Open-Label Clinical Study of Droxidopa in Patients With Neurogenic Orthostatic Hypotension (NOH): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Open-Label Clinical Study of Droxidopa in Patients With Neurogenic Orthostatic Hypotension (NOH) (NCT00738062), a randomized phase 3 study. The primary outcome is Change in Orthostatic Hypotension Questionnaire Composite Score (OHQ).

2. Clinical Question

3. Trial Design

The registry describes a Phase 3, randomized, quadruple-masked, parallel study with 103 participants enrolled. The study title identifies it as open-label, and the primary outcome description clarifies the sequence: all participants received open-label droxidopa for 3 months before randomization, followed by a double-blind randomized phase. Thus, the open-label period preceded the comparison of continued droxidopa with placebo. The primary outcome timeframe was 14 days.

This withdrawal design addresses whether outcome changes differ after participants already receiving droxidopa are randomized to continue it or switch to placebo. It does not estimate the effect of initiating droxidopa versus initiating placebo in a population that has not received the drug. The enrolled population included people with neurogenic orthostatic hypotension and associated conditions named in the registry, including non-diabetic autonomic neuropathy, Multiple System Atrophy, and dopamine beta hydroxylase deficiency.

The primary analysis was based on the intention-to-treat population of all randomized participants. The record says last observation carried forward was used for participants who discontinued early, and one droxidopa participant was excluded because the primary outcome values were not evaluable. The primary groups each had 37 participants in the posted outcome results. The registry also lists secondary measures covering daily activities, symptoms, standing systolic blood pressure, and patient- or clinician-rated global impressions.

The registry record identifies the study as completed. Details such as the original sample-size justification, specific masking procedures, and the full statistical analysis plan are not reported in the registry record. The open-label lead-in and randomized withdrawal phase should be kept in mind when interpreting what the treatment contrast represents.

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.

Open Label Treatment

Reasons for not completing this period:

2 Week Randomized Withdrawal

Open-Label Extension

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The analysis population was based on the ITT population of all patients randomized. Last observation carry forward was used for patients who prematurely discontinued the study. One droxidopa patient was excluded from the analysis because OHQ values were not evaluable.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Omits 1 patient who randomized into the study in error and did not receive study drug.

6. Primary Endpoint

The registry lists the primary outcome as Change in Orthostatic Hypotension Questionnaire Composite Score (OHQ), measured over 14 days.

The primary endpoint was change in the Orthostatic Hypotension Questionnaire (OHQ) composite score over 14 days. The OHQ is the average of the Orthostatic Hypotension Symptom Assessment Scale (OHSA) and the Orthostatic Hypotension Daily Activities Scale (OHDAS). The OHSA averages ratings of six symptom items, including dizziness or faintness, vision problems, weakness, fatigue, concentration difficulties, and head or neck discomfort. The OHDAS averages ratings of four activity items concerning standing and walking for shorter or longer periods.

Each item uses a 0-to-10 Likert scale, with 10 representing the most severe rating. The measure therefore combines patients’ reports of symptoms and the impact of orthostatic hypotension on daily activities. A composite can provide a broader description of patient-reported burden than any single symptom or activity item, though it can also conceal differences between its components.

In this withdrawal design, a positive change indicates worsening during the randomized double-blind phase relative to the value at randomization, when participants were receiving open-label droxidopa. The endpoint is used to compare the average change in the continued-droxidopa and placebo groups. It measures change over the stated timeframe; it is not a direct measure of long-term durability beyond that period. The registry description explains the content and scoring, but a threshold for a clinically important difference is not reported in the registry record.

7. Results Posted in the Registry

• Droxidopa: mean 0.57 versus 0.90 on control; difference -0.33 (95% CI -1.12 to 0.46), standardized effect d = -0.19; z-test p = 0.412.

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 Orthostatic Hypotension Daily Activities (OHDAS) Score

• 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 deviations.
• Result:
  • Droxidopa: mean 0.53 versus 0.71 on control; difference -0.18 (95% CI -1.06 to 0.70), standardized effect d = -0.09; z-test p = 0.690.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Droxidopa and the control. The interval gives the range of effects that remain compatible with the data.

Change in Orthostatic Hypotension Symptom Assessment (OHSA) Composite Score

• 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 deviations.
• Result:
  • Droxidopa: mean 0.59 versus 1.10 on control; difference -0.51 (95% CI -1.33 to 0.31), standardized effect d = -0.28; z-test p = 0.224.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Droxidopa and the control. The interval gives the range of effects that remain compatible with the data.

