High Resolution IR Imaging for Diagnosis in the Acute Limping Child - ThermLimp: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for High Resolution IR Imaging for Diagnosis in the Acute Limping Child - ThermLimp (NCT03312348), a na na study. The primary outcome is Number of Participants for Which Thermal Imaging Technique Correctly Identified Area of Focus for a Limping Child.

2. Clinical Question

The study addresses a diagnostic-localisation question rather than a treatment-effect question. Its stated motivation is that a child may not be able to identify the specific region of pain, and that clinicians may find it difficult to locate the source of a limp. Infrared imaging was investigated as a possible aid to identifying a focus. The study summary also raises the possibility that imaging the limb could reduce unnecessary x-ray exposure, but the posted outcome is not a measure of x-ray use or radiation exposure. It is a participant count based on whether thermal imaging correctly identified an area of focus. Without a reported comparator, reference standard, or account of how correctness was judged, the result cannot establish diagnostic accuracy relative to another method. It describes the reported outcome within the enrolled study group.

3. Trial Design

The registry record describes a completed, single-group study sponsored by Sheffield Children's NHS Foundation Trust. The intervention was infrared imaging, and the arm description says that imaging was undertaken of a region of interest in study participants. The record lists enrollment as 30. It gives the study start as 2016-01 and primary completion as 2016-06. Phase is listed as NA, allocation as NA, and masking as NONE.

These design entries indicate that the record does not describe a randomized allocation or a masked comparison. More importantly for interpretation, the model is recorded as single-group and no comparator arm is reported. The study should therefore be read as a report of an outcome after infrared imaging, not as a trial estimating a relative effect between imaging approaches. The registry record does not describe how participants were recruited, whether the enrolled group completed the imaging procedure, or whether there were protocol deviations.

The primary outcome is a count of participants for whom thermal imaging correctly identified an area of focus for a limping child. Its timeframe is 10 minutes. The record reports 25 for this outcome. It does not explain the reference used to decide whether the area was correctly identified, how the assessment was conducted, or whether the assessor knew other clinical findings. Masking is listed as NONE, but the record does not specify which people were unmasked or how that status related to outcome assessment.

The registry record marks the study as completed. It does not report a protocol, a rationale for the enrollment target, an original statistical analysis plan, or details of follow-up beyond the outcome timeframe. These omissions limit what can be concluded about conduct and analysis. In particular, the enrollment count alone does not show that every enrolled participant contributed to the primary outcome, and the outcome count should not be treated as a complete analysis denominator unless the registry provides that information.

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

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 Number of Participants for Which Thermal Imaging Technique Correctly Identified Area of Focus for a Limping Child, measured over 10 minutes.

The primary endpoint is the number of participants for whom thermal imaging correctly identified an area of focus for a limping child. The registry record reports a count of 25 and gives a timeframe of 10 minutes. This is a count outcome: it records how many participants met the stated criterion, rather than reporting a continuous measurement or a time-to-event outcome.

The endpoint is intended to reflect whether the imaging technique identified a focus that was judged correct. In general, a diagnostic-localisation outcome can be useful for describing whether a method points to a potentially relevant area. However, the meaning of “correctly identified” depends on the reference used to judge the imaging result. The method or reference standard for that judgement is not reported in the registry record. The record also does not state whether the outcome was assessed independently or whether clinical findings were available to the assessor.

The endpoint should not be read as a direct measure of diagnostic accuracy across all possible causes of limping. It does not report sensitivity, specificity, predictive values, or agreement with another diagnostic method. Nor is it a measure of clinical outcomes, changes in care, or x-ray exposure. Those distinctions matter because identifying a focus is not the same as confirming a cause. The posted result describes the count for the stated endpoint, while the information needed to interpret the correctness criterion more fully is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes the study as single-group. In general, a single-group design reports outcomes among participants who receive an intervention, without a concurrent control group for direct comparison. Here, the intervention is infrared imaging, and the primary outcome is the number of participants for whom the technique correctly identified an area of focus. This design can describe what was recorded in the study group. It cannot, on its own, distinguish the contribution of the imaging procedure from other information or processes involved in assessing a participant.

What does the primary count represent?

The endpoint is a count of participants meeting a stated criterion. Counts are often straightforward to communicate, but their interpretation depends on both the criterion and the denominator. The registry reports a count of 25 and lists enrollment as 30. It does not state the number of participants with an evaluable primary outcome, so those two figures should not automatically be treated as a numerator and denominator for a rate. The record also does not specify how “correctly identified” was determined. Without that operational definition, readers cannot assess how the endpoint was adjudicated or reproduced.

What would a confidence interval add?

