Reliability of skin impedance in subjects with chronic neck pain

Abstract

BACKGROUND:

Skin impedance is a biological signal that has been employed in the measurement of pain. However, there are few scientific data on skin impedance, with a great variety of assessment methods and controversial results.

OBJECTIVE:

To examine the intra- and inter-rater reliability of skin impedance measurement in individuals with chronic neck pain.

METHODS:

This is a blind cross-sectional study. Thirty individuals of both genders, aged between 18 and 45 years and with chronic neck pain were included in the study. Two examiners assessed skin impedance of the upper and lower limbs and torso at two intervals separated by one week. For statistical analysis, we used the intraclass correlation coefficient (ICC ${}_{2,3}$ ) to determine the intra- and inter-rater reliability of skin impedance, with its respective confidence interval of 95%, standard error of measurement (SEM) and minimum detectable change (MDC).

RESULTS:

The intra-rater reliability was considered substantial to excellent, with ICC values ranging between 0.843 and 0.978, SEM between 0.58 and 15.26 $\mathrm{\Omega }$ , and MDC between 1.61 and 42.31 $\mathrm{\Omega }$ . The inter-rater reliability was moderate to excellent, with ICC values ranging between 0.761 and 0.997, SEM ranging between 0.22 and 16.72 $\mathrm{\Omega }$ , and MDC ranging between 0.63 and 46.35 $\mathrm{\Omega }$ .

CONCLUSION:

The measurement of skin impedance of the upper and lower limbs and torso in individuals with chronic neck pain has acceptable reliability values when considered at different times and by different examiners.