Coenzyme Q10 in Huntington's Disease (HD): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Coenzyme Q10 in Huntington's Disease (HD) (NCT00608881), a randomized phase 3 study. The primary outcome is Joint Rank (Combination of Time to Death (for Subjects Who Died) and Change in Total Functional Capacity Score (TFC) From Baseline to Month 60 (for Subjects Who Survived)).

2. Clinical Question

The outcome plan initially centered on change in TFC from baseline to Month 60. According to the registry description, the Data and Safety Monitoring Board recommended reconsideration of how deaths and missing data would be accommodated in the primary analysis. Trial leadership then changed the primary analysis to the joint-rank approach. The question therefore concerns the comparison under that revised endpoint, rather than TFC change alone. The record does not state the exact interpretation convention for the reported joint-rank statistic, so its value should be read as the registry's reported estimate rather than assigned an unreported clinical meaning.

3. Trial Design

This was a phase 3, randomized, triple-masked, parallel-group trial sponsored by Massachusetts General Hospital. The registry record lists Huntington's disease as the condition and reports enrollment of 609 participants. One group received coenzyme Q10 at 2400 mg/day and the other received placebo. The listed design features describe the assignment structure and masking; additional details about how masking was implemented are not reported in the registry record.

The trial started in 2008-03, and primary completion was recorded in 2014-11. Its status is terminated. The registry record does not give a reason for termination, so the status alone does not explain whether or how it affected follow-up, outcome collection, or interpretation of the findings. The primary outcome's timeframe is five years, with the component TFC change defined from baseline to Month 60 for participants who survived.

The primary endpoint was changed during the trial. The registry says the initial primary variable was change in TFC score from baseline to Month 60, and that the Data and Safety Monitoring Board recommended reconsidering the treatment of participants who died and missing data in that analysis. Trial leadership changed the primary analysis to a joint-rank approach combining time to death for those who died with TFC change for survivors. Details such as the randomization procedure, allocation concealment, recruitment and eligibility criteria, treatment adherence, and the complete analysis plan are not reported in the registry record. The number enrolled should not be assumed to equal the number included in each endpoint analysis; the posted arm counts differ by outcome and should be interpreted in their stated context.

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.

Overall Study

Reasons for not completing this period:

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 Joint Rank (Combination of Time to Death (for Subjects Who Died) and Change in Total Functional Capacity Score (TFC) From Baseline to Month 60 (for Subjects Who Survived)), measured over 5 years.

The primary endpoint is a joint rank combining two kinds of information: time to death for participants who died, and change in TFC from baseline to Month 60 for participants who survived. This construction was adopted after trial leadership reconsidered how deaths and missing data should be handled in the originally planned analysis of TFC change. A joint endpoint can incorporate an outcome that would otherwise be absent from a survivor-only TFC comparison, but the registry record does not give the detailed ranking rules or the exact interpretation of its reported statistic.

TFC measures functional capacity through five ordinally scaled areas: occupation, financial affairs, domestic responsibilities, activities of daily living, and independent living. The stated total score ranges from zero (worst) to 13 (best). The primary outcome is reported over a five-year timeframe. For participants who survived, the endpoint uses change in this functional score; for those who died, it uses time to death. These components are not interchangeable measures, and the joint-rank approach combines them according to the trial's analysis method. The registry does not report enough detail to reconstruct that method or to translate the estimate into a simple difference in TFC points.

7. Results Posted in the Registry

• A - Coenzyme Q10 2400 mg/Day: mean 303.30 versus 306.70 on control; difference -3.40 (95% CI -31.37 to 24.57), standardized effect d = -0.02; z-test p = 0.812.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Total Functional Capacity (TFC) Score From Baseline to Month 60

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • A - Coenzyme Q10 2400 mg/Day: mean -4.53 versus -4.76 on control; difference 0.23 (95% CI -0.45 to 0.91), standardized effect d = 0.05; z-test p = 0.507.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between A - Coenzyme Q10 2400 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in Functional Checklist Score From Baseline to Month 60

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • A - Coenzyme Q10 2400 mg/Day: mean -7.93 versus -8.02 on control; difference 0.09 (95% CI -1.42 to 1.60), standardized effect d = 0.01; z-test p = 0.907.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between A - Coenzyme Q10 2400 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in Independence Scale Score From Baseline to Month 60

