Reliability of Repeated Measurements on Post-Burn Scars with Corneometer CM 825(®)

The water content in burn scars, the parameter of stratum corneum water holding capacity, is an important feature in evaluation of biophysical properties of scars. Nevertheless, quantifiying this parameter is a challenge. In this study, the reliability of repeated water content measurements with Corneometer CM825(®) on (burn) scars was investigated.

Intra-observer reliability, inter-observer reliability and day-by-day variability were examined on 30 scars by means of intra-class correlation coefficient (ICC) and within-subject coefficient of variation (WSCV). Bland-Altman plots with '95% limits of agreement' were constructed.

Results revealed excellent ICC values (ICCintra  = 0.985; ICCinter  = 0.984) with relatively low WSCV (WSCVintra  = 6.3%; WSCVinter  = 10.6%) for respectively intra- and inter-observer reliability. However, the Bland-Altman plot showed that more than 5% of differences were expected to exceed 4 a.u., the limit of what has been defined as a clinically acceptable difference. Results for day-by-day variability showed good ICC value (ICCday-by-day  = 0.849) and higher WSCV (WSCVday-by-day  = 20.5%).

The Corneometer CM825(®) is an objective and sensitive instrument for water content measurements. On the basis of our results, we concluded that the instrument can be used in clinical trials, but only under very strict conditions with standardized test protocol, preferably in combination with the evaluation of other physiological parameters.