Genecept Assay™ vs. Treatment-as-Usual to Evaluate Efficacy of Assay-Guided Treatment in Adults With MDD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Genecept Assay™ vs. Treatment-as-Usual to Evaluate Efficacy of Assay-Guided Treatment in Adults With MDD (NCT02634177), a randomized na study. The primary outcome is Mean Change From Baseline in SIGH-D-17 Score at 8 Weeks..

2. Clinical Question

The clinical question is whether providing treating investigators with Genecept Assay results to guide antidepressant pharmacotherapy is associated with a different change in depressive symptom scores over 8 weeks than treatment as usual without the investigators knowing the pharmacogenetic results.

This is a comparison of two treatment strategies, not a comparison of assay testing with no testing: participants in both groups provided DNA samples, while the timing and use of assay information differed. The primary measure was assessed by raters, and the registry record says both participants and primary-endpoint raters remained blinded to treatment assignment. The record does not specify whether treating investigators were masked; the intervention descriptions indicate that the AGT investigator received assay results while the TAU investigator did not.

3. Trial Design

The registry describes a prospective, randomized, controlled, double-blind trial with parallel groups and an 8-week assessment period. The trial was completed. The listed phase is NA. The record gives enrollment as 305, with a start date of 2016-01 and primary completion on 2017-07-25.

Participants were assigned to AGT or TAU. DNA samples were collected from all participants at screening for the Genecept Assay. In AGT, the treating investigator received the results and used them to guide pharmacotherapy. In TAU, the investigator treated participants without knowledge of those results. The registry states that assay results for all participants were to be provided to the investigator after all Week 8 visit procedures were complete. It also states that participants and raters of the primary endpoint remained blinded to treatment assignment. The broader masking procedures are not reported in the registry record.

The primary outcome was mean change from baseline in SIGH-D-17 score at 8 weeks. The posted primary comparison includes 138 participants in AGT and 140 in TAU. These outcome denominators are not the same as the overall enrollment count; the record does not explain the difference. The design is a parallel-group comparison, so the reported contrast compares outcomes between the two assigned groups rather than comparing each participant with a separate untreated condition.

The registry lists eight secondary outcomes, including QIDS-SR16 change, response definitions based on SIGH-D-17, QIDS-SR16 and CGI-I, remission definitions based on SIGH-D-17 and QIDS-SR16, and safety assessments. Numerical comparative results are posted for some secondary outcomes, but a complete account of the planned analysis strategy, sample-size justification, or original design assumptions is not reported in the registry record.

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: 304 Randomized

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.

Population: The baseline analysis was completed on the all randomized set as defined in the SAP. All data may not have been available for every endpoint for each patient included in the baseline analysis population. Therefore the number of patients at baseline and the number completed may not match specific endpoints.

6. Primary Endpoint

The registry lists the primary outcome as Mean Change From Baseline in SIGH-D-17 Score at 8 Weeks., measured over Baseline to 8 Weeks.

The primary endpoint is mean change from baseline to 8 weeks in SIGH-D-17 score. SIGH-D-17 is a 17-item, rater-administered structured interview measure based on the Hamilton Depression Rating Scale. The registry describes scores from 0 to 52, with lower scores representing fewer symptoms. It classifies scores of 0-7 as normal, 8-16 as mild, 17-23 as moderate, and scores over 24 as severe.

Change scores describe how the measured symptom score differs between baseline and follow-up. In the posted results, the mean change is negative in both groups, indicating that the average follow-up score was lower than the average baseline score in each group. The primary comparison focuses not on either group’s change in isolation, but on the difference between the two group mean changes. A positive AGT-minus-TAU difference means the AGT mean change was less negative; a negative difference would mean it was more negative.

A continuous change endpoint retains information across the scale rather than reducing outcomes to categories such as response or remission. It can therefore describe the average difference in score change, while still requiring care in interpretation: a group mean does not show the range of individual experiences, and the comparison does not by itself establish what caused any change. The registry record does not report a minimum clinically important difference or another threshold for interpreting the size of the mean difference.

7. Results Posted in the Registry

• Assay-guided Treatment (AGT): mean -9.70 versus -10.16 on control; difference 0.46 (95% CI -1.08 to 2.00), standardized effect d = 0.07; z-test p = 0.558.

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.

Mean Change From Baseline in QIDS-SR16 Score at 8 Weeks.

