TARDIS - Photo Elicitation and Intervention: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TARDIS - Photo Elicitation and Intervention (NCT06972251), a non-randomized na study. The primary outcome is Diabetes Distress Scale Score.

2. Clinical Question

3. Trial Design

TARDIS—Photo Elicitation and Intervention is a completed study listed as non-randomized, unmasked, and single-group. Its registry enrollment is 34. The record lists the study phase as not applicable. The start date is 2022-03-08 and primary completion is dated 2024-03-31.

The study has two aims with different purposes. Aim 3a, TARDIS Photo Elicitation, was intended to further understand diabetes distress in Veterans through visual-based qualitative methods. Participants were instructed to take approximately 20 photos over two weeks and take part in two semi-structured interviews about the experience. Aim 3b, TARDIS Intervention, was described as designing and pilot testing tailored self-management information and supportive services for Veterans with type 2 diabetes, with the aim of promoting engagement in self-management behaviors. The intervention includes coaching and is described as telemedicine-based.

Because allocation was non-randomized and the study model is single-group, the record does not support interpreting the arms as randomized alternatives. In particular, the photo elicitation activity is not a control condition for estimating the intervention’s effect. The registry record does not report a separate comparator group or a randomized assignment procedure. A detailed protocol, allocation process, or statistical analysis plan is not reported in the registry record.

The registry lists Diabetes Distress Scale score as the primary outcome, measured at baseline. It also lists health coaching calls as a secondary outcome. Although the study is marked completed, completion status alone does not provide outcome findings. Numerical primary-outcome results and statistical analyses are 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: For Aim 3a, participants did not complete a follow-up survey to assess their Diabetes Distress Scale score as this was not a part of the study design. Only participants in Aim3b (intervention) completed a baseline and follow-up survey to assess their DDS score.

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 Diabetes Distress Scale Score, measured over Baseline.

The primary endpoint is the Diabetes Distress Scale score, reported as a mean with standard deviation and measured at baseline. The registry describes a 17-item scale with possible scores from 1 to 6. Higher scores indicate higher diabetes distress, which the record also characterizes as a worse outcome. A score below 2.0 is classified as little or no distress; scores from 2.0 to 2.9 are classified as moderate distress; scores of at least 3.0 are classified as high distress.

As a general measurement principle, a continuous score can describe variation across a scale rather than reducing every participant to a category. The mean describes the group’s average score, while the standard deviation describes the spread of individual scores around that mean. The categories can aid interpretation, but they do not replace the underlying score or convey the uncertainty around a group estimate.

The record identifies baseline as the primary endpoint timeframe. It says Aim 3a participants did not complete a follow-up survey for this measure because follow-up was not part of that aim’s study design. Aim 3b participants completed baseline and follow-up surveys, but numerical score results are not reported in the registry record. Thus, the endpoint definition is available, while the actual group score estimates and any change over time are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as a mean on a continuous scale, with standard deviation as the measure of dispersion. The record does not report an analysis of that outcome. The explanations below describe general statistical ideas relevant to interpreting such measures; they are not a description of an analysis reported for this study.

What does a mean describe?

For a continuous measure, the mean is the arithmetic average of the recorded scores in the analysis group. It gives a summary of the group’s central level on the measure, but it does not show whether individual scores are clustered closely together or widely spread. The Diabetes Distress Scale ranges from 1 to 6, and higher values represent more distress according to the registry description. A mean should therefore be interpreted in the scale’s direction and context, rather than as a stand-alone judgment about every participant.

What does the standard deviation add?

The standard deviation describes the spread of observed scores around their mean. A smaller standard deviation generally indicates that scores are closer to the mean; a larger one indicates greater variation. It is not the uncertainty in the mean itself. As a general distinction, uncertainty in an estimate depends on both the variability of observations and the amount of information contributing to that estimate. The registry specifies standard deviation as the endpoint’s dispersion measure, but does not report a value.

How should a confidence interval be read?

A confidence interval is a statistical summary of uncertainty around an estimated quantity, under the assumptions of the method used. A narrower interval indicates greater precision than a wider interval, for the same type of estimate and confidence procedure. A confidence interval does not show the range of individual participant scores, and it does not establish that a result is important in practical terms. No confidence interval for the Diabetes Distress Scale is reported in the registry record, so the precision of a score estimate cannot be assessed.

What does the study design allow?

Random assignment can, under appropriate conduct and analysis, help make comparison groups comparable on average. This study is recorded as non-randomized and single-group, so those protections do not apply to a comparison between the two aims. The aims involve different activities and have distinct purposes. The photo elicitation arm is described as a qualitative approach to understanding distress; the intervention arm is a pilot of tailored self-management support. Treating them as interchangeable comparison groups would not be justified by the registry description.

