Detrusor muscle function declines with age

By Joanna Lyford, Senior medwireNews Reporter

Detrusor muscle function and efficiency decline with increasing age, a urodynamic study of women with stress urinary incontinence indicates.

The study authors say that detrusor hypocontractility should therefore be suspected in older women presenting with lower urinary tract complaints.

Philippe Zimmern (UT Southwestern Medical Center, Dallas, Texas, USA) and colleagues obtained information on 945 women who had participated in the SISTEr (Stress Incontinence Surgical Treatment Efficacy Trial) and TOMUS (Trial Of Mid-Urethral Slings) trials. All women underwent urodynamic testing in advance of surgery for stress incontinence.

In all, 96 (10%) of the women were aged 65 years and older, and they were compared with the remaining 849 under-65s, using propensity score-matching to account for potential confounders.

Writing in the Journal of Urology, Zimmern et al report that three urodynamic parameters – non-instrumented uroflowmetry (NIF) peak flow rate (Qmax), the maximal detrusor pressure at Qmax and Valsalva leak point pressure – were all significantly lower in the over-65s than in younger women.

A further four parameters – time to Qmax in NIF, time to Qmax in pressure flow study, voiding time and volume at first desire – were all significantly higher in over-65s than in younger women.

After adjusting for confounders, women aged 65 years and above were nearly three times as likely to have detrusor hypocontractility as younger women, report Zimmern and co-authors.

Finally, bladder contractility index (BCI) was 115 cm H₂O, on average, for over-65s versus 125.5 cm H₂O in younger women. While this difference did not quite reach statistical significance, BCI and age were inversely correlated, with BCI falling by 8 cm H₂O for each 10-year increase in age.

The researchers say that their results indicate that detrusor contractility and efficiency decline with age, and recommend that detrusor function should be evaluated in older women presenting with stress urinary incontinence.

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