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

1 Introduction

Lower urinary tract symptoms (LUTS) and urinary incontinence are common in school-aged children and may occur during the day, at night, or both. Primary nocturnal enuresis (NE) affects approximately 10%–16% of 7-year-old children (1, 2), while daytime LUTS are reported in 4%–23% of school-aged children (3, 4). The International Children's Continence Society (ICCS) recommends a bladder diary for diagnostic assessment and treatment follow-up and considers it mandatory when history taking indicates daytime LUTS (5–8).

A bladder diary is a home-based assessment tool used to record voiding patterns in daily life over several days. In a conventional paper diary, children or caregivers measure each void using a measuring jug and manually record its time and volume, together with fluid intake, urgency, leakage episodes, and nighttime urine output, in a time-based paper table. It therefore combines quantitative volume measurements with manual registration and subjective symptom reporting to support diagnosis and treatment follow-up (5, 7).

According to ICCS guidelines, accurate interpretation of bladder diary findings, particularly in relation to the child's age-related expected bladder capacity (EBC), is important for guiding treatment (6). When daytime LUTS are present, these symptoms should generally be managed before NE is addressed. In children with monosymptomatic NE, EBC-based assessment of nocturnal polyuria and reduced bladder capacity can inform the choice of alarm therapy and/or desmopressin. Supporting this approach, a recent study reported that diary-guided treatment selection improved response by up to 46% (9).

Despite its clinical value, the conventional paper bladder diary remains burdensome for patients and clinicians. Patients and families must manually measure and record voided volumes using a jug, which can be cumbersome and may result in incomplete, unreliable, or low-quality data (10, 11). Clinicians, in turn, must perform several calculations to translate diary entries into clinically relevant parameters, particularly in children (6, 12, 13). This includes averaging voided volumes, calculating nocturnal urine production, including wet diaper weight when applicable, and interpreting these values relative to age-related EBC. Together, these steps make detailed and accurate paper diary interpretation time-consuming and potentially difficult to implement in routine clinical practice (14).

To overcome these limitations, several digital bladder diaries have been introduced. These diaries have shown promise as reliable alternatives to paper, with studies reporting improvements in usability and patient preference, and some suggesting improved compliance (14–23). They also enable automatic, guideline-based calculations and digital tracking of patient progress. In one study, digital diary interpretation time was almost halved compared with paper diaries, while accuracy in applying guideline definitions nearly doubled (19). However, digital diaries still depend on manual measurement of voided volumes using a jug, followed by digital entry. Consequently, they reduce the burden of manual recording but not the burden or potential inaccuracy of volume measurement, with reported measurement errors reaching or exceeding 10% of the actual voided volume (24–26).

More recent innovations in digital health have introduced automated bladder diaries, which may address this remaining limitation by automatically measuring voided volumes and transferring these data to a digital diary (27). Different technological approaches have been developed to achieve this automation. UScale (28) and the Uro-diary Checker (29) measure urine using a collection bag or cup combined with a separate measuring unit, whereas the Diary Pod (24, 30–34) integrates the collector and measuring sensor into a single device. Initial evaluations in adults have demonstrated promising accuracy and usability (28–34). However, pediatric evidence is lacking. Digital bladder diaries have been evaluated in only a limited number of pediatric studies (20, 23), and automated bladder diaries have, to our knowledge, not yet been assessed in children. This represents a relevant evidence gap, given the clinical value of bladder diaries in pediatric continence care and the specific compliance challenges faced by children and their families (23). Therefore, this study aimed to evaluate the Diary Pod, an automated bladder diary, in a pediatric population by comparing it with a conventional paper diary in terms of agreement, clinical utility, and patient and parent preference.

2 Materials and methods

2.1 Study design and settings

This mixed-methods, multicenter, randomized, two-period crossover study compared an automated bladder diary with a conventional paper bladder diary in terms of agreement, clinical utility, and user experience. The study was conducted across five pediatric nephrology or pediatric urology care settings in Belgium. Participants were randomized in a 1:1 ratio to one of two diary sequences: paper followed by automated diary, or automated followed by paper diary. Each diary was completed at home for at least two consecutive days. Diary periods were separated by an interval of at least two days, during which no changes in urological treatment were allowed.

The study protocol received ethical approval from the Ethics Committee of the University Hospital Antwerp and the University of Antwerp (BUN B3002023000056, 15 May 2023) and was registered at ClinicalTrials.gov (NCT06070675, https://clinicaltrials.gov/study/NCT06070675, 1 October 2023). No important protocol changes were made after study commencement. The reporting of this study was guided by CONSORT 2025 and the CONSORT 2010 extension for randomized crossover trials (see Consort Checklists in Supplementary Material).

