Effects of Coenzyme Q10 (CoQ) in Parkinson Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Coenzyme Q10 (CoQ) in Parkinson Disease (NCT00740714), a randomized phase 3 study. The primary outcome is Change in Unified Parkinson's Disease Rating Scale (UPDRS) (Total Score (Sum of Parts I, II and III Ranges From 0 to 176)).

2. Clinical Question

The UPDRS captures mentation, behavior and mood; activities of daily living; and motor abilities. The registry describes the purpose as evaluating the safety and effectiveness of high dosages of Coenzyme Q10 in slowing clinical decline. The results should be read as comparisons of recorded score changes over the trial's stated follow-up window, rather than as a direct answer about every aspect of Parkinson disease or longer-term outcomes. The registry record does not report the reason for termination or additional details about eligibility, treatment adherence, or the analysis population.

3. Trial Design

This was a randomized, quadruple-masked, parallel-group Phase III trial sponsored by Weill Medical College of Cornell University. The registry lists an enrollment of 600 and a terminated study status. The study start is recorded as 2008-12, with primary completion recorded as 2011-08. The reason for termination is not reported in the registry record.

Three groups were specified: Coenzyme Q10 2400 mg/day with vitamin E 1200 IU/day; Coenzyme Q10 1200 mg/day with vitamin E 1200 IU/day; and placebo with vitamin E 1200 IU/day. Because vitamin E was part of each regimen, the comparisons address Coenzyme Q10 assignment in the context of shared vitamin E use, rather than comparing vitamin E against no vitamin E.

The primary outcome was a continuous measure: change in total UPDRS score. The registry reports least-squares means and standard errors for the groups. The outcome window ran from baseline to 16 months, or to the time of sufficient disability to require dopaminergic therapy or study closure, whichever occurred first. The record does not explain how these differing endpoint times were handled analytically.

Secondary outcomes included measures of independence, disability, quality of life, cognition, disease stage, plasma CoQ10 levels, and adverse experiences. The registry lists 23 outcome measures and 32 analyses. The specific randomization procedure, masking roles, allocation ratio, original sample-size justification, and detailed statistical analysis plan are not reported in the registry record. The listed arm counts for the primary outcome are 196, 201, and 203; those outcome counts should not be assumed to establish which analysis population was used.

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: Patients were required to undergo a thorough screening visit. If patients were taking CoEnzyme Q10 but otherwise eligible for assignment, they were asked to return after a wash out period of 60 to 120 days based on daily dosage.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Eligible research participants were assigned by randomization to one of three treatment groups: CoQ10 2400 mg/day, CoQ10 1200 mg/day or matching placebo. All participants also received 1200 IU of vitamin E daily.

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 Change in Unified Parkinson's Disease Rating Scale (UPDRS) (Total Score (Sum of Parts I, II and III Ranges From 0 to 176)), measured over Baseline to 16 months or the time of sufficient disability to require dopaminergic therapy or study closure, whichever occurs first.

The primary endpoint was change in total Unified Parkinson's Disease Rating Scale (UPDRS) score from baseline to 16 months, or until sufficient disability to require dopaminergic therapy or study closure, whichever occurred first. The scale combines three parts: mentation, behavior and mood; activities of daily living during the week before the visit; and motor abilities at the visit. The registry describes 31 items across these parts, with each item scored from 0 to 4. A score of 0 represents absence of impairment, while 4 represents the highest degree of impairment; total score ranges from 0 to 176.

Because a higher score represents greater impairment, change in score provides a way to track recorded clinical status over time. A positive change means the follow-up score is higher than baseline; a negative change means it is lower. This direction is a property of the scale and does not, by itself, establish a clinically important difference. The registry does not report a threshold for clinical importance.

Using a continuous score retains information across the scale rather than reducing each participant's result to a simple event or no-event classification. In general, continuous outcomes can be summarized with group means and mean differences, while their interpretation depends on the scale, the timing of assessment, and the precision of the estimates. The stated endpoint timing also means that some observations could end before 16 months under the protocol description. Details of how such observations were incorporated are not reported in the registry record.

