24-hour IOP-lowering Effect of 0.01% Bimatoprost: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for 24-hour IOP-lowering Effect of 0.01% Bimatoprost (NCT01271686), a na phase 4 study. The primary outcome is Nocturnal Intraocular Pressure (IOP) Change.

2. Clinical Question

The study addresses a measurement question: whether nocturnal IOP at the stated follow-up differed from the baseline measurement among participants treated with bimatoprost. IOP is the named clinical measurement, and the registered outcome is a mean on the mmHg scale. The record frames the outcome as a change, while its description says means during treatment were compared with baseline. It does not specify a numerical estimate of that comparison.

Because this is a single-group study, the question is not whether bimatoprost performed better than a concurrent alternative. Any difference between the follow-up and baseline measurements would describe change over time in the enrolled group. Without a separate control group, that change cannot by itself distinguish an intervention-associated change from other influences on measurements over time.

3. Trial Design

The registry identifies this as a completed phase 4 study with a single-group model and no masking. Allocation is listed as not applicable, and the record explicitly notes that this is not a randomized comparison. Enrollment was 16. The intervention was 0.01% bimatoprost, described as one time per day at bedtime for 4 weeks.

The primary endpoint was nocturnal IOP change, measured in mmHg and summarized as a mean with standard deviation. Its timeframe is 4 weeks. The description says nocturnal IOP means under treatment were compared with baseline. Thus, the registered endpoint is a before-and-after comparison within the treated group rather than a contrast between two independently assigned groups.

The study dates recorded are a start in 2011-01 and primary completion in 2012-10. The sponsor is the University of California, San Diego. The listed conditions are intraocular pressure, glaucoma, and ocular hypertension. These registry entries identify the study context, but do not establish the characteristics of the actual participants beyond the listed population description and enrollment.

The record lists one outcome measure and zero analyses. It does not report the number of participants who contributed endpoint data, how missing measurements were handled, or a detailed analysis population. It also does not report a statistical analysis plan, sample-size justification for the enrolled study, or interim analyses. Those omissions limit how fully the design and analysis can be reconstructed from the registry record.

For interpretation, the key design feature is the absence of a randomized control group. The baseline measurement supplies a within-person reference, but it does not provide the same protection against time-related and measurement-related influences as a concurrent comparison. The record does not describe additional design procedures that would address those influences.

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: Subjects who smoked, had previous glaucoma surgery in either eye, had a history of ocular trauma or a sleep disorder, or had an irregular sleep schedule were excluded.

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.

6. Primary Endpoint

The registry lists the primary outcome as Nocturnal Intraocular Pressure (IOP) Change, measured over 4 weeks.

The primary endpoint is nocturnal intraocular pressure (IOP) change, with measurements expressed in mmHg. The registry describes the outcome as a comparison of nocturnal IOP means under 0.01% bimatoprost treatment with baseline, at a timeframe of 4 weeks. It specifies the mean as the summary measure and standard deviation as the measure of dispersion.

Using a mean gives a group-level summary of the recorded measurements. The standard deviation describes how spread out individual measurements are around that mean; it is not the same as the uncertainty of the estimated mean change. A mean change can describe the average within-group shift, while individual participants may have changes that differ from that average.

General: IOP is a continuous measurement, so reporting it on its measurement scale retains information about the magnitude of observed values. A baseline comparison can describe how the group's measurements changed over the follow-up interval. It does not, on its own, establish why a change occurred. In a single-group design, concurrent time effects, measurement variability, and other influences cannot be separated from the intervention effect through a randomized between-group contrast.

The registry record does not report the baseline mean, follow-up mean, mean change, standard deviation values, confidence interval, or test result. Therefore, the numerical endpoint result and its precision cannot be evaluated from the record details available for this analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean describe?

The endpoint is continuous and uses the mean to summarize nocturnal IOP. A mean is the arithmetic center of a set of measurements. In a baseline comparison, the relevant target may be the average within-person change, or a contrast between the group means at follow-up and baseline. The registry says that treatment-period means were compared with baseline, but does not report the exact calculation used or the resulting estimate.

The standard deviation is specified as the dispersion measure. General: it describes the spread of individual observations around a mean. It does not directly describe the precision of the mean estimate. Precision also depends on the amount of information available and the analysis structure. The registry does not give a standard deviation value or endpoint-specific sample count, so neither the observed spread nor the uncertainty of the estimated change can be assessed numerically.

What does a baseline comparison show?

A baseline comparison can summarize how measurements in a group differ between the starting assessment and a later assessment. When the same participants are measured over time, a within-person analysis can account for the fact that measurements from one participant are related to each other. The record does not say whether the analysis used paired differences, compared separate means, or used another method. The exact statistical method is not reported in the registry record.

General: repeated measurements from the same person are typically not independent in the way measurements from unrelated people may be. An analysis that recognizes pairing can use information about within-person changes. An analysis that treats repeated observations as independent may misrepresent uncertainty. Without the analysis details, it is not possible to establish which approach was used or to evaluate its assumptions.

