Early Percutaneous Cryoablation for Pain Control After Rib Fractures Among Elderly Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Early Percutaneous Cryoablation for Pain Control After Rib Fractures Among Elderly Patients (NCT04482582), a randomized na study. The primary outcome is Acute Pain Assessed by Numeric Pain Score.

2. Clinical Question

The study’s stated purpose was to provide long-term pain control for elderly patients with rib fractures, minimize their risk of complications, and help return them to baseline functional capacity. The primary endpoint reported in the registry is narrower: a verbal numeric pain score on the day of hospital discharge. Since discharge timing varies for these polytrauma patients, the measurement time is not a fixed interval after injury or presentation.

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. It lists the study as not applicable for phase and reports enrollment of 127. The record names Stanford University as sponsor and marks the study completed. Its listed start date is 2021-06-01 and its primary completion date is 2024-04-25. These dates describe the registry record; they do not, by themselves, establish when every participant was followed or analyzed.

Eligible patients were admitted after traumatic injury, had identified rib fractures, and were 65 years of age or older. The arm descriptions say patients were randomized within 72 hours of presentation to image-guided percutaneous cryoneurolysis or standard of care. The primary outcome lists 56 patients in the pICN group and 54 in the standard-of-care group. The outcome population description also notes that it includes 7 ITT patients per a September 2023 protocol amendment. The relationship between that amendment and the reported group counts is not further explained in the registry record.

The primary endpoint was acute pain measured as a mean numeric pain score at hospital discharge, with standard deviations reported for each arm. The registry lists secondary outcomes including mortality, ICU admission, hospital length of stay, narcotic equivalents, rib-specific readmission, pain questionnaires, functional outcome, and health status. Detailed posted results are available for ICU admission and rib-specific readmission in the record used for this analysis; numerical results for the other listed secondary outcomes are not reported in the registry record.

The record does not report the original sample-size justification, the planned statistical analysis protocol, whether interim analyses were planned or conducted, or detailed missing-data procedures. Those omissions limit reconstruction of the trial’s intended analysis, even though the posted primary comparison identifies a two-sided t-test.

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.

Baseline

Reasons for not completing this period:

1-month follow-up

Reasons for not completing this period:

3-month follow-up

Reasons for not completing this period:

12-month follow-up

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Includes 7 ITT patients per September 2023 protocol amendment

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.

Population: Includes 7 screen failures that were considered ITT. This change was made in October 2023 and is reflected in the protocol.

6. Primary Endpoint

The registry lists the primary outcome as Acute Pain Assessed by Numeric Pain Score, measured over Hospital discharge (up to 1 month).

The primary endpoint is the mean numeric pain score reported verbally on the day of hospital discharge. The scale ranges from 0, meaning no pain, to 10, meaning the worst pain. This is a continuous outcome: each participant’s score can take values across the scale, and the group result is expressed as a mean with a standard deviation. The posted endpoint description specifies hospital discharge, up to 1 month, and notes that discharge timing varies because participants are polytrauma patients.

A discharge pain score addresses acute pain near the end of the hospitalization. It is relevant to the study’s stated interest in pain control, but it does not directly measure pain over an extended follow-up period. Nor is the score itself a measure of complications, functional recovery, or return to baseline capacity. Those concepts appear in the study’s purpose and secondary outcome list, but they are not the primary endpoint.

The reported mean was 5.61 in the pICN group and 5.93 in the standard-of-care group. The unadjusted mean difference, defined as pICN minus standard care, was -0.32. A negative difference means the observed mean was lower in the pICN group; it does not establish that the groups differ reliably. Interpretation also depends on the uncertainty around the estimate and on how the outcome was collected and analyzed. Additional details about missing scores, handling of the amendment population, and any adjustment for other factors are not reported in the registry record.

7. Results Posted in the Registry

• Image-guided Percutaneous ICN (pICN): Group A: mean 5.61 versus 5.93 on control; difference -0.32 (95% CI -1.23 to 0.59), standardized effect d = -0.13; z-test p = 0.490.

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.

