Objective: To evaluate the measurement variability of quantitative sensory testing (QST) in persons with post-stroke shoulder pain.
Design: A test-retest design.
Participants: Twenty-three persons with post-stroke shoulder pain (median age 65 years).
Methods: Thermal detection thresholds (cold and warm), pain thresholds (cold and heat) and mechanical pain thresholds (pressure and pin prick) were assessed twice in both arms, 2-3 weeks apart. Measurement variability was analysed with the intraclass correlation coefficient (ICC2.1), the change in mean (đ) with 95% confidence interval (logarithmic scales), and the relative standard error of measurement (SEM%; re-transformed scales).
Results: The ICCs for thermal thresholds ranged from 0.48 to 0.89 in the affected (painful) arm and from 0.50 to 0.63 in the unaffected arm, and for mechanical pain thresholds from 0.66 to 0.90 in both arms. No systematic changes in the mean (đ) were found. The SEM% ranged from 4% to 10% for thermal detection and heat pain thresholds, and from 17% to 42% for cold pain and mechanical pain thresholds in both arms.
Conclusion: QST measurements, especially cold pain thresholds and mechanical pain thresholds, vary in persons with post-stroke shoulder pain. Before QST can be used routinely to evaluate post-stroke shoulder pain, a test protocol with decreased variability needs to be developed.