Validation of cough-induced leak point pressure measurement in the evaluation of pharmacological treatment of stress incontinence.

To improve routines in clinical practice and research, it is important that new tests are thoroughly evaluated before they gain widespread application. This includes establishing the reliability and validity of the new test. The purpose of this study was to establish the construct and criterion validity of cough-induced leak point pressure (CILPP) measurement. Data on CILPP, maximum urethral pressure (MUP), and a short-term pad test from a phase-I trial of a new pharmacological agent (LS 4416), developed for the treatment of stress incontinence, was used to test the validity of CILPP. Fifteen post-menopausal women with stress incontinence were studied. Phenylpropanolamine (PPA) was used as a positive control. Administration of PPA produced a statistically significant increase in MUP and CILPP. There was a significantly better effect of treatment, expressed as an increase in MUP at 1.5 hr, when PPA was used than with placebo or LS 4416. When CILPP was used to detect change after therapy, PPA produced a significantly greater increase in CILPP than did placebo (least square mean of difference 17.25, P = 0.0202). There was a moderate but statistically significant correlation between CILPP and the short-term Pad Test. Construct validity was demonstrated by the ability of CILPP to detect limited improvement in patients with stress incontinence. Criterion validity was established by the correlation of CILPP to a short-term Pad Test. We propose that, thanks to its greater methodological qualities, leak point pressure measurement should be adopted as a standard method to ascertain the effect of treatment in patients with stress incontinence. Neurourol. Urodynam. 18:591-602, 1999. Copyright 1999 Wiley-Liss, Inc.