Reproducibility and validity of the “PET bottle cap test” for simple evaluation of upper limb functions

Examination of upper limb dysfunction

Abstract

The purpose of the study was to examine the PET bottle cap test (PCT) regarding reproducibility by the test-retest method and validity by correlation analysis with peg test, grip and pinch strengths, and unbuttoning time in 19 patients with upper limb dysfunction. As a result, the intraclass correlation coefficients of the PCT were 0.881 and 0.931 on the affected and unaffected sides, respectively. Furthermore, the PCT was moderately correlated with the peg test and significantly with the unbuttoning time. However,it was not significantly correlated with the grip and pinch strengths. Thus, the PCT was highly reproducible in patients with upper limb dysfunction and useful in evaluating dexterity. The PCT is a highly versatile method because it requires no special measuring equipment and can be conducted only with a PET bottle and a stopwatch, suggesting its utility in clinical practice.