• 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:
  • Assay-guided Treatment (AGT): mean -6.04 versus -6.45 on control; difference 0.41 (95% CI -0.83 to 1.65), standardized effect d = 0.08; z-test p = 0.516.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Assay-guided Treatment (AGT) and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Treatment Responders at Week 8 Based on ≥ 50% Reduction of SIGH-D-17 Score From Baseline.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Assay-guided Treatment (AGT): 42.0% (58/138) versus 51.4% (72/140) on control; risk difference -9.4 percentage points (95% CI -21.1 to 2.3), risk ratio 0.82 (0.63–1.05); unadjusted two-proportion z-test p = 0.116.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Assay-guided Treatment (AGT) and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Treatment Responders at Week 8 Based on ≥ 50% Reduction of QIDS-SR16 Score From Baseline.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Assay-guided Treatment (AGT): 40.7% (57/140) versus 46.1% (65/141) on control; risk difference -5.4 percentage points (95% CI -17.0 to 6.2), risk ratio 0.88 (0.68–1.15); unadjusted two-proportion z-test p = 0.362.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Assay-guided Treatment (AGT) and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover several related but distinct aspects of depressive symptoms and safety. They include another continuous symptom-change measure, categorical response definitions based on symptom reductions or a global-improvement score, remission thresholds, and adverse-event assessments. This breadth can help describe different outcome dimensions, but each definition captures a different feature and should not be treated as an interchangeable replication of the primary endpoint.

Across the numerical secondary comparisons posted, the continuous symptom-change estimates and the available response estimates point in a direction that is not more favorable to AGT than TAU. Their intervals include the null value for the reported difference measures. This broad pattern is consistent with the primary result in that the posted comparisons do not establish a clear separation between groups. It does not demonstrate equivalence, and it does not make each secondary outcome a definitive test of the same question.

Secondary findings carry less weight when many outcomes are examined without a reported multiplicity strategy. With multiple comparisons, the chance of at least one apparently unusual result can increase. A prespecified hierarchy or adjustment can address that concern, but such a strategy is not reported in the registry record. The listed analyses do not include sponsor-reported formal analyses, and the numerical comparisons are unadjusted recalculations from group summaries.

Not all listed secondary outcomes have numerical comparative results in the record. The secondary outcome descriptions include response, remission, and safety measures, but the available posted numerical results cover only some of the listed outcomes. The absence of a posted comparison should not be taken as evidence that the groups were the same on that outcome. The registry record does not report why numerical results are unavailable for the remaining listed measures.

Secondary endpoints can provide useful context, especially when they measure related constructs using different scales or thresholds. Their interpretation should remain subordinate to the primary comparison and should account for multiplicity, incomplete reporting, and the uncertainty in each estimate. They add context to the primary finding, but do not remove its uncertainty or establish a broader conclusion beyond the measured outcomes and follow-up.

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

• Mean Change From Baseline in QIDS-SR16 Score at 8 Weeks.
• Percentage of Treatment Responders at Week 8 Based on ≥ 50% Reduction of SIGH-D-17 Score From Baseline.
• Percentage of Treatment Responders at Week 8 Based on ≥ 50% Reduction of QIDS-SR16 Score From Baseline.
• Percentage of Treatment Responders at Week 8 Based on ≤ 3 Score on the CGI-I.
• Percentage of Remitters at Week 8 Based on ≤ 7 Score on the SIGH-D-17.
• Percentage of Remitters at Week 8 Based on ≤ 5 Score on the QIDS-SR16.
• Safety Outcomes Based on Frequency, Intensity and Burden of Side Effects Rating (FIBSER).
• Safety Outcomes Based on Frequency and Severity of Reported Adverse Events.

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, and the registry reports a mean and standard deviation for each arm. A mean is the arithmetic average of the observed scores or changes. A standard deviation describes how dispersed individual observations are around that average. It is not the same as the standard error, which describes the precision of an estimated mean.

What does the mean difference represent?

The reported contrast is the AGT mean change minus the TAU mean change. The group means are -9.7 and -10.16, respectively, and the estimated difference is 0.46. Because the endpoint is change from baseline, a negative mean indicates a lower average score at follow-up than at baseline. The positive contrast indicates that the AGT average change was less negative than the TAU average change. This direction is a description of the arithmetic contrast, not a judgment about treatment benefit.

For a two-group mean comparison, uncertainty depends on the variability of observations and the number of observations contributing to each group estimate. Greater variability generally makes a difference harder to estimate precisely, while more observations generally improve precision. The registry posts group standard deviations of 6.411 for AGT and 6.689 for TAU, along with the comparison estimate and interval. The recalculated pooled standard deviation is 6.552; this provides a common scale for describing the observed difference relative to within-group spread.

How should the interval and p-value be read?