Number of Participants Requiring ICU Admission

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Image-guided Percutaneous ICN (pICN): Group A: 10.7% (6/56) versus 11.1% (6/54) on control; risk difference -0.4 percentage points (95% CI -12.1 to 11.3), risk ratio 0.96 (0.33–2.81); unadjusted two-proportion z-test p = 0.947.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Image-guided Percutaneous ICN (pICN): Group A and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants With a Rib-specific Readmission Within 30 Days of Discharge

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Image-guided Percutaneous ICN (pICN): Group A: 0.0% (0/55) versus 2.0% (1/49) on control; risk difference -2.0 percentage points (95% CI -6.0 to 1.9); unadjusted two-proportion z-test p = 0.287.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Image-guided Percutaneous ICN (pICN): Group A and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary results do not show a clear separation between groups in the two outcomes with numerical results available for this analysis. ICU admission counts were the same in the two arms, and the estimated risk difference is close to zero with a confidence interval spanning both directions. Rib-specific readmission was rare in the posted outcome data; its estimated difference also has an interval that crosses zero. These secondary observations are compatible with a range of possible differences and should not be read as proof that the groups have equivalent outcomes.

These outcomes address different aspects of the clinical course from the primary discharge pain score. ICU admission and readmission are events, whereas the primary endpoint is a continuous pain rating at discharge. They can add context to the overall pattern, but they do not directly confirm or refute a difference in pain scores. Nor can these limited results establish a broader conclusion about complications, functional recovery, or health status.

The registry lists other secondary outcomes, including mortality, hospital length of stay, narcotic equivalents, pain questionnaires, functional outcome, and health status. Numerical results for those outcomes are not reported in the registry record. As a result, the overall secondary-outcome pattern cannot be fully assessed from the results summarized in the record.

Unadjusted secondary findings generally carry less weight than a prespecified primary analysis because examining multiple outcomes creates more opportunities for chance findings. Without a reported multiplicity strategy, the nominal p-values for secondary comparisons do not account for the broader set of outcomes. The registry does not report whether any adjustment was planned or used. The secondary results are therefore best treated as descriptive context, with particular caution for rare events and unreported outcomes.

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

• 30-day Mortality
• Number of Participants Requiring ICU Admission
• Length of Hospital Stay
• Use of Narcotic Equivalents
• Number of Participants With a Rib-specific Readmission Within 30 Days of Discharge
• The McGill Pain Questionnaire (MPQ) and Pain Rating Index (PRI) Scale Score
• The Glasgow Outcome Scale Extended (GOS-E) Score
• Short Form (SF-12) Health Survey Scale Score

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is a continuous measure, summarized by a mean and standard deviation in each randomized group. A mean difference compares the groups on the original score scale. In this analysis the contrast is defined as the pICN mean minus the standard-of-care mean, so a negative value indicates a lower observed mean in the pICN arm. The difference of -0.32 is a direct contrast of the posted group means, rather than an adjusted estimate from a model with additional covariates.

What does the t-test assess?

The registry reports a two-sided t-test for the primary comparison. In general, a two-sided test evaluates whether the group means differ in either direction, rather than testing only for a lower or higher mean in a prespecified direction. A t-test uses the observed group means and their variability to assess how compatible the contrast is with a null hypothesis of no mean difference. The sponsor’s reported p-value is 0.493. The simple recalculation from the posted summary statistics gives p=0.49. The registry does not report further detail about model adjustments or any alternative primary analysis.

The standard deviation describes variation among individual scores within a group; it is not the uncertainty of the group mean. The posted standard deviations are 2.42 for pICN and 2.44 for standard care. The standard error, by contrast, describes the estimated sampling uncertainty for a group mean. The posted summary includes standard errors of 0.323 and 0.332 for the pICN and standard-of-care means, respectively. Greater variability among individual scores can make a group mean less precise, as can limited information in the analyzed group.

How should the confidence interval be read?

A confidence interval gives a range of estimates that are compatible with the data under the method’s assumptions. The primary 95% interval for the mean difference is -1.228 to 0.588. It contains zero, so the posted data do not rule out no mean difference under this analysis. It also includes values on either side of zero, which means the estimate does not establish a single direction for the difference. A confidence interval is not a guarantee that the true value lies within the particular observed interval, and it does not describe the range of individual patients’ scores.

The interval is based on the unadjusted comparison of the posted summary statistics. The registry’s own reported analysis is the two-sided t-test, and its p-value is 0.493. Since the discrepancy flag is false, there is no identified material disagreement between the sponsor’s analysis and the recalculation. The recalculation remains a check based on posted summary statistics; it does not replace the trial’s own analysis or account for information unavailable in those summaries.

Why do binary outcomes need different interpretation?

ICU admission and rib-specific readmission are binary outcomes: each participant either had the event or did not. Their group results are counts and proportions rather than means. A risk difference is the event proportion in the pICN group minus the event proportion in standard care. For ICU admission, the reported event counts are 6 in each arm. The risk difference estimate is -0.004, with a 95% confidence interval from -0.120 to 0.113. For rib-specific readmission, the counts are 0 and 1, respectively, and the recalculated risk difference is -0.020 with a 95% confidence interval from -0.06 to 0.019.

