Validity testing of the stopwatch urine stream interruption test in radical prostatectomy patients

Abstract

Objective: To assess convergent validity of the stopwatch urine stream interruption test (UST). Specific aims were to describe relationships among stopwatch UST scores and 4 common clinical indices of pelvic floor muscle strength: 24-hour urine leakage, confidence in performing pelvic muscle exercise, 24-hour pad count, and daily pelvic muscle exercise count.

Design: Secondary analysis; instrumentation study.

Methods: The final sample consisted of baseline stopwatch UST scores and measurements of comparison variables from 47 participants in a randomized clinical trial of 3 approaches to pelvic floor training for patients with urinary incontinence following radical prostatectomy. The sample size provided 80% power to detect correlations of moderate strength or higher. The stopwatch UST was conducted in an examination room at the study site by trained study personnel (MP, ADC, JP, SM). Measurements of comparison variables were obtained from 3 instruments: 24-hour pad test, Broome pelvic muscle self-efficacy scale, and 3-day bladder diary. Relationships among study variables were evaluated with Pearson correlation coefficients.

Results: Stopwatch UST scores were moderately correlated with 24-hour urine leakage on the 24-hour pad test (r = 0.35, P < .05), the most robust comparison measure. Correlations between stopwatch UST scores and all other comparison measures were in the appropriate direction, although weak, and did not reach statistical significance.

Conclusion: Findings suggest that the stopwatch UST may be a valid index of pelvic floor muscle strength in men following radical prostatectomy. With further testing, the stopwatch UST could become a valuable clinical tool for assessing pelvic floor muscle strength in radical prostatectomy patients with urinary incontinence.