The reliability and validity of the timed up and go test in individuals following lumbar spinal surgery

Background Although the Timed Up and Go (TUG) test is frequently used in lumbar pathologies, its test – retest reliability, convergent validity, and measurement error have not yet been established in the postoperative period.Objective The purpose of this study was to comprehensively evaluate the test – retest reliability, convergent validity, andmeasure menterr or of the TUG test in individuals after lumbar spinal surgery.Methods A cross-sectional study was conducted with 100 individuals (mean age 55.0 ± 8.9 years; 48 women, 52 men) at least 6 weeks after lumbar spinal surgery. Participants performed the TUG, Five-Repetition Sit-to-Stand Test (5xSTS), and 10-Meter Walk Test (10MWT). The TUG was repeated after a 1-hour rest period. Test – retest reliability was evaluated using the intraclasss correlation coefficient (ICC2,1). Measurement error was evaluated using the standard error of measurement (SEM), the minimal detectable change at the 95% confidence level (MDC95), and the Bland – Altman limits of agreement (LoA). Convergent validity was assessed using the Pearson correlation coefficient with the 5xSTS and 10MWT.Results Excellent test – retest reliability was demonstrated (ICC2,1 = 0.99; 95% CI: 0.98–0.99). The SEM and MDC95were 0.26 seconds (s) and 0.72 s, respectively. The mean difference (bias) was −0.00 s (95% CI: −0.80 to 0.70), with lower and upper limits of agreement of −0.74 s (95% CI: −0.87 to −0.61) and 0.73 s (95% CI: 0.60 to 0.86), respectively. The TUG showed strong positive correlations with the 5xSTS (r = 0.95, p < .001) and the 10MWT (r = 0.92, p < .001).Conclusion The TUG is a reliable and valid tool for measuring functional mobility in individuals after lumbar spinal surgery, providing objective data to complement subjective assessments.