When event counts are sparse, proportions and their differences can be sensitive to a small number of observations. A wide interval indicates that the data are compatible with a range of possible risk differences. General statistical principle: a non-significant test does not establish equivalence or prove that risks are the same. Demonstrating equivalence or non-inferiority requires a prespecified margin and a suitable analysis; such a margin is not reported in the registry record.

What does over-dispersion mean in general?

Over-dispersion is a general concern for count outcomes when the observed variability is greater than a statistical model expects. If a model underestimates variability, its standard errors may be too small and its intervals too narrow. The primary endpoint is a continuous pain score, not a count outcome, and the registry reports a t-test rather than a count model. The record does not provide enough detail to assess whether over-dispersion was relevant to any secondary count analyses. It is therefore a general concept, not a reported feature of this trial’s analysis.

For all recalculated results, the estimates are unadjusted and use the posted summary counts or means. They should be read as transparent checks, not as a reconstruction of unreported patient-level analyses. The registry does not report detailed handling of missing observations, covariate adjustment, or analysis choices beyond the methods named for the posted tests.

11. Confidence Intervals and Precision

The primary mean difference is -0.32, with a 95% confidence interval from -1.228 to 0.588. This interval includes zero and extends into both negative and positive values. It therefore leaves uncertainty about whether the population mean score was lower or higher in the pICN group. It also indicates that the point estimate alone gives an incomplete account of the result: the range of values compatible with the data is substantially broader than the single estimate.

Precision concerns how narrowly an estimate is determined by the data and the analysis. The primary interval is not a prediction interval for individual pain scores, and it does not mean that most individual scores fall between its endpoints. It is an interval for the mean difference. The standard deviations, 2.42 for pICN and 2.44 for standard care, describe spread in the participant-level scores; the confidence interval describes uncertainty in the between-group estimate.

The ICU-admission risk-difference interval, -0.120 to 0.113, also includes zero and allows a range of possible directions and sizes. The readmission interval, -0.06 to 0.019, likewise crosses zero. Sparse events contribute to the difficulty of obtaining precise estimates for the readmission comparison. These intervals should not be read as evidence that the risks are identical; they show that the posted data leave uncertainty around the differences.

The precision of any registry result also depends on the analyzed population and missing observations. The primary description notes 7 ITT patients per a September 2023 protocol amendment, but the record does not provide enough detail to determine how the amendment affected the analysis or how missing endpoint values were handled. Those omissions constrain interpretation of the interval’s scope.

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 figures are planning illustrations based on the observed effect, not the trial’s original design justification. For the continuous primary outcome, the figures are participants per arm. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect equal to the stated fraction of the observed effect. The original design assumptions are not reported in the registry record.

The 80% power column describes the number of participants per arm that the planning calculation estimates would be needed to have an 80% chance of detecting the specified effect under its assumptions. The 90% power column gives the corresponding planning number for a 90% chance. These are design targets, not observed results. The figures are not observed power.

The primary planning illustration gives 906 participants per arm for 80% power and 1,212 participants per arm for 90% power when planning for 100% of the observed effect. Planning for 75% of the observed effect gives 1,610 participants per arm for 80% power and 2,155 for 90% power. Planning for 50% of the observed effect gives 3,621 participants per arm for 80% power and 4,847 for 90% power. The pattern reflects a general statistical principle: smaller effects are harder to distinguish from random variation and therefore require more participants, all else equal.

The sample-size display and curve should be understood as illustrations tied to the observed estimate and stated assumptions, not as evidence that the completed study had a particular probability of success. They do not establish what the original investigators planned, whether the assumed effect is clinically important, or whether those assumptions are appropriate for a future study.

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 = -0.320; pooled standard deviation σ = 2.430.
2. n = 2 × (1.96 + 0.842)² × 2.430² / -0.320² = 905.1, rounded up to 906 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 <- -0.319999999999999                      # observed difference in means
sigma <- 2.42983538537079                     # 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(4482582)
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 = 906 (80% power), 1,212 (90% power)
 75% of observed effect: n per arm = 1,610 (80% power), 2,155 (90% power)
 50% of observed effect: n per arm = 3,621 (80% power), 4,847 (90% power)
power.t.test: 906.1 
Simulated power at n = 906 per arm: 0.795 (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. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary comparison as a two-sided t-test with p=0.493. A simple unadjusted recalculation from the posted means, standard deviations, and group sizes gives a mean difference of -0.32, a 95% confidence interval from -1.228 to 0.588, and p=0.49. The small difference between the displayed p-values reflects their reported precision; the registry does not flag a discrepancy.

