DilaCheck Cervical Dilation Measurement Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for DilaCheck Cervical Dilation Measurement Trial (NCT03440723), a randomized na study. The primary outcome is Interexaminer Agreement.

2. Clinical Question

This is a question about inter-examiner agreement: whether separate examiners record the same measurement under the assigned examination approach. The comparison is between the number of participants with agreement in the standard examination group and the number with agreement in the DilaCheck group. The primary outcome was measured immediately upon examination.

The registry also lists pain with examination and ease of use as secondary outcomes. The posted results include pain scores, but an ease-of-use result is not reported in the registry record. The record does not describe a separate clinical outcome such as a change in labor course; the primary question is specifically about agreement between physicians’ measurements.

3. Trial Design

The DilaCheck Cervical Dilation Measurement Trial, NCT03440723, is listed as a completed randomized controlled trial. Its official title describes an inter-examiner agreement comparison of a device for measuring cervical dilation in labor. The registry identifies a parallel-group design with no masking. Phase is listed as not applicable.

The record lists enrollment of 42. The Standard Dilation Exam group had 21.0 participants, and the Dilation Exam With DilaCheck group had 21.0 participants. In the standard group, two different physicians performed two standard digital examinations. In the DilaCheck group, two different physicians performed two examinations using DilaCheck devices. The registry describes the comparison as randomized, but the randomization method and any allocation concealment procedures are not reported in the registry record.

The trial began on 2020-01-06, reached primary completion on 2020-03-30, and is marked completed. Elm Tree Medical Inc. is listed as the sponsor. The record lists cervical dilation, labor pain, labor fast, and labor; irregular as conditions.

The primary outcome was inter-examiner agreement, counted as participants whose two measurements were the same. The stated timeframe was immediately upon examination. Pain with examination was assessed immediately within 5 minutes of examinations. Ease of use is listed among the secondary outcomes, but its measure and result are not reported in the registry record. The registry does not report details of masking beyond identifying the trial as unmasked, nor does it report the trial’s original sample-size rationale or a detailed statistical analysis plan.

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

Analysis population for the primary outcome, as defined in the registry: All enrollees

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 Interexaminer Agreement, measured over Immediate upon examination.

The primary endpoint counts participants for whom two physicians recorded the same cervical dilation measurement. For each participant, identical measurements were classified as agreement and different measurements as disagreement. The endpoint was assessed immediately upon examination, and the listed population is all enrollees.

Agreement is useful when the research question concerns consistency between examiners. It describes whether two measurements match, rather than how close two different measurements are or whether either measurement corresponds to an independent reference standard. In this trial, the endpoint therefore addresses reproducibility between two physicians using the assigned examination approach. It does not, by itself, establish the accuracy of either physician’s measurement.

The posted counts are 9.0 participants with agreement among 21.0 in the Standard Dilation Exam group and 4.0 among 21.0 in the Dilation Exam With DilaCheck group. The comparison is expressed as a risk difference, with the DilaCheck group contrasted against the standard group. A negative risk difference corresponds to a lower observed proportion with agreement in the DilaCheck group. The registry record does not report additional endpoint details such as a method for resolving disagreements or a reference measurement against which the examinations were checked.

7. Results Posted in the Registry

• Dilation Exam With DilaCheck: 19.0% (4/21) versus 42.9% (9/21) on control; risk difference -23.8 percentage points (95% CI -50.8 to 3.2), risk ratio 0.44 (0.16–1.22); unadjusted two-proportion z-test p = 0.095.

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.

Pain With Examination

• 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:
  • Dilation Exam With DilaCheck: mean 3.10 versus 2.80 on control; difference 0.30 (95% CI -1.42 to 2.02), standardized effect d = 0.11; z-test p = 0.733.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Dilation Exam With DilaCheck and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes add context to the primary agreement question but address different aspects of the examinations. Pain with examination captures participants’ reported experience, whereas ease of use is listed as an outcome but has no result reported in the registry record. Neither outcome is a substitute for inter-examiner agreement, and a pattern in one endpoint does not establish what happened on another.