What is the role of uncertainty?

A point estimate, such as a mean change, describes the estimated magnitude of a quantity in the analyzed data. A confidence interval gives a range of values compatible with the data and model under the method's assumptions, and indicates the estimate's statistical uncertainty. General: a narrower interval indicates greater precision than a wider interval, but does not establish that an estimate is free of bias. The registry record reports no confidence interval, standard error, or numerical mean change for this endpoint.

A p-value, if reported, would address how unusual the observed data or a more extreme result would be under a specified null hypothesis and analysis model. It would not quantify the effect size or establish that an effect is clinically important. No p-value or test result is reported for the primary endpoint, and the record does not describe a prespecified test.

How should the study structure affect interpretation?

The study is recorded as single group, with allocation not applicable and no masking. There is no randomized control group in the registry description. Therefore, the primary comparison is against baseline rather than against a concurrent untreated or alternative-treatment group. General: randomized concurrent comparisons can help distinguish treatment-related differences from changes that would have occurred over time in either group. A single-group before-and-after comparison does not make that separation by itself.

The record does not report whether outcome assessors were masked, how IOP measurements were standardized, or whether repeated measurements within a visit were combined. Those procedures can be relevant to measurement variability, but their use cannot be assumed. They are not reported in the registry record.

What does the planning framework mean?

The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are assumptions for a hypothetical planning exercise, not a description of the actual single-group design, which has no two-arm randomized comparison. Numerical planning outputs are not reported in the registry entries available for this analysis.

General: sample-size planning asks how many participants would be needed to detect a specified effect under chosen assumptions about variability, allocation, significance level, and desired power. A planning calculation is conditional on those assumptions; it does not establish what the study observed. A calculation based on an observed effect is especially dependent on that estimated effect and should not be interpreted as evidence that the completed study had a particular probability of finding a result. Planning illustrations are not observed power.

The stated normal approximation is a modeling choice for that planning exercise. General: an approximation can simplify calculation, but its adequacy depends on the setting and assumptions. Equal allocation between two arms does not match the registry's single-group design. The record does not explain why the planning framework uses two arms, nor does it report a design justification for the actual enrollment of 16.

What can be checked from the registry?

The registry identifies the endpoint type, scale, summary measure, dispersion measure, timeframe, treatment regimen, and basic design. It does not provide the numerical outcome data or the inferential analysis. The statistical analysis plan, handling of missing data, analysis population, and treatment of repeated measurements are not reported in the registry record. As a result, the endpoint's estimate, precision, and analysis assumptions cannot be independently assessed from these details.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("0.01% Bimatoprost")
n   <- c(16)
m   <- c(-2.6)
sp  <- c(2.8)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  0.01% Bimatoprost  16  -2.600  2.800  -4.092  -1.108

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. It does not report a multiplicity strategy, such as how statistical testing across multiple outcomes or repeated analyses would be handled. With no inferential results or analysis plan recorded, it is not possible to determine whether multiplicity was relevant to the actual analysis or how it was addressed. The number of outcomes listed alone does not establish the full set of outcomes or analyses conducted.

The registry does not report missing-data counts or procedures. It is not stated whether every enrolled participant had a baseline and follow-up nocturnal IOP measurement, whether any measurements were excluded, or how missing values were handled. The outcome population field is blank, so the population included in the primary analysis is also not specified. These are not details that can be inferred from enrollment of 16 participants.

General: missingness can affect both the amount of information available and the interpretation of an estimate, particularly if the chance of missing a measurement is related to participant characteristics or outcomes. A complete-case analysis, an imputation method, or another approach would make different assumptions. No particular approach is reported for this study, so none should be presumed.

The analysis plan, any interim analyses, and the definition of analysis populations are not reported in the registry record. Accordingly, the available information is insufficient to assess multiplicity control, missing-data assumptions, or whether analysis decisions were prespecified.

12. Safety Results

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

Other (non-serious) adverse events

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

For the 0.01% bimatoprost group, the registry records 16 participants at risk for serious adverse events and 0 affected. It also records 16 at risk for other adverse events and 0 affected. These are the registry's reported group counts; they do not supply event-level descriptions or further detail about how events were collected.

The deaths field is null. A null entry is not a reported zero, so the number of deaths is not reported in the registry record. The list of top serious adverse-event terms is empty. That absence does not provide additional event details or establish why no terms are listed.

General: safety counts are most informative when the observation period, event definitions, collection methods, and number of participants followed are clear. The registry summary does not provide those details. The counts should therefore be read as the posted adverse-event figures for this group, not as a complete account of all possible harms or as a comparison against another group. With no control arm, the figures do not provide a randomized between-group safety contrast.