A confidence interval gives a range of values compatible with the data under the calculation method and its assumptions. The primary interval runs from -1.08 to 2.0. Since it crosses zero, the data are compatible with no mean difference as well as with differences in either direction. The registry does not state the confidence level for the posted intervals, so no confidence level should be inferred from the record.

The unadjusted p-value is 0.558. A p-value measures how unusual data at least as discrepant as those observed would be under a specified null model and its assumptions. It is not the probability that the null is true, nor the probability that the observed result occurred by chance in a general sense. The record does not report a multiplicity adjustment for the secondary outcomes, so the label unadjusted matters when interpreting those comparisons.

What is a standardized effect?

The recalculated standardized effect, d, is 0.070. Standardization expresses the mean difference relative to a measure of outcome variability, allowing the difference to be described without relying only on the original score units. It does not replace the original-scale estimate or its interval. A standardized estimate also does not supply a clinical-importance threshold, which is not reported in the registry record.

These comparisons are simple, unadjusted recalculations from posted group summaries. No sponsor-reported statistical analyses are listed for the primary or secondary outcomes. The registry record does not report whether the trial’s original analysis used covariate adjustment, a particular missing-data method, or any other model-based procedure. The posted calculations should therefore be understood as summary-statistic comparisons, not as a full reconstruction of an unreported protocol analysis.

Why can over-dispersion matter?

For general statistical context, over-dispersion means that observed variability is greater than a model assumes. If a model understates variability, its standard errors may be too small and its intervals too narrow. If variability is represented adequately, uncertainty estimates are more credible. This is a general consideration, not a finding about this trial: the registry does not report an over-dispersion assessment or a model that would allow one to be evaluated.

For binary secondary outcomes, such as response status, the outcome is a count of participants meeting a criterion rather than a continuous score. A risk difference compares the proportions between groups on the probability scale. Its interval expresses uncertainty in that difference. A risk ratio and an odds ratio describe the same type of group contrast on different scales. These measures are not interchangeable, and their interpretation depends on the outcome frequency. The secondary comparisons posted in the record are unadjusted.

In general, a null value is zero for a difference and one for a ratio. An interval that includes the relevant null value does not establish a difference on that scale. This general principle helps read the posted comparisons but does not itself determine clinical importance. For the continuous primary endpoint, zero is the null difference; the reported interval includes it.

Statistical methods cannot resolve information the record does not contain. The original sample-size justification, planned primary analysis, interim analyses, missing-data procedures, and analysis populations are not reported in the registry record. The registry also does not provide an endpoint-specific account of exclusions or deviations. Those gaps mean that the posted summary comparisons can be described, but their relationship to a prespecified full analysis plan cannot be verified.

11. Confidence Intervals and Precision

The primary estimate is a mean difference of 0.46 units, and the interval extends from -1.08 to 2.0. The interval is the main guide to the precision of the estimated contrast: it displays a range of values compatible with the data under the calculation method. Its inclusion of zero means that the observed summaries do not distinguish clearly between a difference in one direction, no difference, or a difference in the other direction.

The interval is not a range containing every plausible individual response. It concerns the between-group mean difference, not the spread of outcomes among participants. The reported standard deviations, 6.411 in AGT and 6.689 in TAU, describe within-group dispersion; the interval around the mean difference describes uncertainty about the estimated group contrast. These quantities answer different questions.

Precision is affected by sample size and variability. The primary outcome counts are 138 in AGT and 140 in TAU, and the observed standard deviations are reported for both groups. The registry does not explain why these counts differ from overall enrollment, or how missing observations were handled. That limits assessment of whether the posted interval captures all relevant uncertainty associated with exclusions or incomplete follow-up.

The registry record does not identify the confidence level of the displayed interval. It is therefore appropriate to describe its endpoints and whether it includes zero, but not to assign an unreported confidence level. Nor does the interval alone establish whether a difference would be clinically important: a clinical interpretation threshold is not reported. Overall, the interval leaves meaningful uncertainty about the direction and size of the average difference.

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 based on the observed effect, not the trial’s original design justification. The registry record does not report the trial’s original sample-size assumptions. For these illustrations, the stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect.

For these continuous and binary outcomes, the displayed figures are participants per arm, not total participants across the trial. The 80% power column gives the number of participants per arm estimated to yield an 80% chance of detecting the specified effect if that effect is the true one and the planning assumptions hold. The 90% power column uses a higher target chance of detection under the same assumptions. Higher target power generally requires more participants for a given effect.

Rows planning for 100%, 75%, and 50% of the observed effect show how the hypothetical target changes. Smaller effects need more participants because they are harder to distinguish from random variation. The figures are therefore sensitive to the effect chosen: the observed effect is not guaranteed to recur in another trial, and planning for only a fraction of it produces larger required sample sizes.

