Nociceptors, Neurotrophic Factors and Cytokine Expression in Gastroesophageal Reflux Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nociceptors, Neurotrophic Factors and Cytokine Expression in Gastroesophageal Reflux Disease (NCT02114216), a non-randomized na study. The primary outcome is TRPV1, GDNF, and NGF mRNA Expression of Esophageal Mucosa.

2. Clinical Question

3. Trial Design

This is a nonrandomized, parallel-group study of gene expression in esophageal mucosal samples. The registry lists the allocation as nonrandomized and masking as none. There was no treatment assignment: participants were classified by symptom reports and upper gastrointestinal endoscopy findings, and endoscopic mucosal biopsy was performed in every group. The stated enrollment is 75; the number enrolled in each group and the numbers contributing samples to each analysis are not reported in the registry record.

The control group is described as having no mucosal breaks consistent with reflux esophagitis and no GERD symptoms. The NERD group is described as having symptoms without mucosal breaks. The ERD group is described as having mucosal breaks and/or symptoms. These categories represent clinical and endoscopic classifications, not randomized treatment arms. In particular, differences between a group and the control group could reflect the characteristics used to define group membership, along with other factors not described in the record. The design does not establish that group status caused any expression difference.

The intervention field identifies endoscopic mucosal biopsy as a procedure. The primary outcome concerns TRPV1, GDNF, and NGF mRNA expression in esophageal mucosa, measured as fold change and summarized using means and standard errors. The primary outcome timeframe is listed as up to 24weeks. PAR2 and IL-8 expression is listed as a secondary outcome. The record does not report how the timeframe relates to biopsy scheduling or whether repeated measurements were taken.

The study is marked completed, with a start date of 2013-03 and primary completion of 2014-08. Its phase is listed as NA. The sponsor is Seoul National University Bundang Hospital. The registry record does not report random allocation, blinding, a statistical analysis plan, or group-specific results. Since there is no randomized assignment, the comparison should be interpreted as an observational association rather than an estimate of the effect of a treatment.

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: Subjects were excluded if there was a history of gastrointestinal surgery, Barrett's esophagus, esophageal motility disorder, duodenal ulcer, benign gastric ulcer or gastroduodenal cancer and any history of systemic disease requiring chronic medication (except for hypertension and diabetes mellitus).

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 TRPV1, GDNF, and NGF mRNA Expression of Esophageal Mucosa, measured over up to 24weeks.

The primary endpoint is the expression of TRPV1, GDNF, and NGF mRNA in esophageal mucosa, reported in fold change. The registry describes these as continuous measurements summarized by their means and standard errors. The laboratory method uses real-time qPCR, with Homo b-actin as a reference to normalize each sample. The relative change in target-gene expression is determined by fold-change analysis.

Gene expression is measured because the study aims to examine molecular features that may be associated with GERD symptoms and endoscopic findings. The record's brief summary identifies TRPV1 and PAR2 as receptors implicated in acid-induced inflammation and states that the investigators aimed to assess expression in GERD patients and its relationship with endoscopic findings and reflux symptoms. This explains the biological rationale, but does not establish that expression is a direct measure of symptoms, inflammation, or clinical severity.

A fold-change endpoint represents relative expression after normalization, rather than a direct count of symptoms or a clinical event. Interpretation depends on how the reference and fold-change procedure are applied and on the distribution and variability of the measurements. The registry provides some laboratory protocol details, but does not report the exact contrast used for the primary endpoint, the reference condition for fold change, or numerical estimates. The outcome timeframe is listed as up to 24weeks; further details of assessment timing are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods described in the record combine clinical classification with laboratory measurement. Participants were grouped according to GERD symptoms and endoscopic evidence of mucosal breaks. A biopsy was performed for every subject, and the study assessed mRNA expression in the esophageal mucosa. This is a nonrandomized design: people were not assigned to symptom or endoscopy categories by the investigators. The comparisons can address whether expression varies across the recorded groups, but cannot on their own isolate a causal effect of symptoms, endoscopic findings, or a treatment.

What does fold change represent?

Fold change expresses target-gene levels relative to a reference after normalization. The registry says that each sample was normalized on the basis of its Homo b-actin content, and that relative changes in target-gene expression were determined using fold-change analysis. Normalization is intended to account for differences in the amount of starting material or other technical variation. It does not remove every possible source of measurement error or biological variation. The record does not state the precise reference condition used to calculate fold change, so the exact interpretation of the reported scale cannot be reconstructed from the registry entry alone.

How was expression measured?

The registry describes real-time qPCR using primers designed with PrimerExpress Software V2.0, based on sequence information from the National Center for Biotechnology Information database. The assay used a StepOnePlus Real-time PCR instrument and SYBR Premix Ex TaqTM, following manufacturer instructions and protocols. The record states that qPCR was performed in triplicate. Triplicate measurement refers to repeated laboratory measurements, but the registry does not clarify how these replicates were combined or how technical variation was handled in the final outcome values.