2.2 Randomization and blinding

The allocation procedure was prepared by the first author, who was not part of the treating clinical team. No stratification was used, and allocation was balanced by preparing equal numbers of indistinguishable study packages for each diary sequence. At inclusion, clinicians blindly selected one package, thereby randomly assigning the participant to a diary sequence. Participants and clinicians were unaware of the assigned sequence before allocation.

To support adherence to the allocated sequence, the second diary format was stored in a locked document pouch, for which participants received the unlock code only after completing the first diary period and corresponding survey (Supplementary Figure S1). Blinding after allocation was not feasible because use and review of the two diary formats made them distinguishable.

2.3 Participants

Pediatric patients presenting to the participating clinics and identified by their treating clinician as requiring a bladder diary for diagnostic or therapeutic purposes were eligible. Children up to 13 years of age, both boys and girls, were included. Participants or their parents had to be able to use a smartphone or tablet. Exclusion criteria were inability to use the Diary Pod during voiding and inability to speak, read, or write Dutch.

Participants were recruited during routine outpatient visits. Eligible patients and parents received verbal and written study information. Written informed consent was obtained from parents or legal guardians; children aged 12 years and older also provided written informed consent, while younger children provided assent. Clinicians provided standardized verbal and written instructions for both diary formats and ensured correct setup of the automated diary.

2.4 Bladder diary procedures

2.4.1 Paper bladder diary

The paper bladder diary (Figure 1) required manual recording of voids, urgency, fluid intake, and leakage episodes in a time-based table. In line with routine clinical practice, participants measured voided volumes using a self-provided measuring jug and recorded them manually. Paper diaries were reviewed and interpreted by clinicians during the follow-up visit.

2.4.2 Automated bladder diary

The automated bladder diary (Figure 2) consisted of the Diary Pod and the Minze Flow app (Minze Health, Antwerp, Belgium). The Diary Pod and Minze Flow app are CE-marked medical devices. The Diary Pod is a capacitance-based device that automatically measures voided volume. After each void, participants pressed a button on the device to register both the measured volume and the time of voiding. For this study, a handle was attached to facilitate use by children or parents during voiding. Data were transmitted via encrypted Bluetooth to the Minze Flow app, which prompted users to record additional information, including urgency, fluid intake, and leakage episodes. Automatic, guideline-based calculations and a timeline overview were made available for clinical review via the cloud-based portal. Automated diary data were pseudonymized and stored in the cloud, with personal identifiers and health data maintained separately. Data were encrypted during transmission and at rest, and access was restricted to authorized users in accordance with the General Data Protection Regulation.

2.4.3 Bladder diary parameters

Both diary formats collected the same variables: voiding times, voided volumes, urgency scores per void according to the International Consultation on Incontinence Questionnaire (ICIQ) bladder diary, fluid intake times and volumes, leakage episodes, and sleep and wake-up times. For analysis, automated diary data were exported directly from the cloud-based portal, while paper diary data were manually digitized into the same structured format. Diary parameters were calculated according to the definitions in Table 1 using a predefined analysis script. Parameters were calculated per diary cycle and averaged across cycles for each diary format.

Table 1. Definitions of bladder diary parameters and guideline-based classifications.

2.5 Clinician and patient/parent surveys

For each participant, clinicians completed a survey in which they rated both diary formats for quality on a 10-point Likert scale and clinical usefulness on a 5-point Likert scale, and indicated their preferred format, if any. Patients and parents completed an online survey after each diary format assessing usability using 5-point Likert-scale questions and diary format preference, if any. Both clinician and patient/parent surveys included open-ended questions for qualitative feedback.

The surveys were developed specifically for this study, drawing on the expertise of the supervising team, including a pediatric urologist, a urotherapist/physiotherapist, and a healthcare product design researcher. The content and wording were iteratively reviewed and internally tested by the research team until consensus was reached.

2.6 Semi-structured interviews

In addition, purposively selected subsamples of parents and clinicians participated in semi-structured interviews to further explore experiences with both diary formats. Interviews were audio-recorded with consent, transcribed verbatim, and pseudonymized before analysis.

2.7 Safety and harms

Given the non-invasive and non-therapeutic nature of the study, no formal adverse event monitoring or statistical analysis of harms was performed. Participants were instructed to report any adverse events to the treating clinician or study personnel during the study period.

