Intravesical botox injection is recommended in majority of the guidelines as second line intervention for patients with overactive bladder syndrome. Despite the robust evidences on efficacy of this treatment, there are limited studies available on the long term effectiveness of the intravesical abobotulinum toxin A injection .
The aim of this study was to evaluate the long term efficacy of abobotulinum toxin A injection  in a single teaching hospital.

For this study all patients who underwent intravesical intravesical abobotulinum toxin A injection between 2011 and 2012 in our hospital were contacted. 
At our clinic, patients with OAB and urodynamically proven detrusor overactivity (DO) who had failed first line antimuscarinic therapy, underwent intramuscular injections with 500-900 unites of abobotulinum toxin A, divided in 30-35 injections in the bladder wall.
We identified 530 patient with urodynamically proven DO, who had undergone a single intravesical abobotulinum toxin A injection between 2011 and 2012 as described above. 
From this cohort,  387 patients were reached and gave consent for our study. These patients were contacted 5 years after their initial injection and interviewed on the phone.

In our study population of 387 patients (age 18-82 years, 295 females and 92 males) , 77 out of 387 patients had neurogenic DO. The remaining patients had idiopathic DO. Our telephone interview revealed that  45,3% of the patients had either complete resolution of their symptoms for a long period of time or had significant reduction of their symptoms to a level that could be managed with oral antimuscarinic therapy. The mean duration of symptom improvement was 26,3 months.
The success rates of the treatment reduced in time as shown in the ROC curve. However,  still about half of our patients were happy with their initial intravesical abobotulinum toxin A injection.

Our retrospective study results show that in a sub-population of OAB patients with DO who have failed first line therapy, a single injection with intravesical abobotulinum toxin A injection can resolve patient symptoms either completely or reduce the symptoms to an acceptable level that can be controlled with antimuscarinics.

In patients with OAB and prven DO, intravesical abobotulinum toxin A injection can have significant reduction of symptoms in about 45 % of patients with a medium duration of  26,3 months.