We read with interest “Trends in urodynamics study utilization in a Southern California managed care population” by Lippman et al.

In the introduction, the authors state “in patient with demonstrable stress incontinence on office evaluation and normal post-void residuals, urodynamic measurements were not predictive for success and did not predict voiding dysfunction.” This is a misinterpretation of the VALUE (Value of Urodynamic Evaluation) study, which potentially is damaging for our patients; unfortunately, this message is scattering via different journals. Midurethral slings are potentially obstructive procedures that carry a special risk in patients with preexisting voiding dysfunction. The VALUE study was not designed to elucidate this risk. However, subgroup analysis confirmed the increased risk of poor outcome. Thus, only 62.1% of the patients with voiding dysfunction (as defined by the authors) met the primary outcome measure compared with 78.3% of the patients without voiding dysfunction. Clinically, this is a highly significant difference, although statistically borderline ( P = .064), but it is important to realize that only one-half of the entire population was included in this subgroup analysis; thus, the statistical insignificance is therefore most likely due to a lack of power (a type 2 error). In our view this should be taken seriously, and patients with preexisting voiding dysfunction should be informed at least about the increased risk of poor outcome and offered an opportunity to decide for alternative treatment.

Voiding dysfunction is defined as abnormally slow and/or incomplete micturition. The only objective way to find out whether the patient has voiding dysfunction is by noninvasive urodynamic screening in terms of uroflowmetry and postvoid residual urine volume measurement and eventually invasive urodynamics, to sort out whether a patient has obstruction or hypoactive detrusor function.

Urinary incontinence symptoms are unreliable as to the underlying dysfunction, thus, women with mixed symptoms (even pure stress incontinence) may present underlying pure detrusor overactivity or different combinations of stress incontinence with or without detrusor overactivity and with or without voiding dysfunction. The preoperative work-out depends on the complexity of symptoms. In most cases, simple noninvasive screening for voiding dysfunction will do it. However, if maximum flow rate is decreased significantly, if the flow pattern is repeatedly abnormal, and/or if postvoid residual is repeatedly increased, there will be an indication for invasive urodynamics. Voiding dysfunction does not necessarily exclude a midurethral sling, but the patient obviously needs to be informed sufficiently about the decreased success of surgery in this situation.