A Prospective Analysis of Preoperative Fascia Iliaca Block for Hip Arthroscopy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Prospective Analysis of Preoperative Fascia Iliaca Block for Hip Arthroscopy (NCT02623361), a randomized phase 4 study. The primary outcome is Numeric Pain Score.

2. Clinical Question

The clinical question is whether assignment to the preoperative block was associated with a different immediate postoperative pain score than assignment to a sham procedure. The primary measure is a numeric rating scale score from 0, meaning no pain, to 10, meaning the worst pain imaginable. The endpoint captures the highest reported score in the post-anesthesia care unit during the specified period, rather than a single score at a fixed time or a measure of pain over a longer recovery period.

The posted results also include leg strength at discharge from the ambulatory center and patient satisfaction. These outcomes add information about function and patient experience, but they are distinct from the primary pain question. The registry record describes the study as prospective and randomized, and reports a sham comparator. It does not report further details about how the sham was delivered or how participants and staff were kept unaware of group assignment.

3. Trial Design

The registry record describes a prospective, randomized, parallel-group study of preoperative fascia iliaca block for patients having hip arthroscopy. It lists phase 4 and quadruple masking. The planned groups were a fascia iliaca compartment block using ropivacaine and a sham block; the brief study description says all patients would receive general anesthesia for surgery. The registry record identifies the sponsor as the University of California, San Francisco.

Enrollment is listed as 80. The posted primary-outcome results include 40 participants in the sham group and 38 in the block group. These are the sample counts attached to the reported outcome summaries; the registry record does not explain the difference between the enrollment figure and the outcome counts. It does not report whether that difference reflects missing measurements, exclusions after enrollment, or another reason, so no explanation can be assumed.

The study start is listed as 2015-02, primary completion as 2017-01, and status as completed. The registry record identifies the primary outcome as numeric pain score, measured within one hour after surgery. It also lists leg strength at discharge from the ambulatory center and patient satisfaction as secondary outcomes, with measurement timeframes of 2 hours after surgery and 48 hours, respectively.

Although the record identifies randomization and quadruple masking, further operational details are not reported in the registry record. The method used to generate and conceal the allocation sequence, the exact parties included in the masking designation, and the procedures used to maintain masking are not reported. The original protocol’s sample-size justification and statistical analysis plan are also not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Exclusion criteria for enrollment included age younger than 18 years, contraindications for regional anesthesia, pre-existing neurologic deficits of the lower extremity, and a history of chronic pain requiring chronic opioid medication.

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 Numeric Pain Score, measured over within one hour after surgery.

The primary endpoint is the highest numeric pain score reported in the post-anesthesia care unit within one hour after surgery. The numeric rating scale runs from 0, no pain, to 10, the worst pain imaginable. The posted summaries present the outcome as a group mean with a standard deviation, so the comparison describes average scores and the spread of scores among participants in each group.

Using the highest reported score in a specified early recovery window is intended to capture the peak pain recorded during that period. It is not the same as measuring pain at one fixed moment, averaging repeated assessments over time, or measuring pain after discharge. Interpretation should therefore remain tied to the endpoint’s particular setting and timeframe: it concerns reported pain in the post-anesthesia care unit within one hour after surgery.

The registry record’s description identifies the endpoint as the primary endpoint and gives the scale anchors. It does not report the schedule or number of pain assessments within the window, how a missing assessment was handled, or how the highest score was selected if multiple observations were available. Those details matter for understanding exactly how the endpoint was assembled, but they are not reported in the registry record.

7. Results Posted in the Registry

• FICB: mean 6.00 versus 7.00 on control; difference -1.00 (95% CI -1.89 to -0.11), standardized effect d = -0.50; z-test p = 0.027.

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.