The posted pain comparison is imprecise, with an interval that includes differences in either direction. It therefore does not provide a firm basis for inferring a group difference in mean pain scores. The primary result likewise has a broad interval spanning zero. Considered together, the recorded results do not resolve whether the examination approaches differ on agreement or pain, and no posted ease-of-use result is available to add to that interpretation.

Secondary findings generally warrant more caution when multiple outcomes are assessed and the record does not report adjustment for multiple testing. Each unadjusted test can produce an apparently notable result by chance, even when no real difference exists. This is a general statistical concern, not evidence that any particular result in this trial is false. The registry record does not report a prespecified hierarchy, multiplicity procedure, or the analyses for the secondary outcomes. It lists no reported secondary analyses.

Accordingly, the secondary outcomes are best read as descriptive context rather than independent confirmation of the primary comparison. Their interpretation is limited by the available reporting, the uncertainty in the posted pain estimate, and the absence of an ease-of-use result. They do not change the central statistical point: the posted estimates have limited precision, and the registry does not provide enough analysis detail to support stronger conclusions.

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

• Pain With Examination
• Ease of Use

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is binary at the participant level: the two physician measurements either matched or did not match. The registry reports counts of participants with agreement and the group sizes. A risk difference expresses the difference between the two group proportions. In this comparison, DilaCheck is contrasted with standard examination, so a negative value means the observed proportion with agreement was lower in the DilaCheck group. The risk difference is an absolute comparison in proportion units; it is not a ratio.

What does the interval communicate?

A confidence interval gives a range of values compatible with the observed data under the statistical procedure used. It communicates uncertainty about the effect estimate rather than the range of individual participant outcomes. A narrower interval represents greater precision, while a wider interval represents greater uncertainty. For the primary risk difference, the interval runs from -0.508 to 0.032. Because that range crosses zero, the data are compatible with no difference as well as with differences in either direction. The registry record does not state the confidence level or detailed procedure used to construct the interval.

How should the p-value be understood?

The primary comparison has an unadjusted p-value of 0.095. A p-value describes how unusual data at least as incompatible with a specified null hypothesis would be if that null model and the test assumptions held. It is not the probability that the null hypothesis is true, nor does it quantify the probability that the observed result arose by chance in an unrestricted sense. It also does not convey the size or practical importance of a difference. For that reason, the p-value should be read with the estimate, interval, outcome definition, and study limitations.

“Unadjusted” indicates that the reported p-value has not been adjusted for a family of statistical tests. The registry record lists more than one outcome, but it does not report a multiplicity adjustment. Where several outcomes are examined, interpreting each unadjusted test as if it were the only test can overstate the strength of evidence. This is a general statistical concern; the record does not explain how the trial investigators handled it.

What does the pain comparison estimate?

Pain with examination is recorded as a continuous score and summarized by a mean and standard deviation in each group. The posted mean difference compares the DilaCheck mean with the standard-examination mean. The estimate is 0.3, and its interval extends from -1.424 to 2.024. This interval includes both negative and positive differences, so the data do not tightly determine the direction or size of the mean difference. The standard deviation describes variation among scores within a group; it is not a confidence interval for the group mean.

The record gives a standard deviation of 2.8 for the standard group and 2.9 for the DilaCheck group. A standard deviation helps describe how dispersed observed scores are around their group mean. It should not be confused with the standard error, which describes the sampling uncertainty of an estimated mean. The registry record also lists standard errors of 0.611 and 0.633 for the two group means.

Why can sparse binary outcomes be uncertain?

When an outcome is a count of participants with an event, the information available for estimating a proportion depends in part on how many participants experience that event. With relatively few observed agreements in each group, the estimated proportions can be sensitive to the outcomes of individual participants. General statistical methods for binary outcomes may also rely on assumptions about the sampling distribution; the registry record does not identify the exact method used for the primary interval or test. This makes it important to retain the stated uncertainty and avoid interpreting the point estimate as an exact population difference.