Change in Systolic Blood Pressure (SBP) Measurements 3 Minutes Post Standing

• 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 deviations.
• Result:
  • Droxidopa: mean -8.40 versus 0.00 on control; difference -8.40 (95% CI -18.76 to 1.96), standardized effect d = -0.37; z-test p = 0.112.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Droxidopa and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover two components closely related to the primary composite: daily activities and symptoms. They also include standing systolic blood pressure and patient- and clinician-rated global severity or improvement. The posted results therefore offer several perspectives on the same randomized withdrawal period, but they do not all measure the same construct. Symptom and activity scales are patient-reported, blood pressure is a physiological measure, and global impressions are ratings by patients or clinicians.

Across the posted continuous secondary outcomes, the recalculated mean differences have confidence intervals that include zero. The registry’s reported p-values for these outcomes also do not show strong statistical evidence of between-group differences. This overall pattern is consistent with the uncertainty in the primary outcome rather than providing a clear, independent signal that resolves it. It does not establish that every measured outcome was identical between groups.

The secondary findings should carry less weight than the primary result for several reasons. The registry does not report a multiplicity adjustment or explain a confirmatory testing hierarchy. When many outcomes are examined, the chance of at least one apparently unusual result can increase, even if none represents a reproducible effect. Unadjusted secondary p-values do not account for that family of comparisons. The registry’s full analysis plan and the status of each secondary analysis as prespecified are not reported in the registry record.

Secondary outcomes can still help characterize the results by showing whether symptom, activity, physiological, and global-rating measures tell a broadly similar story. Their value is descriptive and contextual. They should not be selected in isolation to make a definitive treatment claim, especially when the primary estimate itself is imprecise and no clinical-importance threshold is reported.

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

• Change in Orthostatic Hypotension Daily Activities (OHDAS) Score
• Change in Orthostatic Hypotension Symptom Assessment (OHSA) Composite Score
• Change in Systolic Blood Pressure (SBP) Measurements 3 Minutes Post Standing
• Patient Reported Clinical Global Impression - Severity
• Clinician Recorded Clinical Global Impression - Severity
• Patient Reported Clinical Global Impression - Improvement
• Clinician Rated Clinical Global Impressions - Improvement

9. Statistical Interpretation

10. Statistical Methods Explained

General explanation: The primary outcome is continuous, and the registry reports group means and standard deviations. A mean describes the average observed change within a group; a standard deviation describes how dispersed individual changes are around that average. These statistics answer different questions: a group can have a modest average change while individual responses vary considerably.

The recalculated comparison is an unadjusted difference between the group means, expressed as droxidopa minus placebo. A negative estimate means the average change was lower in the droxidopa group. For this outcome, lower change is in the direction of less worsening because positive change is defined as worsening. The mean difference is an estimate from the observed group summaries; it is not an adjusted treatment effect and does not account for any design features beyond the unadjusted calculation.

General explanation: A confidence interval describes a range of values compatible with the estimate under the statistical method and its assumptions. It is not a range containing a known proportion of individual participant responses. If an interval for a mean difference includes zero, the observed data do not distinguish the estimate from no average difference at the conventional two-sided significance level corresponding to that interval. The width also matters: a wide interval leaves more uncertainty about the magnitude of the underlying difference.

General explanation: A p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that null hypothesis and the test assumptions were true. It is not the probability that the null hypothesis is true, nor a measure of clinical importance. The unadjusted p-value accompanying the recalculated comparison is based on the posted summary statistics. The registry separately reports the sponsor’s analysis p-value using a Mantel-Haenszel method. The detailed specification of that analysis, including any stratification variables, is not reported in the registry record.

The analysis population is described as based on all randomized participants. Last observation carried forward was used for participants who prematurely discontinued. This method carries a participant’s last recorded outcome forward to represent later missing outcomes. General explanation: It is simple to implement, but it assumes that the carried-forward value is a reasonable substitute for the unobserved later value. If outcomes would otherwise change after discontinuation, the method can misrepresent the later course. The registry notes that one droxidopa participant was excluded because the OHQ values were not evaluable.

What does the randomized contrast estimate?

The open-label droxidopa period occurred before randomization. During the randomized phase, the contrast was continued droxidopa versus placebo among participants who had reached randomization after that period. This structure makes the estimate specific to the withdrawal setting. It is not the same estimand as a trial randomizing participants at the outset to droxidopa or placebo. The registry record does not report further details about treatment adherence or how the analysis handled changes in exposure during the randomized period.

Why can over-dispersion matter?