Leg Strength at Discharge From Ambulatory Center, Surgical Leg

• 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:
  • FICB: mean 41.00 versus 139.00 on control; difference -98.00 (95% CI -134.30 to -61.70), standardized effect d = -1.18; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for FICB than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Patient Satisfaction

• 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:
  • FICB: mean 10.00 versus 10.00 on control; difference 0.00 (95% CI -0.32 to 0.32), standardized effect d = 0.00; z-test p = 1.000.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between FICB and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the record beyond immediate postoperative pain by addressing surgical-leg strength at discharge and patient satisfaction at 48 hours. Taken together, their posted summaries show that the outcome pattern is not uniform across domains: the strength comparison differs in direction from the satisfaction comparison, while satisfaction averages are at the top of the rating scale in both groups. These results provide context but do not change what the primary endpoint measures.

The secondary outcomes relate to the primary result because they describe other aspects of the same postoperative experience, but they do not serve as confirmation of the pain comparison. Pain, measured in the post-anesthesia care unit within one hour after surgery, is distinct from strength measured 2 hours after surgery and satisfaction measured at 48 hours. A pattern in one endpoint cannot be assumed to explain or validate a pattern in another.

The comparisons are unadjusted, and the registry record lists no reported analyses. It also does not report whether the secondary outcomes were prespecified for formal hypothesis testing, how many comparisons were planned, or whether multiplicity was addressed. When several endpoints are considered, the chance of at least one apparently notable result can increase if each is assessed separately without adjustment. In general, secondary findings without a reported multiplicity strategy warrant more cautious interpretation than a prespecified primary result.

The registry record reports three outcome measures overall, with two secondary outcomes posted, but does not explain whether any other planned measure was omitted or unavailable. The secondary results are therefore best viewed as descriptive evidence from the posted summaries. They can motivate questions about function and experience, but they do not supply a complete account of the trial’s secondary analysis plan or resolve uncertainty about the primary result.

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

• Leg Strength at Discharge From Ambulatory Center, Surgical Leg
• Patient Satisfaction

9. Statistical Interpretation

10. Statistical Methods Explained

What does a difference in means represent?

For a continuous measure, a difference in means subtracts one group’s average from the other group’s average. In this comparison, the reported direction is block minus sham. A negative estimate therefore means the observed mean was lower in the block group. The estimate of -1.0 is expressed in units of the numeric pain scale. It is a difference between group averages, not a statement that every participant’s score changed by that amount.

The posted group summaries also include standard deviations. A standard deviation describes how dispersed individual observations are around a group mean. It is not the uncertainty of the mean itself, and it is not a confidence interval. The primary outcome’s standard deviation is 2.0 in each group. A group average and standard deviation together describe the center and spread of the observed scores, but they do not show the full distribution or reveal whether there were unusual values or floor and ceiling patterns.

How should the confidence interval be read?

In general, a confidence interval gives a range of estimates compatible with the data and the method used to calculate the interval. It conveys precision: a narrower interval represents less uncertainty about the estimated contrast than a wider interval, under the assumptions of that calculation. For the primary comparison, the interval runs from -1.888 to -0.112. It is an interval for the group mean difference, not a range containing a stated proportion of individual participants’ scores.

In general, an interval’s coverage interpretation depends on the statistical procedure and its assumptions. The registry record does not report the original analysis method or a sponsor-reported confidence interval. The posted comparison is a simple unadjusted recalculation from summary statistics. It should therefore be understood as a summary-statistic comparison, rather than as evidence that a particular adjusted or covariate-based model was used by the trial investigators.

What does the p-value add?

In general, a p-value describes how incompatible the observed data are with a specified null model, assuming that model and the analysis assumptions hold. It is not the probability that the null hypothesis is true, nor does it measure the size or importance of an effect. The unadjusted p-value for the primary comparison is 0.027. It does not account for other endpoints unless a multiplicity adjustment is used; such an adjustment is not reported in the registry record.

The reported comparison is unadjusted. That means it does not reflect adjustment for baseline characteristics or other covariates. The registry record does not report whether an adjusted primary analysis was planned or performed. The record also lists no reported analyses, so there is no sponsor-reported analysis result to compare with the simple recalculation. The recalculated estimate and p-value should not be presented as if they were a reported protocol-based model.

Why can variability matter?

In general, variability affects how precisely group means and their difference can be estimated. More dispersed observations tend to make an average less precise when sample size is unchanged. The primary-outcome standard deviations are 2.0 in both groups, and the outcome counts are 40 and 38. These summaries provide some information about observed spread and group size, but not about the shape of the score distributions or dependence among repeated measurements.

