This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for The Effects of the Water Drinking Test on Intraocular Pressure (NCT01507584), a randomized na study. The primary outcome is 24-hour IOP Patterns.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01507584 |
| Phase | NA |
| Condition | Glaucoma |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 23 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, San Diego |
| Results posted | Yes |
2. Clinical Question
Population
The study summary describes patients with glaucoma or ocular hypertension. The registry lists glaucoma as the condition and records an enrollment of 23. The primary outcome description refers to glaucoma patients; the record does not give a separate count for either diagnosis.
Intervention
The listed device is SENSIMED Triggerfish, used for 24-hour intraocular pressure monitoring. The study summary says monitoring was planned three times at monthly intervals under different therapeutic regimens, and that the study would evaluate detection of changes after the water drinking test.
Comparator
The arm descriptions refer to a water drinking test after washout, with treatment, and with a prostaglandin analogue or beta blocker add-on. They also name prostaglandin analogue and carbonic anhydrase inhibitor regimens. The record does not report outcome results for comparisons among these conditions.
Primary question
The primary outcome is described as 24-hour intraocular pressure patterns: day-versus-night patterns and changes after the water drinking test. The central question is whether the monitoring approach detects those patterns and changes under the described study conditions. The registry record does not report the measurements or an answer to that question.
3. Trial Design
The registry identifies NCT01507584 as a randomized, non-masked crossover study. Its title concerns the effects of the water drinking test on intraocular pressure, and the official title specifies glaucoma patients undergoing 24-hour continuous monitoring with SENSIMED Triggerfish. The listed enrollment is 23. The study status is completed; the recorded start is 2011-08 and the primary completion date is 2013-04-30.
The study summary describes three monitoring occasions at monthly intervals under different therapeutic regimens. The arm descriptions name a prostaglandin analogue regimen and a carbonic anhydrase inhibitor regimen. For each, they list a water drinking test after washout at Visit 1, a test with treatment at Visit 2, and a test with a prostaglandin analogue or beta blocker add-on at Visit 3. The descriptions also include the abbreviations PGA + BB and CAI+ BB. The record does not explain the allocation sequence or how participants moved between these conditions.
A crossover design generally means that participants receive more than one study condition, allowing comparisons within participants as well as across conditions. That is a general description, not a confirmation of the precise analysis used in this study. Randomization identifies an allocation method, but the sequence, concealment procedures, and allocation details are not reported in the registry record. Masking is listed as none.
The registry reports that the study data could not be located after the principal investigator left the institution and that attempts were made to contact the study team. Consequently, the record gives no outcome estimates or analysis results. It also does not report the protocol details needed to determine how the crossover conditions were scheduled or analyzed.
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: The PI has left the institution and the study data can not be located. Multiple attempts where made to reach the study team, so there are no results to report.
Overall Study
| Stage | ALL PARTICIPANTS |
|---|---|
| STARTED | 0 |
| COMPLETED | 0 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The PI has left the institution and the study data can not be located. Multiple attempts where made to reach the study team, so there are no results to report.
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: The PI has left the institution and the study data can not be located. Multiple attempts where made to reach the study team, so there are no results to report.
| Characteristic | Unit | ALL PARTICIPANTS |
|---|---|---|
| Participants analysed | 0 | |
| Sex: Female, Male: Female | — | |
| Sex: Female, Male: Male | — |
6. Primary Endpoint
The registry lists the primary outcome as 24-hour IOP Patterns, measured over 24-hour.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled “24-hour IOP Patterns.” Its description says it assesses intraocular pressure patterns between daytime and nighttime and changes after the water drinking test. The timeframe is 24-hour. The outcome is therefore framed around patterns over time and response to the test, rather than a single measurement at one stated moment.
As a general statistical matter, measuring a variable repeatedly across a day can describe whether its level or pattern differs across times or conditions. A water drinking test can be studied as a defined challenge, with measurements used to examine changes associated with that challenge. Continuous monitoring may be used to capture temporal variation that isolated measurements could miss. These are general reasons for such an endpoint; they do not establish how measurements were summarized or compared in this study.
The registry does not provide a unit, summary parameter, dispersion measure, numerical definition of a change, or a reported estimate for this endpoint. It also does not report the results. The record therefore identifies what the endpoint was intended to assess, but does not show the magnitude, direction, or precision of any observed pattern.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
No primary outcome results are reported in the registry record. The stated reason is that the principal investigator left the institution and the study data could not be located, despite attempts to contact the study team. There are consequently no posted estimates of day-versus-night patterns, changes after the water drinking test, uncertainty intervals, or statistical tests to interpret.
