Intra- and Inter-Investigator Reliability of Measurement of Lip-Seal Strength in Adults.

The purpose of this methodological study was to clarify intra- and inter-investigator reliability of lip-seal strength measurement in adults. Lip-seal strength was measured with a digital medical strain gauge using the button-pull method. The coefficient of variation (CV) of intra-investigator reliability of measurement in 24 healthy adult volunteers (16 men, 8 women; mean age, 26 +/- 3 years) ranged from 0.088 to 0.103 (mean for 3 investigators, 0.098). The intraclass correlation coefficient (ICC [1,1]) of intra-investigator reliability of this method of lip-seal strength measurement ranged from 0.759 to 0.832 (mean, 0.804). The ICC (2,1) of inter-investigator reliability of the measured values was 0.737. The CV of intra-investigator reliability of lip-seal strength measurement by a single investigator in 54 adult patients (14 men, 40 women; mean age, 49 +/- 16 years) was 0.072. The ICC (1,1) of intra-investigator reliability of this measurement method of lip-seal strength was 0.863. A CV of approximately 0.2 or lower is considered to indicate excellent agreement; an ICC of approximately 0.75 or higher is considered indicative of good reliability. These results demonstrate that measurement of lip-seal strength in adults with this device offers sufficient intra- and inter-investigator reliability.