Agreement between the visual analogue scale (VAS) and the dysfunctional voiding scoring system (DVSS) in the post-treatment evaluation of electrical nerve stimulation in children and adolescents with overactive bladder.

Introduction: Electrical nerve stimulation is one of the most commonly used and well-tolerated treatments for overactive bladder (OAB); however, different studies have used different instruments to assess patients' response to treatment.
Objective: To analyze agreement between use of the visual analogue scale (VAS) and the Dysfunctional Voiding Scoring System (DVSS) for assessing improvement in urinary symptoms following electrical nerve stimulation treatment in children and adolescents with OAB.
Study Design: A cross-sectional analytical study including children and adolescents of 4-17 years of age diagnosed with OAB who underwent 20 sessions of transcutaneous (TENS) or percutaneous (PENS) electrical nerve stimulation. The DVSS and the VAS were used to assess daytime urinary symptoms before and following treatment. While the DVSS was always applied by a physician, the VAS was applied separately by a physiotherapist and then by a physician. Treatment was considered successful when the DVSS score was zero and the VAS score was ≥90%. Correlations between post-treatment VAS and DVSS scores were evaluated using the kappa coefficient. The VAS scores evaluated by the different professionals were compared for agreement using intraclass correlation and the Bland-Altman plot.
Results: Data from 49 cases were available for analysis. Of these, 27 (55.1%) were girls. Mean age was 7.1 ± 2.6 years. There was agreement between the two instruments used, the DVSS and the VAS, in 36/49 patients (73.5%), with a moderate Kappa of 0.44. There was moderate agreement between the VAS scores applied by the two different professionals.
Discussion: imitations of the present study include the small sample size and the fact that the inter-observer evaluation was conducted following a single sequence, i.e. all the patients were first evaluated by the physiotherapist and then by the physician, which may have biased answers and the post-treatment VAS scores. Furthermore, although the child participated actively in completing the questionnaires, in cases of divergent answers, the questions were redirected to the responsible adult, and the final answer may not fully represent the patient's true situation.
Conclusion: The present study found moderate agreement between the DVSS and the VAS, and moderate agreement between VAS scores when the instrument was applied by two different professionals. Although both tools appear to be important, and possibly complementary, a DVSS score of zero precludes the need to apply the VAS.
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