General explanation: a confidence interval expresses the statistical uncertainty around an estimate under a specified analysis. For a count or a proportion, an interval can show that an observed estimate is not necessarily a precise description of the underlying population value. The registry record does not report a confidence interval for the primary outcome, and no alternative inferential result is listed. Therefore, the precision of the posted count is not quantified by an interval in the registry record. An interval would not resolve uncertainty about the outcome definition or reference standard; those are design and measurement questions.

Why does the missing comparator matter?

General explanation: a comparative study can estimate how outcomes differ between groups when its design and analysis support that comparison. This record does not report a comparator group, so there is no between-group contrast to interpret. The count cannot establish whether infrared imaging identifies a focus more often, less often, or as often as another method. Any comparison with clinical examination or x-ray imaging would require data and a design not reported in the registry record.

What can masking tell a reader?

Masking can reduce the influence of knowledge about an intervention or other information on assessment, depending on who is masked and how the study is conducted. The registry lists masking as NONE. It does not describe the roles of the people involved in image interpretation or outcome assessment, or whether the outcome assessor had access to other findings. The masking entry therefore signals that masking was not reported as part of the design, but it does not give enough detail to reconstruct the assessment process.

How should planning calculations be read?

General explanation: sample-size calculations are planning exercises based on assumptions about a future study, such as the effect worth detecting, the significance level, allocation, and analysis method. They are not observed results and do not measure the probability that a completed study’s finding is correct. The registry record’s planning assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of the observed effect. They are described as planning illustrations, not as the trial’s own design. Because this study is recorded as single-group and has no reported comparator, those two-arm assumptions should not be mistaken for the design used in the study. Any sample-size figures are planning illustrations, never observed power. The protocol’s own sample-size justification is not reported in the registry record.

What analyses are available?

The registry record does not report an inferential analysis for the primary outcome. It gives the endpoint count but no analysis method, confidence interval, or hypothesis test. In general, a statistical analysis plan would specify how outcomes are summarized, how missing observations are handled, and which analysis population is used. Those details are not reported in the registry record. Without them, readers should avoid inferring an analysis method from the endpoint type alone or treating the count as evidence of a statistically established effect.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Infrared Imaging Undertaken")
n      <- c(30)
events <- c(30)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Infrared Imaging Undertaken  30  30  100.0  88.4  100.0  88.6  100.0  88.8  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary outcome measure and does not report statistical analyses. It therefore does not provide enough information to determine whether multiple hypotheses or alternative endpoint analyses were planned or performed. Multiplicity concerns arise when several outcomes, subgroups, or analyses are tested, because selective emphasis can affect interpretation. Whether this issue arose in this study is not reported in the registry record. No adjustment for multiple testing is reported.

Missing-data handling is also not described. The record lists enrollment as 30 and reports a primary outcome count of 25, but it does not state the number of participants with an evaluable result, the reason for any unavailable outcomes, or how missing observations were treated. It is not possible to determine from the record whether the difference between those two reported counts represents missing outcome data, a different reporting convention, or another explanation. The outcome count should not be assumed to use enrollment as its denominator.

The analysis population is not reported in the registry record. There is no statement identifying whether the primary outcome was assessed among everyone enrolled, among participants who completed imaging, or under another rule. The record also does not report exclusions or protocol deviations. These omissions limit reproducibility and make it difficult to judge whether the reported count represents all eligible participants or a selected subset.

In general, transparent reporting of outcome availability, analysis populations, and any multiplicity procedures helps readers evaluate how robust a result may be to analytic choices. For this study, those details are not reported in the registry record. The posted count can be described as the reported primary result, but the record does not support a fuller assessment of missingness or selective analysis.

12. 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 adverse-event record lists 30 participants at risk in the infrared imaging group. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths. These are the event figures recorded for the group, and they should be read as counts rather than as proof that no harm occurred.

General explanation: an observed count of zero means that no events of the specified type were recorded in the reported data. It does not establish that the true risk is zero, particularly when the amount and completeness of safety monitoring are not described. The registry record does not give a detailed collection period, definitions for the adverse-event categories, or information about how events were solicited and assessed. It also does not report the completeness of follow-up for safety outcomes.

The record’s at-risk count is not evidence that every participant had identical follow-up or that all possible events were captured. No serious adverse-event terms are listed. The reported figures provide a limited summary of recorded events for this group; they do not support a broader safety conclusion or a comparison with another imaging method.

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

The result establishes that the registry record reports 25 participants for whom thermal imaging correctly identified an area of focus for a limping child. The stated timeframe is 10 minutes. This is a descriptive result for the study group, and it records the outcome as defined in the registry.