The listed thermal cycling protocol began with initial denaturation at 95 °C for 10s, followed by 40 cycles of 95 °C for 5 s and 60 °C for 33s. These details describe the assay procedure; they do not supply evidence about the quality or reproducibility of the resulting measurements. The record does not report assay validation results, batch handling, laboratory blinding, or quality-control thresholds.

What do means and standard errors convey?

The primary outcome is continuous and is described using a mean and standard error. A mean represents the average measured value within a group. The standard error describes the estimated precision of that mean, rather than the dispersion of individual observations. General statistical explanation: a confidence interval combines an estimate with its uncertainty to show a range of values compatible with the data under the chosen method. The registry record does not report confidence intervals or group-specific standard errors, so the uncertainty around the relevant comparisons cannot be judged.

A comparison of group means can be informative when the analysis and outcome scale are appropriate, but gene-expression measurements may have distributions that are asymmetric or influenced by extreme values. General statistical explanation: if a continuous outcome is strongly skewed, a mean can be sensitive to a small number of observations, and a model based on a different scale or a robust method may be considered. The record does not report the observed distributions, transformations, model assumptions, or diagnostic checks. It is therefore not possible to assess whether the selected summary and any inferential method adequately represented the data.

What analysis was used?

The statistical model, comparison procedure, covariate adjustment, hypothesis tests, and handling of repeated or correlated measurements are not reported in the registry record. The record lists two outcome measures, but does not provide analysis details or numerical results. No conclusions about statistical significance or the size of group differences can be drawn from the endpoint descriptions alone. When interpreting a reported mean difference, readers would ordinarily need its estimate, uncertainty, analysis population, and the model used to obtain it. Those details are not available in this record.

The record also does not report sample-size justification or a prospective statistical plan. General statistical explanation: a study's ability to estimate an effect depends on factors such as the amount of data, outcome variability, and the analysis method. Enrollment alone does not reveal the precision of a particular group contrast, especially when group sizes and missing data are unknown. No power or sample-size conclusion should be inferred from the enrollment figure.

These methodological details matter because laboratory measurements and clinical classifications each introduce sources of uncertainty. Replicate assays can address technical repeatability, while participant-level variability and group composition affect the clinical comparison. The registry record describes the measurement procedure but does not report enough analysis information to determine how these sources of uncertainty were incorporated into the reported inference.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome covering TRPV1, GDNF, and NGF mRNA expression, and a secondary outcome covering PAR2 and IL-8 expression. Multiple genes and group comparisons can create multiple opportunities to observe an apparently notable result. Whether the investigators specified a hierarchy of tests, adjusted for multiplicity, or treated some gene comparisons as exploratory is not reported in the registry record. There are no reported analysis details or numerical results with which to assess the implications.

The registry record does not report an analysis population for any outcome. Although enrollment is listed as 75, group-specific sample sizes, numbers with usable biopsy measurements, exclusions, and analysis denominators are not reported. Missing-data amounts and the methods used to address missing measurements are also not reported in the registry record. Consequently, the completeness of the gene-expression data and the possibility that availability of measurements differed by group cannot be assessed.

The record does not describe a prespecified statistical analysis plan, interim analyses, or adjustments for covariates. It is therefore unclear whether the analyses were planned before examining the data, which contrasts were considered primary, and how the investigators handled potential confounding. The record lists two outcome measures, but that listing alone does not establish the number of statistical tests performed. The number and form of analyses are not reported in the registry record.

These omissions limit assessment of selective reporting and the reliability of any inferential claim. They do not demonstrate that multiplicity, missing data, or confounding were mishandled; they mean that the registry entry does not provide the information needed to evaluate those issues.

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

The record establishes that the study assessed esophageal mucosal gene expression in groups defined by GERD symptoms and endoscopic findings. It also describes the qPCR approach and names the target genes. It does not provide numerical outcome results. Accordingly, the record alone does not show how large any expression differences were, how uncertain they were, or whether any comparison met a statistical criterion.

The official title describes an association between symptomatic GERD and increased TRPV1 and PAR2 mRNA expression. That wording is part of the title, but the underlying estimates, group comparisons, and uncertainty are not reported in the registry record. The title should not be treated as a substitute for results. It also does not establish that a difference in expression causes symptoms, predicts clinical outcomes, or reflects a specific biological pathway in individual participants.

Because the study is nonrandomized, group comparisons are observational. General statistical explanation: an association can arise from the exposure or characteristic of interest, from other differences between groups, or from a combination of these. The record does not describe adjustment for possible confounders, so it is not possible to determine whether any reported relationship was independent of other factors.