The sponsor’s result is the trial’s own reported analysis and should be distinguished from the recalculation, which is derived from summary statistics. The recalculation does not use participant-level data and cannot reproduce adjustments or data-handling steps that are not described in the registry. In this case, the reported test and recalculation tell a consistent broad statistical story: the estimated mean difference is modest in magnitude relative to its uncertainty, and the interval includes zero.

The registry does not report a sponsor confidence interval for the primary test, so the interval presented in the recalculation is not a sponsor-reported interval. It is an unadjusted estimate based on the posted summaries. It should not be treated as a substitute for a fuller analysis plan or patient-level analysis.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study examines several outcomes or makes several statistical comparisons. Even if each test is conducted at a conventional significance threshold, testing a collection of outcomes increases the opportunity for at least one apparently notable result to occur by chance. A prespecified primary endpoint helps focus interpretation, while secondary analyses can provide additional context. Their evidential weight depends in part on whether the analysis plan specified how multiple comparisons would be handled.

The registry identifies acute pain at hospital discharge as the primary outcome and lists multiple secondary outcomes. It does not report a multiplicity adjustment or state whether any hierarchy among secondary outcomes was prespecified. The posted secondary p-values should therefore be interpreted as unadjusted results, not as evidence that has been protected against testing across the full outcome set. The record does not report interim analyses or any associated adjustment to the statistical threshold.

Missing-data handling is another uncertainty. The primary outcome population description notes 7 ITT patients per the September 2023 protocol amendment. The record does not explain the details of the amendment, how it affected the analysis population, whether all randomized participants contributed a discharge pain score, or how missing scores were handled. It also does not report sensitivity analyses for missing data. The primary outcome’s group counts are 56 and 54, but the registry summary alone does not establish the reasons for any difference between enrollment and outcome-specific counts.

The endpoint’s timing also varies: pain was assessed at hospital discharge, up to 1 month, and the record notes that discharge timing differs among these polytrauma patients. That makes the assessment a discharge-based endpoint rather than a measurement at an identical elapsed time for every participant. Further details about timing variation and its handling in the analysis are not reported in the registry record.

These omissions do not invalidate the posted results, but they limit how completely an independent reader can reconstruct the intended analysis. The primary comparison can be interpreted as reported, while claims about multiplicity control, missing-data robustness, interim monitoring, and the planned analysis beyond the named test cannot be made from the registry record.

16. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: non chest wall related readmission (23.2%), rib specific readmission (1.9%).

The adverse-event summary reports serious adverse events affecting 13 of 56 participants in the pICN group and 11 of 54 in the standard-of-care group. Other adverse events affected 9 of 56 and 24 of 54, respectively. Deaths are reported for 3 participants in each group. These are descriptive counts; they do not establish that an event was caused by the assigned intervention or that the groups differ in safety.

The registry lists “Non chest wall related readmission” at 23.2% and “Rib specific readmission” at 1.9% among the top serious-event terms. The record does not provide enough detail to interpret those terms as treatment-related risks or to connect them to a specific group. Serious adverse event totals can include events with different causes and clinical significance, and the summary does not supply individual event narratives or attribution.

Safety interpretation is also limited by the scope of the posted summary. The figures should be read alongside the trial’s outcome definitions and follow-up procedures, which are not fully described in the registry record. They should not be used alone to infer comparative safety or make treatment decisions.

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

The primary result is an observed mean discharge pain score of 5.61 in the pICN group and 5.93 in standard care, with an unadjusted mean difference of -0.32. The 95% confidence interval, -1.228 to 0.588, includes zero and spans both directions. The posted analysis therefore does not precisely establish the direction or size of a difference in mean discharge pain scores.

This does not demonstrate that the treatments are equivalent, and it does not prove that there is no effect. A failure to establish a difference is not the same as showing that any difference is small enough to be unimportant. The registry does not report a clinical equivalence margin or a non-inferiority margin. The p-value of 0.493 is not the probability that the null hypothesis is true; it is a measure of how compatible the test result is with that hypothesis under the analysis assumptions.