2.8 Outcomes

The primary outcome was agreement between automated and paper bladder diaries for average daytime voided volume, expressed as the relative difference (%). The absolute volume difference (mL), daytime and nighttime voiding frequency, urgency frequency, and leakage frequency were assessed as secondary outcomes. Guideline-based classification agreement was assessed using predefined thresholds for reduced bladder capacity and nocturnal polyuria (Table 1). Additional secondary outcomes included clinician-reported diary quality, clinical usefulness, and diary format preference. Patient- and parent-reported outcomes included diary usability and diary format preference. Finally, qualitative data were used to contextualize findings on agreement, clinical utility, and user experience.

2.9 Statistical analysis

Agreement between automated and paper bladder diaries was assessed using Bland–Altman analysis, reporting mean differences and 95% limits of agreement. Agreement was additionally quantified using Lin's concordance correlation coefficient (CCC) for the continuous diary outcomes. Supplementary crossover analyses used linear mixed-effects models including diary method, period, and randomized sequence as fixed effects and participant as a random intercept. Paired binary outcomes were compared using McNemar's test, and paired ordinal outcomes using the Wilcoxon signed-rank test. All paired analyses included participants with available paired data for the outcome of interest using complete-case analysis; no imputation was performed. Independent categorical outcomes were compared using Fisher's exact test.

For analysis and visualization, 5-point Likert-scale usability responses were dichotomized into positive responses, defined as scores 4–5, versus all other responses. Negatively phrased items were reverse-coded so that higher scores consistently reflected a more positive user experience. All quantitative data analyses were conducted using R version 4.5.2 (R Foundation for Statistical Computing, Vienna, Austria; RRID:SCR_001905) within RStudio (Posit Software, PBC, Boston, MA, USA; RRID:SCR_000432).

Qualitative data from open-ended survey responses and semi-structured interviews were analyzed thematically using a deductive coding framework informed by the quantitative findings, while allowing additional themes to emerge inductively from the data.

Data extraction and both the quantitative and qualitative analyses were performed by the first author. Blinding during data extraction and analysis was not feasible because the diary format was evident from the source material.

2.10 Sample size

The sample size was determined to ensure adequate precision for estimating agreement between diary methods using Bland–Altman analysis. Based on average daytime voided volume data from three prior diary comparison studies (18, 19, 22), the expected mean relative difference between methods was 0.6%, with a standard deviation of 10.6%. Using a prespecified reference agreement margin of ±30%, at least 47 paired observations were required. Allowing for 40% dropout or incomplete diary data based on previous studies (20, 22, 23), the target sample size was set at 80 participants. No interim analyses or stopping guidelines were planned.

3 Results

3.1 Participant flow and baseline characteristics

Participants were recruited between October 2023 and June 2025, and final follow-up was completed in September 2025. Eighty eligible patients agreed to participate, provided informed consent, and were randomized: 40 (50%) to the paper-first sequence and 40 (50%) to the automated-first sequence. Paired diary data were available for 49 participants for frequency-based parameters and for 48 participants for voided volume-related parameters, as one paper diary had missing voided volumes (Figure 3).

Noncompletion, defined as no data or fewer than two days of recordings in one or both diary formats, resulted in 38.8% (31/80) of randomized participants without analyzable paired diary data, consistent with the anticipated dropout rate. Completers and non-completers were descriptively similar in age (mean 7.2 ± 2.0 vs. 7.5 ± 1.9 years) and sex distribution (63.3% vs. 58.1% boys). Among completers, 53.1% (26/49) had been allocated to the automated-diary-first sequence, compared with 45.2% (14/31) of non-completers. Reasons for noncompletion were unavailable for most participants, generally because families did not return for follow-up or provide further information. Documented reasons included a technical issue with the automated diary, absence of a suitable smartphone, a lost paper diary, and difficulty completing the paper diary.

Completion was numerically higher for the automated diary than for the paper diary (71.3% [57/80] vs. 63.8% [51/80]; McNemar p = 0.11) and among participants who started with the automated diary than among those who started with paper (65.0% [26/40] vs. 57.5% [23/40]; Fisher's exact p = 0.65). These findings did not indicate a clear association between completion and diary format or randomized sequence.

Clinician ratings were completed for 49 participants with both diary formats available for review. Patient/parent surveys were completed by 58 and 48 participants after the first and second diary periods, respectively. Paired usability analyses included 47 participants who provided responses for both diary formats, while preference data were available for 48 participants. Semi-structured interviews were conducted with 13 parents and 2 clinicians. No adverse events were reported.

Participant characteristics are presented in Table 2. Among participants with paired diary data, the mean age was 7.2 years (SD 2.0; range 5–13). Nearly three quarters completed the diaries in the context of a first consultation (36/49, 73.5%), and most had no prior experience completing a bladder diary (38/49, 77.6%). Participants presented with a range of urinary complaints, most commonly NE (41/49, 83.7%) and daytime urinary incontinence (24/49, 49.0%). Approximately half of the children owned a smartphone or tablet, and a similar proportion reported daily use of these devices.

