Paper 31: Pelvic Muscle Strength Decreases with Increasing Age, Parity and Symptoms of Stress Incontinence

Abstract

OBJECTIVES: To determine whether digital assessment of pelvic muscle strength as rated by the Brink system is associated with patient characteristics and measures of urinary incontinence symptom severity in a cohort of women with stress incontinence scheduled to undergo surgery. METHODS: Baseline data from patients enrolled in the Urinary Incontinence Treatment Network Stress Incontinence Surgical Treatment Efficacy (SISTEr) trial were included in this analysis. At baseline, pelvic floor strength was assessed using the Brink scale (possible score range 3–12). Patient demographic variables included age, race, parity and history of prior incontinence surgery. Severity of urinary incontinence was measured by the Medical, Epidemiological, and Sociological Aspects of Aging (MESA) questionnaire, by standardized pad-weight testing, and by the number of daily incontinence episodes in urinary diaries. ANOVA was used to determine whether the Brink score differed significantly by each categorical independent variable, and linear regression was used to examine associations between the continuous independent variables and Brink scores. RESULTS: Baseline Brink data were available for 643 of the total 655 randomized patients in the UITN SISTEr trial. The sample was predominantly non-Hispanic white (73%). Mean (+/− SD) Brink score was 9 (+/− 2). Although absolute differences were small, the Brink score differed significantly by race (P=0.04), with mean Brink score for non-Hispanic black women being highest. There was a statistically significant difference in Brink score between patients who had prior hysterectomy and those who did not (P=0.004). The magnitude of the correlations between Brink score and the continuous independent variables were all small, but statistically significant in the case of negative correlations with age (r=−0.16, P<0.0001), number of vaginal deliveries (r=−0.10, P=0.01), and MESA scores (r=−0.09, P=0.02). Brink score did not correlate with clinical measures of incontinence severity including pad weights (r=−0.06, P=0.16) and number of accidents per day (r=0.02, P=0.53). CONCLUSION: Overall, pelvic muscle strength as rated by the Brink score was high in this cohort of incontinent patients. Associations between Brink scores and age, parity and MESA score were present but fairly small. The finding that Brink scores did not correlate with other clinical measures of incontinence severity suggests that the scale may be relatively insensitive to clinically important differences.