The endpoint is a pain score taken at hospital discharge, with discharge timing varying among participants. It does not by itself answer whether pain control is sustained long term, whether complications are minimized, or whether participants return to baseline functional capacity. Those aims appear in the study’s purpose, but the primary outcome is not a direct measurement of each aim. The record lists secondary measures relevant to some of these domains, but numerical results for most of them are not reported in the registry record.

The secondary ICU and readmission estimates are also uncertain, and their p-values are unadjusted. They provide limited descriptive context rather than a comprehensive assessment of clinical outcomes. Likewise, adverse event counts describe what was recorded but do not establish causation or a definitive difference in safety.

Accordingly, the registry supports a careful description of the posted comparisons and their uncertainty. It does not support a broad claim about long-term benefit, equivalence, overall recovery, or comparative safety. Such conclusions would require fuller outcome reporting and details about analysis populations, missing data, and prespecified clinical interpretation.

18. Why This Trial Matters Statistically

This trial illustrates why an estimated effect should be read together with its uncertainty. The observed primary difference is -0.32 points, but the confidence interval extends from -1.228 to 0.588 and includes zero. Reporting only the group means or only the p-value would conceal the range of differences that remains compatible with the posted data. The estimate, interval, and endpoint definition each contribute to interpretation.

It also illustrates the distinction between an outcome’s clinical purpose and what is actually measured. The study’s stated purpose concerns long-term pain control, complications, and functional capacity, while the primary endpoint is a verbal pain score at discharge. That score is a meaningful acute outcome, but it is not interchangeable with long-term pain or functional recovery. Statistical interpretation depends on keeping the measurement and the broader research aim distinct.

The secondary data show another important issue: event outcomes can be sparse, and estimates based on few events may remain imprecise even when the observed counts look similar. A point estimate near zero does not demonstrate equivalence. Confidence intervals communicate uncertainty that counts alone cannot.

Finally, the registry record leaves important analysis details unreported, including missing-data procedures, multiplicity handling, and the original sample-size justification. These limits matter when judging how far results can be generalized or how strongly secondary findings should be interpreted. A transparent account separates what the data estimate from what the record does not establish.

19. 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 primary endpoint is measured at hospital discharge, and the registry notes that discharge timing varies because participants are polytrauma patients. Thus, the assessment does not occur at a fixed elapsed time for every participant. The record does not explain how this timing variation was handled analytically or whether it influenced interpretation.

The endpoint population description refers to 7 ITT patients per the September 2023 protocol amendment, but the amendment’s details and its relationship to the analysis are not reported. The record does not state how missing pain scores were handled, whether all randomized patients were included in the primary analysis, or whether sensitivity analyses were conducted. These details limit assessment of robustness.

The standard-of-care group is not described in detail in the arm description. The record also does not give further procedural detail for the cryoneurolysis intervention in the information. These reporting limits make it difficult to assess variation in care or relate the result to a more specifically defined clinical protocol.

The primary interval includes zero and is broad enough to leave uncertainty about the direction and size of a possible difference. The secondary events are limited in number, and the readmission comparison is especially sparse. Numerical results for most listed secondary outcomes are not reported in the registry record, and no multiplicity strategy is described. These factors constrain any attempt to draw conclusions across the full set of clinical outcomes.

The study is randomized and unmasked according to the registry. The record does not provide further detail about outcome-assessor procedures or whether the pain score was collected under standardized conditions. As a subjective verbal rating, pain measurement can reflect individual reporting, while the registry summary does not describe additional measurement safeguards.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Early Percutaneous Cryoablation for Pain Control After Rib Fractures Among Elderly Patients — NCT04482582.
• Registry record last updated 2026-03-27; status last verified 2025-08.
• Results first posted 2026-03-27.
• 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.

23. Record Summary

NCT04482582 is a completed, randomized, parallel-group trial with no masking, sponsored by Stanford University. It compared image-guided percutaneous intercostal nerve cryoneurolysis with standard of care in patients 65 years of age or older admitted after traumatic injury with rib fractures. The arm descriptions specify randomization within 72 hours of presentation.

The primary outcome was mean numeric pain score at hospital discharge, up to 1 month. The observed means were 5.61 for pICN and 5.93 for standard care. The unadjusted mean difference was -0.32, with a 95% confidence interval from -1.228 to 0.588; the registry reports a two-sided t-test p-value of 0.493.

The registry lists several secondary outcomes, but numerical results are posted for only a limited subset in the record analyzed. Important details about missing data, multiplicity, and the original sample-size justification are not reported. The primary estimate should therefore be read with its interval and with attention to the limits of the registry’s analysis detail.