7. Results Posted in the Registry

• A. Coenzyme Q10 2400 mg/Day With Vitamin E 1200 IU/Day: mean 8.01 versus 6.92 on control; difference 1.09 (95% CI -0.66 to 2.84), standardized effect d = 0.12; z-test p = 0.221.
• B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day: mean 7.50 versus 6.92 on control; difference 0.58 (95% CI -1.15 to 2.31), standardized effect d = 0.07; z-test p = 0.512.

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 Modified Schwab & England Independence Scale From Baseline to 16 Months

• 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 With Vitamin E 1200 IU/Day: mean -4.94 versus -4.07 on control; difference -0.87 (95% CI -2.59 to 0.85), standardized effect d = -0.10; z-test p = 0.321.
  • B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day: mean -4.29 versus -4.07 on control; difference -0.22 (95% CI -1.94 to 1.50), standardized effect d = -0.02; z-test p = 0.802.
• 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 With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in Modified Rankin Scale From Baseline to 16 Months

• 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 With Vitamin E 1200 IU/Day: mean 0.38 versus 0.40 on control; difference -0.02 (95% CI -0.16 to 0.12), standardized effect d = -0.03; z-test p = 0.777.
  • B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day: mean 0.31 versus 0.40 on control; difference -0.09 (95% CI -0.23 to 0.05), standardized effect d = -0.13; z-test p = 0.203.
• 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 With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in PD Quality of Life Scale From Baseline to 16 Months

• 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 With Vitamin E 1200 IU/Day: mean 5.06 versus 5.57 on control; difference -0.51 (95% CI -2.98 to 1.96), standardized effect d = -0.04; z-test p = 0.685.
  • B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day: mean 6.12 versus 5.57 on control; difference 0.55 (95% CI -1.89 to 2.99), standardized effect d = 0.04; z-test p = 0.659.
• 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 With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between B. Coenzyme Q10 1200 mg/Day With Vitamin E 1200 IU/Day and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover functional independence, disability, quality of life, cognition, disease stage, plasma CoQ10 levels, and adverse experiences. The registry lists 22 posted secondary outcomes. Taken as a group, the reported continuous-outcome comparisons do not show a consistent pattern of clearly separated results between either Coenzyme Q10 assignment and placebo. The available estimates vary in direction and their reported intervals include zero. This broad pattern is compatible with the uncertainty in the primary comparison, rather than providing a clear contrasting signal.

Secondary measures can add context because they assess different aspects of function and experience. They do not replace the primary endpoint, which was the prespecified main outcome in the registry record. Nor should a collection of secondary comparisons be treated as though each were a separate definitive test. The registry reports 23 outcome measures and 32 analyses, but the multiplicity plan and the status of each outcome as prespecified or exploratory are not reported in the registry record.

In general, when many outcomes and comparisons are examined, the chance of obtaining an apparently noteworthy result by chance can increase. Unadjusted secondary results therefore carry less weight than a clearly specified primary analysis, particularly when the statistical plan and multiplicity correction are not available. A result on one secondary scale would need to be considered alongside its uncertainty, the measurement's meaning, consistency across related outcomes, and whether it was part of a prespecified analysis. The secondary results should be interpreted as supporting context, not as independent confirmation of a treatment effect or as proof that an effect is absent.

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

• Change in Modified Schwab & England Independence Scale From Baseline to 16 Months
• Change in Modified Rankin Scale From Baseline to 16 Months
• Change in PD Quality of Life Scale From Baseline to 16 Months
• Change in Symbol Digit Modalities Test From Baseline to 16 Months
• Change in Hoehn & Yahr Score From Baseline to 16 Months
• CoQ10 Levels in Plasma
• Adverse Experiences: Back Pain
• Adverse Experiences: Constipation

9. Statistical Interpretation

10. Statistical Methods Explained

In general, a randomized comparison aims to make treatment groups comparable at the point of assignment, so differences in outcomes can be evaluated in relation to assigned groups. Randomization is reported for this study, but the registry record does not describe the sequence-generation method, allocation concealment, or the roles covered by quadruple masking. The design is listed as parallel, meaning the groups are treated as separate assignments rather than as a crossover sequence.