These values are not observed power. They are forward-looking planning illustrations, not a measure of the probability that the completed trial detected an effect. The record does not provide the assumptions used when the trial was originally designed, and the illustration should not be read as evidence that the completed trial was designed around the displayed participant counts.

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 = 0.460; pooled standard deviation σ = 6.552.
2. n = 2 × (1.96 + 0.842)² × 6.552² / 0.460² = 3,185.2, rounded up to 3,186 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 <- 0.460000000000001                      # observed difference in means
sigma <- 6.55248166174742                     # 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(2634177)
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 = 3,186 (80% power), 4,265 (90% power)
 75% of observed effect: n per arm = 5,663 (80% power), 7,581 (90% power)
 50% of observed effect: n per arm = 12,741 (80% power), 17,057 (90% power)
power.t.test: 3186.1 
Simulated power at n = 3,186 per arm: 0.800 (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 endpoint and multiple secondary outcomes, but it does not report a multiplicity plan. In a trial with several statistical comparisons, some apparently notable findings can arise by chance even when there is no underlying group difference. Statistical approaches such as adjusting significance thresholds or defining a hierarchy of outcomes can address this issue, but the registry record does not say whether any such approach was prespecified or used.

The posted secondary comparisons are unadjusted. They should therefore be treated as exploratory context rather than as a collection of independent confirmatory conclusions. The record lists no sponsor-reported analyses for the posted secondary outcomes. The registry does not report whether additional analyses were conducted or how any analyses not posted were handled.

Missing-data methods and analysis populations are also not reported in the registry record. The overall enrollment is 305, while the primary endpoint counts are 138 for AGT and 140 for TAU. Counts also vary across posted secondary outcomes. The record does not state why the denominators differ, how many observations were missing at each time point, whether missingness was related to outcomes, or whether the analysis used an intention-to-treat, per-protocol, or other population.

These omissions matter because the validity of a group comparison depends not only on the calculation but also on which participants contribute and how incomplete measurements are addressed. Random assignment supports comparability at allocation, but it does not by itself establish that the analyzed groups remain comparable after losses or exclusions. Without participant-flow details and missing-data procedures, the potential effect of incomplete data cannot be assessed from the registry record.

The trial’s original statistical analysis plan, sample-size justification, and interim analysis procedures are not reported in the registry record. It is therefore not possible to determine from this record whether the posted comparisons match the prespecified primary analysis or whether other analyses were planned. These limitations qualify interpretation of the posted results; they do not change the numerical values themselves.

15. Safety Results

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

Deaths

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: pneumonia (1.3%), appendicitis (0.7%), streptococcal sepsis (0.7%), syncope (0.7%), asthma (0.7%).

The registry reports serious adverse event figures separately by group. In AGT, 6 participants were recorded as affected among 150 at risk; in TAU, 3 were recorded as affected among 153 at risk. Deaths were recorded as 0 in each group. The registry also reports other adverse events affecting 107 participants among 150 at risk in AGT and 111 among 153 at risk in TAU.

These counts describe the reported safety experience during the registry’s specified reporting period, but the record does not provide enough detail to establish whether all events were related to treatment. Serious events and other adverse events are different categories and should not be combined. The listed serious-event terms include pneumonia, appendicitis, streptococcal sepsis, syncope, asthma, and multiple sclerosis, with registry percentages of 1.3% for pneumonia and 0.7% for each of the other listed terms.

Event counts are descriptive and do not, by themselves, establish a causal difference between groups. The denominators differ, and the record does not provide a comparative statistical analysis of safety outcomes. The figures should be read as reported counts and terms, not as proof that either treatment strategy caused or prevented an event.

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

The primary estimate describes the average difference in SIGH-D-17 change between the randomized groups over the stated 8-week period. The reported difference is 0.46, and its interval extends from -1.08 to 2.0. The interval includes zero and allows for values on either side, so the posted result does not establish a clear difference in average change between AGT and TAU.

This does not establish that the approaches are equivalent. Equivalence requires a prespecified margin and a design and analysis intended to assess whether the difference lies within that margin; no such margin or equivalence analysis is reported in the registry record. The result also does not show that no individual participant changed, or that both groups had identical outcomes. Group averages can conceal variation among participants.

The findings are limited to the measured outcomes and follow-up described in the record. The primary question concerns SIGH-D-17 change by 8 weeks; it does not answer whether any difference persists beyond that point, or address outcomes not listed in the registry. The record does not report a threshold for clinically important change, so statistical estimates cannot be translated into a categorical judgment of clinical importance from this information alone.

