Efficacy Study of Light Therapy as an Adjunctive Treatment for Parkinson's Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy Study of Light Therapy as an Adjunctive Treatment for Parkinson's Disease (NCT02175472), a randomized na study. The primary outcome is Change in the Combined Scores (Sum) of Parts I, II, and III of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (M (MDS-UPDRS) From Baseline to Endpoint at 6 Months..

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study of a light therapy device for Parkinson's disease. The study status is completed. It was sponsored by PhotoPharmics, Inc.; the recorded start was 2014-06 and primary completion was 2016-10. The registry lists the phase as NA, which does not specify a conventional drug-development phase. Enrollment was 92.

Participants were assigned to the Spectramax light therapy device or the control light device. The devices were described as identical in appearance and operation, with different bandwidths and light intensities. The study summary places light therapy alongside ongoing pharmacotherapy, with a six-month treatment period. Randomization and double masking are recorded, but the registry record does not describe the allocation sequence, concealment procedures, who was masked, or how masking was assessed.

The posted primary endpoint is change from baseline to the six-month endpoint in the combined scores of MDS-UPDRS Parts I, II, and III. The registry also lists four secondary outcomes covering clinical global impression, Parkinson's disease questionnaire scores, disturbed sleep, and sleepiness. Primary endpoint results are posted for 44 participants in the Spectramax group and 47 in the control group. The reasons that these outcome counts differ from overall enrollment are not reported in the registry record.

Although the study summary states that safety and efficacy were to be evaluated, detailed protocol information, original design assumptions, planned analysis populations, and a full statistical analysis plan are not reported in the registry record. The record identifies the trial structure and posted outcomes, but it does not establish how all trial conduct and analysis decisions were made.

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

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 the Combined Scores (Sum) of Parts I, II, and III of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (M (MDS-UPDRS) From Baseline to Endpoint at 6 Months., measured over Six Months.

The primary endpoint is change from baseline to the six-month endpoint in the combined sum of MDS-UPDRS Parts I, II, and III. Part I assesses non-motor impact on experiences of daily living; Part II assesses motor impact on daily living; and Part III is an evaluator-administered motor examination. The registry describes questions scored from 0 to 4 in each part and notes that higher scores indicate greater severity.

Combining these parts gives a measure spanning non-motor experiences, the motor impact on everyday activities, and motor signs assessed by an evaluator. That breadth makes the endpoint relevant to the study's question about changes across several aspects of Parkinson's disease, rather than a single symptom domain. The endpoint is continuous, and the posted group results are least-squares means with standard errors.

Change scores describe movement from each participant's baseline value to the endpoint; the group contrast compares those changes between assigned groups. A negative change indicates a decrease in the score as recorded. Because higher scores are described as more severe, a decrease is a movement toward a lower score on this scale. The registry record does not report the precise model specification or whether any particular magnitude of change was designated as clinically important. Statistical differences and clinical importance are therefore separate questions.

7. Results Posted in the Registry

• Spectramax Light Therapy Device: mean -17.70 versus -9.70 on control; difference -8.00 (95% CI -16.78 to 0.78), standardized effect d = -0.37; z-test p = 0.074.

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 the Clinical Global Impression- Improvement Scale (CGI-I) From Baseline to Endpoint at 6 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:
  • Spectramax Light Therapy Device: mean -0.60 versus -0.20 on control; difference -0.40 (95% CI -0.68 to -0.12), standardized effect d = -0.59; z-test p = 0.005.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Spectramax Light Therapy Device than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in the Score of the Parkinson's Disease Questionnaire - 39 From Baseline to Endpoint at 6 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:
  • Spectramax Light Therapy Device: mean -1.30 versus 4.30 on control; difference -5.60 (95% CI -10.90 to -0.30), standardized effect d = -0.44; z-test p = 0.038.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Spectramax Light Therapy Device than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in the Score of the Parkinson's Disease Sleep Scale-Disturbed Sleep, From Baseline to Endpoint at 6 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:
  • Spectramax Light Therapy Device: mean -0.00 versus 0.70 on control; difference -0.70 (95% CI -2.23 to 0.83), standardized effect d = -0.19; z-test p = 0.370.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Spectramax Light Therapy Device and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover different domains: clinician global impression, Parkinson's disease-related quality of life, disturbed sleep, and daytime sleepiness. The posted estimates do not form a uniformly consistent pattern across these measures. Some recalculated contrasts have confidence intervals that exclude zero and unadjusted p-values below 0.05, while another has a confidence interval that includes zero. This mixed pattern sits alongside a primary contrast whose interval also includes zero.

