To Measure Pain Perception With Electronic Pressure Algometer of Different Size Probes : a Healthy Subjects Research: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for To Measure Pain Perception With Electronic Pressure Algometer of Different Size Probes : a Healthy Subjects Research (NCT01618942), a randomized na study. The primary outcome is Pressure Pain Threshold (PPT)With 1 cm2 Probe.

2. Clinical Question

The study description also says that the investigators explored factors affecting pain measurement and subjects’ and testers’ evaluations. It lists skinfold thickness, time per procedure, types of pain perception, receptivity, perceived accuracy, and tester laboriousness among the recorded information. The registry record does not include posted results for every item described in that summary, so the primary comparison should be read as one part of a broader measurement-focused investigation.

3. Trial Design

The registry record describes a completed, randomized, single-group study with single masking and enrollment of 100. It lists the study start as 2012-06 and primary completion as 2012-12. The phase is listed as NA. Although the allocation field says randomized, the posted groups are male subjects and female subjects, and the arm descriptions say that subjects were grouped by gender and underwent pressure pain testing. The record does not explain what was randomized, how randomization was conducted, or who was masked.

The device intervention is a pressure algometer. According to the study description, measurements were taken at three spots on the right forearm using probes ranging from 1cm2 to 0.01cm2. The primary outcome is specifically PPT using a 1 cm2 probe, summarized as a mean and standard deviation. The outcome timeframe is 1 hour after the procedure, and the description says the value was calculated as an average across different measurement sites.

The posted comparison is therefore a comparison of the male and female groups’ measurement summaries, rather than a comparison between algometer and no algometer, or between two treatment assignments. No separate control treatment is described. The record does not report the protocol, the original sample-size justification, the precise sequence of measurements, or the details of the masking procedure. These details matter when interpreting a measurement study because order, operator technique, and participant expectations can affect how repeated pain-threshold measurements are obtained.

The record lists two secondary outcomes: time per test procedure and skinfold thickness. It does not provide reported analyses for those outcomes. Results are posted as group means and standard deviations, while the male-versus-female estimates and p-values are recalculated unadjusted comparisons based on those summaries. There are no sponsor-reported analyses listed in the registry record. The design should thus be understood from the descriptive information available, without assuming an analysis plan or randomization procedure that is not recorded.

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: There was no significant events and approaches for the overall study.

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 Pressure Pain Threshold (PPT)With 1 cm2 Probe, measured over 1 hour after the procedure.

Pressure pain threshold (PPT) is the pressure at which a participant first experiences pressure as painful. The primary outcome records PPT using a 1 cm2 probe, with the result expressed in kg/cm2. The registry record says the value is an average across different measurement sites and gives the timeframe as 1 hour after the procedure. This makes the endpoint a continuous measurement rather than a count of events or a categorical response.

A threshold measure can be useful in a measurement study because it provides a numerical way to describe the pressure associated with the transition to pain. The mean summarizes the group’s average recorded threshold, while the standard deviation describes the spread of individual measurements around that mean. Together, these summaries convey both the typical level and the variability in each group. They do not by themselves describe every participant’s response or establish that the measurement procedure is repeatable.

The endpoint is relevant to the study’s stated interest in how probe size and other factors relate to pain measurement. However, the posted primary result is for the 1 cm2 probe. The registry record does not post the primary outcome results for the other probe sizes, nor does it report a formal analysis comparing probe sizes. The primary outcome therefore informs the specific male-versus-female comparison for this probe and measurement definition; it cannot answer every question raised by the broader study description.

7. Results Posted in the Registry

• Female Subjects: mean 2.20 versus 2.61 on control; difference -0.41 (95% CI -0.73 to -0.09), standardized effect d = -0.51; z-test p = 0.011.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Time of Each Test Procedure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Female Subjects: mean 14.20 versus 16.80 on control; difference -2.60 (95% CI -4.60 to -0.60), standardized effect d = -0.51; z-test p = 0.011.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Female Subjects than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Measuring Values of Skinfold Thickness

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Female Subjects: mean 4.30 versus 3.40 on control; difference 0.90 (95% CI 0.43 to 1.37), standardized effect d = 0.75; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Female Subjects than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes broaden the measurement context beyond the primary PPT threshold. They concern the time required for a test procedure and skinfold thickness, while the study description also mentions other evaluations that do not have posted results in the registry record. These outcomes describe procedural burden and a participant characteristic rather than another direct treatment comparison.

