Genetic Research in Schizophrenia Using DNA Markers and Clinical Phenotypes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Genetic Research in Schizophrenia Using DNA Markers and Clinical Phenotypes (NCT00108303), a registered phase not stated study. The primary outcome is Heritability Coefficient.

2. Clinical Question

3. Trial Design

The record describes “Genetic Research in Schizophrenia Using DNA Markers and Clinical Phenotypes in Individuals Extensively Diagnosed and Genotyped.” Its stated purpose is to investigate genetic abnormalities associated with childhood- and adult-onset schizophrenia. The condition listed is schizophrenia, and the sponsor is the VA Office of Research and Development. The study status is completed; its recorded start is 2004-01 and its primary completion is 2008-12.

This is not a randomized clinical comparison of treatments. The registry record states that allocation was not stated and that the arms are not a like-for-like control comparison. It lists a diagnostic intervention and describes the diagnostic arm as “A diagnostic was performed.” The record does not explain what the diagnostic involved or describe a treatment assigned to participants. The probands, relatives, and controls are participant categories for the research question, not evidence of randomized assignment.

The primary outcome is a heritability coefficient for P50 sensory gating, with a timeframe listed as 5 years. The population description includes schizophrenia probands, relatives, and controls. The record lists 3 outcome measures and 3 analyses, but their full definitions and analytic specifications are not reported in the registry record. The enrollment entry is 538; the number contributing to each analysis is not reported in the registry record.

The registry record does not report the recruitment process, eligibility criteria, how diagnostic status was established, or how DNA markers were selected or analyzed. It also does not report a protocol-level statistical plan, a sample-size justification, or the intended handling of incomplete observations. These omissions limit what can be inferred about how the research was conducted from the registry information alone.

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

Analysis population for the primary outcome, as defined in the registry: People with schizophrenia and their relatives in families and controls as members of single families were used to establish the log of the odds ratio.

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 Heritability Coefficient, measured over 5 years.

The primary endpoint is titled “Heritability Coefficient,” measured as a coefficient. The description identifies it as h squared, which ranges from 0 to 1, and says it is similar to a Pearson correlation coefficient. In this application, the variable is P50 sensory gating, and the relationship is considered across schizophrenia probands, schizophrenia relatives who are not ill, and controls who are not ill and have no known ill relative.

P50 is described as a positive wave in a scalp-recorded auditory evoked potential that occurs 50 msec after a sound stimulus. P50 sensory gating is the decrement in this wave in response to the second of repeated sounds. The outcome therefore concerns a measured physiological response and how that response relates across the stated participant statuses. It is not itself a count of schizophrenia cases, a direct measure of a specific DNA marker, or a treatment response.

As a general statistical interpretation, a heritability coefficient is intended to characterize a pattern of resemblance or variation under a specified analysis; it is not a direct estimate of the effect of a particular genetic variant on an individual. The registry record does not provide the coefficient estimate, its confidence interval, or a test result. The reason for choosing P50 sensory gating as the primary phenotype beyond the description of the research objective is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods need to be interpreted in light of the question and the design. This research concerns genetic markers and clinical phenotypes, with P50 sensory gating identified as the primary phenotype. The participant categories are schizophrenia probands, relatives without schizophrenia, and controls without illness or a known ill relative. The registry record says the study is not a randomized comparison and that the arms are not a like-for-like control comparison. It does not report the allocation method, which is not stated.

What does the coefficient represent?

The primary measure is a heritability coefficient, described as h squared and compared conceptually with a Pearson correlation coefficient. The description says it represents correlation in P50 sensory gating across participant statuses. Its stated range is 0 to 1. That range describes the possible scale, not the study’s result. The actual coefficient is not reported in the registry record.

As a general statistical explanation, a coefficient compresses a pattern of association into a numerical summary. Its interpretation depends on the precise model, data structure, and assumptions used to estimate it. A coefficient is not automatically a causal effect, and the word “heritability” does not mean that a particular person’s phenotype is genetically predetermined. The registry record does not identify the formula or model used, the variables entered, or the assumptions checked. Those details are needed to assess whether the reported label and the estimate can be interpreted as intended.

What would uncertainty add?

As a general statistical explanation, a confidence interval conveys a range of values compatible with the data under the method’s assumptions. It helps readers assess precision rather than relying on an estimate alone. The registry record does not report a confidence interval or other uncertainty measure for the primary coefficient. It also does not report a p-value or a test procedure. Statistical significance and precision therefore cannot be assessed from the registry outcome information.