For the leg-strength endpoint, the posted standard deviations differ between groups, with 99.0 in the sham group and 61.0 in the block group. In general, unequal variability can matter when an analysis assumes equal variances; the appropriate method depends on the design and assumptions. The registry record does not report which formal method was selected for that secondary comparison. No conclusion about the investigators’ modeling choices should be inferred from the displayed summary statistics.

What is a standardized effect?

A standardized effect expresses a difference relative to a measure of variability, making the scale-free magnitude easier to compare across measures with different units. The posted primary comparison includes a standardized difference of -0.5. This is a descriptive standardized summary, not a clinical threshold and not a separate outcome. It does not replace the original-scale estimate of -1.0 numeric rating scale units, which is more directly interpretable in the measurement scale used for pain.

Standardization depends on the variability measure used. It does not make different clinical constructs equivalent, and it does not by itself indicate whether a result matters to patients. The registry record does not report a prespecified threshold for interpreting the standardized estimate.

What do the analysis omissions mean?

The registry record lists no reported analyses. It does not report the trial’s statistical analysis plan, the primary model, any adjustment variables, the treatment of missing outcomes, or a defined analysis population. These are important for distinguishing an intention-to-treat analysis from an analysis based on participants with observed outcomes, and for understanding how exclusions or incomplete measurements were addressed. Because those details are absent, the posted group summaries cannot establish which analytic population or missing-data approach was used.

In general, a complete interpretation combines effect size, uncertainty, design, and the analysis plan. Here, the randomized parallel-group design supports a comparison of assigned groups in principle, but the registry record’s limited analysis details prevent a full audit of how the reported outcomes were analyzed. The descriptive estimates can be read as comparisons of the posted summaries, with that limitation kept explicit.

11. Confidence Intervals and Precision

The primary mean difference is -1.0 numeric rating scale units, with a 95% confidence interval from -1.888 to -0.112. The interval communicates uncertainty about the estimated average contrast. Its endpoints span estimates that are closer to zero and estimates farther from zero than the point estimate. The confidence interval is not a prediction interval for individual pain scores and does not mean that all participants experienced a difference within those limits.

The interval excludes zero, which is consistent with the unadjusted p-value of 0.027 for a test of no mean difference under the calculation’s assumptions. That statistical feature does not establish a clinically important effect. No minimally important difference or other clinical interpretation threshold is reported in the registry record. The estimate should be interpreted in its original units and in relation to the immediate post-surgery setting measured.

Precision also depends on the number of observed outcomes and variability. The primary summaries include 40 sham participants and 38 block participants, with a standard deviation of 2.0 in each group. The registry record reports enrollment of 80 but does not explain the smaller counts attached to the outcome summaries. It does not report whether missing observations, exclusions, or another process accounts for that difference. This uncertainty about the analysis population should be considered alongside the interval.

The displayed interval is a recalculated unadjusted interval based on posted summary statistics, not a sponsor-reported interval, as no reported analyses are listed. Its precision does not address possible bias from missing data, departures from the randomization procedure, or selective reporting. Nor does it reflect multiplicity across the primary and secondary outcomes. Those matters are not resolved by an interval around one comparison.

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 participants per arm, not total events. They are illustrative calculations based on the observed effect, not the trial’s original design justification. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; each scenario uses the stated fraction of the observed effect as the effect to detect. The trial’s own original sample-size assumptions are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm for an analysis to have an 80% chance of detecting the specified effect under the planning assumptions, if that effect and those assumptions were correct. The 90% power column gives the corresponding figure for a 90% chance. These are design-planning concepts, not guarantees about the result of a future study. The figures are not observed power for this completed trial.

The scenarios use 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. The smaller the effect a study is intended to detect, the more participants it generally needs, because a smaller signal is harder to distinguish from random variation. The listed participant requirements increase across those smaller-effect scenarios. They are planning illustrations for the primary comparison and should not be read as a retrospective evaluation of whether the enrolled study was adequately designed.

