Assessment of the perceptual threshold of touch (PTT) with high-frequency transcutaneous electric nerve stimulation (Hf/TENS) in elderly patients with stroke: a reliability study.

OBJECTIVE: To evaluate the inter-rater reliability and reliability between occasions of assessing the perceptual threshold of touch (PTT) with high-frequency transcutaneous electric nerve stimulation (Hf/TENS) in elderly patients with stroke.
DESIGN: A test-retest study of reliability using intraclass correlation coefficient (ICC) and limits of agreement.
SETTING: Geriatric rehabilitation unit.
SUBJECTS: Thirty-two consecutive patients with stroke > or = 65 years of age. MAIN OUTCOME MEASURES: Two-channel current stimulator TENS CEFAR Tempo with four self-adhesive skin electrodes. The stimulator delivered a high-frequency constant current of 40 Hz. The strength of the stimulation was quantifiable and assessed in milliampere (mA).
INTERVENTIONS: The assessments were performed on the hands and feet by two raters. The PTT was identified as the level registered in milliampere (mA) at which the patients perceived a tingling sensation.
RESULTS: The ICC values (0.94-0.99) were shown to be good for inter-rater reliability, as well as reliability between occasions. However an additional analysis with limits of agreement showed a high level of agreement for assessment of the hand but a moderate to low agreement for assessment of the foot where some bias was also identified. Clinical acceptable reliability: > or = 1 mA for the hand and > or = 5 mA for the foot are so far recommended for establishing real differences in clinical measures.
CONCLUSION: Hf/TENS shows an overall high reliability for assessing the PTT of the hand and moderate to low reliability for the foot. Additional research with exclusion of bias is needed to determine the reliability of assessing the foot.