For a bounded coefficient, an analysis should also account appropriately for the scale and distribution of the measure. As a general consideration, methods designed for an unbounded outcome may not be suitable without justification when estimates are constrained. The record does not identify the estimation method, describe diagnostics, or explain how the range from 0 to 1 was handled. It would be inappropriate to assume a particular model or transformation.

What can the analysis counts tell readers?

The registry lists 3 outcome measures and 3 analyses. These counts indicate that multiple outcomes and analyses are registered, but they do not reveal the analysis population, model specifications, outcome hierarchy, or whether each analysis corresponds to a separate measure. The names and details of the other outcomes and analyses are not reported in the registry record. No multiplicity procedure is described.

As a general principle, conducting multiple analyses can increase the chance that at least one result appears noteworthy by chance if results are selected or interpreted without accounting for that multiplicity. A prespecified hierarchy or adjustment can help address that concern, but the registry record does not report whether either was used. The existence of multiple registered analyses alone does not show that the study’s conclusions were biased; it does mean the analysis plan is needed for a fuller evaluation.

How should planning calculations be read?

The registry record’s planning illustration is described as being computed from the observed effect, rather than as part of the trial’s own design. Its stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. These are planning assumptions, not evidence that the research itself used that allocation or analysis. The record also states that such calculations are illustrations, not observed power. The trial is explicitly not a randomized, like-for-like comparison, so those assumptions should not be mistaken for its design.

As a general statistical explanation, a sample-size planning calculation estimates the information needed for a future study under chosen assumptions. It does not show the probability that the completed study detected an effect, and it does not substitute for the observed estimate and its uncertainty. The registry record does not report the study’s own sample-size justification or protocol-level planning assumptions.

Finally, the primary outcome timeframe is listed as 5 years, but the registry record does not describe repeated measurements, the timing of assessments, or a longitudinal model. No statistical test, covariate adjustment, subgroup approach, or sensitivity analysis is specified. These methods are not reported in the registry record, so they cannot be reconstructed from the endpoint description alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 3 outcome measures and 3 analyses, but does not identify the full set of outcomes or explain how the analyses were related. It does not report whether the heritability coefficient was the sole primary test, whether there was a prespecified hierarchy among outcomes, or whether any adjustment for multiple testing was used. The statistical plan and analysis-specific hypotheses are not reported in the registry record.

As a general statistical consideration, multiplicity matters when researchers evaluate several outcomes, contrasts, or models. Without a prespecified approach, interpreting a selected result as if it were the only test can overstate the strength of evidence. This is a general concern, not a claim that the study used selective reporting. The registry information does not permit an assessment of how multiplicity was handled.

The record lists enrollment as 538, but does not report the number analyzed for each outcome or the reasons participants may have been excluded from an analysis. The amount and pattern of missing data, any imputation, and any sensitivity analyses are not reported in the registry record. The analysis populations, including whether they were defined differently for different outcomes, are also not reported.

Interim analyses, stopping rules, and changes to the statistical plan are not reported in the registry record. The record does not provide enough information to establish whether the completed analyses followed a prespecified protocol. These omissions limit assessment of the robustness and reproducibility of the reported research, independent of the study’s scientific rationale.

11. 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.

The registry record lists serious adverse events and other adverse events separately for schizophrenia probands, schizophrenia relatives, and controls. For each listed group, it records 179 at risk and 0 affected for serious events, and 179 at risk and 0 affected for other events. No serious adverse-event terms are listed. These are the registry’s recorded figures for the named categories and groups.

These entries should not be interpreted as a complete safety assessment. The registry record does not describe how events were collected, the observation period for adverse events, or whether the absence of recorded events means none occurred or none were entered. Deaths are not reported in the registry record. The listed diagnostic intervention is not a treatment comparison, and the record does not give enough information to assess adverse events by procedure or exposure.

The safety entries do not provide evidence about the primary genetic research question or the P50 sensory-gating coefficient. They also do not establish that participation carried no risk. They should be read only as the reported adverse-event counts and accompanying at-risk entries, with the limitations of the registry information kept in view.

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

The registry record establishes the study’s stated research aim, primary measure, participant categories, and completion status. It describes genetic research using DNA markers and clinical phenotypes, with a primary heritability coefficient for P50 sensory gating across schizophrenia probands, relatives, and controls. It also states a broader goal of investigating genetic abnormalities associated with childhood- and adult-onset schizophrenia.