It does not establish how often infrared imaging would correctly identify a focus in other settings or in a broader population. The registry record does not report a comparator group, a reference standard for judging correctness, or an inferential analysis. The result therefore cannot be used to quantify diagnostic accuracy relative to clinical examination, x-ray imaging, or another method. It also cannot show whether the imaging result changed clinical decisions or improved patient outcomes.

The study summary describes potential benefits that motivated the investigation, including imaging an entire limb and possibly reducing unnecessary exposure to x-rays. Those are stated aims or possibilities, not outcomes reported by the primary endpoint. The registry record does not report x-ray use, radiation exposure, subsequent diagnosis, treatment, or health outcomes as measured results.

There is also uncertainty about the denominator for the primary endpoint. Enrollment is listed as 30, while the primary outcome is reported as a count of 25. The registry record does not explain whether every enrolled participant was included in the outcome assessment or how any unavailable results were handled. The figures should therefore not be converted into a rate without clarification.

In short, the posted result is a count under a registry-defined outcome. Its meaning is constrained by the single-group design, the lack of a reported reference standard and comparator, and the absence of reported uncertainty estimates and analysis details. It should not be interpreted as proof of comparative benefit, overall diagnostic accuracy, or reduced x-ray exposure.

14. Why This Trial Matters Statistically

This study raises a useful statistical distinction between an observed diagnostic result and evidence of comparative performance. A count of participants meeting an outcome criterion can describe what was recorded in a study group. To determine whether a diagnostic approach performs better than another, the study needs an appropriate comparison and clearly defined outcome assessment. The registry record describes a single-group design and does not report a comparator.

The endpoint also illustrates why operational definitions matter. The registry uses the phrase “correctly identified area of focus,” but the reference used to judge correctness is not reported in the registry record. Without a clear reference standard and assessment process, readers cannot fully evaluate what the count measures. A well-defined outcome is necessary both for meaningful interpretation and for replication.

The distinction between a stated motivation and a measured result is important. The study summary discusses the possibility of reducing unnecessary x-ray exposure, but the primary endpoint is a count of correct identifications. The record does not report x-ray use or exposure as an outcome. A statistical interpretation should stay with what was measured rather than treating a proposed downstream benefit as an observed effect.

Finally, the record shows why outcome counts need context about denominators, missing data, and uncertainty. Enrollment is reported, but the primary analysis denominator and any inferential analysis are not. Those gaps prevent assessment of precision and completeness. The study is statistically informative as a record of a diagnostic-localisation investigation, while its design and reporting do not support comparative conclusions.

15. 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 principal limitation is the single-group design. Without a comparator, the reported outcome cannot estimate relative performance against another diagnostic method. Allocation is listed as NA, and masking as NONE. The record does not describe the roles of assessors or the information available during outcome judgement.

The endpoint depends on whether imaging correctly identified an area of focus, but the reference standard and assessment procedure are not reported in the registry record. This makes it difficult to know how correctness was determined or whether the outcome can be reproduced. The endpoint also does not directly measure the underlying cause of the limp, subsequent clinical decisions, patient outcomes, or x-ray use.

The primary result is reported as a count of 25, and enrollment is listed as 30. The registry record does not state the primary analysis denominator, whether all enrolled participants were assessed, or how unavailable results were handled. No confidence interval, hypothesis test, or inferential analysis is reported, so the precision of the result is not quantified.

Other study details are also limited. Eligibility criteria, participant characteristics, recruitment procedures, imaging procedures, follow-up beyond the outcome timeframe, and protocol deviations are not reported in the registry record. The registry lists the study as completed but does not provide a detailed account of outcome assessment or analysis populations. These reporting gaps constrain conclusions about the result’s generalisability and robustness.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: High Resolution IR Imaging for Diagnosis in the Acute Limping Child - ThermLimp — NCT03312348.
• Registry record last updated 2021-01-22; status last verified 2021-01.
• Results first posted 2019-04-24.
• 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.

19. Record Summary

The registry record describes a completed, single-group study of infrared imaging in children with a limp, sponsored by Sheffield Children's NHS Foundation Trust. Enrollment is listed as 30. The study start is recorded as 2016-01 and primary completion as 2016-06. Phase and allocation are listed as NA, and masking as NONE.

The primary outcome is the number of participants for whom thermal imaging correctly identified an area of focus. The registry reports 25 for this outcome and gives a timeframe of 10 minutes. The method used to judge correctness, the primary analysis denominator, and any inferential analysis are not reported in the registry record. No comparator group is described.

The adverse-event record reports 0 serious adverse events, 0 other adverse events, and 0 deaths among the group listed as at risk. These figures describe the events recorded in the registry and do not establish comparative safety.