Impact of Behavioral Treatment of Insomnia on Nighttime Urine Production: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Impact of Behavioral Treatment of Insomnia on Nighttime Urine Production (NCT03883724), a randomized na study. The primary outcome is Change in Nocturnal Polyuria Index.

2. Clinical Question

The clinical rationale in the registry is that nocturia can reduce quality of life, while the causes of nighttime urine production are not fully understood. The study focuses on whether sleep-related treatment is associated with a change in the proportion of 24-hour urine production that occurs at night. That is a physiological measurement, rather than a direct measure of how disruptive nighttime voiding is to participants.

The record also lists change in nocturia and change in duration of uninterrupted sleep as secondary outcomes. Those outcomes address symptoms and sleep continuity more directly than the primary measure. The registry does not give the participant criteria, the numerical outcome results, or a reported estimate of the between-group difference. Consequently, the clinical question can be described from the registered design, but the results cannot be used to determine the size or precision of any treatment-group contrast.

3. Trial Design

This was a randomized, parallel-group study with no masking reported. The registry lists 56 participants as the enrollment and describes two behavioral arms: brief behavioral treatment for insomnia and information-only control. The study status is completed. Its recorded start date is 2019-02-01, and its primary completion date is 2021-11-30. The phase is listed as NA.

In a parallel design, participants are assigned to one of the study groups and remain in that group for the comparison, rather than crossing from one treatment to another. Random allocation is intended to make the groups comparable on average at the start of a study, although it does not guarantee balance in every characteristic, especially in a study of this size. The record does not describe the randomization sequence, allocation concealment, or any stratification factors.

No masking was reported. The intervention descriptions also distinguish individualized behavioral instructions from information and video content. The record does not say whether outcome assessors, diary reviewers, or analysts were masked to group assignment, so those details are not reported in the registry record.

The primary outcome is a change from baseline in nocturnal polyuria index at 4 weeks. Participants were to complete a 3-day bladder diary before and after the intervention, recording the time and volume of voids. The registry identifies the index as a mean of a continuous measure and describes its dispersion as a standard deviation. It also lists change in nocturia and change in duration of uninterrupted sleep as secondary outcomes.

The registry enrollment is 56, but the record does not report the number included in each outcome analysis or explain whether all enrolled participants contributed data. It does not report a detailed statistical analysis plan, a sample-size justification from the investigators, or the handling of missing diary entries. These omissions limit how much can be inferred about the actual analysis from the design description alone.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: After the telephone screening, the eligible participants completed a home sleep apnea assessment using device ApneaLink Air that was sent to them via mail with instructions for use at home. Those with AHI≥15 were excluded per study exclusion criteria before the in-person Visit 1 or signing the informed consent.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Overall, 56 participants were eligible, 29 randomized to BBTI and 27 to control group

6. Primary Endpoint

The registry lists the primary outcome as Change in Nocturnal Polyuria Index, measured over change from baseline nocturnal polyuria index at 4 weeks.

The primary endpoint is change from baseline in nocturnal polyuria index at 4 weeks. The index is the percentage of 24-hour urine production excreted at night. Its calculation uses nocturnal urine volume divided by 24-hour urine volume. Nocturnal volume includes voids between the diary-recorded time of going to bed with the intent of sleeping and the first awakening to void; the first void after waking is included. Participants were to record void times and volumes in a 3-day bladder diary before and after the intervention.

This measure is used to characterize the nighttime share of total urine production, rather than simply counting nighttime voids. As general statistical context, expressing nighttime volume as a proportion of total daily volume can help distinguish a change in the timing or distribution of urine production from a change in total volume alone. It does not, by itself, describe how often an individual wakes, how long they remain awake, or how burdensome the symptoms feel.

Because the endpoint is continuous, the registered summary uses a mean and standard deviation. A change score compares the post-intervention value with the baseline value for a participant, and a group comparison can then estimate whether average change differs between the assigned groups. The registry record does not report a single numerical primary-outcome comparison, so the magnitude and precision of any such difference cannot be described from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered design is randomized and parallel, with no masking reported. As general statistical context, randomization assigns participants to groups using chance and is intended to reduce systematic differences in baseline characteristics. It supports causal interpretation when the comparison is analyzed appropriately, but does not remove the need to report allocation methods, participant flow, outcome completeness, and the analysis population. Those implementation details are not reported in the registry record.

What does a mean and standard deviation describe?

The primary measure is continuous and is summarized in the record as a mean with a standard deviation. A mean describes the center of a set of values by averaging them. A standard deviation describes how spread out individual values tend to be around that mean. These summaries answer different questions: the mean concerns the average level or change, while the standard deviation describes participant-to-participant variability. Neither statistic alone gives the precision of a between-group effect estimate. Precision depends in part on the amount of data and the variability, and is ordinarily expressed using a standard error or confidence interval.

The endpoint is a change from baseline, so the intended measure compares each participant's post-intervention nocturnal polyuria index with their baseline index. A group-level analysis could summarize average change within each arm and compare those changes, or use a model that adjusts for baseline value. These approaches can differ in their assumptions and precision. The registry record does not specify which analysis was used, and it does not provide a single numerical comparison to interpret.

