Traditional Chinese Medicine (TCM) for Temporomandibular Dysfunction (TMD): A Whole Systems Multi-site Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Traditional Chinese Medicine (TCM) for Temporomandibular Dysfunction (TMD): A Whole Systems Multi-site Trial (NCT00856167), a randomized phase 2 study. The primary outcome is Characteristic Facial Pain Score.

2. Clinical Question

3. Trial Design

This was a randomized, phase 2, parallel-group trial with no masking, according to the registry record. The sponsor was the University of Arizona. The record lists 135 participants enrolled and the status as completed. It gives a start date of 2006-10 and a primary completion date of 2010-01. These registration details describe the study’s administrative record; they do not supply outcome estimates or explain the rationale for each design choice.

The study summary frames the investigation around different combinations of a self-care program and Traditional Chinese Medicine. It describes stepped care as varying levels of care depending on participant responses at different study time points, and says the study sought to examine both short-term and long-term outcomes. The stated short-term follow-up was 8 weeks, while long-term follow-up was described as 18-months. The primary outcome timeframe specifically refers to measurements at the beginning and end of each treatment period, with the end measurement 8 weeks later. Results for long-term follow-up are not reported in the registry record.

For Period 1, the registry record reports allocation of 79 subjects, with 39 assigned to Traditional Chinese Medicine and 40 to self-care. It says 36 subjects in the Traditional Chinese Medicine group completed that period and that all were removed from the allocation group for Period 2 per study plan. It reports 35 Period 1 self-care completers and then gives an incomplete description of Period 2 allocation: 29 were allocated to Traditional Chinese Medicine or self-care, with the remaining description cut off. The safety entries list different group sizes for Period 2, but the record does not explain how those groups relate to the incomplete participant-flow description.

Although the study is identified as parallel and randomized, detailed allocation procedures, sequence generation, concealment, and the operational rules for stepped care are not reported in the registry record. Masking is listed as none. The record does not state whether outcome assessors or analysts were masked. A detailed protocol and a full statistical analysis plan are also not reported in the registry record, so the design features beyond the listed characteristics should not be inferred.

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: In the 1st period, 79 subjects were allocated to TCM (39) or SC (40). 36 TCM subjects completed the 1st period; all were removed from the allocation group for the 2nd period per study plan. 35 SC subjects completed the 1st period. 29 were allocated to TCM (15) or SC (14) for the 2nd period; 6 were removed from the allocation group due to subject choice or insufficient pain. 56 additional subjects were allocated to TCM (27) or SC (29) for the 2nd period. 135 subjects total were allocated.

Period 1

Reasons for not completing this period:

Period 2

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: In the 1st period, 79 subjects were allocated to TCM (39) or SC (40). 36 TCM subjects completed the 1st period; all were removed from the allocation group for the 2nd period per study plan. 35 SC subjects completed the 1st period. 29 were allocated to TCM (15) or SC (14) for the 2nd period; 6 were removed from the allocation group due to subject choice or insufficient pain. 56 additional subjects were allocated to TCM (27) or SC (29) for the 2nd period. 135 subjects total were allocated.

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 Characteristic Facial Pain Score, measured over Beginning of each treatment period, end of each treatment period (8 weeks later).

The primary endpoint was the Characteristic Facial Pain score, a continuous measure reported as a mean with standard deviation. Its description says it combines participant reports of worst pain over the previous two weeks, average pain when experiencing pain over the previous two weeks, and current pain. Each component is reported on a 0-10 VAS scale, where 0 means no pain and 10 means worst possible pain. The score is therefore intended to capture several aspects of the participant’s recent and current facial-pain experience rather than a single isolated moment.

Repeated measurement at the beginning and end of a treatment period can describe how scores change over that period. A comparison between groups can then help distinguish a within-group change from a difference in change between treatment approaches. These are general statistical interpretations of a continuous outcome; the registry record does not provide the means, standard deviations, changes, or a comparative estimate needed to make them for this trial.