Table 2. Baseline characteristics of all randomized participants and participants with paired diary data, by randomized sequence.

DUI, daytime urinary incontinence; FI, fecal incontinence; NE, nocturnal enuresis; SD, standard deviation; UTI, urinary tract infection.

3.2 Agreement between automated and paper diaries

For the primary outcome, the mean relative difference (%) in average daytime voided volume between automated and paper diaries was 3.2% (95% CI −4.4%–10.9%; N = 48). The lower and upper limits of agreement were −48.5% (95% CI −61.7%–−35.3%) and +54.9% (95% CI 41.8%–68.1%), respectively (Figure 4). The predefined ±30% agreement criterion was therefore not met, indicating substantial individual-level variability.

For secondary diary outcomes, Bland–Altman results and Lin's CCC are presented in Table 3. When average daytime voided volume was assessed on the absolute scale (mL), the mean between-method difference was −2.9 mL (95% CI −11.1–5.3 mL), with limits of agreement ranging from −58.2 to 52.4 mL. Frequency-based outcomes showed mean differences close to zero, while the limits of agreement indicated individual differences of approximately ±2–3 events per day for most outcomes. Urgency frequency showed the widest limits of agreement (−4.9–2.7 events per day) and a mean difference corresponding to approximately one fewer void with reported urgency per day in the automated diary. The variation in agreement across outcomes was also reflected in Lin's CCC estimates. Concordance was highest for average daytime voided volume (0.896), lower for daytime and leakage frequencies (0.616 and 0.548, respectively), and lowest for nighttime and urgency frequencies (0.234 and 0.295, respectively).

Table 3. Agreement analyses for bladder diary outcomes between automated and paper bladder diaries.

Differences were calculated as automated minus paper. Relative difference was calculated as (automated−paper)/paper × 100%. Limits of agreement were calculated as the mean difference ± 1.96 SD.

CCC, concordance correlation coefficient; CI, confidence interval; LoA, limits of agreement; SD, standard deviation.

The supplementary crossover analyses similarly identified a method effect only for urgency frequency, which was lower in the automated diary (−1.1 events per day, 95% CI −1.7–−0.6; p = 0.0002). No period effects (p = 0.075–0.563) or sequence effects (p = 0.303–0.776) were observed for any diary outcome (Supplementary Table S1).

Classification agreement was 68.8% (33/48; 13 positive and 20 negative by both formats) for reduced bladder capacity and 76.7% (33/43; 4 positive and 29 negative by both formats) for nocturnal polyuria. Discordant classifications occurred in 15/48 participants (31.3%; 9 positive by the automated diary only and 6 by the paper diary only) for reduced bladder capacity and 10/43 participants (23.3%; 4 positive by the automated diary only and 6 by the paper diary only) for nocturnal polyuria. Most discordances for reduced bladder capacity occurred near the predefined cutoff, with 13/15 (86.7%) discordant cases within ±10% of the threshold in at least one diary format. For nocturnal polyuria, 5/10 (50.0%) discordant cases were within ±10% of the threshold. McNemar's tests showed no evidence of systematic classification differences between formats for either reduced bladder capacity (χ² = 0.27, p = 0.61) or nocturnal polyuria (χ² = 0.10, p = 0.75).

Qualitative findings suggested that, despite differences in individual diary values, clinicians often derived similar overall clinical interpretations from the two formats (Table 4). Reported explanations for variability included day-to-day contextual factors, a potential self-monitoring effect after the first diary, methodological differences between formats, and subjective symptom interpretation. Methodological differences mainly reflected variability in measuring jugs used for paper diaries (Figure 5), while urgency ratings were especially prone to subjective scoring, with some parents using their own understanding of the urgency scale. This was particularly reported for paper diaries, where the score definitions were provided only in the written instructions, whereas the app displayed them with each entry. These qualitative findings provide context for the difference in urgency frequency observed between formats.

Table 4. Qualitative themes related to agreement between diary formats.

3.3 Clinical utility

Clinicians rated both diary formats highly. The automated diary received slightly higher quality ratings than the paper diary, although this difference was not statistically significant (median 9, interquartile range [IQR] 8–9, vs. median 8, IQR 7–9; p = 0.11). Clinical usefulness ratings were similarly high for both formats (median 5, IQR 4–5 for both; p = 0.44). When asked to indicate an overall preference per patient, clinician preferences were mixed: the automated diary was preferred in 19/49 cases (39%), the paper diary in 12/49 cases (24%), and no preference was reported in 18/49 cases (37%). Qualitative findings further showed that preferences were influenced by data completeness, perceived reliability, readability, and whether diary completion coincided with atypical or hectic days, rather than by diary format alone (Table 5).