The overall pattern across the posted secondary summaries is that the male and female group contrasts are not identical in direction or evidential strength. This points to more than one dimension of measurement and participant variation being present in the record. The secondary findings can be considered alongside the primary comparison as contextual information, but they do not explain the primary contrast or establish that skinfold thickness or procedure time caused it. The registry record does not report a model connecting these secondary measures to PPT.

These outcomes relate to the primary result by highlighting that recorded pain thresholds arise within a measurement process involving both participants and testers. Time per test can characterize how long a procedure takes, and skinfold thickness can describe an observed physical measurement. Neither outcome directly validates the accuracy or reproducibility of the PPT measure. The posted results do not include a reference standard, repeatability coefficient, or formal mediation or adjustment analysis.

The secondary comparisons are unadjusted. When several outcomes or comparisons are examined, the chance of obtaining an apparently notable result among them can increase, depending on how many analyses are conducted and how they are related. The registry record does not state whether outcomes were prespecified for confirmatory testing or whether any multiplicity adjustment was planned. Consequently, unadjusted secondary results carry less weight as confirmatory evidence than a clearly prespecified primary analysis would. They are most useful as descriptive findings that can inform future measurement research, not as independent proof of a mechanism or broad conclusion.

The record lists two posted secondary outcomes, but the study description names additional information recorded during testing. Results for those other described items are not reported in the registry record. This distinction matters: absence of posted results does not establish that a measurement was not collected, and it does not establish what its result would have been. The secondary evidence should be limited to what is actually posted.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Time of Each Test Procedure
• Measuring Values of Skinfold Thickness

9. Statistical Interpretation

10. Statistical Methods Explained

For a continuous outcome such as PPT, a group mean is a concise description of the average recorded measurement. The standard deviation describes how dispersed measurements are around that average. A mean and standard deviation are not interchangeable: groups can have similar means but different variability, or similar variability but different means. The posted summaries give both pieces of information for male and female subjects.

What does a mean difference describe?

A mean difference subtracts one group mean from another, with the direction determined by the chosen ordering. The recalculated primary contrast is expressed as the female-group mean relative to the male-group mean. A negative estimate therefore indicates a lower mean in the female group for this outcome. Reporting the contrast in kg/cm2 keeps the result in the measurement’s original units, which makes it possible to relate the estimate to the scale used in the study. The mean difference is a comparison of group averages, not a description of every individual’s response.

What does the p-value tell the reader?

The posted p-value for the primary comparison is unadjusted and recalculated from summary statistics. In general, a p-value describes how unusual data at least as incompatible with a stated null model would be if that model and the statistical assumptions were correct. A small p-value is not a probability that the null model is true, and it does not indicate the probability that a finding is due to chance. It also does not quantify the size, importance, or reproducibility of the difference. The estimate and its interval provide complementary information about magnitude and precision.

Because the primary comparison is a simple unadjusted contrast between group means, its interpretation depends on the suitability of the assumptions behind that comparison. The registry record does not describe a model that adjusts for other characteristics, repeated measurements, measurement site, or probe size. It also does not report a formal analysis plan. The listed means and standard deviations allow a straightforward summary comparison, but they do not establish that a more complex design was accounted for.

Why does variation matter?

Variation affects how precisely a group mean and a difference between means can be estimated. When participant measurements vary substantially, the group average is generally less precise than it would be with less variation, all else being equal. The standard deviations in the posted results help readers judge the scale of within-group spread. The registry record does not provide participant-level observations, so the distribution shape, unusual values, and potential departures from assumptions cannot be examined from these summaries.

Repeated measurements are especially relevant to a study involving multiple forearm sites and several probe sizes. Measurements taken from the same person may be related rather than independent. A statistical analysis of all such observations may need to account for that dependence. The primary result is described as an average across sites, but the registry record does not explain the calculation in detail or report an analysis of the repeated measurements. It would therefore be inappropriate to infer that site-level or probe-level dependence was modeled in a particular way.

How should the comparison be distinguished from an experiment?

