Efficacy of Solifenacin, Mirabegron and Combination Therapy in Children With Daytime Urinary Incontinence (BeDry)

Inclusion Criteria: 1. The participants custody holder(s) must voluntarily sign and date an informed consent prior to initiation of any study specific procedures. 2. Age 5 to 14 years (inclusive) at the time of inclusion. 3. Overactive bladder as per International Children's Continence Society criteria 4. At least 2 daytime urinary incontinence episodes per week 5. Inadequate effect of at least 4 weeks urotherapy (non-pharmacological treatment) 6. No previous treatment with solifenacin, mirabegron or bladder/sphincter botulinum toxin injections 7. No current constipation as per ROME IV criteria or fecal incontinence (laxative treatment is accepted) 8. Per investigator's judgment, the participant can swallow or can learn to swallow study medication Exclusion Criteria: 1. Inability of the patent(s) or legal guardian(s) to understand the Danish written and oral information 2. Known or suspected hypersensitivity to study medication 3. Any contraindication to the use of the study medication 4. Known urogenital anatomical abnormalities affecting lower urinary tract function 5. Known kidney or bladder stones 6. Known diabetes insipidus 7. Ongoing symptomatic urinary tract infection 8. Recurrent urinary tract infection or ongoing prophylactic antibiotic treatment 9. Known QTc prolongation, QTc \>460 ms, or risk of QTc prolongation (hypokalaemia, exercise-induced syncope, or familial long QT syndrome) 10. Other significant electrocardiogram abnormalities 11. Known hypertension 12. ≤3 daily voiding, evaluated by 48-hour frequency-volume chart 13. Uroflowmetry suggestive of other pathology than overactive bladder (staccato-shaped, interrupted-shaped, or plateau-shaped curve) 14. Post-void residual \>50 ml after double voiding 15. Dipstick haematuria (≥2+ erythrocytes) or macroscopic haematuria 16. Pregnancy or breastfeeding 17. Female subjects of childbearing potential 18. Ongoing constipation according to Rome IV-criteria which is intractable to medication or fecal incontinence 19. Inability to swallow study medication 20. Use of any medication during study period, except permitted medication