For continuous outcomes, standard deviation describes within-group variability, while the mean difference estimates separation between group averages. A wide interval can result when the data are variable or the amount of information is limited. Here, the posted pain interval is broad enough to include differences in either direction. These are general interpretations of estimation and precision, not claims about the clinical importance of a particular pain-score difference.

What statistical details are not reported?

The registry record does not report the original design assumptions behind the trial’s enrollment, a detailed statistical analysis plan, the exact tests or interval procedures, handling of missing observations, or whether any interim analyses took place. The registry lists zero reported analyses for the primary outcome and no reported analyses for the secondary outcomes. These omissions limit the ability to determine whether the posted comparisons were prespecified, how any departures from the planned analysis were addressed, or how missing outcomes were treated.

The record does describe random allocation and a parallel design, but it does not explain the randomization sequence or concealment. No masking was used. These design features matter because they affect the interpretation of a comparison, but they do not replace careful reporting of the analysis and measurement procedures. The posted estimates can be described as recorded; more detailed judgments about model choice, adjustment, and analysis populations are not supported by the registry entry.

11. Confidence Intervals and Precision

The primary risk difference is -0.238, with an interval from -0.508 to 0.032. The interval is wide and crosses zero. It therefore leaves considerable uncertainty about the direction and size of the difference in agreement between the groups. The point estimate is one summary of the data, but it should not be treated as a precise estimate of what would occur in a broader population.

For a risk difference, zero represents equal observed proportions in the groups. Values below zero favor a lower agreement proportion in the DilaCheck group under the stated comparison direction; values above zero correspond to a higher agreement proportion in that group. Because the reported interval includes values on both sides of zero, the posted data do not pin down which direction is compatible with the underlying difference. The registry record does not state the confidence level or the method used to calculate this interval.

The pain mean difference is 0.3, with an interval from -1.424 to 2.024. This range also includes negative and positive differences. It indicates that the observed group means alone do not give a precise estimate of the direction or magnitude of the average score difference.

In general, confidence intervals are more informative than a point estimate alone because they show the range of values compatible with the data under the analysis method. Their width depends on the amount of information and variability in the observations, as well as the method used. The registry does not report enough detail to assess every modeling assumption or the handling of missing data, so the intervals should be interpreted as posted rather than as a complete account of all uncertainty.

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 planning figures are illustrations based on the observed effect, not the trial’s original design assumptions. For the outcomes in this trial, the figures are participants per arm, not a total across arms or a total number of events. The general calculation assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The original trial’s own sample-size assumptions are not reported in the registry record.

The 80% power column gives the planned number of participants per arm under those assumptions for an 80% chance of detecting the specified effect if that effect is present and the assumptions hold. The 90% power column gives the corresponding number per arm for a 90% chance. Power is a planning property tied to a chosen effect and statistical assumptions, not a measure of whether a completed trial succeeded.

For agreement, the planning illustration gives 58 participants per arm for 80% power and 78 for 90% power when planning for 100% of the observed effect. Planning for 75% of the observed effect gives 110 per arm for 80% power and 146 per arm for 90% power. Planning for 50% of the observed effect gives 257 per arm for 80% power and 344 per arm for 90% power. For the pain outcome, the corresponding 80% and 90% figures are 1,418 and 1,898 per arm for 100% of the observed effect; 2,520 and 3,373 per arm for 75%; and 5,669 and 7,589 per arm for 50%.