The study summary states an intention to investigate the efficacy profile of SENSIMED Triggerfish during 24-hour monitoring and to evaluate detection of intraocular pressure changes after the water drinking test. These are research aims, not findings. Without recorded measurements and analysis results, the registry cannot establish whether patterns were detected, how they differed across conditions, or how precisely any difference was estimated.
The study is listed as randomized and crossover, but those design labels do not substitute for outcome data. Randomization can help address systematic differences between assigned conditions, while a crossover can allow comparisons within participants. In general, interpretation also depends on how treatment sequence, period effects, possible carryover, repeated measurements, and missing observations are handled. The registry record does not report the analysis used for these matters.
The adverse-event entry lists ALL PARTICIPANTS with zero participants at risk and zero affected for serious and other adverse events, and zero deaths. These entries should not be read as evidence that no events occurred: the registry also states that study data could not be located, and the recorded at-risk counts are zero. The record does not provide event narratives or a separate account that would clarify these entries.
No effect estimate, confidence interval, p-value, or comparison-specific result is available. Thus, neither a claim of a difference nor a claim of no difference can be supported from the posted results. The missing results also prevent assessment of whether any estimate would be clinically or statistically precise. The completed status indicates the registry's status designation; it does not supply the absent outcome findings.
9. Statistical Methods Explained
What the design labels mean. In general, random allocation is used to reduce the influence of systematic differences when assigning study conditions. A crossover design generally exposes participants to more than one condition, so each participant may contribute observations under multiple conditions. This can make within-participant comparisons informative because stable characteristics are shared across those observations. These are general properties of the design labels, not details of the study's statistical plan. The registry does not report the allocation sequence, sequence balance, washout duration, or the method used to account for treatment order.
Why repeated measurements require care. Measurements collected from the same participant are usually related rather than independent. A general analysis should account for that correlation; treating every measurement as unrelated can make uncertainty estimates misleading. The registry's endpoint describes day-versus-night patterns and changes after the water drinking test, but the record does not state the measurement schedule, the unit of analysis, or the model used to represent repeated observations. It does not provide a numerical outcome summary.
Time patterns and crossover periods. General analyses of repeated measurements may distinguish changes over time from differences between study conditions. A crossover study may also require attention to period effects, sequence effects, and carryover from an earlier condition. Carryover is a general possibility when the effect of one condition could persist into a later period. The arm descriptions mention a washout condition, but the registry does not give its duration or report whether carryover was assessed. No particular statistical model or adjustment can be attributed to this study from the record.
Effect estimates and uncertainty. In general, an effect estimate describes the contrast or pattern observed in the data, while a confidence interval describes uncertainty around an estimate under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, but precision is not the same as importance. A p-value, when reported, describes how compatible the data are with a specified statistical null model; it does not measure the probability that a research hypothesis is true. None of these inferential results is reported for this study. With no available measurements, there is no estimate or interval to explain.
Variability and distribution. General statistical summaries need to reflect the data's distribution and variability. If observations are more variable than a model assumes, uncertainty can be understated unless the analysis accounts for that extra variability. Likewise, a mean can conceal different time patterns among participants. The registry does not report distributions, dispersion measures, participant-level results, or methods for handling unusual observations. It is therefore not possible to judge whether a specific summary or model would have been appropriate.
Multiplicity. In general, testing multiple outcomes, time points, or comparisons can increase the chance of at least one apparently unusual result when no effect is present. A statistical plan may identify a primary comparison or use an adjustment strategy, but no such strategy is reported in the registry record. The registry names a primary outcome and lists secondary outcomes, including ocular adverse events; it does not provide an analysis plan or explain how multiple comparisons would be handled. The count of analyses recorded is zero.
Sample-size planning. A sample-size calculation generally depends on the target effect, outcome variability, significance level, desired power, allocation, and analysis method. A planning illustration based on an observed effect is a different exercise from the trial's original design justification, and it is not observed power. The registry record does not report the trial's sample-size justification or the inputs used to plan enrollment. Because no observed effect is available, a planning illustration based on that effect cannot be interpreted as evidence about the study's ability to detect a difference.
What can be concluded methodologically. The available record supports identification of the study as randomized, non-masked, and crossover, along with its stated endpoint and intended monitoring schedule. It does not document the statistical analysis, analysis populations, missing-data methods, inferential estimates, or model checks. General statistical principles explain why those details matter, but they cannot replace study-specific methods or results.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies 24-hour intraocular pressure patterns as the primary outcome and lists ocular adverse events as a secondary outcome. It does not report a statistical analysis plan, an approach to multiplicity, or how the named endpoint was divided into specific comparisons or time points. The number of analyses recorded is zero. As a general matter, multiplicity procedures can matter when several outcomes, time points, or treatment contrasts are examined, because the interpretation of isolated statistical tests depends on the analysis strategy. No such strategy can be inferred.
