12-Month Stability of Diurnal IOP Control on Cosopt: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for 12-Month Stability of Diurnal IOP Control on Cosopt (NCT00379834), a na phase 4 study. The primary outcome is Diurnal Intraocular Pressure Control.

2. Clinical Question

This is a question about pressure measurements over the day and across follow-up visits, rather than a direct comparison between Cosopt and another treatment. Diurnal intraocular pressure was measured every two hours from 8AM to 8PM. The registry describes the primary measure as a mean, with dispersion to be expressed as a standard deviation, and gives millimeters of mercury as the unit.

The study record does not report the numerical change from baseline, its standard deviation, or a statistical comparison. Consequently, the registry record alone does not establish the size or precision of any observed change. It also does not show whether individual participants had similar pressure patterns or whether the group average was influenced by variation among participants. The clinical question is identifiable from the planned outcome description, but the posted record does not provide the primary outcome findings needed to characterize the observed stability.

3. Trial Design

The registry identifies this as a completed Phase 4 study with a single-group model. Enrollment was 10. The intervention was Cosopt, described as twice daily in both eyes, for people with glaucoma. The registry record gives the study start as 2006-09 and primary completion as 2008-04.

Allocation is recorded as not applicable, and masking is recorded as none. The study therefore does not provide a randomized treatment allocation or a masked comparison. A single-group design can describe measurements collected in participants receiving the intervention, but it cannot separate changes during follow-up from changes that might also have occurred without that intervention. This is a general feature of uncontrolled designs, not a finding about the participants in this study.

The primary outcome timeframe is 12 months. Measurements were specified at baseline and at on-treatment visits at week 1, months 1, 6, and 12. The outcome description says that diurnal intraocular pressure was measured every two hours from 8AM to 8PM, and that the change from baseline in mean diurnal pressure was averaged across the on-treatment visits. The record does not explain how the baseline value was formed or how the repeated measurements and visits were combined beyond that description.

The population description says selection was based on the level of funding available. Further recruitment details, eligibility criteria, participant flow, and reasons for any loss to follow-up are not reported in the registry record. The record lists one outcome measure and no analysis entries. It does not report a statistical analysis plan or a sample-size justification for the study itself. Any planning illustration based on the observed effect is distinct from the trial's original design and cannot substitute for a prospective justification or a reported outcome analysis.

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: No patients excluded at any time

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Selected by level funding available

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 Diurnal Intraocular Pressure Control, measured over 12 months.

The primary endpoint is change from baseline in mean diurnal intraocular pressure, measured in millimeters of mercury. Diurnal pressure was to be measured every two hours from 8AM to 8PM. The description states that the change was averaged across on-treatment visits at week 1 and months 1, 6, and 12, within a 12-month timeframe. The endpoint is continuous: it represents a numerical measurement, rather than a count or a time until an event. The registry identifies the mean as the summary measure and the standard deviation as the dispersion measure.

As a general statistical concept, repeated measurements across the day can describe pressure over a broader daily period than a single measurement at one time. Averaging across visits can also represent the overall pattern across scheduled follow-up points, although an average can conceal variation between visits or participants. The endpoint description does not state how a participant's multiple daily readings were combined at each visit, how missing readings were handled, or how the baseline was calculated. Those details are not reported in the registry record.

The registry record does not report the numerical endpoint result, standard deviation, confidence interval, or test statistic. Thus, the stated endpoint explains what the study was designed to assess, but the posted record does not show the magnitude or precision of the observed change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is continuous because intraocular pressure is recorded numerically in millimeters of mercury. The registry identifies the target summary as a mean and the measure of dispersion as a standard deviation. These terms describe different aspects of data: the mean represents a group-level average, while the standard deviation describes how spread out observations are around that average. The registry does not report numerical values for either measure for the primary endpoint.

What does the mean change describe?

In general, a change-from-baseline outcome compares a follow-up measurement with a baseline measurement for the same study population or participant. The stated endpoint is the change in mean diurnal pressure from baseline, averaged across the on-treatment visits. A change score can focus attention on movement relative to baseline, but interpretation depends on how baseline and follow-up values are constructed and analyzed. The registry description does not specify those calculation details beyond the stated daily measurement schedule and averaging across visits.

The repeated daily readings have a time structure: measurements were scheduled every two hours from 8AM to 8PM. The follow-up visits also have a time structure: week 1 and months 1, 6, and 12. In general, measurements from the same participant are related rather than independent. An analysis of repeated measurements may need to account for this dependence if it uses the individual readings directly. Alternatively, a prespecified summary could reduce readings to a participant-level value before comparison. The registry record does not state which analytic approach was used, and no analysis entries are listed.

Why does variability matter?

