Inter-rater reliability study of the modified Oxford Grading Scale and the Peritron manometer

Abstract

Objective: To evaluate the inter-rater reliability of the modified Oxford Grading Scale and the Peritron manometer. Design: All participants were evaluated twice, first by one examiner and 30 days later by a second examiner. Measurements of vaginal squeeze pressure were compared with the results from the palpation test. Participants: Nineteen women with a mean age of 23.7 years (range 21 to 28 years). Results: Inter-rater reliability for vaginal palpation was fair (κ=0.33, 95% confidence interval 0.09 to 0.57). Using the Peritron manometer, the difference between examiners was less than 10cmH2O in 11 of the 19 (58%) cases. The palpation test did not differentiate between weak, moderate, good and strong muscle contractions. This study found fair inter-rater reliability for the modified Oxford Grading Scale and moderate inter-rater reliability for the Peritron manometer. Conclusions: The inter-rater reliability of vaginal squeeze pressure measurement using the Peritron manometer is acceptable and can be used in re-evaluations performed by different examiners in clinical practice. However, for research purposes, the ideal situation would be for a single examiner to assess and re-assess the subject. Vaginal palpation is important in the clinical assessment of correctness of a pelvic floor muscle contraction, but this study does not support the use of the modified Oxford Grading Scale as a reliable and valid method to measure and differentiate pelvic floor muscle strength. © 2010 Chartered Society of Physiotherapy.