What does a mean difference represent?

In general, a mean difference is one group's average outcome minus another group's average outcome, with the order of subtraction determining its sign. For this trial, the simple re-calculations compare each Coenzyme Q10 group with placebo. A positive difference indicates a higher change in UPDRS in the active-assignment group than in placebo under that subtraction order. Since higher UPDRS scores represent greater impairment, direction is useful context, but the difference still needs to be considered alongside its uncertainty and clinical importance.

The registry's primary group summaries are least-squares means with standard errors. In general, a least-squares mean is a model-based group estimate, often adjusted for variables included in the model. The particular covariates and model specification for the primary endpoint are not reported in the registry record. Standard error describes uncertainty in an estimated mean; it is not the same as the spread of individual participant scores.

What role does ANCOVA play?

The sponsor's posted primary comparisons are identified as ANCOVA. In general, analysis of covariance estimates group differences while accounting for specified covariates, which may include baseline outcome values. The registry record does not identify the covariates, the exact model, or the assumptions used for this ANCOVA. Therefore, the reported sponsor estimates should be treated as the registry's own adjusted analysis, without attributing particular adjustments that are not documented.

The separate unadjusted re-calculation uses the posted group summary statistics to estimate a mean difference and its uncertainty. The pooled standard deviations used for those calculations are marked as approximate. In general, using summaries rather than participant-level data cannot reproduce an adjusted model, account for all features of the trial analysis, or check its assumptions. The recalculated p-values are therefore not substitutes for the sponsor's analysis. In this record, the discrepancy flag is true, so the sponsor's own analysis takes precedence.

Why do confidence intervals matter?

In general, a confidence interval gives a range of values compatible with the data and the method used, at the stated confidence level. A wide interval indicates limited precision: the data do not sharply distinguish among values across that range. An interval that includes zero does not establish a nonzero mean difference at its corresponding confidence level. It also does not demonstrate that the true difference is zero. The intervals reported for the primary comparisons include zero and extend to values on both sides of it.

A p-value summarizes how surprising the data would be under a specified null hypothesis and statistical model. It does not measure the probability that a treatment is effective, nor does it show the probability that the null hypothesis is true. The sponsor's p-value entries use the threshold notation reported in the registry, so they are best read as transcribed rather than as fully documented tests: the analysis plan and the reason for the differing reported confidence levels are not reported in the registry record.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a model assumes. It can make standard errors too small if the model does not accommodate the extra variation, leading to intervals that are too narrow and tests that appear more conclusive than they should. The primary endpoint is continuous, and the registry does not report an over-dispersion assessment. This general concept is more directly relevant to outcomes analyzed with count or other variance-constrained models; it should not be assumed to have affected this trial's primary analysis.

Interpretation also depends on endpoint timing, missing-data handling, and the population included in each analysis. The registry describes a follow-up endpoint that could be measured at 16 months or earlier under specified circumstances, but does not explain the analysis of incomplete or earlier observations. It also does not report whether the primary analysis followed intention-to-treat, per-protocol, or another population definition. Those missing details limit independent assessment of the analysis, without changing the fact that the sponsor's posted ANCOVA results are the registry's own reported results.

11. Confidence Intervals and Precision

For the primary comparison of Coenzyme Q10 2400 mg/day with placebo, the sponsor reports a mean difference of 1.09 and a 95% confidence interval from -0.85 to 3.03. For Coenzyme Q10 1200 mg/day compared with placebo, it reports a mean difference of .59 and a 97.5% confidence interval from -1.33 to 2.51. Each interval crosses zero, indicating that the posted estimate is not precise enough to rule out a zero difference at the reported confidence level. Each also includes values in both directions.