The listed timeframe is the beginning of each treatment period and its end 8 weeks later. The record indicates that the outcome has multiple categories or time points and is not reduced to one comparison. The specific primary contrast, the method for combining the pain components, and the handling of repeated measurements are not reported in the registry record. Although the study summary mentions an 18-month long-term follow-up, the primary endpoint description posted in the registry record is tied to treatment-period measurements; long-term endpoint values are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a continuous primary outcome summarized as a mean and standard deviation. It does not give the numerical estimates or an analysis plan, so the discussion below explains general statistical concepts relevant to this kind of outcome rather than identifying methods used in the trial.

What does a mean summarize?

General: A mean is the arithmetic average of observed scores in a group. For a pain score collected from participants, it gives a single summary of the group’s central level, but it does not show whether participants’ experiences were similar or widely spread. A mean can also be affected by unusually high or low observations. The score description combines reports of worst pain, average pain when having pain, and current pain, and places them on a 0-10 VAS scale. The registry record does not give the group means or explain the calculation used to combine those reports into the Characteristic Facial Pain score beyond describing it as a mean.

General: A standard deviation describes the spread of individual scores around a group mean. It is not the uncertainty in the mean itself and is not a treatment effect. Means and standard deviations can help readers understand both the average score and its variability, but they do not by themselves show whether groups differ. For a treatment comparison, an estimate of the contrast and an uncertainty interval are needed. Those numerical summaries are not reported in the registry record.

Why does the comparison matter?

General: When an outcome is measured at the beginning and end of a treatment period, several possible questions can be asked. An analysis might compare end-of-period scores, compare changes from the beginning, or model repeated observations jointly. Each approach defines a different statistical contrast and can rely on different assumptions. A within-group change alone does not establish that one treatment approach differs from another: changes can occur in both groups for reasons unrelated to the treatment contrast. The registry record does not specify which contrast was intended or which method was used.

General: Random assignment is intended to make comparison groups similar on average at the point of allocation, including with respect to characteristics that may not have been measured. It does not guarantee identical groups in a particular trial, nor does it address losses to follow-up automatically. Interpretation also depends on how participants are counted in the analysis and how missing outcomes are handled. The registry record identifies the study as randomized but does not report the allocation procedure or the analysis population for the primary endpoint.

What do confidence intervals and p-values add?

General: A confidence interval gives a range of values compatible with the observed data and the assumptions of the method, at a stated confidence level. Its width reflects statistical precision: a wider interval indicates greater uncertainty about the effect estimate. It should be read alongside the estimate and the outcome scale, not as a substitute for them. No confidence interval for the primary outcome is reported in the registry record.

General: A p-value measures how compatible data are with a specified null hypothesis under a statistical model. It is not the probability that the null hypothesis is true, and it does not quantify the size of an effect. A small p-value does not alone establish importance, while a larger one does not establish no difference. The registry record does not report a p-value for the primary outcome or describe a testing plan.

How should planning illustrations be read?

The registry record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. The illustrations are planning exercises, not observed trial outcomes and not evidence that the trial had a particular probability of detecting an effect. The registry record does not report a sample-size justification for the trial. Numerical planning requirements and the observed effect used for those illustrations are not reported in the registry record, so no planning total can be interpreted from the record alone.

General: A planning calculation depends on assumptions about the effect one wants to detect, outcome variability, the significance threshold, allocation, and the statistical method. Changing those assumptions changes the calculated sample size. A calculation based on an observed effect can be especially sensitive to uncertainty in that observed estimate. Such calculations are not observed power: they do not show the probability that the completed trial detected a true effect. They are hypothetical design illustrations conditional on their assumptions.

Why can repeated outcomes complicate interpretation?

The Characteristic Facial Pain score is described at the beginning and end of each treatment period, and the registry record indicates that the outcome has several categories or time points rather than one reduced comparison. General: Repeated measurements from the same participant are related, so treating them as independent observations can misrepresent uncertainty. A suitable analysis may account for that within-participant relationship, but the choice depends on the design and the question of interest. The statistical model, covariance assumptions, and primary contrast are not reported in the registry record. No particular repeated-measures method should therefore be attributed to this trial.

