VANCOUVER—Repeat injections of onabotulinumtoxinA (BTXA) appear to benefit patients with non-neurogenic overactive bladder (NNOAB).

Australian researchers retrospectively reviewed the records of 52 NNOAB patients who received repeated BTXA injections from 2004 to 2011. Among the 37 patients from whom Patient Global Impression of Improvement (PGI-I) scores were obtained, most felt better after each injection.

“The pattern of PGI-I scores among patients with two, three, four, or five or more injections indicated that higher numbers of injections appeared to be associated with a greater proportion of patients who felt either no change or a little worsening after the injections,” said lead investigator Vincent Tse, MD, of the University of Sydney. “One of the factors to explain this includes a sampling error due to a smaller number of patients having a higher number of repeat injections, so the percentages may appear more polarized. Another factor may be development of antibodies to BTXA.”

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“Overall, this is a very reassuring bit of information for patients whose quality of life has been decimated by this condition,” Dr. Tse told Renal & Urology News. “We can also give confidence to our elderly population afflicted with this condition that it is safe to undergo this treatment if they wish, as the side effects are minimal.”

He added: “As our population is aging, more elderly will be afflicted with NNOAB and it is reassuring to know that repeated BTXA is safe in this population.” 

Dr. Tse and his co-investigators analyzed information from any patient with detrusor overactivity not attributed to a neurogenic cause at time of urodynamic diagnosis and who had not responded to at least two anticholinergic agents. All patients had responded favorably to an initial BTXA injection. The 37 women and 15 men had a mean age of 67.4 years (range 26-93 years), and 28 (54%) were aged 70 and older. Most of the patients received 100 to 200 units of BTXA cytoscopically. Nine of the 140 injections, however, involved doses of more than 200 units. The mean period between treatment and review of the data was 49 months (range 9-101 months).

Thirty-three patients (64%) received two injections only, 15 (29%) had three or four injections, and four (7%) had five to eight injections. The average time between injections was 9.3 months. Eight individuals started taking oral anticholinergic medications again between the BTXA injections.

“This study helps us to let our patients know that if the first injection is helpful, it is likely to predict future injections would be successful,” Dr. Tse said.

Nine patients had a urinary tract infection and three developed transient urinary retention requiring catheterization for less than two weeks. Three patients died from unrelated causes.

Cerebrovascular accidents occurred in two patients, Parkinson’s disease developed in two, and multiple sclerosis developed in one, but Dr. Tse noted that “there is no link between the injections and the neurological conditions.”