Instrument validity and reliability of a choice response time test for subjects with incomplete spinal cord injury: relationship with function.

OBJECTIVES

To investigate instrument validity and reliability of a choice response time (CRT) test for the lower extremities in subjects with incomplete spinal cord injury (iSCI). CRT in subjects with iSCI is hypothesized to be increased because of, for example, muscle weakness or increased corticospinal conduction velocity.

DESIGN

Case-control study.

SETTING

Spinal cord injury center of a university hospital in Switzerland.

PARTICIPANTS

Patients with iSCI (N=28; mean age, 51y; 57% men; neurologic level, C3-L5; median time since injury, 148d) compared with age-matched controls (50% men) to assess instrument validity by comparing CRTs. A subgroup of subjects with iSCI (n = 9) and controls (n = 13) to determine reliability.

INTERVENTION: Not applicable.

MAIN OUTCOME MEASURES: CRTs of the lower extremity were assessed and divided into reaction and movement times. Additionally, subjects with iSCI were tested for lower-extremity muscle strength, gait capacity and mobility, independence, history of falls, and fear of falling.

RESULTS

CRTs in the control group (mean ± SD, 517 ± 71 ms) were significantly faster than those in the iSCI group (743 ± 177 ms; P<.001). Retest reliability was high in controls (intraclass correlation coefficient [ICC]>.98) and subjects with iSCI (ICC>.93). In subjects with iSCI, there were moderate to good correlations between CRT and several functional outcome measures, but not with reported number of falls.

CONCLUSION

Lower-extremity CRT testing appears reliable in healthy controls and ambulating subjects with iSCI.