walk tests (6MWTs) and 10-meter walk tests (10mWTs) scheduled <1 week apart. The SAM was 97% accurate compared with hand-tallied step counts. SAM values were stable across repeated walking performances (intraclass correlation coefficient = 0.97-0.99). Standard error of measurement values were 6.0 steps and 0.8 steps for the 6MWT and 10mWT, respectively. Ninety-five percent confidence intervals were 203.7 to 177.0 steps for the 6MWT and 16.1 to 12.7 steps for the 10mWT. The SAM is an accurate and reliable device for capturing walking activity in individuals with iSCI.

Validity and reliability of the 10-m walk test and the 6-min walk test in spinal cord injury patients

“…3 Therefore, the recovery of ambulation has become the target of several pharmacological and rehabilitative approaches 4 and a precise evaluation of ambulation in these patients has become mandatory. Although several walking measures have been suggested for assessment of walking function in patients with SCI, over the past 5 years most studies have focused on the 10-m walk test (10MWT), 5-14 the 6-min walk test (6MWT) [5][6][7][8][9][10]13,15 and the Walking Index for Spinal Cord Injury (WIS-CI). 5,7,9,12,14,[16][17][18][19][20] This set of measures allows a comprehensive assessment of walking function, which includes the use of walking aids, braces, physical assistance, and speed and endurance.…”

“…Both the 10MWT and the 6MWT have been utilized in studies of SCI patients. [5][6][7][8][9][10][11][12][13][14][15][16] Both tests showed good inter-and intra-rater reliabilities, 5 a good relationship with lower limbs strength 17 and with other walking tests (the WISCI and the 'timed up and go'). 5 Furthermore, both tests seem to have a greater sensitivity to detect changes of performance in less severely injured SCI patients if compared with the WISCI, which has a ceiling effect.…”

“…[25][26][27][28] The distance of the track varied from 85 m, 25 39 m 26 to 20-m corridors with 1801 turns 28 for several studies on stroke subjects. A few studies of SCI defined distances and turns, which varied from non-standardized hallways of 50 feet or more with 901 turns 8 to 53 (reviewed in Olmos et al 10 ) and 60 m, 13 with 901 turns and different surfaces. Several other studies in SCI by the same authors did not identify either the shape of the track or the frequency of turns.…”

“…Several other studies in SCI by the same authors did not identify either the shape of the track or the frequency of turns. 5,7,8,15 Therefore, we propose to test the following hypotheses: 10MWT…”

Reliability of Ambulatory Walking Activity in Patients With Hematologic Malignancies

“…[32] Examples of these statistics are the SE of measurement procedure and the SDD. [33,34] to be clinically useful, an assessment procedure must have a small measurement error to detect a real change. A test-retest difference in a patient with a value smaller than the SE of measurement is likely to be the result of measurement noise and is unlikely to be detected reliably in practice; a difference greater than the smallest real difference is highly likely (with 95% confidence) to be a real difference.…”