In general, a confidence interval reflects both the estimated effect and its sampling uncertainty under the analysis method. It is not a range that contains a fixed proportion of individual participant outcomes. Here, the intervals span values that could correspond to different magnitudes and directions of mean change. The registry does not report a clinical-importance threshold, so the endpoints of the intervals cannot be classified against such a threshold from this record.

The sponsor's intervals are not identical to those from the unadjusted re-calculation, and their confidence levels differ between the two primary comparisons. The re-calculated intervals use approximate pooled standard deviations and posted summary statistics; they are not a reconstruction of the sponsor's ANCOVA. Given the true discrepancy flag, the sponsor's estimates and intervals take precedence. The registry record does not explain the different confidence levels, the reported p-value threshold notation, or the statistical plan that generated them. Precision should therefore be described from the sponsor's results as posted, while recognizing that fuller model documentation is unavailable.

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 sample-size illustrations are planning calculations based on the observed effect, not the original design justification for this trial. The primary outcome is continuous, so the figures for it are participants per arm, not total events. The registry's planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The assumed effect to detect is the stated fraction of the observed effect. The original trial's sample-size assumptions are not reported in the registry record.

The 80% power column means the number of participants per arm estimated to give an 80% chance of detecting the assumed effect under those planning assumptions, if that effect and the model assumptions were correct. The 90% power column expresses the analogous planning target at a higher chance of detection. These are design targets, not guarantees for a future study. The sample-size figures are illustrations based on the observed trial effect, not the trial's own design calculations.

Rows using a smaller fraction of the observed effect require more participants per arm. That is expected in general: smaller differences are harder to distinguish from random variation, all else being equal. The figures can be read as sensitivity illustrations for different target effects, rather than as claims about the appropriate size of a future study. Other design choices, outcome variability, analysis methods, and follow-up can affect a real sample-size calculation. These figures are not observed power.

For time-to-event outcomes, the stated convention is total number of events, but that convention does not apply to this continuous primary endpoint. The actual statistical plan, any allowance for attrition, and the assumptions used in the original design are not reported in the registry record.

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 = 1.090; pooled standard deviation σ = 8.900.
2. n = 2 × (1.96 + 0.842)² × 8.900² / 1.090² = 1,046.5, rounded up to 1,047 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 <- 1.09                      # observed difference in means
sigma <- 8.89977774041101                     # 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(740714)
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 = 1,047 (80% power), 1,401 (90% power)
 75% of observed effect: n per arm = 1,861 (80% power), 2,491 (90% power)
 50% of observed effect: n per arm = 4,187 (80% power), 5,604 (90% power)
power.t.test: 1047.5 
Simulated power at n = 1,047 per arm: 0.801 (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 registry reports the sponsor's primary comparisons as ANCOVA mean differences. For 2400 mg/day versus placebo, the estimate is 1.09, with a 95% confidence interval from -0.85 to 3.03 and p > 0.025. For 1200 mg/day versus placebo, the estimate is .59, with a 97.5% confidence interval from -1.33 to 2.51 and p > 0.025. These are the trial's posted analysis results and should be distinguished from the simple unadjusted re-calculation.

The re-calculation uses posted arm-level summary statistics and produces estimates of 1.09 and 0.58, with unadjusted p-values of 0.221 and 0.512. It is not an independent replication of the sponsor's ANCOVA: the registry does not give the sponsor's model details, and summary-statistic methods do not reproduce participant-level adjustment. The small difference between the lower-dose estimates is one visible element of the discrepancy; the reported inferential results also differ in method and presentation.

