One-minute stair climbing, 50-foot walk, and timed up-and-go were responsive measures for patients with chronic low back pain undergoing lumbar fusion surgery.

Physical capacity tasks are useful tools to assess functioning in patients with low back pain (LBP), but evidence is scarce regarding the responsiveness (ability to detect change over time) and minimal important change (MIC). The aim was to investigate the responsiveness and MIC of 5-min walk, 1-min stair climbing, 50-ft walk, and timed up-and-go in patients with chronic LBP undergoing lumbar fusion surgery. In this clinimetric study, 118 patients scheduled for lumbar fusion surgery for motion-elicited chronic LBP with degenerative changes were included. All patients performed the physical capacity tasks 5-min walk, 1-min stair climbing, 50-ft walk, and timed up-and-go 8-12 weeks before and six months after surgery. Responsiveness was evaluated by testing five a priori responsiveness hypotheses. The hypotheses concerned the area under the receiver operating characteristics (ROC) curve and correlations (Spearman's rho) between the change scores of the physical capacity tasks, the Oswestry Disability Index 2.0 (ODI), and back pain intensity measured with visual analog scale (VAS). At least 80% of the hypotheses would have to be confirmed for adequate responsiveness. Absolute and relative MICs for improvement were determined by the optimal cut-off point of the ROC curve based on the classification of improved and unchanged patients according to construct-specific global perceived effect (GPE) scales. One-minute stair climbing, 50-ft walk and timed up-and-go displayed adequate responsiveness (≥ 80% of hypotheses confirmed), while 5-min walk did not (40% of hypotheses confirmed). The absolute MICs for improvement were 45.5 m for 5-min walk, 20.0 steps for 1-min stair climbing, - 0.6 s for 50-ft walk, and - 1.3 s for timed up-and-go. The results of responsiveness for 1-min stair climbing, 50-ft walk, and timed up-and-go implies that these have the ability to detect changes in physical capacity over time in patients with chronic LBP who have undergone lumbar fusion surgery.