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • A - Coenzyme Q10 2400 mg/Day: mean -26.30 versus -24.86 on control; difference -1.44 (95% CI -6.73 to 3.85), standardized effect d = -0.04; z-test p = 0.594.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between A - Coenzyme Q10 2400 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary measures spanning functional capacity, independence, motor performance, behavior, and cognitive testing. The detailed numerical comparisons in this record cover change in TFC, Functional Checklist, and Independence Scale scores from baseline to Month 60. Each of their sponsor-reported 95% confidence intervals includes zero. Taken together, these posted estimates do not show a consistent, clearly separated pattern across the three reported functional measures. Their interpretation remains uncertain because the intervals allow a range of differences.

These secondary outcomes are related to, but distinct from, the primary joint-rank endpoint. TFC change is a component used for survivors in the primary endpoint, while the primary analysis also incorporates time to death for participants who died. The secondary TFC comparison therefore does not capture the same composite question. The Functional Checklist and Independence Scale provide other functional summaries; they are not interchangeable with TFC or with the joint-rank outcome.

The registry includes multiple secondary outcomes, so isolated secondary findings would carry less evidential weight than a prespecified primary result. In general, examining many outcomes increases the opportunity for chance findings, especially when results are interpreted without adjustment for multiple comparisons. The recalculated secondary p-values are unadjusted, and multiplicity procedures are not reported in the registry record. The detailed results for all listed secondary domains are not included in the analysis details for this record; no conclusion about those unreported numerical comparisons should be inferred from the three detailed outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Total Functional Capacity (TFC) Score From Baseline to Month 60
• Change in Functional Checklist Score From Baseline to Month 60
• Change in Independence Scale Score From Baseline to Month 60
• Change in Total Motor Score From Baseline to Month 60
• Change in Behavioral Frequency Score From Baseline to Month 60
• Change in Behavioral Frequency x Severity Score From Baseline to Month 60
• Change in Symbol Digit Modalities Test (SDMT) From Baseline to Month 60
• Change in Verbal Fluency Test From Baseline to Month 60

9. Statistical Interpretation

10. Statistical Methods Explained

The registry presents a sponsor-reported primary analysis and separately calculated comparisons based on posted summary statistics. These answer related but not identical questions. Reading them correctly requires distinguishing the joint-rank endpoint from ordinary mean differences, and reported inferential results from illustrative planning calculations.

What does the joint-rank endpoint combine?

The trial's primary analysis combines time to death for participants who died with TFC change from baseline to Month 60 for participants who survived. The registry explains that leadership changed the primary analysis after a Data and Safety Monitoring Board recommendation about handling deaths and missing data. A joint-rank method is a way to analyze an outcome that combines information from more than one type of measure. In general, ranking methods compare participants' relative ordering under specified rules rather than expressing the treatment contrast in the original units of one scale. The precise ranking rules, tie handling, and interpretation of the reported statistic are not reported in the registry record.

The posted primary estimate is π hat 0.494, with a 95% confidence interval from 0.454 to 0.534. The analysis method and p-value are not reported in the registry record. Because the statistic's interpretation convention is not specified in the posted analysis, the estimate should not be re-labelled as a probability, a risk, or a difference without further information.

What is the mean-difference recalculation?

The recalculated primary comparison uses the posted arm means and standard deviations to produce an unadjusted mean difference, confidence interval, and p-value. It reports a difference of -3.4, a 95% confidence interval from -31.37 to 24.57, and an unadjusted p-value of 0.812. This simple comparison does not use the joint-rank outcome, nor does it replicate any adjustment, ranking, or missing-data procedures that may underlie the sponsor's analysis. It is best treated as a descriptive statistical cross-check of the posted continuous summaries, not as a competing primary analysis.

For the secondary TFC, Functional Checklist, and Independence Scale outcomes, the recalculations also use arm-level summaries. The record identifies the TFC arm estimates as least-squares means with standard errors, while the other two use means with standard errors. A standard error describes uncertainty in an estimated mean; it is not the same quantity as the spread of individual participant scores. Recalculation from such summaries may require assumptions about the underlying variation and analysis structure. The exact models and adjustment details are not reported in the registry record.

How should confidence intervals and p-values be understood?