These measures complement the primary composite by looking at perceived overall change, daily-life impact, and sleep-related experiences. Agreement across measures can sometimes strengthen the coherence of an interpretation, while disagreement can indicate that effects differ across domains, measurement properties, or uncertainty. The registry results alone do not identify which explanation accounts for the observed pattern. Secondary outcomes should not be treated as interchangeable with the primary combined MDS-UPDRS score.

The recalculated secondary comparisons are unadjusted. When multiple outcomes are tested, the probability of at least one nominally notable result can be higher than for a single test. The registry record does not report a multiplicity adjustment, a hierarchy for testing secondary outcomes, or a statistical analysis plan specifying how these results were to be interpreted. Therefore, an isolated unadjusted p-value carries less weight than a result supported by a prespecified testing strategy and a coherent body of evidence.

The record lists four secondary outcomes, but its reported-analysis entries are empty. The numerical comparisons accompanying the posted summaries are recalculations from aggregate statistics, not a report of the sponsor's analysis methods. These outcomes can be considered exploratory descriptions of the posted data, but should not override the uncertainty in the primary result or be read as independent confirmation. In particular, statistical significance in an unadjusted secondary comparison does not establish clinical importance or resolve the limitations in the available analysis record.

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

• Change in the Clinical Global Impression- Improvement Scale (CGI-I) From Baseline to Endpoint at 6 Months.
• Change in the Score of the Parkinson's Disease Questionnaire - 39 From Baseline to Endpoint at 6 Months
• Change in the Score of the Parkinson's Disease Sleep Scale-Disturbed Sleep, From Baseline to Endpoint at 6 Months.
• Change in the Score of the Epworth Sleepiness Scale From Baseline to Endpoint at 6 Months.

9. Statistical Interpretation

10. Statistical Methods Explained

The posted primary outcome is continuous: it is a score change rather than a count of events or a time until an event. The group summaries are least-squares means, with standard errors. Least-squares means are model-based estimates of group means; the registry record does not report enough detail to reconstruct the model or its covariates. A standard error describes the precision of an estimated mean, not the spread of individual participant scores.

How to read the group contrast

The contrast compares the Spectramax group with the control group. The recalculated mean difference is -8.0 units, based on the posted changes of -17.7 and -9.7. The negative sign indicates that the estimated change was more negative in the Spectramax group under this ordering. The calculation is a simple unadjusted comparison of posted summary statistics, not a new adjusted model. It does not account for participant-level data or establish what covariates were included in the trial's own analysis.

A confidence interval gives a range of values compatible with the observed data under the assumptions of the calculation. For the primary contrast, the 95% interval runs from -16.78 to 0.785. Because it includes zero, the result is compatible with no group difference as well as with differences on either side of zero. A p-value of 0.074 is the unadjusted value associated with this recalculated contrast. A p-value is not the probability that the null hypothesis is true, and it does not describe the size or clinical relevance of an effect.

Why standard errors and approximations matter

The recalculated comparison uses an approximate standard deviation derived from the posted standard errors and group sizes. The approximation is necessary because individual participant data and directly reported standard deviations are not available in the registry record. Any analysis built from aggregate summaries can only reflect the information retained in those summaries. It cannot reproduce a participant-level analysis, account for unreported features of the study model, or check distributional assumptions from the underlying observations.

Over-dispersion is a general concern when a model assumes less variability than the data contain. If observed variability is greater than assumed, standard errors can be too small and intervals too narrow; if variability is smaller, the reverse can occur. This is a general statistical point, not a finding about this trial. The registry record does not report a diagnostic assessment of dispersion or enough modeling detail to assess that issue for the original analysis.