Table 5. Qualitative themes related to clinician preferences and clinical utility.

Although preferences depended on the individual diary and patient context, clinicians reported several perceived advantages of the automated format. It was perceived as more readable and particularly useful for parents who were less precise or consistent in recording diary data. Digital accessibility was considered an important advantage, making diaries easier to retrieve, whereas paper diaries could get lost or be unavailable at follow-up. Moreover, automated calculations could reduce manual counting and support more consistent, guideline-based interpretation, as some parameters might otherwise be interpreted differently or overlooked depending on the clinician or resident reviewing the diary. The availability of consistently calculated parameters across diaries, together with automated comparisons of progress over time, was also identified as a potential benefit for longitudinal follow-up and the assessment of treatment effectiveness.

However, the findings also revealed a gap between the availability and clinical use of guideline-based calculations. Although these calculations were generated automatically by the automated diary, clinicians did not routinely consult them because of additional computer interactions, established workflows, and time pressure. In contrast, paper diaries remained appreciated for their familiarity and rapid visual overview during face-to-face consultations. Yet guideline-based calculations and classifications were not consistently documented for paper diaries in the clinician surveys, suggesting that this rapid, pattern-based visual review may not always have been accompanied by systematic calculation and guideline-based interpretation.

3.4 User experience

Parent-reported experience outcomes for the 47 participants with paired usability responses are summarized in Figure 6 and Supplementary Table S2. Positive response percentages were higher for the automated diary across all outcomes. Significantly more parents reported positive responses for motivation (87.2% vs. 72.3%; p = 0.039), pleasant use (72.3% vs. 25.5%; p < 0.001), child involvement (100.0% vs. 76.6%; p < 0.001), and perceived error-free use (53.2% vs. 27.7%; p = 0.012).

Qualitative findings contextualized these user experience outcomes (Table 6). Although motivation was high for both formats and was mainly linked to the desire to improve the child's urinary symptoms and support participation in social activities, the diary format also played a role. Some parents described the extensive paper tables as cumbersome or overwhelming, which reduced their motivation to complete the diary. In contrast, the automated format was perceived as more engaging and interactive: children could use the Diary Pod, press the button, interact with the app, and view the measured volume, which often made them curious. In contrast, the paper diary was more parent-led because measuring and recording volumes with a measuring jug often required parental assistance. Some participants also perceived the Diary Pod as more hygienic and less prone to spilling than the measuring jug, although its length made seated voiding difficult for some children.

Table 6. Qualitative themes related to user experience and preference.

Automated registration of voided volumes and timestamps was perceived as reducing burden and errors. By prompting follow-up questions at the time of registration, the automated diary encouraged real-time data entry and more complete recording. Smartphone-based registration also made the diary portable and discreet, especially outside the home. In contrast, the paper diary was easier to forget, less portable, and more prone to delayed, incomplete, or incorrect registration. However, app-based registration also introduced challenges related to dependence on a parent's phone, involvement of multiple caregivers, and remembering manual fluid intake registration despite automated urine registration.

Preferences reflected the more favorable user experience with the automated diary. Most parents preferred the automated diary (42/48, 87.5%), as did most children (35/48, 72.9%). Although affordability remained a concern, willingness to pay appeared higher when the diary was perceived as part of a longer-term therapy or training trajectory rather than as a short-term diary assessment.

4 Discussion

4.1 Principal findings

Average differences between the automated and paper diaries were generally small at the group level, but the prespecified ±30% agreement margin at the individual participant level was not met. Qualitative findings suggested that this individual variability may partly reflect the sensitivity of bladder diary outcomes to real-life day-to-day context and methodological differences between formats, including the substantial variation in self-provided measuring jugs used for paper diaries.

Clinicians nevertheless generally derived comparable overall clinical interpretations from both formats and rated both clinically useful, although their preferences were mixed across patients. The findings also showed a gap between the availability and clinical use of guideline-based calculations. Automatically generated outputs were not routinely consulted, while corresponding calculations and classifications were not consistently documented for paper diaries.

Families showed a clear preference for the automated diary, with most parents and children preferring this format. User experience was more favorable across all evaluated outcomes, and significant differences were observed for motivation, pleasant use, child involvement, and perceived error-free use. However, overall diary completion did not differ significantly between formats.

