Prospective Trial of the Effect of Preoperative Forced-air Warming on Perioperative Body Temperature Following Neuraxial Anesthesia in Total Hip Arthroplasty Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prospective Trial of the Effect of Preoperative Forced-air Warming on Perioperative Body Temperature Following Neuraxial Anesthesia in Total Hip Arthroplasty Patients (NCT01626690), a randomized phase 4 study. The primary outcome is Patient Temperature at the Time of Incision as Measured by SpotOn (3M) Temperature Monitoring System...

2. Clinical Question

The trial focused on temperature control around surgery. Its primary measure was a continuous temperature reading at incision, and the posted comparison reports a group mean and standard deviation for each arm. The outcome description also says temperatures were to be obtained every 30 minutes while patients were in the operating room, but the primary outcome is specifically the measurement at incision.

This question concerns a difference in average recorded temperature between randomized groups. It does not, by itself, establish how often participants crossed any particular temperature threshold: no threshold-based primary outcome is reported. Nor does the primary comparison describe other clinical outcomes, such as shivering or cardiac events. The record lists those among secondary outcomes, but numeric results for them are not reported in the registry record.

3. Trial Design

The registry identifies this as a Phase 4, randomized, parallel-group trial with no masking. Enrollment was 100. The study status is terminated; the reason for termination is not reported in the registry record. The record gives a study start of 2012-05 and primary completion of 2014-12.

The two named groups are Pre-Warming and Control. The intervention list includes Bair-Paws and Bair-Hugger warming devices, while the arm descriptions are empty. As a result, the registry record does not establish which device corresponds to the pre-warming group or provide a procedural description of the control group. The stated study purpose was to evaluate whether placing a forced-air warming device before regional anesthesia improves perioperative temperature control in total hip arthroplasty patients.

For the primary outcome, the posted summaries include 47 participants in Pre-Warming and 51 in Control. Those are the arm counts reported with that outcome; the record does not explain any difference between those counts and the enrollment figure. No further information is reported about participant flow, exclusions, adherence, or the population included in the analysis.

The primary outcome was temperature at incision measured using the SpotOn (3M) system, reported in degrees Celsius as a mean and standard deviation. The treatment period is described as starting with consent and application of the preoperative warming device and ending when the patient leaves the recovery room, with an average duration of 4-8 hours following enrollment. The status, allocation, and masking labels describe the registered design, but do not supply details about sequence generation, concealment, or the conduct of blinding.

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:

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 Patient Temperature at the Time of Incision as Measured by SpotOn (3M) Temperature Monitoring System.., measured over The treatment period starts with the patient consenting to the study and application of preoperative forced-air warming device and ends when the patient leaves the PACU (average 4-8 hours following enrollment)..

The primary endpoint is patient temperature at the time of incision, measured in degrees Celsius with the SpotOn (3M) temperature monitoring system. The outcome description specifies temporal artery readings and says measurements were to be taken at incision and every 30 minutes while the patient was in the operating room. The reported primary value is the mean temperature at incision for each arm, accompanied by a standard deviation.

Temperature is a continuous measurement, so comparing group means provides a concise description of the average recorded temperature in the two randomized groups. The standard deviation describes the spread of participant readings within each group; it is not the uncertainty around the group mean. The comparison of means directly addresses the stated question about temperature at incision.

As a general statistical point, a continuous endpoint can retain information across the measurement scale rather than reducing observations to categories. That is useful when the research question concerns average temperature. However, a mean comparison does not show the full distribution of readings or the proportion of participants meeting a clinical threshold. No threshold definition or threshold-based primary result is reported in the registry record.

The endpoint is temporally specific: it is the reading at incision, not a summary of every operating-room reading or the whole perioperative period. Although repeated temperature readings are described, the registry record does not report a primary analysis that combines them over time. The posted endpoint therefore should be interpreted as a comparison at the designated incision time point.