How should a confidence interval be read?

As general statistical context, a confidence interval describes uncertainty around an estimated quantity under the assumptions of the statistical model and the method used to construct the interval. A narrower interval indicates greater precision than a wider interval, but precision is not the same as importance. Whether a range includes values that would matter clinically depends on a clinical judgment and context that are not specified in the registry record. No primary-outcome confidence interval is reported as a single comparison.

A significance test and its p-value address a related but different question. Under a null hypothesis and specified analysis assumptions, the p-value measures how incompatible the observed data are with that null model. It does not state the probability that the null hypothesis is true, and it does not quantify the size of an effect. Statistical significance, if available, would not by itself show whether a difference is clinically meaningful. The registry record does not report a single primary-outcome test for interpretation.

Why does the diary measurement matter?

The nocturnal polyuria index is derived from diary-recorded times and volumes. The record specifies a 3-day diary and explains which nighttime voids contribute to the nocturnal volume, including the first void after waking. The quality and completeness of those records matter because errors in the timing or volume entries can affect the measured nighttime and 24-hour totals, and therefore the index. The registry does not report diary completeness, rules for unusable entries, or any procedures for checking diary data.

As general statistical context, measurements repeated over time within the same person are related rather than independent. A method that accounts for baseline and follow-up measurements can therefore be preferable to treating each observation as unrelated. The registry identifies a baseline-to-4-week change but does not describe its statistical model. It also does not report whether the analysis adjusted for baseline values or included other covariates.

What do the planning assumptions mean?

The registry's planning description says that sample-size illustrations are based on the observed effect, use a two-sided significance level of 0.05, assume equal allocation between the arms, and use a normal approximation. It also specifies that the effect to detect is a stated fraction of the observed effect. Such illustrations are planning calculations, not observed trial results and not observed power. They describe how many participants per arm might be needed under the stated assumptions; they do not show what the study actually achieved.

Because the primary outcome is not available as a single comparison, the underlying observed effect and the planning illustration values cannot be independently interpreted from the registry record. The record also does not report the investigators' own sample-size justification. A planning calculation based on an observed effect should not be confused with a design target set before the trial, nor should it be read as proof that the study was adequately or inadequately powered.

Over-dispersion is a general issue for some count-data models, where observed variability exceeds what a simple model assumes. The primary endpoint is described as a continuous percentage and summarized by a mean and standard deviation, not as a count outcome. The registry does not report a model that would allow readers to assess whether over-dispersion was relevant to any secondary analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and three analyses. The primary measure is change in nocturnal polyuria index; the secondary outcomes are change in nocturia and change in duration of uninterrupted sleep. The record does not report how the analyses correspond to the outcome measures, whether there were multiple comparisons within an outcome, or which analysis was designated as the principal test beyond the primary endpoint description.

As general statistical context, multiplicity arises when several hypotheses or comparisons are tested. If many tests are considered without an appropriate plan, the chance of at least one apparently unusual result can increase. Common approaches include defining one primary comparison in advance, adjusting significance thresholds, or interpreting secondary analyses as exploratory. Which approach was used in this study is not reported in the registry record. No multiplicity adjustment or hierarchy of secondary outcomes is reported.

Missing data are especially relevant for diary-based outcomes because the endpoint depends on recorded void times and volumes at baseline and follow-up. The record does not state how incomplete diary days, missing participant visits, or other unavailable measurements were handled. It also does not report the numbers included in each outcome analysis, reasons for missingness, or any sensitivity analyses addressing missing data.

The analysis population is also not described. The registry does not say whether the reported analyses followed all randomized participants according to assigned group, included only participants with complete measurements, or used another population definition. As general context, excluding participants with incomplete data can affect a randomized comparison if missingness is related to group assignment or outcome. Without participant-flow and analysis-population information, readers cannot assess that risk.

The record therefore identifies outcome domains and a primary measurement, but leaves multiplicity procedures, missing-data handling, and analysis populations unreported. These omissions do not establish that the analyses were inappropriate; they mean the registry record does not provide enough detail to evaluate those choices.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists 29 participants at risk in the brief behavioral treatment for insomnia group and 27 in the information-only control group. It records zero serious adverse events and zero other adverse events in each group, as well as zero deaths in each group. These are the registry's recorded figures for the groups and event categories listed.

As general statistical context, a zero count in a registry entry means that no events are recorded in that category for the stated group. It does not establish that an event is impossible, nor does it show that all possible harms were measured or reported. The record does not provide further detail about how events were defined, how they were collected, how long participants were monitored for safety, or whether event reporting was complete.

The group sizes listed at risk are not necessarily a full description of exposure or follow-up time. The registry does not report person-time or a detailed safety-analysis population. Thus, the zero entries should be read as the reported event counts, not as a complete assessment of risk or a comparison that proves equivalence between groups. The serious-event list contains no specific serious-event terms.