General: If outcome variability is greater than a model assumes, standard errors and tests based on that model may be unreliable. This is often described as over-dispersion in settings where a model expects less variation than the data contain. For a continuous score, the practical lesson is to examine the distribution and the fit of the chosen model rather than assume that a summary mean alone settles the question. The registry record does not report model diagnostics or a discussion of over-dispersion; this is a general consideration, not a finding about this trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and one analysis, but it also indicates that the primary outcome includes several categories or time points and is not reduced to a single comparison. Those statements do not reveal how the multiple measurements were handled in analysis, which comparison was designated primary, or whether any adjustment for multiple testing was planned. The multiplicity plan is not reported in the registry record. Without that information, it is not possible to assess how the reported analysis, if any, related to the several outcome time points.

Missing-data handling is also not reported in the registry record. The available participant description gives Period 1 allocation and completion counts, and notes that Period 1 Traditional Chinese Medicine completers were removed from the allocation group for Period 2 per study plan. The account of later allocation is incomplete. The record does not state whether all participants with observed outcomes were analyzed, how incomplete pain measurements were treated, or whether any imputation or sensitivity analysis was used.

General: Missing outcomes can affect both the estimated group contrast and its uncertainty, especially if the chance of an outcome being missing is related to the participant’s experience or group assignment. Analyses based only on observed outcomes can be biased under some missingness patterns. Imputation and sensitivity analyses can explore how conclusions depend on assumptions, but no such methods should be attributed to this trial without documentation.

The record also does not specify an intention-to-treat population, a per-protocol population, or another analysis set for the primary endpoint. It is therefore not possible to determine from the registry record how participants were included in the pain analysis or whether exclusions occurred beyond the stated Period 2 allocation note.

11. 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 non-serious adverse event terms

The registry record lists serious adverse events, other adverse events, and deaths for four groups. Serious adverse events are recorded as zero in each group, and deaths are recorded as zero in each group. Other adverse events are recorded as one among 39 at risk in Traditional Chinese Medicine - Period 1, and zero among 40 at risk in Self-care, 43 at risk in Traditional Chinese Medicine - Period 2, and 42 at risk in Self Care - Period 2. These are the posted counts; no additional event-rate calculations are needed to describe them.

The registry record lists no serious adverse event terms. It does not provide detailed definitions of the adverse-event categories, event descriptions for the non-serious event, severity, relatedness, or the duration and completeness of safety follow-up. The group sizes differ across periods, and the record does not explain how the safety populations correspond to the incomplete participant-flow description. These details limit interpretation of comparisons across groups or periods.

General: A zero count means that no event in that category was recorded in the stated group in the registry entry. It does not prove that the true risk is zero or that an event could not occur. Safety counts should be interpreted in light of group size, follow-up, event definitions, and completeness of reporting. The counts alone do not establish whether one approach is safer than another.

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

The registry record documents a randomized, unmasked phase 2 study of Traditional Chinese Medicine and self-care for temporomandibular dysfunction. It identifies the Characteristic Facial Pain score as the primary outcome and describes the score’s components, scale, and treatment-period measurement timing. It also provides partial participant-flow information and adverse-event counts. These details help explain what the study set out to measure and what safety counts were entered.

However, the record does not report numerical results for the primary pain outcome. There is no group mean, change, comparative effect estimate, confidence interval, or p-value in the available record. As a result, the direction, magnitude, and precision of any difference between treatment approaches cannot be assessed from this information. The absence of a reported estimate is not evidence that there was no difference; it means the outcome comparison is not available in the registry record.

The record’s description of stepped care and follow-up indicates a broader study objective, but does not provide enough detail to reconstruct all treatment sequences, allocation decisions, or analysis contrasts. The later participant-flow description is incomplete, and missing-data methods and analysis populations are not reported. Those omissions make it difficult to judge how the intended design maps onto the participants contributing to any outcome analysis.

The safety entries record no serious adverse events or deaths in the listed groups and record one other adverse event in Traditional Chinese Medicine - Period 1, with zero in the remaining listed groups. These counts are descriptive. Without fuller event definitions, follow-up information, and clear population accounting, they cannot establish comparative safety.

