Test-Retest Reliability of Quantitative Sudomotor Axon Reflex Testing

Purpose: To determine the reliability of quantitative sudomotor axon reflex testing (QSART). Methods: The QSART at four sites was performed at two time points (n = 20 healthy participants) to determine the intraclass correlation coefficient with 95% confidence intervals. The standard error of measurement and minimal detectable change for men and women was obtained from QSART values from a larger cohort (n = 67). Results: Intraclass correlation coefficients (95% confidence intervals) for the forearm, proximal leg, distal leg and foot were 0.75 (0.46 to 0.89), 0.49 (0.07 to 0.77), 0.71 (0.38 to 0.88) and 0.48 (0.07 to 0.76). Standard error of measurements ranged from 0.666 to 0.978 mu L for men and 0.273 to 0.653 mu L for women. Minimal detectable changes ranged from +/- 1.847 to +/- 2.712 mu L for men and +/- 0.756 to +/- 1.809 mu L for women. Conclusions: We observed moderate test-retest reliability for QSART with a large standard error of measurements and minimal detectable changes for both men and women. The results of this study suggest limited utility of QSART for monitoring sudomotor function in longitudinal and interventional studies.