Inconsistency in the line spread test as an objective measurement of thickened liquids

Abstract

There is no objective measurement clinically used to confirm consistency of thickened liquids in dysphagia management. This research was designed to examine the line spread test (LST) as an objective measurement following Paik et al.’s (2004) LST tool model with its acceptable ranges of thickened liquids. The original method was to measure nectar and honey consistency of thickened liquids mixed by four naïve adults, four SLPs, four dietary staff members, four licensed nurses, and four registered nurses. In the initial three naïve adult’s trials: 10 out of 12 cases for nectar consistency failed to meet the acceptable range and 1 out of 12 cases for honey consistency failed. From this preliminary data, the clinical validity of the LST tool was questioned. The research method was modified to measure LST values of pure drinks. The LST measure was performed by the investigator, four SLPs, and six naïve adults. The objectives of this modified research were to obtain LST values of pure base drink and to verify what caused the discrepancy in LST values. It was found that using different plates (glass and Plexiglas) caused significant differences in LST value of all pure base drinks. Overall values measured on a Plexiglas plate were less than those on a glass plate. No significant difference was found for person who performed the LST or time of day the LST was performed. This research found that the LST tool was not a reliable method to measure the consistency of thickened liquids. Depending on which plate was used, LST values obtained varied for all base drinks. Measurements obtained in this study did not agree with values reported by Paik et al. (2004).