7. Results Posted in the Registry

• Pre-Warming: mean 35.70 versus 35.40 on control; difference 0.30 (95% CI 0.11 to 0.49), standardized effect d = 0.62; z-test p = 0.002.

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.

Patient Temperature Prior to Entering OR as Measured by SpotOn (3M) Temperature Monitoring System.

• 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:
  • Pre-Warming: mean 36.70 versus 36.60 on control; difference 0.10 (95% CI -0.06 to 0.26), standardized effect d = 0.25; z-test p = 0.216.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pre-Warming and the control. The interval gives the range of effects that remain compatible with the data.

Patient Temperature 30 Minutes Following Incision as Measured by SpotOn (3M) Temperature Monitoring System.

• 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:
  • Pre-Warming: mean 35.70 versus 35.40 on control; difference 0.30 (95% CI 0.14 to 0.46), standardized effect d = 0.75; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Pre-Warming than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Patient Temperature on Arrival to Recovery Room as Measured by SpotOn (3M) Temperature Monitoring System.

• 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:
  • Pre-Warming: mean 35.40 versus 35.10 on control; difference 0.30 (95% CI 0.02 to 0.58), standardized effect d = 0.43; z-test p = 0.038.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Pre-Warming than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The additional posted temperature comparisons show a broad temporal pattern: the group averages were close before operating-room entry, while the pre-warming group had higher averages at subsequent recorded time points, including arrival in recovery. This direction is consistent with the primary comparison at incision. It describes the pattern of posted means; it does not establish a uniform difference for every participant or for every time point between those measurements.

The pre-operating-room comparison has an interval that includes zero and an unadjusted p-value of 0.216. The comparisons after incision and at recovery have intervals that exclude zero, with unadjusted p-values of <0.001 and 0.038, respectively. These are secondary results and should not be treated as equivalent to the designated primary endpoint. Their interpretation is also limited by the absence of reported multiplicity procedures and analysis methods for the collection of outcomes.

The registry lists secondary outcomes concerning postoperative shivering, intraoperative blood loss, perioperative cardiac events, and differences between temporal artery and SpotOn readings. Numeric results for these outcomes are not reported in the registry record. Their absence means that the available secondary temperature pattern cannot stand in for results on those other questions.

In general, when multiple outcomes or time points are examined, the chance of at least one apparently unusual result can increase if each is assessed independently without adjustment. That is one reason unadjusted secondary findings usually carry less weight than a prespecified primary comparison. The record does not report whether the secondary outcomes were prioritized, whether their analyses were prespecified, or whether any correction was used. The secondary findings are best viewed as descriptive context for the primary result rather than as independent confirmation.

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

• Patient Temperature Prior to Entering OR as Measured by SpotOn (3M) Temperature Monitoring System.
• Patient Temperature 30 Minutes Following Incision as Measured by SpotOn (3M) Temperature Monitoring System.
• Patient Temperature on Arrival to Recovery Room as Measured by SpotOn (3M) Temperature Monitoring System.
• Incidence of Postoperative Shivering in Recovery Room.
• Intraoperative Blood Loss.
• Incidence of Perioperative Cardiac Events.
• Temporal Artery Verus SpotOn (3M) Temperature Readings.

9. Statistical Interpretation

10. Statistical Methods Explained

The posted primary comparison is an unadjusted comparison of means for a continuous endpoint. Each arm has a reported mean, standard deviation, and participant count. The recalculated difference is expressed as Pre-Warming minus Control, so a positive value denotes a higher group mean in Pre-Warming. The comparison does not adjust for other variables or other outcome measurements in the information reported by the registry.

What does a mean difference represent?

A mean is the arithmetic average of the observations in a group. A difference between group means describes how far apart those averages are on the original measurement scale. Here, the scale is degrees Celsius, so the reported difference retains that unit. The contrast is interpretable as an average difference at incision, rather than as a relative change or a difference in the proportion meeting a threshold.