What randomization and masking contribute

Random allocation is intended to make assignment independent of participant characteristics, on average, while masking is intended to limit expectations influencing care, reporting, or assessment. The record identifies the trial as randomized and double-masked, and describes the control device as matching the intervention device in appearance and operation. Those features strengthen the design's comparative intent. They do not show whether masking remained successful, how allocation was implemented, or whether all analyses retained the advantages of randomization. Those details are not reported in the registry record.

The parallel-group structure means participants were assigned to one device group rather than switching between devices as part of a crossover design. This is the design recorded in the registry. The registry does not report details of adherence, exposure received, or protocol deviations, so the posted comparison cannot be interpreted as a quantified comparison of actual device use.

What the unadjusted p-values do and do not say

The endpoint-specific p-values are unadjusted recalculations. They do not account for testing multiple outcomes, and the record does not report a multiplicity procedure. When several outcomes are examined, the chance of at least one apparently unusual result can increase if each is tested without adjustment. This general issue makes isolated secondary p-values less persuasive than a prespecified primary analysis interpreted in the context of the full plan.

The registry record lists zero reported analyses for the primary outcome and empty reported-analysis entries for the secondary outcomes. This does not prove that no analysis was conducted; it means detailed analysis results and methods are not reported in the registry record. The calculations described alongside the posted summaries should therefore be understood as transparent, approximate comparisons, not as a substitute for unavailable trial-specific analysis documentation.

Reading statistical and clinical importance separately

Statistical uncertainty concerns the range of effects compatible with the data and assumptions. Clinical importance concerns whether an effect matters in the context of the measure and the people being studied. The posted results do not give a threshold for an important change, and the registry record does not report such a threshold. It is not possible to infer clinical importance solely from a point estimate or a p-value. General statistical interpretation also does not establish that the observed group pattern would recur in another study.

11. Confidence Intervals and Precision

The primary contrast is estimated as -8.0 units, with a 95% confidence interval from -16.78 to 0.785. This interval is the principal guide to the precision of the recalculated contrast. It spans zero, so the summary statistics are compatible with no difference and with effects in either direction. The negative point estimate alone should not be treated as a precise estimate of the size of a group difference.

A confidence interval is a range produced by a statistical method that, under its assumptions, reflects uncertainty in an estimate. It is not a range containing a known percentage of individual participant responses, nor is it a probability statement about a particular fixed effect. Wider intervals represent less precision than narrower intervals on the same scale. The registry record does not provide an interval for each group mean, but it does provide the standard errors for the group estimates.

The contrast interval and p-value are recalculated from posted aggregate summaries. The recalculation uses approximate variability, rather than participant-level observations or a fully documented trial model. That means the interval's precision depends on simplifying assumptions. It also means the result cannot incorporate unreported covariate adjustment, missing-data handling, or other features of the sponsor's analysis. No discrepancy is flagged, but that does not make the recalculation equivalent to a prespecified sponsor analysis.

The observed arm counts are 44 and 47. These counts and the standard errors affect precision, but they do not alone establish whether the study was adequately sized for its original aims. The original sample-size justification and design assumptions are not reported in the registry record. The posted result is best read as an estimate with substantial uncertainty rather than as a definitive determination of the effect's direction or magnitude.

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 figures are planning illustrations expressed as participants per arm, not total participants and not total events. They use the observed effect as a reference and show planning for 100%, 75%, or 50% of that observed effect. For example, the primary-outcome illustration for 100% of the observed effect lists 114 participants per arm for 80% power and 153 participants per arm for 90% power. The other rows show the planning implications of targeting smaller fractions of the observed effect.

The calculation assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect equal to the stated fraction of the observed effect. These are assumptions for the planning illustration, not the trial's original design assumptions. The trial's own sample-size justification is not reported in the registry record.

In plain language, the 80% power column gives the estimated participants per arm for a design that would have an 80% probability of detecting the specified effect under the calculation assumptions, if that effect were the true effect and those assumptions held. The 90% column uses a higher target probability of detection. Reaching a higher target generally requires more participants under otherwise comparable assumptions. Smaller effects are harder to distinguish from random variation, so planning for a smaller effect requires more participants.

These figures are planning illustrations, not observed power. They do not measure the probability that the trial's result is true, and they do not change the uncertainty in the completed trial's posted estimate. The calculations also use an effect estimated from the trial itself, which can be an unstable basis for planning. The numbers should therefore be interpreted as conditional illustrations of sample-size requirements rather than as a retrospective verdict about the trial's design.