The registry record labels allocation as randomized, but its groups are male and female subjects and both are described as undergoing the pressure pain test. The record does not explain what allocation applied to, or how the randomized label relates to the gender-defined groups. Randomization of a treatment, when specified and implemented, can support causal interpretation by balancing expected differences between assigned groups. That logic cannot simply be applied to a comparison between gender groups. The posted primary estimate is best interpreted as an association between group membership and the measured outcome in this sample.

The term “single-group” is also listed for the study model. This is consistent with the absence of a separate untreated comparator in the posted descriptions, but it does not resolve the unexplained randomization field. The study involves a device-based measurement procedure, and the primary comparison is not a test of whether the device outperforms another method. No alternative measurement device or reference standard is identified in the posted results.

What can and cannot be inferred from the analysis record?

The registry record lists no reported analyses. The displayed primary and secondary contrasts are recalculated unadjusted comparisons from posted group summaries. They should not be represented as sponsor-reported analyses or as evidence of the study’s original statistical plan. The original sample-size justification, missing-data procedures, analysis populations, interim analyses, and adjustment for multiple comparisons are not reported in the registry record.

In general, a statistical analysis plan clarifies which outcomes and comparisons were selected in advance, how measurements are handled, and how uncertainty is quantified. Without that information, readers cannot determine from the registry record whether the displayed analyses match the original plan or were selected after the results were known. This does not make the descriptive summaries unusable; it limits how strongly the inferential results can be interpreted.

Finally, statistical significance and measurement relevance are separate questions. A p-value can indicate compatibility with a null model under specified assumptions, while the mean difference gives the scale and direction of the contrast. Neither statistic alone shows whether the difference is important for measurement practice, whether the procedure is reliable, or whether the result generalizes beyond the enrolled healthy undergraduate students. Those questions require information not reported in the registry record, including a stated meaningful-difference criterion, repeatability results, and broader validation evidence.

11. Confidence Intervals and Precision

A confidence interval expresses uncertainty around an estimated contrast. In general, it gives a range of values compatible with the observed data under the calculation’s assumptions. A narrower interval indicates greater precision than a wider interval, but an interval does not account for every source of uncertainty, such as bias in measurement or an analysis that was not prespecified. The registry record does not identify the confidence level for the posted comparison intervals.

For the primary mean difference, the recalculated interval lies below zero. This is consistent with the direction of the estimate: the female-group mean is lower than the male-group mean in the posted summaries. The interval is more informative than the p-value alone because it conveys a range of plausible contrast sizes rather than only a measure of compatibility with a null value. The exact interval bounds are not repeated in this interpretation; the posted comparison gives them alongside the estimate.

Precision should be considered in relation to the sample and the measurement. Each gender group contains 50 subjects, and the group standard deviations show appreciable spread in the measured values. Those summaries affect how tightly the group difference can be estimated. They do not reveal whether individual measurements are normally distributed, whether there are influential observations, or how repeatable the test was for the same person.

The interval describes uncertainty in the unadjusted group contrast under its assumptions. It does not establish a causal effect, correct for unreported multiplicity, or show how well the result generalizes beyond this sample. The registry record also does not report a clinically or practically meaningful threshold for PPT differences. Statistical precision can therefore be discussed, but the practical meaning of the interval cannot be determined from the posted information alone.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size planning figures are participants per arm, not total events. They are planning illustrations based on the observed contrast, rather than the original design calculation for this study. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning row asks what sample size would be needed to detect a stated fraction of the observed effect under those assumptions.

The 80% power column gives the number of participants per arm for a design with an 80% chance of detecting the specified effect if that effect were the true one and the assumptions held. The 90% power column gives the corresponding per-arm number for a 90% chance. Power describes the operating characteristics of a proposed study under a particular assumed effect and analysis; it is not a measure of how likely the observed result is to be true.

Planning for 100% of the observed effect gives 62 participants per arm for 80% power and 82 participants per arm for 90% power. Planning for 75% of the observed effect gives 109 participants per arm for 80% power and 146 participants per arm for 90% power. Planning for 50% of the observed effect gives 245 participants per arm for 80% power and 327 participants per arm for 90% power. The progression illustrates a general design principle: smaller effects require more participants to detect with the same target power, all else being equal.