4.2 Measurement agreement and clinical interpretation

Previous studies comparing digital, automated, and paper bladder diaries have reported mixed findings regarding agreement, completeness, and compliance (17–23, 29, 33–35). Our findings similarly revealed a nuanced picture. Although average differences between formats were small at the group level, individual-level agreement varied considerably across participants: the limits of agreement for average daytime voided volume exceeded the prespecified ±30% margin, differences in frequency-based outcomes extended to approximately ±2–3 events per day, and classifications differed between formats for approximately one-third of participants for reduced bladder capacity and one-quarter for nocturnal polyuria. The findings therefore indicate that the two formats do not always produce equivalent results at the individual participant level. Some of these differences may be clinically meaningful for individual children. Nevertheless, the observed numerical and classification differences did not necessarily affect clinicians’ overall assessments, possibly because diary findings were considered alongside other assessments and because guideline-based calculations were not consistently consulted or documented. Moreover, among the discordant classifications, 13 of 15 for reduced bladder capacity and half for nocturnal polyuria involved at least one value close to the respective cutoff.

However, this comparison does not validate one method against the other. The paper diary served as the conventional comparator but not as a reference standard. Its recognized burden and susceptibility to incomplete, unreliable, or low-quality data should therefore be considered when interpreting disagreement between methods (10, 11). In the absence of a true reference standard, which is difficult to obtain in home-based bladder diary studies, disagreement between diary formats cannot be definitively attributed to one format being more accurate than the other. Our qualitative findings suggest that such differences may reflect a combination of day-to-day contextual variation, a potential self-monitoring effect, differences in methodology and participant engagement between formats, and subjective symptom interpretation. This aligns with previous bladder diary research showing substantial day-to-day variability in diary parameters (36, 37) and suggesting that diary completion itself may influence behavior (38). This self-monitoring effect is also reflected in the use of bladder diaries as part of urotherapy for children with daytime symptoms (39). Self-monitoring may thus have affected individual families, even though no consistent period or sequence effects emerged at the group level. In a two-period, two-sequence crossover design, however, any resulting carryover is difficult to distinguish from other order-related effects.

Although the present study cannot establish which format was more accurate under real-life conditions, the underlying measurement processes differ substantially. The Diary Pod has previously been evaluated for automated volume measurement in controlled bench testing against a calibrated laboratory scale (30). In line with routine practice at the participating centers, participants used self-provided measuring jugs for the paper diary. Paper diaries therefore depend on the accuracy and scale resolution of the measuring jug, manual reading and estimation, and subsequent written registration. The substantial variation observed in the measuring jugs used by participants represents an important real-world finding and highlights a potential source of measurement variability that clinicians should consider when interpreting paper diaries. A previous study similarly reported discrepancies in manually measured voided volumes (24). Furthermore, the automated diary registered the measured volume and time immediately after participants pressed the button following each void, thereby reducing reliance on later recall and transcription. This standardized measurement and registration process may reduce sources of measurement variability associated with paper diaries, although superior accuracy under real-life conditions cannot be established from the present study.

4.3 Clinical use of automated calculations

Automated calculations may improve the consistency and efficiency of bladder diary interpretation. Guideline-based interpretation of bladder diaries requires several calculation steps, including averaging voided volumes, calculating nocturnal urine production, and interpreting results relative to age-related EBC (6). Performing these steps manually can be challenging under clinical time pressure. Previous research showed that automated calculations almost halved interpretation time and nearly doubled the correct application of guideline definitions compared with manual interpretation of paper diaries (19).

However, our findings suggest that guideline-based calculations remain underused in routine clinical practice. For the automated diary, the calculations were generated automatically but not routinely consulted because of established habits, additional computer interactions, time pressure, and workflow constraints. Paper diaries, by contrast, continued to be valued for their familiarity and rapid visual overview, although the calculations had to be performed manually and the resulting parameters and classifications were not consistently documented. Together, these findings indicate a gap in both workflow integration and clinical review practices. This gap may also help explain why numerical differences between formats did not necessarily alter clinicians’ overall interpretations. Automation removes the burden of manual calculation, but its clinical value cannot be fully realized unless clinicians systematically use the resulting outputs.

Realizing the potential value of automated calculations will require improved integration into routine care. Calculated parameters should be immediately visible, rapidly interpretable, and accessible within clinicians’ existing workflows. Printable summaries, electronic health record integration, and decision-support features may support this process. Further human-factors and behavioral research involving clinicians could help determine how these outputs should be presented and integrated to encourage their systematic use. Making these guideline-recommended calculations more accessible could complement clinical expertise and facilitate their use without adding to the consultation burden, thereby supporting more consistent guideline-based management across patients.