12. What the Result Does, and Does Not, Mean

The registry record establishes that the study was designed to compare brief behavioral treatment of insomnia with an information-only control, using change in nocturnal polyuria index at 4 weeks as the primary endpoint. It also records secondary outcomes concerning nocturia and uninterrupted sleep. These details explain the scientific question and the measures selected to address it.

The record does not establish the size or direction of the primary effect. The primary outcome was not reduced to one reported comparison, and no single between-group estimate, confidence interval, or test is available to interpret. The outcome definition and study completion status cannot substitute for those results. Consequently, the record does not support a conclusion that the behavioral intervention changed nighttime urine production or that it did not.

As general statistical context, an estimate can be compatible with a range of effects, and uncertainty matters when judging what the evidence can establish. A small, imprecise study may be consistent with possibilities that differ substantially; a precise estimate may narrow those possibilities. Here, the relevant primary estimate and its precision are not reported in a single interpretable form. The same limitation applies to numerical conclusions about the listed secondary outcomes.

The randomized parallel design is relevant because it aims to compare groups assigned to different approaches. Yet assessment of the actual comparison would require details about participant allocation, adherence, outcome availability, analysis populations, and statistical methods. The registry record does not report many of these details. This does not mean the study lacked procedures; it means they are not available in the record being summarized.

The safety entries record no serious or other adverse events and no deaths in either group. Those entries are limited to the reported categories and do not establish the absence of every possible harm. Overall, the record is useful for understanding what was intended to be measured and how the two groups differed, but it does not provide a basis for a conclusion about treatment effect or clinical benefit.

13. Why This Trial Matters Statistically

This trial is statistically notable for linking a sleep-focused intervention to a urine-production measure rather than restricting its outcomes to sleep symptoms alone. The primary endpoint is a percentage-based index derived from a 3-day bladder diary, connecting nighttime urine volume with total 24-hour urine volume. That definition makes the target of measurement explicit and distinguishes the endpoint from a simple count of nighttime voids.

The comparison also illustrates why an outcome definition and a result are different kinds of information. A registry can describe the intended measurement in detail, including the diary window and the calculation, while still failing to provide a single result that answers the comparative question. Reporting an estimate with uncertainty is essential for judging both the direction and precision of a group difference. In this record, that primary comparison is not available in a single interpretable form.

The randomized parallel-group structure gives the study a design intended to support a comparison between behavioral treatment and an information-only control. The control is not described as receiving no sleep-related content: it received information and video content overlapping substantially with BBTI, but without individualized behavioral instructions. This distinction is important for defining what the contrast represents. The question is about the difference between these approaches, not simply treatment versus no contact.

More broadly, the record highlights reporting issues that matter for clinical research: analysis populations, missing diary data, multiplicity, and uncertainty estimates. These are not merely technical details. They help readers judge how directly the reported analysis corresponds to the randomized comparison and how much confidence to place in a result. Since these items are not fully reported, the study's intended question can be understood more clearly than its statistical answer.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpretation is that the primary outcome is not reported as a single comparison. The registry identifies change in nocturnal polyuria index at 4 weeks and describes how it was measured, but does not provide an estimate and uncertainty interval that can be interpreted as the between-group result. Numerical results for the named secondary outcomes are also not reported in the registry record.

The enrolled population is not fully characterized in the record. Although sleep fragmentation, poor quality sleep, nocturia, and nocturnal enuresis are listed as conditions, eligibility criteria and participant characteristics are not reported. The total enrollment is 56, but the number contributing data to each outcome analysis is not reported. It is therefore not possible to judge from the record how representative the analyzed participants were or how much outcome data were available.

The primary measurement depends on diary entries for void timing and volume. The record describes the diary approach but does not report adherence, completeness, data-quality checks, or rules for handling incomplete records. It also does not describe whether outcome assessment or analysis was masked, beyond listing the study as having no masking.

Details of random sequence generation, allocation concealment, analysis methods, missing-data handling, analysis populations, and multiplicity procedures are not reported in the registry record. The record also does not provide the investigators' sample-size justification. These gaps prevent a detailed appraisal of potential bias, precision, and the relation between the planned and performed analyses. They do not show that any particular problem occurred; they limit what can be verified from the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Impact of Behavioral Treatment of Insomnia on Nighttime Urine Production — NCT03883724.
• Registry record last updated 2022-12-22; status last verified 2022-11.
• Results first posted 2022-12-22.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03883724 is a completed randomized, parallel-group study sponsored by the University of Pittsburgh. The registry lists enrollment of 56, no masking, a start date of 2019-02-01, and a primary completion date of 2021-11-30. The listed arms were brief behavioral treatment for insomnia and information-only control.

The primary endpoint was change from baseline in nocturnal polyuria index at 4 weeks, measured using a 3-day bladder diary. The registry also lists change in nocturia and change in duration of uninterrupted sleep as secondary outcomes. The record describes the index calculation but does not provide a single reported primary-outcome comparison. Group-level outcome estimates, uncertainty intervals, analysis-population details, and missing-data procedures are not reported in the registry record.

The adverse-event entries record zero serious adverse events, zero other adverse events, and zero deaths in both groups. The registry's planning description states assumptions for sample-size illustrations, but does not report the investigators' own design justification.