In general, a confidence interval represents a range of estimates compatible with the observed data under a specified statistical procedure. Its width reflects precision: wider intervals allow a broader range of values than narrower intervals. A p-value, when reported, describes how unusual data at least as inconsistent with a null hypothesis would be under that hypothesis and the model's assumptions. It is not the probability that the null hypothesis is true, nor does it measure clinical importance.

The recalculated p-values are explicitly unadjusted. They do not account for the fact that multiple endpoints may have been examined. The sponsor-reported primary analysis has no posted p-value in this record. No p-value should be inferred from its confidence interval or from the recalculated comparison.

Why can over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model expects. When a model assumes less variability than the data have, standard errors may be too small and confidence intervals too narrow, making results appear more precise than warranted. The primary endpoint combines rankings across different outcome components, and its analysis details are not reported in the registry record. The record does not state whether over-dispersion was assessed or relevant to the sponsor's method; no claim about its presence can be made from the posted information.

What are the planning calculations?

The sample-size figures are planning illustrations based on the observed effect, not the trial's original design. Their listed assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. For these continuous-outcome calculations, figures are participants per arm. In general, such calculations estimate a sample size for a chosen power under stated assumptions; they do not describe the achieved power of a completed trial. The original trial's sample-size justification, design assumptions, and any interim analyses are not reported in the registry record.

11. Confidence Intervals and Precision

The sponsor-reported primary joint-rank estimate is π hat 0.494, with a 95% confidence interval from 0.454 to 0.534. The registry does not report a p-value for this analysis or define the statistic's precise interpretation. The interval is the key posted indication of statistical precision for the primary endpoint: it leaves a range of possible values around the estimate rather than identifying one exact underlying effect. Its interpretation depends on the joint-rank method and its unreported analysis details.

The unadjusted recalculation from posted primary arm means gives a mean difference of -3.4, with a 95% confidence interval from -31.37 to 24.57. That interval spans a broad range and includes zero. Since this calculation uses a mean comparison rather than the sponsor's joint-rank endpoint, its precision cannot be used as a direct precision statement about the joint-rank estimate.

For the secondary comparisons, the registry-reported 95% intervals are 0.23 (-0.44 to 0.91) for TFC change, 0.09 (-1.40 to 1.58) for Functional Checklist change, and -1.44 (-6.68 to 3.79) for Independence Scale change. Each interval includes zero, and the widths show that the estimates remain compatible with a range of differences. These intervals are attached to their respective outcomes and should not be read as evidence that all possible values in the interval are equally likely.

In general, a confidence interval's width depends on the amount of information and variability as well as the analysis method. A confidence interval does not by itself resolve concerns about endpoint selection, missing data, multiplicity, or model assumptions. The registry record does not report all details needed to assess those features, so statistical precision is only one part of the interpretation.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning estimates describe participants per arm for these continuous outcomes; they are not total event counts. The registry's planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row uses a stated fraction of the observed effect as the effect to detect. The original trial's own sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm needed to have an 80% chance of detecting the specified effect under the planning assumptions, if that effect and the assumptions were correct. The 90% power column gives the corresponding illustration for a 90% chance. Power is a design property under a particular assumed effect and analysis; it is not the probability that a reported finding is true. These sample-size illustrations are not observed power.

Rows planning for a smaller fraction of the observed effect require larger participant counts. For example, the planning estimates for 50% of the observed effect are larger than those for 75% or 100% for each reported comparison. This follows the general statistical principle that smaller effects are harder to distinguish from random variation, all else being equal. The estimates are sensitive to the observed effect used as their starting point; they should not be treated as recommendations or as evidence that the trial was planned around these numbers. They also do not account for unreported design features, follow-up patterns, or analysis details.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -3.400; pooled standard deviation σ = 176.089.
2. n = 2 × (1.96 + 0.842)² × 176.089² / -3.400² = 42,106.2, rounded up to 42,107 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -3.39999999999998                      # observed difference in means
sigma <- 176.089291506315                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(608881)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 42,107 (80% power), 56,369 (90% power)
 75% of observed effect: n per arm = 74,856 (80% power), 100,211 (90% power)
 50% of observed effect: n per arm = 168,425 (80% power), 225,473 (90% power)
power.t.test: 42107.1 
Simulated power at n = 42,107 per arm: 0.795 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The primary sponsor-reported result is the joint-rank estimate, π hat 0.494, with a 95% confidence interval from 0.454 to 0.534. The registry does not report its analysis method or p-value. This result corresponds to the primary endpoint that combines time to death and TFC change for survivors.

