The cotton swab test. Receiver-operating characteristic curves

The purpose of this prospective, cohort study was to perform a receiver-operating characteristic (ROC) analysis of the cotton swab test and its ability to predict stress incontinence. The study was performed in a tertiary care gynecologic urology clinic over a period of 3.5 years. Two hundred sixty-three women presenting with the complaint of urinary incontinence formed the basis of the cohort. Subjects were classified as having genuine stress urinary incontinence or incontinence secondary to another factor following urodynamic testing. The cotton swab test was performed as part of the standard urogynecologic assessment. Measurement was made of the resting, straining and calculated resultant change in angle. ROC curves were calculated for each of the angles measured. The resultant ROC curves demonstrated that straining angle has the best discriminatory power in the diagnosis of genuine stress urinary incontinence. The optimum cut-off point for this discrimination is a deflection of 40 degrees from the horizontal, with a resultant sensitivity of 83%. Despite the diagnostic trend, the sensitivity of the straining angle does not allow one to confidently make a diagnosis of genuine stress urinary incontinence without a confirmatory evaluation. The test, however, can be beneficial in the counseling and triage of women with lower urinary tract complaints.