Smaller effects require more participants to detect under the same planning assumptions. These figures are not observed power; they are planning illustrations calculated from the observed effects, not an assessment of the trial’s probability of detecting an effect after completion.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.429; treatment proportion p₁ = 0.190; average p̄ = 0.310.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6538 = 1.2814.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6317 = 0.5317.
4. n = (1.2814 + 0.5317)² / (-0.2381)² = 58.0, rounded up to 58 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
p0 <- 0.428571428571429                          # control proportion
p1 <- 0.19047619047619                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(3440723)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 58 (80% power), 78 (90% power)
 75% of observed effect: n per arm = 110 (80% power), 146 (90% power)
 50% of observed effect: n per arm = 257 (80% power), 344 (90% power)
power.prop.test: 58 
Simulated power at n = 58 per arm: 0.804 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 lists inter-examiner agreement as the primary outcome and lists pain with examination and ease of use as secondary outcomes. It does not report a detailed statistical analysis plan, a testing hierarchy, or a procedure for adjusting comparisons for multiplicity. The posted p-values are identified as unadjusted. Without a stated plan for handling several outcomes or tests, a nominal p-value should not be interpreted as if only one statistical question had been examined.

Multiplicity is a general issue: as more hypotheses are tested, the chance of at least one apparently unusual result can increase. Adjustments and prespecified outcome hierarchies are possible ways to address this, but the registry record does not say whether any such approach was planned or used. No multiplicity adjustment should therefore be assumed. The appropriate emphasis is on the estimated effects and their intervals, while recognizing that secondary analyses carry less confirmatory weight when the testing plan is not reported.

The registry record lists zero reported analyses for the primary outcome and no reported analyses for the secondary outcomes. The posted numerical comparisons are available, but there is no further analysis description to establish which methods were prespecified or how analysis decisions were made. Interim analyses are not reported in the registry record.

Missing-data handling and analysis populations beyond the primary outcome’s listed population of all enrollees are also not reported in the registry record. The entry does not state how many measurements or questionnaire responses were missing, whether all enrolled participants contributed to every outcome, how incomplete observations were handled, or whether an intention-to-treat or per-protocol approach was used. No assumptions about missingness or exclusions should be inferred from the posted group counts.

The record identifies randomization and a parallel design but gives no detail about sequence generation or allocation concealment. It also states that masking was absent. These reporting gaps do not erase the recorded results, but they limit assessment of bias, reproducibility, and the relationship between the reported estimates and the trial’s original analysis plan.

15. 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 serious adverse events for 21 participants at risk in each group and records 0 serious adverse events in each. It also reports other adverse events for 21 participants at risk in each group, with 0 recorded in each. Deaths are listed as 0 in both groups.

These figures describe the adverse-event counts posted in the registry record. A zero count means no events of that category were recorded in the listed group; it does not establish that the risk is zero or that no unrecorded events occurred. The record does not provide serious adverse-event terms, since no serious-event terms are listed, or additional detail about event definitions, surveillance procedures, or the duration of safety follow-up.

Safety counts should be interpreted in the context of the group sizes and the available reporting. With the reported numbers of participants at risk, the absence of recorded events does not precisely establish the frequency of uncommon events. These data are a description of the registry entries, not a comprehensive safety assessment.

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

The primary result shows fewer recorded agreements in the DilaCheck group than in the standard examination group in this trial. The risk-difference estimate is negative, and its interval extends across zero. The posted result therefore describes an observed difference but does not estimate its direction and size precisely. It should not be treated as proof that the approaches differ, or as proof that they are equivalent.

The endpoint concerns whether two physicians produced the same measurement. Agreement is not the same as accuracy. If two examiners match, that alone does not establish that their shared measurement is correct; if they differ, the result does not show which measurement is closer to a reference. The registry record does not report a reference standard or a process for adjudicating disagreement.

The study was randomized and parallel, but it was unmasked. The posted findings are specific to the trial’s recorded comparisons and its stated outcome definitions. The record does not report enough methodological detail to assess every aspect of implementation or analysis, and it does not provide an ease-of-use result. The pain estimate also has an interval spanning differences in either direction.

These data do not establish the reason for any disagreement or pain-score pattern, and they do not support a claim about broader clinical outcomes not measured in the record. The small amount of information reflected in the group counts and the width of the intervals require cautious interpretation. The results are best understood as an uncertain comparison of inter-examiner agreement, accompanied by an imprecise pain estimate and limited reported safety detail.