The recalculated primary comparison is based instead on the posted arm means and standard deviations. It gives a mean difference of -3.4, a 95% confidence interval from -31.37 to 24.57, and an unadjusted p-value of 0.812. Because it is an unadjusted summary-statistic calculation and does not analyze the joint-rank endpoint, it is not a reproduction of the sponsor's analysis. Its interval and p-value should not be substituted for the sponsor-reported primary result.

The record does not flag a discrepancy between the sponsor's analysis and the recalculation. Even so, the distinctions in endpoint and method remain important: agreement or disagreement between two estimates is meaningful only when they target the same outcome and use compatible methods. The sponsor-reported joint-rank analysis is the relevant posted result for the designated primary endpoint; the recalculation is supplementary context based on continuous summaries.

15. Multiplicity, Missing Data and Analysis Populations

The registry record describes a change to the primary analysis after the Data and Safety Monitoring Board recommended that trial leadership reconsider how to accommodate missing data from participants who died. Leadership changed the primary analysis from TFC change alone to a joint-rank approach combining time to death for those who died and TFC change for survivors. This is an important design and analysis detail because the primary endpoint is not simply the originally described score change.

The posted description does not specify how other missing observations were handled, how participants with incomplete follow-up contributed to analyses, or what assumptions were used for missing data. The exact ranking rules and analysis population for the joint-rank outcome are also not reported in the registry record. Thus, the rationale for revising the death-related component is documented, but the complete operational method cannot be reconstructed from the posted description.

The registry lists several primary and secondary outcomes, and the recalculated p-values are unadjusted. The multiplicity strategy—whether outcomes were tested in a hierarchy, adjusted by a formal procedure, or treated as descriptive—is not reported in the registry record. Without that information, secondary results should be interpreted cautiously, since evaluating multiple outcomes can increase the chance of apparently notable findings arising from random variation.

The analysis populations, including whether results use an intention-to-treat population or another defined group, are not reported in the registry record. The number enrolled is 609, while posted arm counts for the primary summaries are 303 and 306. Those counts alone do not establish the inclusion rules or completeness of follow-up for every endpoint. Interim analyses, stopping boundaries, and the statistical plan are also not reported in the registry record. The trial's terminated status is recorded, but its reason and statistical consequences are not stated.

16. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: suicide attempt (3.3%), suicidal ideation (2.3%), depression (2.0%), pneumonia (1.6%), fall (1.6%).

The registry reports serious adverse events affecting 76 of 303 participants in the coenzyme Q10 group and 83 of 306 in the placebo group. Other adverse events affected 276 of 303 and 280 of 306, respectively. These are the posted participant counts; no additional comparative estimate or uncertainty interval for these counts is reported in the registry record. Death counts are not reported in the registry record.

The listed serious-event terms include SUICIDE ATTEMPT at 3.3%, SUICIDAL IDEATION at 2.3%, DEPRESSION at 2.0%, PNEUMONIA at 1.6%, FALL at 1.6%, and SUBDURAL HAEMATOMA at 1.6%. The record does not specify the arm allocation for these term percentages in the registry entries, so they should not be assigned to one group or interpreted as between-group rates.

Adverse-event counts are safety summaries, not proof that a treatment caused or prevented an event. Their interpretation depends on event definitions, collection and coding procedures, follow-up duration, and the populations assessed; those details are not reported in the registry record. Counts from groups of different sizes should not be treated as a formal comparison without an appropriate analysis.

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

The results describe uncertainty in a randomized comparison of coenzyme Q10 at 2400 mg/day and placebo among people with Huntington's disease. The sponsor-reported primary joint-rank estimate is 0.494 with a 95% confidence interval from 0.454 to 0.534. The registry does not report a p-value or a detailed interpretation convention for this statistic. It should therefore be understood as the posted joint-rank result, not as a TFC-point difference or a direct probability without further methodological information.

The recalculated mean comparison of the primary arm summaries is a separate analysis, with a difference of -3.4 and a 95% confidence interval from -31.37 to 24.57. It is not an analysis of the joint endpoint. The reported secondary intervals for the three detailed functional outcomes also include zero, but the analyses are unadjusted or incompletely described and do not establish a common result across all secondary domains.