In general, a trial’s title, randomization, and enrollment count are not substitutes for its outcome estimates and uncertainty. Statistical interpretation requires knowing what was compared, how observations were analyzed, and how precise the resulting estimate is. The registry record does not provide those details for the primary outcome. No conclusion that either treatment approach works, fails, or is equivalent to the other follows from the posted information.

13. Why This Trial Matters Statistically

This trial raises several useful statistical issues because its stated objective involves different care combinations and stepped-care patterns, while its primary measure is collected at the beginning and end of treatment periods. A comparison in that setting depends on defining which groups, periods, and changes answer the main question. The registry record does not report the exact primary contrast or the statistical model, so the intended comparison cannot be fully reconstructed.

The Characteristic Facial Pain score combines participant reports covering different time windows, including recent worst pain, average pain when having pain, and current pain. That construction makes clear why outcome definition matters: a summary score must be interpreted according to its components, scale, timing, and scoring method. The registry description gives some of this context but not the full calculation procedure or the observed values.

Participant flow also matters statistically. The record reports Period 1 allocation and completion counts, describes a Period 2 removal from an allocation group, and then gives an incomplete later allocation account. Safety entries give separate at-risk counts for Period 2. When group membership and outcome availability are not fully reconciled, readers cannot readily tell which participants contribute to each analysis or how missing observations might affect comparisons.

Finally, the entry illustrates the distinction between statistical planning and trial results. It describes planning assumptions based on an observed effect, but the numerical effect estimate and planning requirements are not reported in the registry record. Planning illustrations are hypothetical calculations and do not replace estimates from the completed trial. The record’s limited statistical detail means that the central lesson is about interpretation: endpoint definitions, complete flow accounting, explicit analysis choices, and uncertainty estimates are all needed to evaluate a randomized comparison.

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 most important trial-specific limitation in the registry record is the absence of numerical primary-outcome results. Although the Characteristic Facial Pain score is identified and its scale and timing are described, no group means, standard deviations, changes, treatment contrast, confidence interval, or p-value are reported. The posted information therefore cannot support a quantitative interpretation of the primary comparison.

The participant-flow description is incomplete. It gives Period 1 allocation and completion counts, notes a planned removal from the allocation group for Period 2, and begins describing a later allocation before ending mid-sentence. The safety entries list Period 2 groups with at-risk counts, but the record does not explain the relationship between those counts and the incomplete allocation account. This prevents a clear reconstruction of participant accounting across periods.

The record does not report the exact primary comparison, the analysis model, missing-data methods, multiplicity handling, or the analysis population. It also does not report the detailed allocation procedure, a sample-size justification, or a statistical analysis plan. The outcome is measured at multiple time points, but the approach to repeated measurements is unspecified. These gaps limit assessment of the validity and precision of any analysis.

The study summary mentions 18-month long-term follow-up, but outcome results at that follow-up are not reported in the registry record. Safety reporting is also limited to counts, without detailed event definitions, descriptions, relatedness, or complete follow-up information. These limitations concern what can be learned from the registry record; they should not be mistaken for evidence about unreported trial results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Traditional Chinese Medicine (TCM) for Temporomandibular Dysfunction (TMD): A Whole Systems Multi-site Trial — NCT00856167.
• Registry record last updated 2025-10-23; status last verified 2022-06.
• Results first posted 2025-10-23.
• 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.

18. Record Summary

The registry record describes a completed, randomized, unmasked, phase 2, parallel-group study of Traditional Chinese Medicine and self-care for temporomandibular dysfunction. It lists 135 participants enrolled and the University of Arizona as sponsor. The primary outcome was the Characteristic Facial Pain score, measured at the beginning and end of treatment periods, with the endpoint description specifying 8 weeks later.

Period 1 allocation and completion counts are reported, but the later participant-flow description is incomplete. The record lists zero serious adverse events and zero deaths in each safety group, with one other adverse event in Traditional Chinese Medicine - Period 1 and zero in the remaining groups.

Numerical results for the primary outcome, the analysis method, missing-data handling, and the detailed statistical plan are not reported in the registry record. The available information describes the study and its recorded safety counts, but does not permit an estimate of the comparative pain outcome.