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 = -8.000; pooled standard deviation σ = 21.546.
2. n = 2 × (1.96 + 0.842)² × 21.546² / -8.000² = 113.9, rounded up to 114 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 <- -8                      # observed difference in means
sigma <- 21.5463388792881                     # 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(2175472)
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 = 114 (80% power), 153 (90% power)
 75% of observed effect: n per arm = 203 (80% power), 272 (90% power)
 50% of observed effect: n per arm = 456 (80% power), 610 (90% power)
power.t.test: 114.8 
Simulated power at n = 114 per arm: 0.802 (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. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and four secondary outcomes. Examining multiple outcomes raises a general statistical issue: if each is tested separately without adjustment, the chance of obtaining at least one apparently notable result by chance can increase. A prespecified approach may address this through adjusted significance thresholds, a hierarchy of tests, or another strategy. The registry record does not report whether such a plan was used, so the recalculated secondary p-values should be regarded as unadjusted rather than as confirmatory evidence under a documented multiplicity procedure.

Detailed analysis methods are also limited. The primary endpoint is reported as a least-squares mean with a standard error, but the model specification, covariates, and analysis population are not reported in the registry record. For the secondary endpoints, reported-analysis entries are empty. The record does not say whether the principal analyses were intention-to-treat, per-protocol, or based on another population. It also does not report how deviations from assigned device use were handled.

Missing-data methods are not reported in the registry record. The overall enrollment is 92, while the primary outcome results include 44 participants in the Spectramax group and 47 in the control group. The record does not explain why those counts differ, whether outcome data were unavailable for any participants, or how any missing observations were treated. It would be inappropriate to infer a particular reason or method from the counts alone.

The registry record does not report interim analyses, stopping rules, a protocol-defined sample-size justification, or a full statistical analysis plan. These omissions limit assessment of whether the posted analyses follow prespecified decisions and how robust the results are to alternative assumptions. They do not establish that a particular analysis was or was not performed; they identify details that are not reported in the registry record. As a result, inferential claims should be kept close to the posted endpoint estimates and their uncertainty.

15. Safety Results

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

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: transient ischemic attack (2.2%), accident (2.2%), rib fracture (2.2%), hip deterioration (2.1%).

The registry lists serious adverse events for 3 participants at risk in the Spectramax group, which had 45 participants at risk, and for 1 participant at risk in the control group, which had 47 participants at risk. Other adverse events are listed for 5 participants at risk in the Spectramax group and 2 participants at risk in the control group. These counts describe the posted groups; they do not by themselves establish that an event was caused by the device or that the groups differ reliably in risk.

The registry also lists several serious adverse event terms with percentages: Transient Ischemic Attack and Accident at 2.2% each, Rib fracture at 2.2%, and Hip deterioration at 2.1%. The event-term percentages are registry entries and should be interpreted in the context of the trial's size and the way events were coded and reported. The record does not provide enough detail to infer causation or compare individual event types statistically.

Deaths are not reported in the registry record. Safety counts are descriptive, and the posted information does not establish comparative safety or exclude uncommon harms. These figures are not medical advice.

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

The posted primary results show a greater decrease in the combined MDS-UPDRS score in the Spectramax group than in the control group at six months. The recalculated mean difference is -8.0 units, but its 95% confidence interval, -16.78 to 0.785, includes zero. The unadjusted p-value is 0.074. This combination describes a point estimate in one direction with uncertainty that does not rule out no difference under the calculation assumptions.

The result does not establish that the device produces a meaningful change for an individual, because the registry record does not report a threshold for clinical importance or participant-level responses. Nor does it demonstrate that the observed estimate would be reproduced in a new trial. The group summaries cannot explain why individual scores changed, and they cannot show that the device caused changes in outcomes beyond the comparison supported by the trial design and analysis.

Randomization and double masking are important design features for a comparison, but detailed information about allocation procedures, adherence, masking success, analysis populations, and missing data is not reported in the registry record. The primary result is a recalculation from aggregate summaries rather than a documented sponsor analysis. These limits make it important not to interpret the result more strongly than the posted evidence allows.