As a general principle, a before-and-after comparison within one group can describe how measured outcomes differ over time among participants with both measurements. It does not, on its own, separate an intervention-related change from other explanations, such as changes over time or differences in who completed follow-up. The registry says Aim 3b participants completed baseline and follow-up surveys, but does not report scores, a paired analysis, or how missing follow-up data were handled. Aim 3a had no follow-up survey for this endpoint by design.

What is reported about statistical planning?

The registry lists no statistical analyses. It does not report an analysis plan, a hypothesis test for the primary outcome, an adjustment strategy, a confidence level, or a model specification for the outcome. Those details are not reported in the registry record and should not be inferred from the study’s design label or endpoint definition.

The record contains planning assumptions for illustrative sample-size calculations based on an observed effect: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It specifies that the effect to detect is a stated fraction of the observed effect. These are described as planning illustrations, not as the trial’s own design calculations. Numerical planning results and a numerical observed effect are not reported in the registry record. Such illustrations are not observed power and do not establish that the study was adequately powered for its endpoint.

More generally, sample-size planning depends on the outcome, target effect, variability, analysis method, and assumptions about missing observations. A planning calculation is conditional on those assumptions; it is not a guarantee that a study will produce a precise estimate or a statistically significant result. The registry record does not report a study-specific sample-size justification.

Why does over-dispersion matter?

Over-dispersion is a general issue for count data: it occurs when variability exceeds what a chosen model assumes. In that setting, standard errors from a model that understates variability can be too small, which can make uncertainty appear less than it is. The primary endpoint in TARDIS is a continuous scale score, not a count outcome, and the registry does not report an over-dispersion analysis. This concept is therefore general context rather than a reported feature of the study’s primary analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and no statistical analyses. It identifies Diabetes Distress Scale score at baseline as the primary outcome and health coaching calls as a secondary outcome. The record does not report a family of statistical hypotheses, which outcomes were tested, or any procedure for adjusting for multiple comparisons. It is therefore not possible to determine from the registry whether multiplicity was addressed in an analysis.

Missing data also require careful distinction. For Aim 3a, the registry explicitly says participants did not complete a follow-up Diabetes Distress Scale survey because follow-up was not part of the study design. Those follow-up scores were not planned for that aim, so they should not be described as observed values lost to follow-up. For Aim 3b, participants completed baseline and follow-up surveys, but the registry does not report the scores, outcome-specific analysis counts, or any missing-data method.

Enrollment does not necessarily equal the number contributing data to each endpoint. The registry does not report analysis populations, eligibility rules for particular analyses, exclusions, or whether analyses included all enrolled participants or only those with measured outcomes. It also does not report imputation, sensitivity analyses, or assumptions about missing observations. These elements are not reported in the registry record, and their absence prevents assessment of how missingness or analysis-population choices might affect an estimate.

As a general statistical point, results across several outcomes or comparisons can increase the chance of finding an apparently noteworthy result by chance if multiplicity is not considered. Whether adjustment is appropriate depends on the questions and analysis plan. No multiplicity method or analysis plan is reported for this study, so no claim about adjustment can be made.

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.

The registry reports no serious adverse events, other adverse events, or deaths in either listed arm. For Aim 3a, 14 participants are listed as at risk for serious and other adverse events; the reported counts affected are 0 for each category, with 0 deaths. For Aim 3b, 20 participants are listed as at risk for those event categories; the reported counts affected are 0 for each category, with 0 deaths.

These entries describe the events recorded in the registry, not proof that no adverse events occurred outside the record or that every possible safety outcome was assessed. The record does not report detailed event definitions, collection procedures, follow-up duration for safety, or a narrative explaining the zero counts. It also does not list serious adverse event terms.

As a general statistical point, zero recorded events in a group do not establish that the underlying risk is zero. The precision of a safety estimate depends on the amount and duration of observation and on how events were sought and classified. The registry figures should therefore be read narrowly as reported counts, not as a guarantee of absence of risk or as a comparative safety result.

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

The registry record describes a completed, non-randomized study with two related but distinct aims: qualitative photo elicitation to better understand diabetes distress, and a pilot of tailored self-management support for Veterans with type 2 diabetes. It defines the primary outcome as baseline Diabetes Distress Scale score and explains how higher scores and score categories are interpreted.

The record does not report numerical primary-outcome results or statistical analyses. It does not provide a baseline mean, standard deviation, follow-up score, estimated change, confidence interval, or hypothesis test. As a result, readers cannot determine from this record the level of diabetes distress represented by the participants’ scores, whether scores changed over time in Aim 3b, or how precisely any such change was estimated.

