Comparison of an automated and paper bladder diary in pediatric patients: mixed-methods, randomized crossover study

Bladder diaries are recommended for assessing pediatric lower urinary tract symptoms, but paper diaries require manual measurement, recording, and interpretation. Automated diaries may reduce this burden by combining automated volume measurement, digital registration, and guideline-based calculations. We compared an automated and a paper bladder diary regarding agreement, clinical utility, and user experience.

In this mixed-methods, multicenter, randomized crossover study, children up to 13 years completed an automated diary (Minze Diary Pod) and paper diary in random order. Bland-Altman analysis assessed agreement; surveys and semi-structured interviews assessed clinical utility, user experience, and preferences.

Eighty participants were randomized; diary completion did not differ significantly between formats. Paired data were available for 49 children for frequency outcomes and 48 for volume outcomes (mean age 7.2 years, SD 2.0). The mean relative difference in average daytime voided volume was 3.2%, but the 95% limits of agreement (-48.5%-54.9%) exceeded the prespecified ±30% margin. Most frequency-based outcomes showed near-zero mean differences, with limits of agreement of approximately ±2-3 events per day. Classification differed between formats for 31.3% of participants for reduced bladder capacity and 23.3% for nocturnal polyuria, without statistically significant differences. Qualitative findings suggested that differences reflected day-to-day variation, self-monitoring effect, methodological differences between formats, including the variable measuring jugs used for paper diaries, and subjective symptom interpretation. Clinicians rated both formats clinically useful, but preferences were mixed across patients. Automated calculations were valued but not routinely consulted because of workflow constraints. Paper diaries remained appreciated for their familiarity and rapid visual overview, although guideline-based calculations were not consistently documented. The automated diary was preferred by 87.5% of parents and 72.9% of children, with significantly higher positive responses for motivation, pleasant use, child involvement, and perceived error-free use.

The automated diary showed strong usability and family preference, but individual-level measurement equivalence with the paper diary was not demonstrated. Without a true reference standard, disagreement did not establish which format was more accurate. Its standardized measurement and automated calculations may offer particular value for repeated monitoring, although workflow integration, clinician adoption of guideline-based calculations, and independent real-world evaluation remain necessary.