Clinical measurement of the static rear stability of occupied wheelchairs.

Abstract

To evaluate a new clinical test, platform testing of the static rear stability of wheelchairs occupied by their users (using methods adapted from the International Organization for Standardization [ISO]), from the perspective of its measurement properties, safety, and comfort. Within-subject comparisons. Rehabilitation center. Ninety-seven wheelchair users. Static stability (with the brakes locked and unlocked, the occupant leaning forward and back, and with antitip devices in place), dynamic stability (the criterion measure), reliability, validity, sensitivity, specificity, predictive values, and likelihood ratios. Test-retest reliabilities (n = 18 to 24) were all >.93. The test's construct validity was demonstrated by the finding that static stability was appropriately affected by locking the brakes, body position, and antitip devices (p < .0001). Spearman's rank correlations between static and dynamic stability ranged from .29 to .65. Sensitivity ranged from 46% to 85%, specificity from 59% to 78%, positive predictive values from 76% to 86%, negative predictive values from 42% to 69%, positive likelihood ratios from 1.56 to 2.95, and negative likelihood ratios from .22 to .71. There were no adverse events, and the subjects tolerated the tests well. In the clinical setting, the ISO platform test of static rear stability has good to excellent measurement properties, is safe, and is well tolerated. Static-stability testing in this setting should be performed in the context of a comprehensive evaluation of wheelchair safety and performance.