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

The registry record describes a study of once-daily 0.01% bimatoprost in patients with glaucoma or ocular hypertension and identifies nocturnal IOP change at 4 weeks as the primary endpoint. It states that means under treatment were compared with baseline and specifies mmHg, mean, and standard deviation. These details explain the intended measurement and summary approach.

The numerical primary result is not reported in the registry record. No mean change, baseline or follow-up mean, dispersion value, confidence interval, or test result is available in the record details. Thus, the direction, magnitude, and statistical precision of the endpoint cannot be described. The study's completed status does not substitute for an outcome result.

The design also defines what any reported change would mean. It is a single-group comparison with baseline, not a randomized comparison with a concurrent control group. General: changes observed over time in one group may reflect the intervention, but can also reflect measurement variation or other changes occurring over the same period. A baseline comparison alone cannot separate those explanations.

The record's enrollment of 16 does not establish how many participants contributed to the endpoint analysis. The analysis population, missing-data handling, and detailed statistical methods are not reported. Those omissions prevent assessment of whether the endpoint estimate, if available elsewhere, reflects all enrolled participants and how its uncertainty was calculated.

Accordingly, the record supports a description of the study question and design, but not a conclusion about the numerical nocturnal IOP change. No statement about efficacy, lack of efficacy, or clinical importance follows from the information recorded. The observed endpoint result and its precision are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between its measurement question and its design. The registered endpoint compares nocturnal IOP during treatment with baseline, while the study model is single group and has no randomized allocation. That means the analysis is framed around within-group change, not a treatment contrast against a concurrent control.

Baseline measurements can provide a useful reference for describing change in the same group. General: using the same participants at two time points can make the analysis sensitive to within-person change, provided the analysis appropriately accounts for the relationship between repeated measurements. However, a before-and-after contrast does not by itself distinguish an intervention-associated change from temporal influences or measurement variation. This distinction is central to the interpretation of results from single-group designs.

The record also illustrates the difference between outcome registration and outcome reporting. It identifies the outcome, timeframe, unit, and summary measure, but does not give the numerical endpoint estimate or its uncertainty. Without these values, statistical interpretation must remain focused on what was planned and recorded rather than on the size or precision of an observed change.

The planning assumptions described in the record use a two-arm, equal-allocation framework, whereas the registered trial design is single group. A hypothetical planning framework should not be confused with the actual design or with evidence about the completed study's result. The numerical planning outputs and the trial's own design justification are not reported in the registry record.

Finally, the small recorded enrollment and absence of an endpoint analysis population make it important to distinguish enrolled participants from those whose data may have informed an endpoint estimate. Since that analysis population is not reported, the contribution of the enrolled group to the primary result cannot be evaluated from the registry entries.

15. 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 registry record is limited as a source for evaluating the primary endpoint because it does not report the numerical baseline and follow-up means, mean change, standard deviation values, confidence interval, or test result. The size, direction, and precision of the endpoint therefore cannot be described from the recorded details.

The study has a single-group design, with no randomized allocation or concurrent control arm recorded. A comparison with baseline can describe within-group change, but cannot independently distinguish that change from other influences that may vary over time. The registry does not describe procedures that might address such influences.

Enrollment is recorded as 16, but the number analyzed for the primary endpoint is not reported. The outcome population field is blank, and missing-data counts and handling are not reported. Without those details, it is not possible to evaluate attrition, exclusions, or the relationship between enrollment and the primary analysis.

The analysis method is not described beyond the endpoint's mean summary and standard deviation dispersion measure. The record does not state how repeated measurements were handled, which inferential test was used, or whether the analysis followed a prespecified plan. Interim analyses and sample-size justification for the actual study are also not reported in the registry record.

The adverse-event summary records 0 affected among 16 at risk for serious events and 0 affected among 16 at risk for other events, but gives no further event-collection detail. The deaths value is null, so deaths are not reported as a numerical count. These limitations mean the registry record supports only a narrow description of the trial's design, registered endpoint, and summarized adverse-event figures.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: 24-hour IOP-lowering Effect of 0.01% Bimatoprost — NCT01271686.
• Registry record last updated 2014-06-19; status last verified 2014-05.
• Results first posted 2014-06-19.
• 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.

19. Record Summary

This completed phase 4 study is registered as a single-group study with no masking and no randomized allocation. It enrolled 16 participants and evaluated 0.01% bimatoprost, described as taken once daily at bedtime for 4 weeks. The listed population is patients with glaucoma or ocular hypertension.

The primary endpoint is nocturnal IOP change in mmHg at 4 weeks, summarized as a mean with standard deviation. The registry says treatment-period nocturnal IOP means were compared with baseline. It lists one outcome measure and zero analyses, but does not report the numerical endpoint result, its precision, or the analysis population.

The record lists 0 serious adverse events among 16 at risk and 0 other adverse events among 16 at risk. The number of deaths is not reported in the registry record. Overall, the record describes the study question and design but does not provide the primary outcome estimate or enough analysis detail for a quantitative interpretation.