The usefulness of the line spread test as a measure of liquid consistency

Although dietary modification is a common treatment strategy used to manage dysphagic patients who aspirate thin liquids, there are no standard definitions for thickened liquid preparation. This lack of standardization leads to variability in practice and points to the need for a simple tool for clinicians to assess thickened liquid consistency. The current study analyzed the utility of the Line Spread Test (LST) in this regard. Twenty-six liquids (10 powder-thickened "nectar" juices, 10 powder-thickened "honey" juices, and 6 barium mixtures) were assessed using both a viscometer for objective measurement of viscosity and the LST. Whereas the LST was able to separate the juices into nectar and honey categories, it was not able to separate barium mixtures into these categories nor compare barium to juices. Furthermore, the LST was not predictive of viscosity. Thus, the results of the current study suggest that the LST may be useful in the broad categorization of fluids into therapeutically significant groupings but that it cannot be used more specifically to measure fluid viscosity. Further studies of this and other tools are necessary to identify inexpensive practical tools for quantification of thickened liquid consistency.