Because the discrepancy flag is true, the sponsor's own analysis takes precedence. The record does not explain the source of the discrepancy, identify the ANCOVA covariates, or document the analysis plan in enough detail to resolve it. The sponsor's results still require cautious interpretation: both confidence intervals include zero and allow differences in either direction. No claim about treatment effectiveness follows from choosing the sponsor's results over the re-calculation.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists 23 outcome measures and 32 analyses, including one primary outcome and 22 posted secondary outcomes. Multiple outcomes and group comparisons create a multiplicity issue: in general, the more statistical tests that are conducted, the greater the chance that at least one result may appear unusual even when there is no underlying effect. Appropriate interpretation depends on which tests were planned in advance and whether the analysis controlled the overall error rate or used another prespecified strategy.

The multiplicity strategy is not reported in the registry record. The sponsor's primary comparison results use different confidence levels for the two dose comparisons, but the record does not explain why those levels differ or how they relate to any adjustment. The p-value entries are recorded as p > 0.025. Without the statistical plan, these entries cannot establish the exact testing framework or whether the threshold reflects a multiplicity procedure. The unadjusted re-calculated p-values do not account for multiple outcomes or comparisons and should not be used to settle that question.

Missing-data handling is also not reported. The primary endpoint was intended for baseline to 16 months or an earlier endpoint time related to sufficient disability requiring dopaminergic therapy or study closure. The record does not state how incomplete visits, withdrawals, or outcomes ending before 16 months were handled, whether imputation was used, or what assumptions were made about missingness.

The analysis population is not reported in the registry record. Although the study is randomized and outcome group counts are posted, the record does not say whether the primary analysis included all randomized participants, a modified intention-to-treat population, or another subset. It also does not describe sensitivity analyses or interim analyses. These omissions limit evaluation of bias and reproducibility; they do not justify assumptions about which methods were used.

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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pelvic floor dysfunction (1.6%), pacemaker battery replacement (1.0%), pneumonia (1.0%), prostate cancer progression (0.8%), benign prostatic hypertrophy (0.8%).

The registry reports serious adverse experiences affecting 7 participants in the 2400 mg/day Coenzyme Q10 group, 13 in the 1200 mg/day group, and 13 in the placebo group. The listed numbers at risk are 196, 201, and 203, respectively. For other adverse experiences, the affected counts are 106, 113, and 108, with the same respective numbers at risk. These are counts as recorded, not a comparison adjusted for follow-up, baseline risk, or other factors.

The record lists serious-event terms including pelvic floor dysfunction, pacemaker battery replacement, pneumonia, prostate cancer progression, benign prostatic hypertrophy, and transurethral resection of the prostate, with percentages recorded for those terms. The listing does not provide enough detail to attribute a particular term to a specific treatment group or establish a causal relationship. Death counts are not reported in the registry record.

In general, adverse-event counts describe events recorded during a study and should be interpreted with attention to definitions, exposure time, and completeness of reporting. The registry record does not provide the detailed safety analysis plan, event-level narratives, or a causal assessment. These figures alone do not establish comparative safety or explain why the study was terminated.

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

The result is a set of comparisons of recorded UPDRS change among participants assigned to two Coenzyme Q10 doses or placebo, with vitamin E used in each group. The sponsor's ANCOVA estimates are positive for both Coenzyme Q10 comparisons, and both reported confidence intervals include zero. The intervals also extend to values on either side of zero, so the posted results leave uncertainty about the direction and size of the group differences.

That uncertainty is not the same as evidence that the groups were identical. A confidence interval that includes zero can arise when the data do not distinguish a nonzero difference from no difference with the stated precision. Conversely, the point estimates alone do not establish an effect. The registry does not state a threshold for a clinically important UPDRS change, and no such threshold can be inferred from the group estimates.

The scope of the comparison is also specific. Each group received vitamin E, so the result concerns Coenzyme Q10 assignment against placebo in the setting of shared vitamin E use. The endpoint followed participants to 16 months or an earlier defined stopping point, rather than measuring every possible longer-term outcome. The posted results do not answer questions about outcomes outside the measures and follow-up described in the registry record.