These calculations also do not account for details not included in their stated assumptions, such as possible missing outcomes or any adjustment for multiple endpoints. The registry record does not report the trial’s original sample-size justification, so the illustrative figures cannot establish what assumptions guided enrollment.

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 = -1.000; pooled standard deviation σ = 2.000.
2. n = 2 × (1.96 + 0.842)² × 2.000² / -1.000² = 62.8, rounded up to 63 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 <- -1                      # observed difference in means
sigma <- 2                     # 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(2623361)
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 = 63 (80% power), 85 (90% power)
 75% of observed effect: n per arm = 112 (80% power), 150 (90% power)
 50% of observed effect: n per arm = 252 (80% power), 337 (90% power)
power.t.test: 63.8 
Simulated power at n = 63 per arm: 0.793 (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 identifies a primary endpoint and two secondary outcomes, but does not report a multiplicity strategy. Multiplicity arises when several outcomes, timepoints, or statistical comparisons are examined. In general, conducting many separate tests can increase the chance that at least one result appears noteworthy by chance. Adjustments or a prespecified hierarchy can address this issue, but no such procedure is reported in the registry record. The unadjusted p-values should therefore not be interpreted as if they were adjusted for all outcomes.

The record lists no reported analyses. It does not state which analysis population was intended, whether the main comparison followed randomized assignment regardless of treatment received, or whether an alternative population was used. The registry record also does not report how missing outcome data were handled, whether imputation was used, or whether sensitivity analyses were conducted. These details are relevant because missing observations can affect both the group summaries and the interpretation of a randomized comparison.

For the primary endpoint, outcome counts are 40 in the sham group and 38 in the block group, while overall enrollment is listed as 80. The reason for the difference between enrollment and the outcome counts is not reported in the registry record. Counts for the secondary outcomes also vary by outcome. The record does not describe participant flow, the number assessed at each timepoint, or the reasons for unavailable measurements.

The registry record includes randomization and quadruple masking as design features, but does not report the allocation method, concealment procedures, the details of masking, or whether masking was assessed. It also does not report a detailed statistical analysis plan, model diagnostics, or any interim analysis plan. These are unreported details, not evidence that a particular procedure was or was not used. Their absence limits a reader’s ability to assess the analysis independently and to distinguish prespecified decisions from choices made after observing the data.

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 serious adverse events in 0 of 40 participants at risk in the sham group and 0 of 38 participants at risk in the fascia iliaca block group. It also lists zero other adverse events in each group, with the same group counts at risk. These are the posted entries for the adverse-event categories recorded in the registry.

Zero recorded events in these groups should be read as a report of the registry entries, not as proof that no event could occur or that all possible events were captured. The record does not provide event descriptions, severity details beyond the serious-versus-other grouping, or information about the surveillance and reporting procedures. Death counts are not reported in the registry record.

These figures are separate from the pain and functional outcomes and should not be used to infer efficacy. They also do not establish comparative safety beyond the events and participants represented in the posted record. The sample counts are limited, and the registry record does not report additional safety analyses.

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

The posted primary summaries show a lower mean immediate postoperative numeric pain score in the block group than in the sham group, with an unadjusted mean difference of -1.0 and a 95% confidence interval from -1.888 to -0.112. This is a comparison of group averages for the highest pain score reported in the post-anesthesia care unit within one hour after surgery. It is not a statement about every participant, pain at later timepoints, or outcomes in settings beyond the one described.

The result does not establish clinical importance because the registry record does not report a threshold for a meaningful difference on the scale. It also does not establish that the same estimate would occur in other populations or under different procedures. The confidence interval describes statistical uncertainty under the recalculation’s assumptions; it does not cover uncertainties arising from unreported analysis choices, missing data, or study conduct.

The randomized design is relevant to comparing groups, but the record does not report enough analysis detail to assess whether the posted summaries reflect a prespecified intention-to-treat analysis or another analysis population. There is no reported sponsor analysis in the registry record, and the comparison is an unadjusted recalculation from summary statistics. The findings should be read with that distinction in mind.

