Objectives: To present a new water displacement measurement, the Simplified Water Displacement Instrument (SWDI), and to evaluate its intra- and intertester reliability.
Design: Reliability design.
Setting: Hospital setting.
Participants: Fifty-six healthy people were studied. Intratester reliability was evaluated once a week for 4 weeks in 20 women and 10 men. Intertester reliability was assessed by 2 physical therapists in 26 people.
Interventions: Not applicable.
Main outcome measures: Coefficients of variation (CVs) and intraclass correlation coefficients (ICCs).
Results: The intratester reliability showed a CV range of 2.2% to 2.6% and an ICC range of .98 to .99. The intertester reliability showed a CV of 1.3% and an ICC of .99. There was a significant increase in arm volume in men compared with women. There were no significant differences in changes in volume over the 4 weeks. There was a significant greater right arm volume (3.3%) among the right-handed subjects (P<.001).
Conclusions: Both intra- and intertester reliability were satisfactory for the SWDI.