Standard deviation is a descriptive measure of variability. A small or large standard deviation, considered in context, can indicate whether observations tend to cluster or differ substantially around the mean. It is not the same as the uncertainty in the estimated mean. General statistical methods use the standard error or a confidence interval to describe uncertainty in an estimate; these depend on the data and analytical assumptions. Neither a standard deviation nor a confidence interval for the primary outcome is reported in the registry record, so precision and participant-level variability cannot be evaluated from the posted results.

General methods for repeated data also need to address incomplete observations. If some scheduled readings or visits are missing, the analysis method can affect the estimate and its uncertainty. The registry does not report missing-data counts, reasons for missingness, or methods for handling missing values. No assumption about complete follow-up or a particular missing-data procedure can be made from the outcome description alone.

What can a single-group design establish?

As a general concept, a single-group study can describe what was observed among participants followed under the study conditions. Without a separate control group, it does not provide a randomized between-group estimate. Changes over time may have multiple explanations, and the design cannot isolate a treatment effect from those explanations through a concurrent comparison. This is a design limitation, not evidence that a particular alternative explanation occurred in this study.

The registry lists allocation as not applicable and masking as none. It identifies the model as single-group and the intervention description as Cosopt twice daily in both eyes. No masking means the record does not describe concealed knowledge of treatment assignment; in a single-group study, there is no treatment assignment between study arms to mask. The record does not provide further information about measurement procedures or safeguards against measurement-related bias.

How should planning calculations be read?

General sample-size calculations estimate how many participants may be needed under specified assumptions to detect an effect of a stated size with a chosen error rate and power. In this record, the planning illustration is explicitly based on the observed effect and is not the trial's own design. The assumptions state a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The calculations are described as targeting a stated fraction of the observed effect. For time-to-event outcomes, the stated convention is total events; for other outcomes, it is participants per arm.

Those planning assumptions do not match the recorded single-group design, which has no two-arm allocation. The registry record does not report the observed effect value or the numerical planning results in the registry record for this explanation. Such calculations should therefore be understood only as illustrations under their stated assumptions, not as a retrospective measure of the study's power. Observed power is not a substitute for an estimate and its uncertainty, and sample-size illustrations do not recover missing outcome results.

The registry record lists no analysis entries and does not report the prespecified statistical analysis plan, any interim analyses, or an adjustment strategy for covariates. These methods cannot be inferred from the continuous outcome type or from the reported measurement schedule. The registry's outcome description supports an account of what was intended to be measured, but not a reconstruction of the analysis actually performed.

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("Cosopt")
n   <- c(10)
m   <- c(-4.4)
sp  <- c(2)
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  Cosopt  10  -4.400  2.000  -5.831  -2.969

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, identified as the primary measure, and no analysis entries. It does not report a statistical analysis plan explaining how the primary outcome was analyzed or whether additional outcomes or analyses were planned outside the registry record. The record also does not report interim analyses or any adjustment for multiple statistical tests. Multiplicity refers, in general, to the increased chance of a chance-positive result when multiple hypotheses are tested; whether and how that issue applied cannot be determined without a fuller analysis plan and results.

Missing-data information is not reported in the registry record. There are no reported counts of participants with available measurements at each visit, missing daily readings, or withdrawals from follow-up. The record does not state whether an analysis included all enrolled participants, only participants with complete measurements, or another analysis population. It also does not describe an imputation procedure or other method for handling missing observations.

These omissions matter because repeated measurements can be incomplete, and the participants contributing data may differ across visits. In general, the way incomplete observations are handled can affect both an estimate and its uncertainty. No particular pattern of missingness or analysis population can be assumed. The enrollment of 10 describes the number enrolled; it does not establish how many contributed to each endpoint measurement.

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.

The registry reports serious adverse-event figures for the Cosopt group: 10 participants were at risk and 0 were affected. For other adverse events, it also reports 10 at risk and 0 affected. The deaths count is not reported in the registry record. These are the figures recorded for the listed categories and should be read as registry counts, not as a complete account of all safety information that may have been collected.

A count of 0 affected in the reported fields means that no affected participants are listed in those fields. It does not establish how adverse events were defined, how they were solicited, how long each participant was observed for safety, or whether all participants had complete safety follow-up. Those details are not reported in the registry record. The record lists no serious-event terms, so it does not describe the types of serious events assessed or observed.

Because the study has one group and enrollment was 10, these counts do not provide a comparative estimate of adverse-event risk against another treatment or a control group. As a general statistical point, counts from a small group can be imprecise indicators of event frequency, especially when no comparison and no detailed follow-up information are reported. The posted figures should not be interpreted as proof of absence of risk or as a broader conclusion about safety.