Missing-data methods are also not reported in the registry record. More fundamentally, the study summary says the study data could not be located. Without participant-level or summary outcome data, it is not possible to assess how much outcome information is missing, why particular observations might be missing, or whether any method was used to address missingness.
The record does not define analysis populations, such as which participants or observations would be included in each analysis. It does not report whether analyses followed assigned conditions, included participants who completed particular visits, or used another population definition. These distinctions can affect interpretation, especially in a crossover study with repeated measurements. They remain undocumented rather than answerable from the posted record.
11. What the Result Does, and Does Not, Mean
The registry record establishes that a completed randomized, non-masked crossover study was intended to examine 24-hour intraocular pressure patterns and changes after a water drinking test using SENSIMED Triggerfish monitoring. It records an enrollment of 23 and describes monitoring under different therapeutic regimens. It does not provide the outcome data needed to determine what patterns were observed or how they varied among conditions.
The absence of results is not evidence that the device detected no changes, nor is it evidence that it detected changes. It also does not show that different regimens produced the same or different patterns. Such conclusions require measurements and an analysis, neither of which is reported. The registry's completed status does not resolve this evidentiary gap.
In general, a study result is most informative when it includes an estimate and a measure of uncertainty, together with enough methodological detail to understand the comparison. Without those elements, the size and precision of an effect cannot be judged. The adverse-event zeros recorded alongside zero participants at risk likewise do not establish that no adverse events occurred.
The appropriate statistical reading is therefore limited: the record describes a research question and design, but does not report an answer. It cannot support a conclusion about the presence, absence, or magnitude of an effect.
12. Why This Trial Matters Statistically
This study's statistical question concerns a time-varying measurement: intraocular pressure patterns across day and night and changes associated with a water drinking test. Such questions illustrate why the timing and structure of observations matter. A single summary may not capture a pattern that changes over time, while repeated observations from the same participant require methods that account for their dependence. These are general statistical considerations relevant to the stated endpoint.
The crossover design also makes the comparison structure important. In general, within-participant comparisons can reduce the influence of characteristics that remain stable within a participant, but interpretation can depend on sequence, period, and carryover. The registry describes a washout condition and multiple therapeutic regimens, yet does not document how those design features were analyzed. The record therefore illustrates the difference between identifying a design and having enough methods detail to evaluate its statistical implementation.
Most importantly, a study's question and design cannot substitute for its findings. The record says the data could not be located and reports no primary outcome analysis. Without estimates and uncertainty measures, readers cannot assess the strength or precision of any pattern. This is a statistical limitation as well as a reporting limitation: no effect can be quantified from the available record.
13. 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 principal limitation is the absence of study results. The registry states that the principal investigator left the institution, the study data could not be located, and attempts were made to reach the study team. There are no reported primary outcome estimates, statistical tests, or uncertainty measures with which to evaluate the stated question.
Several design details are also not reported in the registry record. It does not specify the randomization sequence, allocation procedures, duration of the washout, timing of measurements within the 24-hour period, or exact operational definition of a change after the water drinking test. It names therapeutic regimens but does not explain the order in which participants received them or how comparisons were defined.
The record does not describe the statistical model, analysis population, missing-data approach, handling of repeated measurements, or assessment of period and carryover effects. It does not report a sample-size justification or multiplicity strategy. These omissions prevent a detailed assessment of the planned analysis and its assumptions.
The adverse-event entries list zero participants at risk and zero affected, so they cannot establish the frequency of adverse events in the enrolled study. The record also does not provide enough information to reconcile those entries with its statement that study data could not be located. These limitations are specific to the available registry record; they do not establish what was or was not observed in the underlying study.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: The Effects of the Water Drinking Test on Intraocular Pressure — NCT01507584.
- Registry record last updated 2019-09-11; status last verified 2019-08.
- Results first posted 2019-09-11.
- 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.
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17. Record Summary
NCT01507584 is a completed randomized, non-masked crossover study titled “The Effects of the Water Drinking Test on Intraocular Pressure.” The registry lists glaucoma as the condition, enrollment of 23, and SENSIMED Triggerfish as the device. The study summary describes 24-hour monitoring at monthly intervals under different therapeutic regimens, with water drinking tests after washout, with treatment, and with an add-on regimen.
The primary outcome is 24-hour intraocular pressure patterns, including day-versus-night patterns and changes after the water drinking test. The registry reports no outcome results because the study data could not be located after the principal investigator left the institution. No statistical analyses are recorded, and no effect estimates or uncertainty measures are available. The record lists ocular adverse events as a secondary outcome, but the adverse-event entries do not establish event rates.