General explanation: Over-dispersion occurs when outcome variability is greater than a statistical model expects. If a method assumes less variability than is actually present, standard errors can be too small and intervals too narrow; if it allows for greater variability, estimates may be less precise. The primary outcome is continuous, and the registry reports standard deviations for the two groups. It does not report an over-dispersion assessment or a model-based adjustment for it, so no such conclusion can be drawn for this analysis.

What is the role of the planning illustrations?

The planning illustrations use the observed effect as a reference and consider smaller fractions of that effect. They use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They are not a description of the original trial’s design process. The original sample-size assumptions and justification are not reported in the registry record. The illustration is especially sensitive to the effect size used: smaller target effects require larger group sizes to achieve the same planned power under the stated assumptions.

The record lists nine outcome measures and nine analyses, with seven secondary outcomes posted. It does not describe a prespecified multiplicity strategy, an interim analysis plan, or the full statistical analysis plan. Accordingly, the posted analyses can be described, but their status as prespecified or adjusted for multiple testing is not reported in the registry record. These missing details limit how confidently the collection of outcome results can be interpreted as a single confirmatory testing program.

11. Confidence Intervals and Precision

The recalculated primary mean difference was -0.33 units, with a confidence interval from -1.118 to 0.458. The interval crosses zero. It therefore includes values consistent with a lower average change in the droxidopa group as well as values consistent with a higher average change. Since positive change represents worsening, the negative point estimate is in the direction of less average worsening with droxidopa, but the interval does not pin down the direction of the underlying difference.

The interval is more informative than the point estimate alone because it displays uncertainty around that estimate. Its width indicates that the data do not tightly identify the size of the group difference. The result is compatible with a range of effects, including little or no average difference. The posted summaries do not support a precise claim about the magnitude of any difference.

The primary group standard deviations were 1.891 for droxidopa and 1.55 for placebo. These describe the spread of observed changes within each group, not uncertainty in the group mean itself. General statistical interpretation distinguishes individual variability from precision of a between-group estimate: precision also depends on the number of participants and the analysis method. The primary outcome groups each included 37 participants.

The registry’s sponsor analysis reports p = 0.438, while the unadjusted recalculation reports p = 0.412. Neither provides strong statistical evidence of a group difference. A p-value alone does not communicate the range of plausible effect sizes, and the sponsor-reported analysis does not include a confidence interval in the posted record. A confidence interval for the sponsor analysis is not reported in the registry record. The numerical uncertainty should also be considered alongside the absence of a reported threshold for clinically important change.

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 figures are participants per arm for 80% power and participants per arm for 90% power. They are not total events: the primary outcome and the other listed planning illustrations are continuous outcomes, and the record’s general planning note specifies participants per arm for non-time-to-event outcomes. The figures use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect.

The 80% power column describes a planning scenario in which the study would have an 80% probability of detecting the specified effect under the assumptions, if that effect and those assumptions were correct. The 90% column describes the corresponding scenario with a higher planned probability of detection. These are design calculations, not guarantees about a future study’s results. The original trial’s sample-size assumptions and justification are not reported in the registry record.

For the primary outcome, the illustration based on 100% of the observed effect gives 431 participants per arm for 80% power and 577 participants per arm for 90% power. Planning for 75% of the observed effect gives 767 participants per arm for 80% power and 1,026 participants per arm for 90% power. Planning for 50% of the observed effect gives 1,724 participants per arm for 80% power and 2,308 participants per arm for 90% power. The pattern reflects the general principle that smaller effects are harder to distinguish from random variation and therefore require more participants under the same assumptions. These figures are not observed power.

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 = -0.330; pooled standard deviation σ = 1.729.
2. n = 2 × (1.96 + 0.842)² × 1.729² / -0.330² = 430.9, rounded up to 431 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 <- -0.33                      # observed difference in means
sigma <- 1.72892755776522                     # 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(738062)
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 = 431 (80% power), 577 (90% power)
 75% of observed effect: n per arm = 767 (80% power), 1,026 (90% power)
 50% of observed effect: n per arm = 1,724 (80% power), 2,308 (90% power)
power.t.test: 431.8 
Simulated power at n = 431 per arm: 0.796 (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 comparison using a Mantel-Haenszel method and gives p = 0.438. The posted record does not provide a sponsor-reported effect estimate, confidence interval, or further detail about the analysis specification. The recalculated unadjusted comparison from the posted group means and standard deviations gives a mean difference of -0.33 units, a confidence interval from -1.118 to 0.458, and an unadjusted p-value of 0.412.