These values are not observed power. They are not a retrospective assessment of the probability that this completed study detected an effect. The original design assumptions and sample-size justification are not reported in the registry record, so the planning illustration should not be mistaken for the study’s actual design basis.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.410; pooled standard deviation σ = 0.808.
2. n = 2 × (1.96 + 0.842)² × 0.808² / -0.410² = 61.0, rounded up to 62 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.41                      # observed difference in means
sigma <- 0.808486239833431                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1618942)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 62 (80% power), 82 (90% power)
 75% of observed effect: n per arm = 109 (80% power), 146 (90% power)
 50% of observed effect: n per arm = 245 (80% power), 327 (90% power)
power.t.test: 62 
Simulated power at n = 62 per arm: 0.801 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record does not report whether the investigators adjusted for multiple comparisons, defined a hierarchy among outcomes, or controlled a family-wise error rate. The study description covers different probe sizes, multiple measurement spots, and several types of recorded information, while the posted outcomes include a primary threshold and secondary measures. Testing multiple contrasts can make isolated small p-values less persuasive if multiplicity is not addressed. The unadjusted p-values should therefore be read as results for individual comparisons, not as multiplicity-controlled evidence.

The original statistical analysis plan is not reported in the registry record. It is not possible to determine whether the posted primary and secondary outcomes were selected before data collection, whether the displayed contrasts were planned, or whether any additional analyses were conducted. No interim analyses are reported, and the registry record does not provide a basis for inferring whether any occurred.

Missing-data methods and the number of participants contributing to each outcome beyond the posted group counts are not reported in the registry record. The primary summaries list 50 subjects in each group, and the secondary summaries also list 50 in each group, but the record does not describe whether there were missing observations, exclusions, or imputation. The listed counts alone should not be used to infer a detailed missing-data process.

The analysis populations are not described. The registry record does not say whether analyses used all enrolled subjects, only those completing the procedure, or another defined set. It also does not report how withdrawals, protocol deviations, or incomplete measurements were handled. These omissions limit assessment of potential selection bias and reproducibility.

Finally, the record does not report a full statistical model for repeated site or probe measurements. It describes averages across sites for the primary outcome, but does not specify how those averages were constructed or how correlation among measurements was handled. These uncertainties do not invalidate the posted descriptive summaries, but they constrain interpretation of the unadjusted inferential results and prevent reconstruction of a prespecified analysis strategy.

15. 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 50 subjects at risk for serious adverse events in each gender group and reports zero serious adverse events in both groups. It also lists 50 subjects at risk for other adverse events in each group and reports zero other adverse events in both groups. These entries indicate that no events are recorded in those categories in the posted safety figures.

The death fields are null rather than populated with a count. Deaths are therefore not reported in the registry record; a null entry should not be interpreted as a reported count of zero. The serious-event terms list is empty, consistent with the posted zero serious events, but the record does not provide additional narrative about how adverse events were defined, collected, or monitored.

These safety entries should be read in the context of the study population and procedure: healthy undergraduate students underwent a pressure measurement procedure. The figures describe what is recorded for this study, not the safety profile of pressure algometry in every population or setting. The registry record does not report a detailed adverse-event assessment method or follow-up beyond the stated outcome timeframes. The absence of recorded events in these entries is not a general guarantee of safety.

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

The posted primary data show different average PPT values for the male and female subject groups when measured with the 1 cm2 probe. The recalculated unadjusted comparison estimates a lower mean in the female group, and its reported interval lies below zero. This is a statistical description of the enrolled sample and the specified measurement procedure. It does not establish a causal explanation for the group difference.

The study is about pain measurement in healthy undergraduate students, not about a treatment intended to relieve pain or change a disease outcome. The primary result cannot be interpreted as evidence that a treatment works or does not work. It also does not establish that one probe size is superior: the primary result concerns one probe size, and comparative results for the other sizes are not reported in the registry record.

The contrast is between gender-defined groups that both underwent testing. Although the registry record labels allocation randomized, the information posted does not explain randomization in a manner that changes the interpretation of this comparison. Gender is not described as an assigned intervention. The result may reflect differences between the groups, but the summary data do not identify the source of any difference.

The interval and p-value quantify aspects of sampling uncertainty under the unadjusted comparison’s assumptions. They do not account for unreported measurement bias, the possible dependence among repeated measurements, selection into the study, or unreported multiplicity. The registry record also does not state what size of PPT difference would matter for measurement practice. Statistical evidence of a group contrast therefore does not, by itself, show practical importance.