A mean does not describe the full distribution. Two groups can have different averages while their individual observations overlap, and a similar average can coexist with different patterns of spread. The standard deviations describe variability among observations around each group mean. They are not standard errors and are not confidence limits. The posted standard deviations, 0.47 for Pre-Warming and 0.49 for Control, describe the observed spread of the incision readings.

How should the confidence interval be read?

A confidence interval expresses the precision of an estimate under the statistical model used to construct it. In repeated use of the same procedure under its assumptions, intervals would capture the target parameter at the stated confidence level at the corresponding long-run rate. For an individual trial, the interval gives a range of values compatible with the data and method; it does not assign a probability to the true value after observing the interval.

The recalculated interval for the primary mean difference runs from 0.110 to 0.490 degrees Celsius. It excludes zero, which is consistent with the unadjusted p-value of 0.002 for a test of no mean difference. The interval is preferable to a p-value alone for seeing both the direction and precision of the estimate. It still does not answer whether the difference is important in practice, because a clinically meaningful threshold is not reported in the registry record.

What does an unadjusted p-value say?

In general, a p-value is calculated under a specified null hypothesis and statistical model. It describes how often data at least as incompatible with that null would occur if the null model and its assumptions held. It does not measure the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The primary unadjusted p-value is 0.002. Its unadjusted status matters because the registry lists several secondary outcomes and repeated temperature measurements, but does not report a multiplicity adjustment.

The registry record reports no sponsor analyses for the outcome. The mean difference, interval, and p-value discussed in the statistical comparison are recalculations from posted summary statistics, rather than a reported adjusted model. The record does not report a covariate-adjusted analysis, a model accounting for repeated readings, or an analysis population definition. Those methods should not be assumed.

Why does variability matter?

In general, the uncertainty of an estimated mean difference depends on the amount of variability in the observations and the number of observations. Greater variability tends to make an estimate less precise, while more observations can improve precision, assuming other conditions remain comparable. This relationship is why standard deviations and participant counts accompany mean comparisons. It does not mean that the observed estimate becomes a causal or clinically meaningful effect simply because it is precise.

The study describes temperature readings at incision and every 30 minutes in the operating room. Repeated observations from the same participant are generally related rather than independent. In general, a method that analyzes repeated measurements may need to account for that within-participant relationship. The registry record does not report such a method for the primary result, so the posted incision comparison should not be interpreted as a longitudinal estimate across the operating-room period.

What is not documented about the analysis?

The record does not report how the randomization sequence was generated or concealed, how missing temperature readings were handled, or whether all randomized participants were analyzed in their assigned groups. It also does not report a prespecified statistical analysis plan, sample-size justification, interim analyses, or adjustments for multiple comparisons. These are gaps in documentation, not evidence that a particular method was or was not used.

The trial's planning assumptions for the illustrative sample-size figures are separate from its original design assumptions. The original design assumptions are not reported in the registry record. The planning illustration uses a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects defined as stated fractions of the observed effect. It is a hypothetical planning exercise, not an account of the trial's actual design process.

11. Confidence Intervals and Precision

The primary mean-difference estimate is 0.3 degrees Celsius. Its recalculated 95% confidence interval extends from 0.110 to 0.490 degrees Celsius. Because the full interval is above zero, it supports a positive difference in average temperature for this unadjusted comparison. The interval also indicates uncertainty about the size of that difference: values across the stated range are compatible with the estimate and method.

Precision is not the same as importance. The interval quantifies sampling uncertainty under the assumptions behind the recalculation, but it does not establish a threshold for clinical relevance. The registry record does not state what difference would be considered meaningful. Nor does the interval show how readings are distributed for individual participants, or whether the group averages correspond to different rates of threshold events.

The standard deviations, 0.47 and 0.49 degrees Celsius, describe within-group spread. The confidence interval instead concerns the difference between the group means. These quantities answer different questions and should not be treated as interchangeable. The arm counts for the primary outcome are 47 and 51; the registry record does not describe missing-data handling or explain whether all randomized participants contributed to the outcome summary.

