Many women regularly experience urinary incontinence, which is associated with significant social and medical problems. Incontinence may be primarily urge, stress, mixed-type, or it may result from other causes (e.g., overflow). Although urge incontinence responds to medications, stress incontinence is most effectively treated with pelvic muscle exercises, and in more severe cases, with surgery. Current guidelines advocate determining incontinence type with a series of time-consuming tests that are impractical for use in primary care offices. Brown and colleagues conducted a multicenter, prospective study to compare the sensitivity and specificity of a three-item questionnaire in classifying the type of incontinence with the standard clinical evaluation.
The study population consisted of 301 women 40 years or older who had at least three episodes of urinary incontinence per week for at least three months. Participants were primarily recruited through newspaper advertisements and underwent eligibility screening at one of five academic medical centers. Exclusion criteria included abnormal urinalysis, recent pregnancy, previous urinary tract instrumentation, major pelvic or abdominal surgery, recurrent urinary tract infections, or a congenital or neurologic condition affecting the lower urinary tract. Women who had been treated for urinary incontinence in the preceding three months also were excluded. The average participant was 56 years of age and had experienced 30 episodes of incontinence per week for seven years. Of all eligible participants, 32.7 percent were postmenopausal, and 93.6 percent had given birth to at least one child.
Eligible women completed the 3 Incontinence Questions (3IQ) at the initial visit. The 3IQ contains an initial question about incontinence in the past three months, a second question about types of incontinence, and a third question (see accompanying table) establishing which type of incontinence occurs most often. Participants completed a second 3IQ at home seven to 10 days later; statistical analysis showed that the 3IQ had fair to good reproducibility. All participants gave a medical history; underwent a complete physical and pelvic examination, cough stress test, and postvoid residual volume measurement; and completed a three-day voiding diary. Study physicians who were blinded to the 3IQ results independently reviewed the clinical evaluations to classify each participant’s type of incontinence. If the physicians disagreed, they discussed the case and reached a consensus diagnosis; this was required for 83 of the 301 participants.
Based on the clinical evaluation, 119 women were classified as having urge incontinence, 132 had stress incontinence, 42 had mixed-type, and eight women had other types. Using this evaluation as the standard, the 3IQ had sensitivities of 0.75 (95% confidence interval [CI], 0.68 to 0.81) and 0.86 (95% CI, 0.79 to 0.90) and specificities of 0.77 (95% CI, 0.69 to 0.84) and 0.60 (95% CI, 0.51 to 0.68) for urge and stress incontinence, respectively. The 3IQ produced positive likelihood ratios of 3.29 for urge incontinence and 2.13 for stress incontinence. Study physicians again reviewed the evaluations of seven participants with other types of incontinence who were incorrectly classified by the 3IQ and agreed that neither a six- to 12-month delay in diagnosis nor incorrect treatment for urge or stress incontinence would have led to dangerous complications.
|During the past three months, did you leak urine most often:
|A. When you were performing a physical activity such as coughing, sneezing, lifting, or exercising?
|B. When you had the urge or the feeling that you needed to empty your bladder, but could not get to the toilet fast enough?
|C. Without physical activity and without a sense of urgency?
|D. About equally as often with physical activity as with a sense of urgency?
The authors conclude that the 3IQ had acceptable sensitivity and specificity for classifying urge and stress incontinence compared with the standard clinical evaluation. Because a correct diagnosis saves time, expense, and inconvenience, and because an incorrect diagnosis is unlikely to produce significant harms, the 3IQ has the potential to be a useful instrument for evaluating and treating women with uncomplicated urinary incontinence in primary care settings.
editor’s note: For family physicians who routinely diagnose and treat urinary incontinence by asking questions similar to those in the 3IQ, Brown and colleagues’ study is important because it objectively measures the diagnostic performance of these questions. But how does one interpret the values assigned to unfamiliar statistical terms such as a likelihood ratio (LR)? LRs illustrate the change in likelihood of a disease produced by a test result. The larger the LR is for a positive test, or the smaller the LR is for a negative test, the more helpful the test is to rule in or rule out the presence of the disease being tested. Conversely, an LR close to 1.0 means that the test does not change the likelihood of disease and is not useful. To help decipher these and other terms being used, American Family Physician publishes a brief evidence-based medicine glossary in every issue1; a more detailed glossary is also available online.2—k.w.l.