OAB is a common chronic urological disorder, with an incidence in school-aged children ranging from 17.8% to 26% [6, 14]. In addition, this condition is liable to impact normal social activities, disrupt sleep and even impair self-esteem, which extremely affects patients’ quality of life. Most urologists take a stepped approach to address this disease, beginning with the least invasive therapy (lifestyle guidance, pelvic floor exercises, biofeedback, bladder training) and progressing to more invasive or costly interventions (anticholinergic drugs, neuromodulation, surgery) [1, 15].

Biofeedback is a form of re-education or learning in which the patient is retrained within a closed feedback loop [7]. Information related to the participant's normally unconscious physiologic processes is presented as a visual, auditory or tactile signal. Biofeedback improves the contractile function of urethral sphincter and anal levator. At the same time, the neuromuscle and afferent nerve are stimulated, coupled with the repeated movement pattern information introduced into the central nervous system, gradually restoring the motor function. Indeed, in recent studies, biofeedback has been successfully applied in cases of urinary incontinence due to detrusor instability, with a reduction in morbidity and adverse effects [13, 16]. However, patients need to be intelligent enough to understand what is expected of them during the operating process. Additionally, biofeedback can be an adjunct to other forms of treatment, such as anticholinergic drugs, and is particularly useful in children [16].

For adult patients, various drugs, such as oxybutynin, tolterodine and solifenacin, have been introduced and used widely with proven efficacy and safety [17,18,19]. In contrast, the drugs available to children are limited. Data about the efficacy and safety of newer anticholinergic drugs in children are scarce [10]. As a consequence, the management of paediatric OAB is still considered to be challenging and complex. To date, only oxybutynin has been officially approved for children by medical authorities in North America [10, 19, 20]. Solifenacin has been accredited by the Food and Drug Administration (FDA) for OAB in adults since 2005. It has a long half-life, excellent bioavailability, and is highly selective for the muscarinic receptor M3 of the bladder than for the salivary glands [11, 12]. Some studies have indicated that the affinity of Solifenacin to M3 receptor is about 14.2 times higher than that of M2 receptor, while the affinity of tolterodine to M3 receptor is almost no difference from M2 receptor. Therefore, the incidence of dry mouth, the greatest problem with anticholinergic drugs, was lower in solifenacin group than tolterodine [21,22,23]. Oxybutynin is one of the most widely used M-receptor antagonists for children with OAB, but many children have experienced unbearable complications (constipation, dry mouth, blurred vision, headaches, flushing of the face, abnormal behavior). There are some reports regarding the side effects of central nervous system, such as cognitive impairment [11, 19, 24]. Two open-label, baseline-controlled, phase 3 studies were conducted in pediatric patients aged 6 months to 18 years with neurogenic detrusor overactivity, who were treated with sequential doses of solifenacin over 40-week treatment period. This study concluded that solifenacin was effective and well tolerated, suggesting this medicine may be a viable alternative to oxybutynin for children [25]. Hoebeke and colleagues performed a retrospective uncontrolled study of 138 children with OAB who were treated with solifenacin for a mean of 23 months. They found solifenacin to be effective with an overall 85% response rate and side effects in only 6.5% of their cohort [12]. A long-term study conducted in Japan enrolled 252 OAB patients, in which treatment was continued for 52 weeks (or 60 weeks), suggesting that solifenacin is a safe drug that could be taken continuously [26]. In our study, side effects were observed in only 4 patients (8.9%), and none of them experienced severe symptoms.

To our knowledge, some studies have shown that the combination of anticholinergic drugs and biofeedback is the most effective approach for adults [7, 13]. Nevertheless, few studies on combined treatment in children have been reported. With this in mind, we conducted a study of solifenacin plus biofeedback applied for paediatric OAB. The subjective perceived benefit and overall satisfaction were better for patients in Group C (combination therapy). We found that the combination therapy led to a significant decrease in voiding frequency and an increase in functional bladder capacity. Moreover, this treatment dramatically improved lower urinary tract symptoms (LUTS), especially in the UI group, with a complete response rate of 87.5% at 12 weeks. According to our results, the combination treatment took only 2 weeks to achieve a complete response rate exceeding 50%. Currently, there was no unified standard for the treatment course of solifenacin or feedback. As a whole, clinical judgement remains paramount to individualize such an approach.

We believe that our study will provide advantageous evidence on the efficacy and safety of the combination of solifenacin with biofeedback for paediatric OAB in clinical practice. However, further randomized controlled studies would be required to obtain official approval and recommend this combination therapy for routine use in children.