The endpoint is a molecular measurement, not a patient-centered clinical outcome. A change in relative mRNA expression does not by itself show a change in symptoms, disease course, or response to treatment. The record does not evaluate a therapeutic intervention, and it does not establish a clinical threshold for interpreting fold change. No medical decision should be based on the endpoint description alone.

The most defensible conclusion from the registry entry is therefore limited: it documents a completed, nonrandomized investigation of gene expression across clinically defined groups and describes the laboratory method. The magnitude, precision, statistical significance, and clinical relevance of the findings are not reported in the registry record.

12. Why This Trial Matters Statistically

This study illustrates a common distinction in biostatistics between measuring a biological signal and establishing what that signal means clinically. The endpoint is relative mRNA expression, measured after normalization and summarized as a continuous outcome. Such a measurement can help characterize biological differences across clinical groups, but its interpretation depends on the assay, reference scale, data distribution, and analysis method. The registry describes parts of the laboratory workflow while leaving the outcome estimates and inferential methods unreported.

The group structure also highlights the difference between an observational comparison and a randomized experiment. Participants were classified using symptoms and endoscopic findings, not assigned to groups. Any expression contrast would therefore be an association within the groups as defined. It cannot, by itself, establish that symptoms or mucosal breaks produced an expression change. Statistical adjustment might address some measured differences, but the record does not report whether adjustment was used or what variables were considered.

The study's several gene outcomes raise a further interpretive issue: results across multiple targets require clarity about which questions were primary and how uncertainty was handled. The registry identifies primary and secondary outcomes but does not report the analysis plan or estimates. Without that context, readers cannot distinguish a prespecified confirmatory result from a more exploratory pattern.

Finally, the entry demonstrates why enrollment is not enough to judge precision. The total listed enrollment does not reveal how many measurements contributed to each group comparison, how variable those measurements were, or how many were missing. Those details, together with effect estimates and uncertainty intervals, are necessary for a statistical assessment. The record's methods and outcome descriptions are useful for understanding the study question, but cannot substitute for reported results.

13. 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 main limitation for interpretation is that the registry record does not report numerical results for the primary or secondary outcomes. It therefore gives no group means, standard errors, contrasts, confidence intervals, or p-values. The title states an association involving TRPV1 and PAR2, but the effect size and its precision cannot be verified from the record.

Group-specific enrollment and analysis denominators are not reported. The listed enrollment of 75 does not indicate how many participants were assigned to each clinical category, provided a usable biopsy, or were included in a particular outcome analysis. The record also does not describe missing measurements, exclusions, or the population used for analysis.

The nonrandomized group definitions limit causal interpretation. Symptoms and endoscopic findings determined the categories, so differences in gene expression could reflect other characteristics associated with those categories. Potential confounders, covariate adjustment, and the statistical model are not reported in the registry record. The description of the ERD group includes mucosal breaks and/or symptoms, while the NERD and control groups are defined separately by symptoms and mucosal breaks; additional classification detail is not reported.

The laboratory description does not include assay validation, quality-control results, handling of triplicate measurements, or the exact reference condition for fold change. The statistical plan, outcome distributions, multiplicity handling, and missing-data approach are also not reported. The timeframe is listed as up to 24weeks, but assessment timing and whether measurements were repeated are not specified.

Finally, the adverse-event entries list zero at-risk and affected counts in each group. With no usable denominator or explanatory detail, those entries should not be read as evidence that adverse events were absent.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Nociceptors, Neurotrophic Factors and Cytokine Expression in Gastroesophageal Reflux Disease — NCT02114216.
• Registry record last updated 2016-05-02; status last verified 2016-04.
• Results first posted 2016-05-02.
• 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.

17. Record Summary

NCT02114216 is a completed, nonrandomized, parallel-group study titled “Nociceptors, Neurotrophic Factors and Cytokine Expression in Gastroesophageal Reflux Disease.” The official title describes symptomatic GERD as associated with increased TRPV1 and PAR2 mRNA expression. The sponsor is Seoul National University Bundang Hospital. The record lists enrollment of 75, a start date of 2013-03, and primary completion of 2014-08. Phase is listed as NA.

Participants were classified as control, ERD, or NERD according to symptoms and endoscopic findings. Endoscopic mucosal biopsy was performed for every subject. The primary outcome is TRPV1, GDNF, and NGF mRNA expression in esophageal mucosa, measured as fold change and summarized as mean and standard error. PAR2 and IL-8 expression is listed as a secondary outcome.

The record describes real-time qPCR and normalization using Homo b-actin. Numerical outcome findings, group-specific sample sizes, analysis methods, and missing-data details are not reported in the registry record. Thus, the record documents the study question and measurement approach, but does not permit assessment of the size or precision of the reported associations.