What the record does not establish is the observed result for the primary endpoint. The coefficient estimate, uncertainty interval, and statistical test result are not reported in the registry record. Without those results, the magnitude and precision of the association cannot be judged. The coefficient’s possible range does not show where the study’s estimate lies, and the listed enrollment does not indicate how much information entered the primary analysis.

The study’s nonrandomized, non-like-for-like group structure also matters. The participant categories are not randomized treatment arms, and the registry does not report a causal design. A pattern across categories would describe an association under the study’s methods; it would not, by itself, prove that a genetic abnormality caused schizophrenia or that schizophrenia caused a change in P50 sensory gating.

The record does not report which DNA markers were assessed, detailed phenotype procedures, diagnostic criteria, analytic methods, or results by onset group. It does not report how missing observations or multiple analyses were handled. These omissions mean readers cannot determine from the registry record whether the analyses address the broader objective, how robust any finding is, or how precisely it was measured.

Accordingly, the record is informative about the question the researchers intended to study, but not about the numerical answer to that question. It supports no conclusion about the success or failure of the genetic hypothesis, and it should not be read as evidence for or against a treatment effect.

13. Why This Trial Matters Statistically

This study illustrates why a clearly named endpoint is not enough to interpret a result. The registry identifies a heritability coefficient for P50 sensory gating and describes the participant statuses across which the measure is considered. But without the coefficient estimate and its uncertainty, readers cannot judge the strength or precision of the observed pattern. A scientific question and a numerical result are separate pieces of evidence.

It also highlights the importance of distinguishing research groups from randomized comparison arms. Probands, relatives, and controls have different stated statuses, and the record says the comparison is not randomized or like-for-like. That distinction affects what statistical conclusions can be drawn: group patterns may be informative for describing an association, but they do not alone establish causation.

The record further shows why analysis details matter when multiple outcomes and analyses are registered. The counts of 3 outcomes and 3 analyses do not explain which results were primary, how multiplicity was addressed, or which participants contributed to each analysis. Those details help readers evaluate whether uncertainty and selection among analyses have been handled transparently.

Finally, planning illustrations should not be confused with observed precision or with the study’s original design. The registry describes planning assumptions, but explicitly separates the illustration from the trial’s own design. In statistical reading, such calculations are conditional on assumptions; they cannot replace the reported estimate, confidence interval, and analysis population. The missing primary results and methods therefore define the limits of what can be learned from this registry record.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record provides limited detail about the study procedures. It does not report eligibility criteria, recruitment methods, diagnostic criteria, or how the proband, relative, and control categories were established. It also does not explain the diagnostic intervention beyond stating that a diagnostic was performed. This makes it difficult to assess how representative the participant groups were or how consistently the categories were defined.

The primary outcome description explains P50 sensory gating and the intended heritability coefficient, but does not give the coefficient estimate or an uncertainty measure. The record does not specify the analytic model, the precise construction of the coefficient, or the handling of the bounded scale. The names and definitions of the other registered outcomes and analyses are also not reported.

Although enrollment is listed as 538, the registry record does not say how many participants contributed to each analysis or describe missing data. It does not report whether there were exclusions after enrollment, how those were handled, or whether the analysis populations differed by outcome. The enrollment entry therefore cannot be treated as the denominator for the primary result.

The record states that the study is not a randomized comparison and that its arms are not like-for-like controls. This limits causal interpretation of differences across the stated participant categories. The genetic markers assessed, the data-collection procedures, and results by childhood- or adult-onset status are not reported in the registry record. The statistical plan, multiplicity handling, and any sensitivity analyses are also not reported. These limitations prevent a detailed evaluation of internal validity, precision, and reproducibility from registry information alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Genetic Research in Schizophrenia Using DNA Markers and Clinical Phenotypes — NCT00108303.
• Registry record last updated 2016-01-07; status last verified 2015-12.
• Results first posted 2016-01-07.
• 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.

18. Record Summary

The completed study, sponsored by the VA Office of Research and Development, concerns schizophrenia and genetic research using DNA markers and clinical phenotypes. The registry record lists enrollment as 538, a start of 2004-01, and primary completion in 2008-12. Its stated purpose is to investigate genetic abnormalities associated with childhood- and adult-onset schizophrenia.

The primary outcome is a heritability coefficient for P50 sensory gating across schizophrenia probands, relatives, and controls, with a timeframe of 5 years. The registry lists 3 outcome measures and 3 analyses. It states that the comparison is not randomized and that the arms are not like-for-like controls. The coefficient estimate, uncertainty, analysis populations, detailed statistical methods, and missing-data procedures are not reported in the registry record.