These findings do not establish a definitive treatment effect or its absence. A confidence interval that includes zero is compatible with no difference under that comparison, while also allowing other values within the interval; it does not prove equivalence. Conversely, a point estimate alone does not show that a difference is clinically important. The registry record does not report a threshold for clinical importance, complete analysis details, or all numerical results across the secondary measures.

The safety counts document reported adverse-event experience in the two groups, but do not by themselves establish causation or a comparative safety conclusion. The trial's terminated status is known, while the reason is not reported in the registry record. The evidence should therefore be read as a set of posted estimates with limits in precision and available methodological detail, rather than as a categorical verdict.

18. Why This Trial Matters Statistically

This trial illustrates how endpoint definition can shape a clinical-trial result. The originally planned primary outcome was change in TFC from baseline to Month 60. After a recommendation concerning deaths and missing data, trial leadership adopted a joint-rank primary analysis that combines time to death for participants who died with TFC change for survivors. The reported result consequently answers a different statistical question from a simple comparison of TFC means.

It also demonstrates why statistical summaries need to be matched to the analysis they describe. The sponsor-reported π hat estimate and the recalculated mean difference use different outcomes and methods. Treating the recalculation as if it were the primary joint-rank analysis would conflate unlike quantities. The registry's description allows readers to identify that distinction, while leaving details such as ranking rules and other missing-data procedures unreported.

Precision matters as much as a point estimate. The primary confidence interval covers a range of estimates, and the recalculated and secondary intervals also span values on both sides of zero. A single estimate cannot convey the uncertainty on its own. The multiple secondary outcomes further show why results outside the primary endpoint require cautious interpretation, particularly when multiplicity adjustments are not described.

Finally, the planning illustrations demonstrate a general design principle: smaller effects require larger participant counts under the same assumptions. They are not the trial's original design justification and cannot establish what power the completed trial achieved. Together, these issues make the record useful for understanding endpoint changes, estimate precision, and the importance of transparent analysis reporting.

19. 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.

Several limitations are specific to the information recorded for this trial. The registry status is terminated, but the reason for termination is not reported in the registry record. The record reports primary completion in 2014-11, but does not explain how termination related to planned follow-up or data collection. No causal explanation for the status can be inferred from the status label alone.

The primary endpoint changed from TFC change to a joint-rank approach that combines death timing and survivor TFC change. Although the reason for reconsideration is described, the exact ranking method, handling of ties, analysis population, and procedures for missing data other than the described concern about deaths are not reported. Those omissions limit independent assessment or reproduction of the sponsor-reported primary analysis.

The primary sponsor analysis has a reported estimate and confidence interval but no p-value or named method in the record. The recalculation uses arm-level means and standard deviations and is not equivalent to the primary joint-rank analysis. Secondary results are available for only selected detailed comparisons in the analysis details, while the record lists a broader set of outcomes. The statistical plan for multiplicity and the analysis populations are not reported.

Safety information is summarized as affected-participant counts and selected serious-event terms. Death counts and arm-specific allocations for the listed term percentages are not reported in the registry record. The registry entries also do not give details about event ascertainment or follow-up by treatment group. These limits restrict the conclusions that can be drawn from safety summaries and from the broader collection of outcomes.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Coenzyme Q10 in Huntington's Disease (HD) — NCT00608881.
• Registry record last updated 2016-03-30; status last verified 2016-02.
• Results first posted 2016-03-30.
• 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.

23. Record Summary

The registry describes a randomized, triple-masked, parallel-group phase 3 trial in Huntington's disease, sponsored by Massachusetts General Hospital and enrolling 609 participants. It compared coenzyme Q10 at 2400 mg/day with placebo. The trial started in 2008-03, primary completion was recorded in 2014-11, and its status is terminated; the reason for termination is not reported in the registry record.

The primary endpoint was revised to a joint-rank analysis combining time to death for participants who died and TFC change for survivors. Its reported estimate is π hat 0.494, with a 95% confidence interval from 0.454 to 0.534; a p-value is not reported. A mean-based recalculation is distinct from that primary method. The detailed secondary comparisons have intervals that include zero. Missing-data procedures, multiplicity strategy, analysis populations, and several other analysis details are not reported in the registry record, so results are best read with those uncertainties in mind.