Evaluating onabotulinumtoxinA effectiveness in overactive bladder according to sex

This study looked at the effectiveness of onabotulinumtoxinA (OBTA; Botox) injections for the treatment of overactive bladder (OAB) according to sex. It found that OBTA improved symptoms of OAB in women and men with lower levels of PSA (a protein made by the prostate that increases when the prostate is enlarged), but not in men with higher PSA levels.

OAB is a condition that causes an increased need to urinate, often associated with a sense of urgency.  This is thought to be caused by spasms of the bladder muscle. It can be treated with medications. When medications do not work, it can be treated with OBTA which is injected into the bladder. This helps to paralyze the bladder muscle and reduce symptoms of OAB.

OAB affects men and women in different ways. One reason that OAB acts differently in men may be due to the size of the prostate gland. When the prostate is enlarged it can affect urination and this may change the way that OAB medications work in men. PSA levels in the blood can show if the prostate gland is enlarged. It is not clear if OBTA has similar effects in men and women and if having an enlarged prostate gland affects how well OBTA works in men.

248 patients with OAB participated in this study. 186 patients were female, 62 were male. Of the male participants, 40 had lower PSA levels (below 1.5 ng/mL) and 22 had higher PSA levels (1.5 ng/mL or higher). Patients were treated with either single-dose OBTA (100 U) or placebo. Symptoms were monitored before treatment and 12 weeks after treatment.

After 12 weeks, female participants treated with OBTA showed a significant improvement in all symptoms. Men with lower PSA levels also showed an improvement in symptoms. On average those treated with OBTA needed to urinate 2-3 fewer times per day than those treated with placebo. However, men with higher PSA levels did not show an improvement in OAB symptoms after OBTA injections.

This study showed that onabotulinumtoxinA is an effective treatment for OAB in women and in men with lower PSA levels. It was not effective in men with higher PSA levels.

This study looked at PSA levels, which indicate an enlarged prostate. However, PSA levels do not inform on the size of the prostate gland. Further studies are needed to see if the size of the prostate impacts the effectiveness of this treatment.