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

The registry record establishes that a completed Phase 4, single-group study enrolled 10 people with glaucoma to receive Cosopt twice daily in both eyes. It specifies a primary outcome intended to assess change from baseline in mean diurnal intraocular pressure over a 12-month timeframe, using measurements every two hours from 8AM to 8PM and averaging across on-treatment visits at week 1 and months 1, 6, and 12. This describes the question and measurement plan, not the numerical outcome.

The record does not report the primary result, its variability, or its precision. Consequently, it does not show how much the group mean changed, how individual measurements differed, or how stable the observed pattern was. It also does not provide an estimated contrast against a control group because none is described. No claim about the size or cause of any change can be drawn from the endpoint description alone.

As a general matter, an uncontrolled longitudinal study can provide descriptive evidence about measurements made in its enrolled participants. It cannot make the same direct comparative inference as a randomized controlled design. The absence of a concurrent comparator leaves changes over time open to explanations other than the intervention. The record does not say whether any such explanations were assessed.

The adverse-event fields list 0 affected participants among 10 at risk for serious events and 0 affected among 10 at risk for other events; a deaths count is not reported in the registry record. These entries are limited to the reported fields and do not establish that every type of event was captured or that safety follow-up was complete.

Overall, the registry record communicates the study's stated objective, design, measurement schedule, and limited adverse-event counts. It does not contain the primary outcome findings needed to judge the observed pressure trajectory or its statistical precision. Conclusions about treatment effects or clinical implications would go beyond what the posted record reports.

14. Why This Trial Matters Statistically

This study is statistically notable because its central question concerns measurements that vary both within a day and across follow-up visits. Diurnal intraocular pressure was scheduled every two hours from 8AM to 8PM, and the outcome was averaged across visits at week 1 and months 1, 6, and 12. Such a schedule makes the definition of the summary important: how repeated readings are reduced and how visit-level values are combined can shape what a mean change represents. The registry states the intended averaging but does not report further analytic detail.

The single-group design also clarifies the boundary between description and comparison. It can frame a question about stability among participants receiving Cosopt, but it has no concurrent group for a randomized comparison. This matters because an observed trajectory, if reported, would not by itself isolate a treatment effect. That is a general property of the design rather than a statement about the unreported outcome.

The small enrollment of 10 makes transparent reporting of participant-level data summaries and uncertainty particularly important for understanding how much the group average represents the enrolled participants. The registry does not report the primary estimate, standard deviation, confidence interval, or analysis entries. Thus, readers cannot assess precision or variability from the posted record.

Finally, the record illustrates why planning calculations must be distinguished from a study's actual design and analysis. The planning illustration uses two-arm assumptions, while this study is recorded as single-group. Without the primary result and the numerical calculations, those planning assumptions cannot serve as evidence about what the trial observed or how precisely it estimated its outcome.

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 main trial-specific limitation in interpreting the registry record is that no numerical primary outcome result is reported. Although the endpoint, unit, dispersion measure, and timeframe are specified, the record does not give a mean change, standard deviation, confidence interval, or test result. The intended question can therefore be described, but the observed pressure pattern cannot be evaluated.

The study is single-group, with no randomized comparison, and masking is recorded as none. The record consequently does not offer a concurrent control for distinguishing changes over time from other influences. This limitation is inherent in the recorded design and should not be mistaken for evidence about the direction or cause of any unreported change.

Enrollment was 10, and the population is described as selected by the level of funding available. The registry does not report further eligibility criteria, participant characteristics, recruitment details, or participant flow. These omissions limit assessment of how the enrolled group relates to other people with glaucoma and whether all enrolled participants contributed measurements at every visit.

Further limitations arise from absent methods information. The registry record does not report how baseline values were constructed, how readings were summarized at each visit, how missing data were handled, or which analysis population was used. It lists no analysis entries and does not report the statistical analysis plan. Finally, the adverse-event counts are not accompanied by event definitions or follow-up details, and the deaths count is not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: 12-Month Stability of Diurnal IOP Control on Cosopt — NCT00379834.
• Registry record last updated 2015-02-10; status last verified 2015-01.
• Results first posted 2015-02-10.
• 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 enrolled 10 people with glaucoma in a single-group design. Cosopt was described as twice daily in both eyes. Allocation was not applicable and masking was none. The registry gives a start of 2006-09 and primary completion of 2008-04.

The primary outcome was change from baseline in mean diurnal intraocular pressure, measured in millimeters of mercury. Measurements were specified every two hours from 8AM to 8PM and averaged across on-treatment visits at week 1 and months 1, 6, and 12. The registry record does not report numerical primary outcome results or analysis entries.

For serious adverse events, 10 were at risk and 0 were affected; the same figures are recorded for other adverse events. The deaths count is not reported in the registry record. The population was described as selected by the level of funding available.