In general, a trial result is most informative when the outcome definition, measurement procedures, analysis plan, handling of missing data, and uncertainty estimates can all be evaluated. Several of those details are not reported in the registry record. The numerical observations remain useful for understanding what was recorded, but they do not settle questions that the endpoint was not designed to answer.

17. Why This Trial Matters Statistically

This trial raises a distinct statistical question from whether a measurement method is accurate: do different examiners obtain the same measurement when using that method? Inter-examiner agreement is important to describe because clinical measurements can vary across observers. The endpoint makes that question explicit by classifying matching physician measurements as agreement and differing measurements as disagreement.

The analysis also illustrates why the point estimate should not be read alone. The posted risk difference favors lower observed agreement in the DilaCheck group, but the interval crosses zero and is broad. The estimate therefore conveys a direction in the observed data while also showing substantial uncertainty about the underlying comparison. A p-value does not remove that uncertainty, and the unadjusted p-value should be considered in light of the multiple outcomes listed.

Another statistical distinction is between reliability and accuracy. Agreement between physicians describes consistency; it cannot establish accuracy without an external reference or validation process. The registry’s stated endpoint addresses consistency, and the record does not report a reference standard. Keeping these concepts separate prevents overinterpretation of an agreement result.

The trial also provides a useful example of how planning values depend on the effect chosen for detection. The planning illustrations require more participants per arm when the target is a smaller fraction of the observed effect. Those figures are not a retrospective measure of success and do not explain the original trial’s enrollment, since its design assumptions are not reported in the registry record.

Finally, transparent reporting matters. The registry provides outcome counts, estimates, and some uncertainty measures, but does not report a detailed analysis plan, missing-data procedures, or ease-of-use results. Those omissions shape the strength of statistical conclusions that can be drawn from the record.

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 the uncertainty around the primary comparison. The agreement counts are 9.0 and 4.0 in groups of 21.0 each, and the risk-difference interval is broad and crosses zero. This limits confidence in both the direction and magnitude of any underlying difference. The record does not report additional analyses that might clarify the estimate.

The outcome is agreement between two measurements, not measurement accuracy against an independent reference. The registry does not report whether physicians followed a standardized examination protocol, how examiner pairs were assigned, whether they were independent, or how disagreements were handled. It also does not provide details about the randomization sequence or allocation concealment. The trial was unmasked, which is a recorded design feature.

Reporting of secondary outcomes is incomplete. Pain with examination is posted, but ease of use is listed without a result in the registry record. The record does not report a multiplicity plan, detailed analysis methods, missing-data handling, or analysis populations for each outcome. It lists no reported analyses for the primary outcome and none for the secondary outcomes. These gaps make it difficult to assess prespecification and the handling of incomplete observations.

The safety record lists zero serious and zero other adverse events in each group, but details of event definitions and follow-up are not reported in the registry record. With limited group sizes, zero recorded events cannot precisely rule out uncommon events. The original sample-size rationale, interim analyses, and trial-specific statistical assumptions are also not reported. These limitations are specific to what the registry record documents and do not imply that unreported procedures were or were not carried out.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: DilaCheck Cervical Dilation Measurement Trial — NCT03440723.
• Registry record last updated 2021-06-22; status last verified 2021-05.
• Results first posted 2021-06-22.
• 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

NCT03440723 is a completed, randomized, parallel-group trial comparing standard digital cervical dilation examinations with examinations using DilaCheck. The registry lists no masking and enrollment of 42. The primary endpoint was agreement between measurements made by two different physicians, assessed immediately after examination.

Agreement was recorded for 9.0 of 21.0 participants in the standard group and 4.0 of 21.0 in the DilaCheck group. The posted risk difference was -0.238, with an interval from -0.508 to 0.032 and an unadjusted p-value of 0.095. The result is imprecise and does not establish a difference or equivalence.

Pain with examination was reported as a secondary outcome. Ease of use was listed, but its result is not reported in the registry record. Serious adverse events, other adverse events, and deaths were recorded as 0 in each group. A detailed analysis plan, missing-data procedures, and original sample-size rationale are not reported in the registry record.