The Michigan Incontinence Symptom Index (M-ISI) is a verified measure for urinary incontinence. This study evaluates the M-ISI as a screening tool for clinically relevant urinary incontinence in a population-based sample of women. The Establishing the Prevalence of Incontinence (EPI) Study is a case-control, population-based study that enlisted women ages 35-64, with and without urinary incontinence. The M-ISI is a validated questionnaire with subdomains for stress and urgency urinary incontinence. 214 EPI subjects were given a clinical evaluation and urodynamic testing to establish the presence and type of urinary incontinence, and also completed the M-ISI. The M-ISI scores were evaluated using receiver operating characteristic (ROC) curves to determine the optimal diagnostic threshold scores above which women were likely to have clinically relevant urinary incontinence. The optimal M-ISI diagnostic threshold scores were determined to be ≥ 3 for the stress urinary incontinence subdomain (area under the curve of 0.79), ≥ 5 for the urgency urinary incontinence subdomain (area under the curve of 0.88), and ≥ 7 for the Total M-ISI score (area under the curve of 0.89). The sensitivity and specificity of the M-ISI questionnaire for stress, urgency, and total urinary incontinence were 77% and 73%, 86% and 76%, and 84% and 75%, respectively.
The M-ISI can be used to screen for clinically relevant urinary incontinence with high sensitivity and specificity among women ages 35-64. A brief, self-administered tool like the M-ISI can help health care providers recognize and manage women with urinary incontinence.