Generalization is limited by the enrolled sample and the available reporting. The participants were healthy undergraduate students, and the record does not provide results for a clinical population. It also does not report validation against another measurement method or detailed reliability results. The findings can be read as observations about this sample and procedure, while broader claims about pain assessment, probe choice, or clinical use require evidence not reported in the registry record.

17. Why This Trial Matters Statistically

This study raises a useful statistical distinction between measuring a characteristic and testing a treatment. A pressure pain threshold is a continuous measurement, and its interpretation depends not only on the group mean but also on variability, measurement conditions, and how repeated observations are handled. The posted summaries allow readers to see both the average values and their spread, while the comparison estimate conveys the direction and scale of the group contrast.

The record also illustrates why design labels need to be read alongside group descriptions. Randomized allocation is listed, but the reported comparison is between male and female subjects, who both underwent testing. Without a description of what was randomized, randomization cannot be assumed to make this gender comparison a causal experiment. Distinguishing assignment from group membership is essential when interpreting any estimated contrast.

Another statistical issue is the gap between a research description and posted results. The study description concerns different probe sizes and several types of evaluation, but the primary result focuses on one probe size and only two secondary outcomes are posted. The resulting evidence addresses a narrower question than the full description might suggest. This makes clear why outcome definitions, analysis plans, and complete reporting matter for reproducibility and interpretation.

Finally, the sample-size planning illustration demonstrates how planning depends on the effect a future study aims to detect. A design sized around the observed contrast can be less informative if the true contrast is smaller. Planning scenarios are therefore useful for considering design sensitivity, but they do not replace the original sample-size justification, which is not reported in the registry record. Together, these points show how careful distinctions among measurement, association, precision, and planning can prevent overstatement of a small study’s conclusions.

18. 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 that the study description and posted outcome record do not align across all aspects of the stated measurement objective. The description names different probe sizes, three right-forearm measurement spots, and several participant and tester evaluations, yet the primary result concerns only PPT with the 1 cm2 probe. Comparative outcome results for the other probe sizes and many described evaluations are not reported in the registry record. The available results therefore cannot establish how probe size affects PPT.

The comparison groups are defined by gender, and the posted summaries do not adjust for other characteristics. The registry record does not provide participant-level measurements or analyses that would show whether an observed group difference is associated with other measured factors. It also does not describe a reference method for evaluating measurement accuracy, despite the study summary mentioning perceived accuracy.

Details needed to assess measurement reliability are not reported. The record does not specify the full measurement sequence, tester training, repeat measurements, or how variation across sites was handled beyond stating that the primary value was averaged across different sites. It does not report whether order effects or dependence among repeated measurements were assessed.

Several analysis details are also absent: the original statistical plan, missing-data handling, analysis populations, adjustment for multiple comparisons, and sample-size justification are not reported in the registry record. The displayed comparisons are recalculated unadjusted estimates, which limits their role as confirmatory evidence. The registry record also does not explain the randomized allocation label in relation to the gender-defined groups or identify who was masked.

Finally, the population is restricted in the record to healthy undergraduate students. The results may not generalize to other groups, and there are no posted clinical outcomes. These limitations do not erase the descriptive information, but they narrow the claims that can be supported by it.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: To Measure Pain Perception With Electronic Pressure Algometer of Different Size Probes : a Healthy Subjects Research — NCT01618942.
• Registry record last updated 2014-04-24; status last verified 2014-04.
• Results first posted 2013-11-26.
• 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.

22. Record Summary

The registry record describes a completed study of pressure pain measurement in 100 healthy undergraduate students, with 50 male and 50 female subjects. Subjects underwent testing with a hand-held pressure algometer; the primary outcome is mean PPT using a 1 cm2 probe, averaged across measurement sites and assessed 1 hour after the procedure.

The posted primary means are 2.61 kg/cm2 for male subjects and 2.2 kg/cm2 for female subjects. The recalculated unadjusted mean difference is -0.41 kg/cm2, with p = 0.011. The registry record also posts secondary summaries for test procedure time and skinfold thickness. It does not report the original sample-size justification, analysis plan, missing-data methods, or adjustment for multiplicity. The primary comparison is a gender-group contrast, not an estimate of a treatment effect.