These results are close in their broad interpretation: neither p-value indicates strong evidence of a difference between the randomized groups. The recalculation is a simple unadjusted comparison from summary statistics, while the sponsor’s analysis is reported under a different named method. They are not interchangeable analyses, and the difference between their p-values should not be treated as a contradiction or as proof that one method is preferable. The record does not report enough detail to reproduce the sponsor’s method or determine precisely why the p-values differ.

The sponsor-reported analysis remains the registry’s own analysis result. The recalculation is useful as a transparent supplementary check of the posted summaries, particularly because it includes an estimated mean difference and confidence interval. Neither result should be interpreted without the withdrawal design, the modest randomized group sizes, the outcome definition, and the uncertainty in the estimate.

15. Multiplicity, Missing Data and Analysis Populations

The record lists nine outcome measures and nine analyses and identifies seven posted secondary outcomes. It does not report whether the investigators controlled the overall type I error rate across these outcomes, used a hierarchy for testing, or designated any secondary outcome as confirmatory. A multiplicity plan is therefore not reported in the registry record. The reported p-values should not be assumed to have been adjusted.

General explanation: When multiple hypotheses are tested, each test carries a chance of a false-positive result under its null hypothesis. Considering a set of tests can increase the chance of at least one nominally positive result. Adjustments, prespecified testing sequences, or a clear distinction between confirmatory and exploratory analyses can address this issue, but the appropriate interpretation depends on the trial’s analysis plan. Without that information, secondary p-values are best treated as descriptive evidence rather than a collection of independent confirmations.

Missing-data handling is partly described. The primary analysis was based on the intention-to-treat population of all randomized participants, last observation carried forward was used for participants who prematurely discontinued, and one droxidopa participant was excluded because OHQ values were not evaluable. The record does not report the number of participants who discontinued early, the timing or reasons for discontinuation, or sensitivity analyses using alternative assumptions for missing outcomes. It also does not report a detailed account of how the missing-data method affected each outcome analysis.

General explanation: Intention-to-treat analysis is commonly intended to preserve the randomized comparison by analyzing participants according to randomized assignment. How closely an analysis achieves that principle depends on the handling of missing outcomes and exclusions. Carrying the last observation forward does not recover an unobserved outcome; it substitutes an assumption about what happened after the last measurement. Results can be sensitive to that assumption if missingness is related to outcome changes.

The original sample-size justification, interim analysis plan, complete statistical analysis plan, and multiplicity procedures are not reported in the registry record. Their absence limits assessment of whether the posted analyses followed a prespecified plan and how confidently secondary findings should be interpreted.

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: syncope (3.9%), hip fracture (2.9%), urinary tract infection (2.7%), pneumonia (2.7%), contusion (2.6%).

The safety record separates the three-month open-label droxidopa period, the double-blind droxidopa group, the double-blind placebo group, long-term follow-up, and a total droxidopa category. For the double-blind period, the registry reports serious adverse events affecting 1 of 38 participants in the droxidopa group and 0 of 37 in the placebo group. These are small group counts and should be read as descriptive observations, not as precise estimates of comparative risk.

For the three-month open-label period, serious adverse events affected 12 of 102 participants. In long-term follow-up, they affected 16 of 74 participants. The total droxidopa category reports 26 of 102 participants with serious adverse events. These periods and categories should not be added together or treated as separate randomized comparisons: the same participants may contribute across study phases, and the record does not provide a participant-level account to assess overlap.

The registry lists serious adverse event terms and their reported percentages, including syncope at 3.9%, hip fracture at 2.9%, urinary tract infection at 2.7%, and pneumonia at 2.7%. These terms describe reported events; they do not establish that study medication caused them. Death counts are not reported in the registry record. The posted safety information does not by itself support a definitive comparison of safety between randomized groups.

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

The primary result is an estimate of average change in OHQ composite score during a short randomized withdrawal phase. The point estimate favors a smaller increase in the droxidopa group than in the placebo group, where positive change means worsening. However, the confidence interval crosses zero and spans effects in either direction. The registry’s reported analysis p-value also does not provide strong evidence of a group difference. The posted data therefore leave meaningful uncertainty about the size and direction of the average difference.

This finding does not establish that the two groups are equivalent. Equivalence requires a prespecified margin and an analysis designed to determine whether the interval lies within that margin; such a margin is not reported in the registry record. Nor does a nonsignificant p-value prove that there is no effect. It indicates that the data, under the reported analysis, do not provide strong evidence against the null comparison.