Secondary outcomes concern strength and satisfaction, not the primary pain endpoint. They provide additional descriptive information but do not independently verify the primary result. No multiplicity plan is reported, so unadjusted secondary comparisons carry additional uncertainty. The absence of posted adverse events is also limited to the registry’s entries and should not be interpreted as a guarantee of safety.

Overall, the record supports describing the observed group summaries and their uncertainty. It does not, by itself, resolve clinical importance, the impact of missing outcomes, or how the investigators’ original analysis plan would have treated the data.

17. Why This Trial Matters Statistically

This study illustrates why a trial result should be read as more than a single p-value. The primary comparison includes a mean difference, a confidence interval, group variability, and outcome counts. Together, these describe the estimated contrast and its precision more fully than a significance label alone. The interval’s relationship to zero is informative about the unadjusted comparison, while its range also makes clear that the estimate is not exact.

The registry record also demonstrates the distinction between a randomized design and a fully documented analysis. Randomization and quadruple masking are listed, but the method for allocation, the operational details of masking, the analysis population, and the missing-data approach are not reported. Without those elements, readers cannot fully evaluate how the planned design was implemented in the analysis.

Comparison across outcome domains is another statistical issue. Immediate pain, later satisfaction, and leg strength are measured on different scales and at different times. Their results should not be combined into one general conclusion, and secondary comparisons need to be interpreted in light of the unreported multiplicity plan. A result’s direction or p-value in one outcome does not settle the interpretation of another.

Finally, planning calculations based on an observed effect are not the same as the trial’s original sample-size justification. They can illustrate how required group size changes when the target effect changes, but they cannot reconstruct the study’s design decisions or establish observed power. Keeping planning quantities, observed summaries, and inferential uncertainty separate is essential for a transparent statistical reading.

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.

Several trial-specific details needed for a fuller interpretation are not reported in the registry record. The record does not explain why primary-outcome counts are 40 and 38 when enrollment is listed as 80, nor does it provide a participant-flow account or reasons for missing outcome measurements. The analysis population and missing-data handling are also not reported. These omissions limit assessment of whether the posted summaries represent all randomized participants or only those with available measurements.

The record lists randomization and quadruple masking but does not describe the allocation sequence, allocation concealment, the identities of those masked, or how masking was maintained. It does not report whether the observed outcomes were analyzed according to a prespecified statistical plan. The registry record lists no reported analyses, so the posted unadjusted recalculations cannot be compared with a reported primary model or adjusted result.

The primary pain measure is specific to the highest score recorded in the post-anesthesia care unit within one hour after surgery. The schedule and number of assessments within that period are not reported. The record also does not provide a threshold for clinical importance, limiting interpretation of the size of the mean difference in practical terms.

For the secondary outcomes, the record does not report a multiplicity strategy or detailed analysis plan. The posted summaries also vary in outcome counts, without an explanation. Adverse-event entries do not include detailed event descriptions or surveillance methods, and death counts are not reported. These limitations do not negate the posted data; they define what the registry record can and cannot support.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: A Prospective Analysis of Preoperative Fascia Iliaca Block for Hip Arthroscopy — NCT02623361.
• Registry record last updated 2018-12-27; status last verified 2018-12.
• Results first posted 2018-07-05.
• 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, prospective, randomized, quadruple-masked, parallel-group phase 4 study of preoperative fascia iliaca block versus sham block for hip arthroscopy. Enrollment is listed as 80. The primary endpoint is the highest numeric pain score reported in the post-anesthesia care unit within one hour after surgery.

The primary outcome summaries include 40 participants in the sham group and 38 in the block group. The unadjusted recalculated mean difference is -1.0 numeric rating scale units, with a 95% confidence interval from -1.888 to -0.112 and an unadjusted p-value of 0.027. Two secondary outcomes are posted: leg strength at discharge and patient satisfaction at 48 hours.

The registry record lists zero serious and zero other adverse events in both groups, while death counts are not reported. It lists no reported analyses and does not report the original statistical plan, sample-size justification, analysis population, missing-data approach, or multiplicity strategy. These omissions limit how completely the posted summaries can be evaluated.