The trial compared treatment strategies in which assay information was used by investigators in one group and withheld from investigators in the other until Week 8 procedures were complete. It did not compare the assay with no DNA collection, since all participants provided a sample. Conclusions about the specific use of results should remain tied to this study’s design and posted outcomes.

Finally, missing-data procedures, analysis populations, and the original statistical plan are not reported in the registry record. Those omissions restrict the extent to which the posted summary estimates can be evaluated against the planned analysis. The appropriate reading is a comparison with substantial uncertainty, not a definitive claim about the presence, absence, or clinical importance of a difference.

17. Why This Trial Matters Statistically

This trial illustrates why a randomized comparison should be interpreted through the between-group estimate rather than by looking only at change within each group. Both groups had negative mean SIGH-D-17 changes, but the primary question is whether their average changes differed. The posted contrast addresses that question directly, while its interval shows that the estimate remains uncertain.

It also demonstrates the distinction between the direction of a point estimate and the strength of evidence. The primary point estimate is positive, but the interval includes zero and extends to negative values as well. A single direction in the point estimate is not enough to establish a reliable difference. Precision and compatibility with the null are central to the interpretation.

The trial’s design raises an important statistical distinction between having an assay performed and using its results to guide treatment. Both groups provided DNA samples; access to the results by treating investigators differed during the study period. The randomized contrast therefore concerns an assay-guided treatment strategy versus treatment as usual under the described information conditions.

The registry also shows why outcome multiplicity and reporting completeness matter. Several secondary outcomes are listed, but formal analyses and a multiplicity strategy are not reported. Without those details, secondary comparisons are best treated as context, rather than as a series of independent definitive tests. Differences between enrollment and outcome denominators likewise make missing-data and analysis-population details important to judging the evidence.

For biostatistical interpretation, the main lesson is to keep the estimate, its uncertainty, the endpoint definition, and the reporting limitations in view together. The posted summaries offer a direct randomized comparison, but they do not resolve all questions about analysis methods, missing observations, or broader outcomes.

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 the information recorded for this trial. The registry reports enrollment of 305, while the primary outcome comparison includes 138 participants in AGT and 140 in TAU. It does not explain the gap, provide a participant-flow account, or describe reasons for missing outcome data. Counts also differ among secondary results, without explanation of the denominator changes.

The primary and secondary comparisons are presented as unadjusted recalculations from group summaries, and no sponsor-reported statistical analyses are listed. The registry does not report whether adjusted analyses were conducted, how missing values were handled, or which analysis population was used. The original statistical plan, sample-size justification, and any interim analyses are not reported in the registry record.

The record lists several secondary measures but does not provide numerical results for every listed outcome. A multiplicity strategy is not reported, which limits the confirmatory interpretation of secondary comparisons. The confidence level for the displayed intervals and a threshold for clinically important change are also not stated in the record.

Masking is described as double, and the record specifically says participants and primary-endpoint raters remained blinded. It does not fully specify masking procedures for other roles. Since investigators in AGT received assay results to guide treatment, the record’s detailed description does not support assuming that all treating investigators were masked.

Finally, the primary assessment is limited to change through 8 weeks. The registry record does not provide longer-term comparative results. These limitations concern the completeness and interpretability of the recorded evidence; they should not be mistaken for findings that the trial itself failed to measure or analyze an outcome.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Genecept Assay™ vs. Treatment-as-Usual to Evaluate Efficacy of Assay-Guided Treatment in Adults With MDD — NCT02634177.
• Registry record last updated 2020-08-28; status last verified 2019-10.
• Results first posted 2020-08-28.
• 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

NCT02634177 is a completed randomized, controlled, double-blind, parallel-group trial of assay-guided treatment versus treatment as usual in adults with major depressive disorder. The registry lists enrollment of 305 and an 8-week assessment period. Participants in both groups provided DNA samples; investigators in AGT received assay results to guide pharmacotherapy, while investigators in TAU treated without knowledge of those results during the study period.

The primary outcome was mean change from baseline in SIGH-D-17 score at 8 weeks. The posted AGT-minus-TAU estimate was 0.46, with an interval from -1.08 to 2.0 and an unadjusted p-value of 0.558. The interval includes zero, leaving uncertainty about the direction and size of the average difference.

The registry lists secondary symptom, response, remission, and safety outcomes. It does not report a multiplicity strategy, original sample-size justification, missing-data methods, analysis populations, or a full statistical analysis plan. The available results are therefore most appropriately read as posted group summaries and unadjusted comparisons, with those reporting limitations in mind.