4.4 Patient and parent preference

Patient preference appears more consistent across previous studies than agreement or compliance, with several studies reporting preference rates of 80% or higher for digital or automated formats (17, 19, 33, 35). Our findings support this pattern: most parents and children preferred the automated diary, and their experience was more favorable across all evaluated usability outcomes.

Child involvement was significantly higher with the automated diary. This contrasts with previous pediatric studies reporting similar child participation between digital and paper formats (20, 23). Pressing the button, interacting with the app, and viewing the measured volume appeared to make diary completion more engaging for children. This suggests that a connected measuring device may offer added value beyond digital registration alone.

Nevertheless, the more favorable user experience did not translate into a significant difference in diary completion between formats. The dropout rate of 38.8% was close to the anticipated 40% and comparable to previous pediatric digital diary studies (20, 23). Diary completion in children depends not only on the diary format but also on coordination between parents and multiple caregivers, school routines, hobbies, and other out-of-home activities. Our qualitative findings reflected this complexity: smartphone-based registration was convenient when the parent was present but became more difficult when care was shared or activities occurred outside the home. Although the Diary Pod can store measurements internally until later synchronization with the app, this functionality must be communicated clearly and repeatedly to ensure that families can make effective use of it.

Previous research on digital bladder diaries in pediatric care has identified similar barriers, including coordination with schools and other caregivers, and co-parenting, as well as software maintenance and privacy and security requirements (23). These privacy and security requirements are particularly important because trust in digital health platforms varies across sociodemographic groups (40). Beyond ensuring trustworthy technology, equitable implementation also requires attention to families’ ability to access and use these technologies. Unequal access to suitable devices and affordable connectivity, together with differences in digital literacy, may limit participation and widen existing disparities (41). Addressing these barriers will require multifaceted strategies, with our willingness-to-pay findings indicating that reimbursement could be one important component.

Despite these implementation challenges, the automated diary was clearly preferred by both parents and children in this study and resulted in greater child involvement. While no significant difference in overall diary completion was observed, greater involvement and motivation may still support more consistent and complete registration within individual diaries, potentially improving the reliability of the collected data. Beyond individual diary periods, these advantages may be particularly valuable for sustaining engagement when diary monitoring is repeated as part of a longer-term treatment trajectory. However, these potential effects were not directly assessed in the present study and require further evaluation.

4.5 Longitudinal monitoring and progress feedback

The potential value of automated diaries may extend beyond a single diagnostic assessment. Longitudinal progression curves could make it easier for clinicians to compare diaries over time. This may be particularly valuable in difficult or treatment-resistant cases, when evaluating responses to successive therapies, or when monitoring children as they grow. During treatment, symptoms may persist even while relevant diary parameters improve. For example, a child may continue to experience urgency or incontinence while average voided volume increases (Figure 7). Structured longitudinal data could help clinicians recognize these changes, evaluate treatment response, and adjust therapy accordingly.

Making such progress visible may also have motivational value for children and parents. Continued wetting may make it difficult for families to recognize gradual improvement, whereas progression curves could demonstrate changes in underlying diary parameters before complete symptom resolution is achieved. This feedback could provide a more nuanced understanding of treatment progress, support shared discussions about treatment goals, and encourage continued engagement and adherence to treatment.

Parent interviews supported the relevance of this longer-term perspective: the Diary Pod was perceived as more valuable when considered part of a longer-term therapy or training trajectory rather than as a short-term assessment tool. Although conducted in adult men, the Lutastic+ pilot study illustrates the feasibility of integrating the Diary Pod and app into a longer-term digital therapy program, with high engagement and improved LUTS outcomes over 12 weeks (42).

4.6 Clinical implementation and recommendations

Our findings suggest that automated bladder diaries may offer the greatest potential added value when diaries must be completed repeatedly. Relevant contexts include complex or treatment-resistant cases, comparisons between therapies, and longer-term digital therapy. In these situations, the ability to compare structured measurements over time and the greater engagement associated with the automated format may help justify the additional cost of the device. For a one-time assessment, a digital diary without a connected measuring device or a conventional paper diary may be sufficient. Regardless of format, clinicians should consider the context and representativeness of the recorded days and provide guidance on suitable measuring jugs with appropriate accuracy and scale resolution given the observed variability in self-provided measuring jugs.

4.7 Strengths and limitations

This study has several strengths. The randomized crossover design allowed participants to use both diary formats, reducing between-participant variability and enabling direct comparison of automated and paper diaries in the same child. The random order of diary formats reduced the risk of systematic order effects. The mixed-methods design provided both quantitative data and qualitative insight into the reasons behind observed differences, preferences, and user experiences from the perspectives of clinicians, parents, and children. To our knowledge, this is the first pediatric evaluation of an automated bladder diary.