The secondary outcomes address related but distinct experiences, and their unadjusted results vary. They may add descriptive context, but the absence of a reported multiplicity plan means they should not be treated as decisive confirmation. Likewise, the safety counts are descriptive and do not establish causality. Overall, the registry record supports a careful account of the observed estimates and their imprecision, not a medical recommendation or a definitive conclusion about treatment benefit or harm.

17. Why This Trial Matters Statistically

This trial is statistically interesting because it combines a randomized, double-masked, parallel-group design with an outcome that brings together several aspects of Parkinson's disease. The primary measure includes non-motor experiences, motor effects on daily living, and evaluator-assessed motor signs. This broad endpoint gives the comparison a wider scope than a single symptom measure, while making clear that a composite score may not represent every domain equally for every participant.

The posted primary group estimates point in the same direction as the recalculated contrast, but the confidence interval crosses zero. That illustrates why an estimated effect and its precision need to be considered together. A point estimate is not a complete statistical conclusion, and a p-value does not quantify practical importance. The contrast is also based on aggregate summaries with approximate variability, which makes the limits of recalculation visible.

The record presents secondary outcomes spanning global impression, quality of life, and sleep. Their mixed pattern illustrates why multiple outcome results require a clear prespecified interpretation plan. Without a reported multiplicity procedure or analysis plan, nominal secondary findings are difficult to distinguish from exploratory signals. This is a useful example of why outcome breadth and statistical control must be considered together.

Finally, the registry record illustrates how a completed trial may have substantial design information but incomplete reporting of analysis details. Randomization and masking are recorded, while missing-data methods, analysis populations, original sample-size justification, and sponsor-reported analyses are not. These omissions do not erase the posted observations, but they constrain the strength and reproducibility of statistical conclusions.

18. 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 interpreting this registry record. The enrollment is 92, while the primary outcome arm counts are 44 and 47. The reasons for the difference are not reported in the registry record, and the available information does not establish whether it reflects missing outcome data, exclusions, or another cause. Missing-data handling and analysis populations are also not reported, so the potential effect of incomplete outcome information cannot be assessed.

The primary least-squares means are posted with standard errors, but the model and any adjustment variables are not described. The recalculated comparison is approximate and unadjusted, using summary information rather than participant-level data. It cannot reproduce a trial-specific model or verify assumptions about the distribution of scores. The registry record does not report the original sample-size justification, the planned treatment of multiple outcomes, or interim analyses.

The control device was designed to resemble the active device while emitting a different bandwidth and intensity. The registry record does not report whether participants or study staff correctly guessed assignments, or whether masking was formally evaluated. It also does not provide detailed adherence or protocol-deviation information. The primary endpoint's clinical-importance threshold is not reported, limiting interpretation of the score difference in practical terms.

Safety reporting is also limited to posted counts and terms; deaths are not reported in the registry record. The trial's completed status and posted outcomes do not resolve these reporting gaps. These limitations do not prove that the trial was poorly conducted or that unreported analyses were not performed. They mean that the conclusions available from the registry record must remain bounded by what it documents.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Efficacy Study of Light Therapy as an Adjunctive Treatment for Parkinson's Disease — NCT02175472.
• Registry record last updated 2018-10-23; status last verified 2018-10.
• Results first posted 2018-10-23.
• 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.

22. Record Summary

The registry record describes NCT02175472, a completed randomized, double-masked, parallel-group study of the Spectramax light therapy device compared with a control light device for Parkinson's disease. Enrollment was 92, with a six-month treatment period alongside ongoing pharmacotherapy described in the study summary. Primary completion was 2016-10.

The primary outcome was change in the combined MDS-UPDRS Parts I, II, and III score at six months. Posted least-squares mean changes were -17.7 in the Spectramax group and -9.7 in the control group. The recalculated mean difference was -8.0, with a 95% confidence interval from -16.78 to 0.785 and an unadjusted p-value of 0.074.

The record lists four secondary outcomes and adverse event counts. Detailed sponsor analyses, missing-data methods, analysis populations, multiplicity procedures, and original sample-size justification are not reported in the registry record. The posted summaries support descriptive comparison, with important uncertainty and reporting limits.