The trial structure also limits the scope of the question. Participants first received open-label droxidopa for 3 months and were then randomized to continued droxidopa or placebo. The result does not directly answer what happens when treatment is first started, nor does the 14-day primary timeframe establish longer-term comparative effects. It applies to the studied randomized withdrawal setting and the participants who reached randomization.

The OHQ captures a combination of symptoms and daily-activity impact, but its average change does not describe every participant or every component. The registry does not report a threshold that would distinguish a clinically important change from a small one. No treatment recommendation follows from these statistics alone. Interpretation should combine the design, uncertainty, endpoint meaning, missing-data approach, and the other information available to clinicians and researchers.

18. Why This Trial Matters Statistically

Statistically, this study is informative because its design separates an open-label exposure period from a randomized withdrawal comparison. That distinction changes the estimand: the randomized data concern continuation versus withdrawal among participants who had already received droxidopa, rather than initial assignment to treatment or placebo. Recognizing the design prevents the result from being generalized to a different treatment question.

The primary endpoint combines patient-reported symptoms with the effect of orthostatic hypotension on everyday activities. This makes the outcome relevant to how participants experience the condition, while also creating an interpretive challenge: a composite average can mask differences among symptoms, activities, or individuals. The component secondary measures provide context, but the registry does not report a multiplicity strategy that would make them independent confirmatory tests.

The comparison illustrates why a point estimate and a p-value are not enough. The mean difference is negative, but its confidence interval includes zero and allows effects in either direction. The sponsor-reported p-value and the unadjusted recalculation tell a broadly similar story of uncertainty. Reporting both the estimate and its precision supports a more careful reading than treating a single threshold as a verdict.

The record also highlights practical questions that matter for interpretation: the use of last observation carried forward, an excluded non-evaluable participant, and missing details about the sample-size justification and analysis plan. These are not merely procedural details; they affect how confidently the result can be understood and whether findings across outcomes should be viewed as confirmatory or exploratory. The posted evidence is best read as a bounded estimate from a specific withdrawal setting, not as a universal statement about treatment effects.

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 primary randomized groups each included 37 participants, and the confidence interval for the mean difference is broad enough to include effects on either side of zero. This limits precision. The planning illustrations indicate that detecting effects smaller than the observed estimate would require larger groups under the stated assumptions, but those illustrations do not show what the original investigators planned. The trial’s sample-size justification is not reported in the registry record.

The primary analysis used last observation carried forward for participants who prematurely discontinued. The record does not provide the number or timing of such discontinuations, reasons for missing outcomes, or sensitivity analyses under alternative missing-data assumptions. One droxidopa participant was excluded because OHQ values were not evaluable. These details make it difficult to assess how robust the result is to missing-data choices.

The study’s open-label lead-in means that the randomized comparison is a withdrawal contrast after participants had received droxidopa, not a comparison of initial treatment. Its primary outcome timeframe was 14 days, which limits what can be concluded about longer-term outcome differences. The registry lists a range of conditions, but does not report detailed participant characteristics needed to assess how well the enrolled group represents particular clinical subgroups.

The sponsor analysis is identified as Mantel-Haenszel, but the record does not report its full specification, effect estimate, or confidence interval. The full analysis plan, multiplicity procedure, interim analysis plan, and clinical-importance threshold are also not reported in the registry record. Safety counts are descriptive, and the categories cover different study periods; they do not provide a clean randomized comparison of long-term safety.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Open-Label Clinical Study of Droxidopa in Patients With Neurogenic Orthostatic Hypotension (NOH) — NCT00738062.
• Registry record last updated 2014-05-16; status last verified 2014-04.
• Results first posted 2014-05-16.
• 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

This completed Phase 3 study enrolled 103 participants and used an open-label droxidopa period followed by a randomized, quadruple-masked, parallel withdrawal comparison of droxidopa and placebo. The primary outcome was change in the OHQ composite score over 14 days, with positive change indicating worsening relative to randomization.

The primary group means were 0.57 for droxidopa and 0.9 for placebo. The recalculated unadjusted mean difference was -0.33, with a confidence interval from -1.118 to 0.458 and an unadjusted p-value of 0.412. The registry reports a Mantel-Haenszel analysis p-value of 0.438. Together, these results leave uncertainty about the direction and size of the average difference.

The posted secondary outcomes provide related symptom, activity, blood-pressure, and global-impression measures. Their interpretation is limited by the absence of a reported multiplicity plan. The registry also describes last observation carried forward for early discontinuation and one non-evaluable primary outcome exclusion. The result should be understood in the context of the withdrawal design, stated timeframe, and limitations in the registry record.