Several limitations should be acknowledged. First, there was no true reference standard for bladder diary outcomes in the home setting. Therefore, disagreement between formats cannot be definitively attributed to either the automated or the paper diary. Moreover, because the two methods differed in both their measurement and registration procedures, the separate contribution of each component to the observed differences could not be isolated. Rather than standardizing the measuring jugs used with paper diaries, the study evaluated the two complete diary methods as implemented in routine practice at the participating centers. This pragmatic approach captured real-world variation in manual measuring equipment and made the comparison more representative of everyday clinical practice.

Second, the relatively short minimum two-day interval between diary periods was chosen based on clinician feedback to facilitate recruitment and completion within suitable periods, such as school holidays. As no treatment was administered, a formal treatment washout was not considered necessary. However, the interval may have been insufficient for self-monitoring effects to disappear. Although no consistent period or sequence effects emerged at the group level, our qualitative findings suggest that self-monitoring may nevertheless have affected individual participants.

Third, dropout was substantial, although anticipated and comparable to previous pediatric bladder diary studies. This may have introduced selection bias toward more motivated, organized, or technologically confident families who were able to complete both diary formats. Although completers and non-completers were descriptively similar in age, sex, and randomized sequence, information on motivation, smartphone use, and technology familiarity was unavailable for most non-completers and could therefore not be meaningfully compared between groups. Consequently, the usability and preference findings may overrepresent families who were able and willing to engage with both diary formats. This could result in overly favorable findings for the automated diary if less technologically confident families were less likely to complete the study. Conversely, the added value of the automated diary may be underestimated, as families who struggle most with conventional paper diaries may have been less likely to participate or complete the study. However, the direction and magnitude of this potential selection bias cannot be determined from the available data.

Fourth, the usability survey was developed specifically for this study with expert input and internal testing, but it was neither based on a validated instrument nor formally pilot-tested or validated in the target population. This may limit comparability with other studies, although it enabled targeted assessment of usability using complementary quantitative and qualitative data. Furthermore, conclusions regarding child engagement and experience were primarily based on parental observations.

Fifth, data extraction and analyses were performed by the first author, an employee of the device manufacturer, without separate blinded review or independent replication. The involvement of developer-affiliated researchers provided device-specific technical and implementation expertise relevant to this early-stage evaluation of a novel automated diary, but may also have introduced bias. Two academic investigators without financial ties to Minze Health supervised the study and contributed to its design, methodology, and interpretation. Furthermore, clinical diary interpretation was independent of the company: all 49 interpretations were performed by clinicians without financial ties to Minze Health. Nevertheless, bias in data handling and interpretation cannot be excluded. Future independent studies, including real-world evaluations of measurement performance, would complement these findings and further strengthen the evidence base for automated bladder diaries in pediatric practice.

Finally, the study evaluated short-term diary completion only. The proposed benefits for longitudinal monitoring, progress visualization, and sustained engagement therefore remain to be established.

4.8 Conclusion

Our findings highlight several potential advantages of the automated diary, including standardized measurement and registration, automatically generated guideline-based calculations, greater child involvement, strong usability, and strong family preference. Together, these features may offer a more engaging and standardized approach to bladder diary completion, particularly for repeated monitoring in complex or treatment-resistant cases and during longer-term digital therapy.

However, individual-level measurement equivalence with the paper diary was not demonstrated, as the limits of agreement exceeded the prespecified margin. In the absence of a true reference standard, the observed disagreement does not establish which format was more accurate. The paper diary served as a conventional comparator rather than a reference standard, and its completion burden, together with the observed variability in self-provided measuring jugs, may affect data completeness and reliability.

Both formats received high clinical usefulness ratings, although clinician preferences were mixed across patients, and paper diaries remained valued for their familiarity and rapid visual overview. Our findings suggest that guideline-based calculations were not consistently used in routine clinical practice, whether they required manual calculation or were generated automatically. Realizing the clinical value of automated bladder diaries will therefore require both effective workflow integration and systematic use of the generated guideline-based outputs by clinicians.

Further independent real-world evaluation is needed to assess the measurement performance of the automated bladder diary and determine whether its potential advantages translate into measurable clinical benefits.

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Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fped.2026.1959698/full#supplementary-material

Supplementary material Supplementary material at the source

Footnotes

Edited by: Cristian Roberto Sager, Garrahan Hospital, Argentina

Reviewed by: Xiao Zeng, Sichuan University, China

Cuma Aytekin, Mersin University, Türkiye