The trial status is terminated, but the reason is not reported in the registry record. The status alone does not show that the study stopped because of efficacy, safety, futility, recruitment, or any other particular cause. The findings should therefore be understood as the posted outcome estimates and their uncertainty, not as a recommendation or a definitive statement about treatment.

18. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation needs more than a comparison of point estimates. The primary group means and the sponsor's between-group estimates describe different quantities: the first show each group's recorded average change, while the second estimate differences between assignments. The confidence intervals add information about precision, showing that the primary estimates remain compatible with a range of possible differences.

It also demonstrates the distinction between a sponsor's adjusted analysis and a summary-statistic re-calculation. A re-calculation can serve as a check on the broad numerical scale of the reported result, but it cannot reproduce an ANCOVA without its model specification and participant-level data. When the record flags a discrepancy, the sponsor's own analysis takes precedence, while the discrepancy remains a reason to avoid treating the simplified calculation as equivalent evidence.

The design includes two active doses and a placebo comparison, with vitamin E included in all groups. That structure makes the comparison interpretable as Coenzyme Q10 assignment against placebo on a shared background regimen. The trial also has multiple secondary outcomes, which illustrates why multiplicity and the prespecification of analyses matter when interpreting a collection of findings.

Finally, the registry record leaves important elements of statistical planning and execution undocumented, including the original sample-size justification, missing-data handling, analysis population, and multiplicity strategy. These omissions do not erase the posted estimates, but they limit how fully an independent reader can assess their assumptions and robustness. Statistical conclusions are strongest when effect estimates, precision, design, and analysis details can be considered together.

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.

The registry record does not report the reason the study was terminated. It also does not provide the original sample-size justification or enough of the statistical analysis plan to evaluate whether the planned enrollment and analyses were matched to a prespecified target effect. The planning illustrations based on observed effects should not be mistaken for the trial's original design calculations.

The primary endpoint could be assessed at 16 months or at an earlier time tied to sufficient disability requiring dopaminergic therapy or study closure. The record does not explain how these different observation times were analyzed, how missing observations were handled, or whether endpoint timing differed across groups. Details of attrition, adherence, and the primary analysis population are also not reported.

The sponsor's ANCOVA is identified by method, but its covariates and model specification are not reported. The sponsor's confidence levels differ between the two primary comparisons, and the p-value entries are given as threshold statements; the record does not explain their statistical rationale. A true discrepancy between the posted sponsor analysis and the simple unadjusted re-calculation is flagged, and the sponsor result takes precedence, but the source of the discrepancy is not documented.

The trial compared Coenzyme Q10 with placebo while vitamin E was included in all groups. Consequently, the study does not report a comparison of vitamin E against no vitamin E. The results also concern the stated UPDRS endpoint and follow-up window; they should not be extended to unreported outcomes, longer-term effects, or other populations. The registry does not state a clinical-importance threshold for interpreting score differences.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Effects of Coenzyme Q10 (CoQ) in Parkinson Disease — NCT00740714.
• Registry record last updated 2013-01-31; status last verified 2012-12.
• Results first posted 2013-01-31.
• 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

NCT00740714 is a randomized, quadruple-masked, parallel-group Phase III trial sponsored by Weill Medical College of Cornell University. The registry describes 600 enrolled participants with early Parkinson disease and lists the status as terminated. The reason for termination is not reported in the registry record.

Participants were assigned to Coenzyme Q10 2400 mg/day, Coenzyme Q10 1200 mg/day, or placebo; each group also received vitamin E 1200 IU/day. The primary outcome was change in total UPDRS score from baseline to 16 months or an earlier specified endpoint time. The sponsor's posted ANCOVA estimates for both dose comparisons have confidence intervals that include zero. A discrepancy is flagged between the sponsor results and the unadjusted re-calculation, so the sponsor's analysis takes precedence.

The registry includes secondary outcomes and adverse-event counts, but does not report the multiplicity strategy, missing-data methods, primary analysis population, or detailed model specification. These limitations constrain interpretation of the posted results.