The design also limits causal interpretation. Non-randomized, single-group status means the arms should not be read as treatment and control. The photo elicitation aim is not a counterfactual for the intervention aim, and a before-and-after score comparison—if reported—would describe change over time rather than isolate the intervention’s contribution without further design and analysis assumptions.

The safety entries report zero serious adverse events, zero other adverse events, and zero deaths in each listed arm. Those are registry counts; they do not establish that the risk of an event is absent. The record does not provide the detail needed to assess event ascertainment or the precision of safety estimates.

In short, the registry supports understanding what TARDIS set out to study and how its primary measure is defined. It does not supply the outcome estimates needed to judge the observed scores or their uncertainty. The completed status should not be mistaken for a reported efficacy finding, and no conclusion about treatment benefit follows from the information recorded.

13. Why This Trial Matters Statistically

This study is statistically interesting because it joins a qualitative aim with an intervention pilot while keeping their purposes distinct. Photo elicitation was intended to help describe diabetes distress in Veterans, whereas the intervention aim was to pilot tailored self-management information and supportive services. Recognizing that distinction is important when interpreting groups, endpoints, and comparisons: the two arms are not randomized alternatives or a like-for-like control comparison.

The endpoint also illustrates why measurement definitions matter. The Diabetes Distress Scale is a continuous score with a stated direction and descriptive categories. A reported mean could summarize group-level distress, while its standard deviation and an uncertainty interval would help readers understand variability and precision. The registry provides the scale description but not the outcome estimates, so it demonstrates the difference between defining an endpoint and reporting evidence about it.

Another statistical lesson concerns follow-up. Aim 3a did not include a follow-up survey for the primary outcome by design, while Aim 3b included baseline and follow-up surveys. Treating those situations as the same kind of missing data would be misleading. Interpretation depends on which measurements were planned, which were collected, and how any unobserved results were handled—details that are not fully reported for Aim 3b.

Finally, registry completeness affects what can be concluded. A completed study record can describe purpose, design, and safety counts without reporting quantitative outcome analyses. Here, the registry lists no statistical analyses, so precision and statistical uncertainty cannot be assessed. That boundary helps readers avoid turning a study description into an unsupported claim about effectiveness.

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 main limitation for interpreting results is that the registry record does not report numerical Diabetes Distress Scale results or statistical analyses. Without outcome estimates, their dispersion, and measures of uncertainty, the primary endpoint cannot be quantitatively evaluated. The record’s completed status does not supply these missing results.

The design is non-randomized and single-group, and the two aims have different purposes. They do not form a like-for-like treatment and control comparison. Any contrast between them would be difficult to interpret as an intervention effect. The registry does not report a separate comparator or random assignment.

Follow-up differs by aim. Aim 3a did not include a follow-up survey for the primary measure as part of the design. Aim 3b participants completed baseline and follow-up surveys, but the registry does not report outcome-specific counts, scores, or missing-data handling. It is therefore not possible to assess follow-up completeness or how analytic choices might affect the results.

The registry lists four outcome measures and no analyses, and does not report a statistical analysis plan, multiplicity approach, analysis populations, or study-specific sample-size justification. These omissions prevent assessment of planned versus reported analyses and the precision intended for the primary endpoint. The listed planning assumptions are described as illustrations rather than the trial’s own design calculations.

For safety, the registry reports zero adverse events and deaths in each arm, but does not provide detailed event definitions, ascertainment procedures, or safety follow-up duration. The recorded counts should be interpreted in that limited context rather than as evidence that risk is absent.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: TARDIS - Photo Elicitation and Intervention — NCT06972251.
• Registry record last updated 2025-10-08; status last verified 2025-09.
• Results first posted 2025-10-08.
• 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

TARDIS—Photo Elicitation and Intervention is a completed, non-randomized, unmasked, single-group study with registry enrollment of 34. Its two aims were photo elicitation to better understand diabetes distress and a pilot intervention providing tailored self-management support to Veterans with type 2 diabetes.

The primary outcome is baseline Diabetes Distress Scale score, a 17-item scale ranging from 1 to 6, with higher scores indicating greater distress. Aim 3a did not include follow-up surveys for this measure by design; Aim 3b included baseline and follow-up surveys. Numerical outcome results and statistical analyses are not reported in the registry record.

The record lists zero serious adverse events, zero other adverse events, and zero deaths for each arm. These are recorded counts, not proof of zero underlying risk. The registry does not report an analysis plan, missing-data methods, or a statistical comparison that would support a causal estimate.