As a general point, confidence intervals depend on the model and data used to calculate them. The displayed interval is an unadjusted recalculation from posted summary statistics, not a reported sponsor interval. The registry record reports no analyses for the primary comparison, and it does not document adjustment for covariates, repeated measurements, or the family of outcomes. The interval therefore describes precision for this particular summary-statistic comparison, not for an undocumented broader model.

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 for 80% power and participants per arm for 90% power; they are not total event counts. For the primary endpoint, planning for 100% of the observed effect gives 41 participants per arm for 80% power and 54 participants per arm for 90% power. Planning for 75% of the observed effect gives 72 and 96 participants per arm, respectively. Planning for 50% of the observed effect gives 162 and 216 participants per arm, respectively.

In plain language, the 80% column gives the estimated number in each group for a design with an 80% chance of detecting the specified effect under the listed assumptions, if that effect and model are appropriate. The 90% column gives the corresponding number for a design with a 90% chance. These are planning probabilities, not guarantees for any particular study. The calculation assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect used is the stated fraction of the observed effect.

Smaller target effects require more participants because they are harder to distinguish from the variability in the outcome. The planning rows illustrate that pattern: the estimates increase as the assumed fraction of the observed effect decreases. These figures are illustrative calculations based on the observed effect, not the trial's original sample-size justification. The original design assumptions are not reported in the registry record. This is not observed power.

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 = 0.300; pooled standard deviation σ = 0.481.
2. n = 2 × (1.96 + 0.842)² × 0.481² / 0.300² = 40.3, rounded up to 41 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 <- 0.300000000000004                      # observed difference in means
sigma <- 0.480520551069358                     # 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(1626690)
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 = 41 (80% power), 54 (90% power)
 75% of observed effect: n per arm = 72 (80% power), 96 (90% power)
 50% of observed effect: n per arm = 162 (80% power), 216 (90% power)
power.t.test: 41.3 
Simulated power at n = 41 per arm: 0.800 (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 lists one primary temperature outcome and multiple secondary outcomes, including several temperature measurements at different times. It does not report a multiplicity adjustment, a hierarchy for interpreting outcomes, or a statistical analysis plan specifying how the collection of tests was to be handled. The posted p-values for the secondary temperature comparisons are unadjusted. Without a documented plan, the extent to which the outcome family was considered in the analysis is not reported in the registry record.

In general, testing many outcomes can increase the chance of at least one small p-value even when there is no true difference for any outcome. Adjustment procedures or a prespecified hierarchy can address this issue, but no such procedure is reported. This does not invalidate an individual result automatically; it means that secondary p-values should be interpreted with the number of outcomes and the lack of documented adjustment in mind.

The record reports no analyses under its analysis listings. It does not state the analysis population, whether analyses followed randomized assignment, how protocol deviations were handled, or how missing outcome measurements were treated. The outcome-specific participant counts are reported, but those counts alone do not identify why observations may be absent or whether all enrolled participants were analyzed. Missing-data methods are not reported in the registry record.

The study description mentions repeated temperature readings during the operating-room period, but the posted primary result concerns temperature at incision. No repeated-measures model or other method for jointly analyzing observations over time is reported. The record also does not describe covariate adjustment or interim analyses. These details should be treated as undocumented rather than inferred from the endpoint summaries.

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.

For Pre-Warming, the registry reports 0 participants with serious adverse events among 47 at risk and 0 participants with other adverse events among 47 at risk. For Control, it reports 0 participants with serious adverse events among 51 at risk and 0 participants with other adverse events among 51 at risk. These are the posted counts for the listed adverse-event categories.

Zero reported events in these groups does not establish that no event could occur, nor does it show that the groups have identical safety profiles. The counts describe what is recorded for the participants at risk in these summaries. The registry record does not provide event terms, additional safety analysis, or enough detail to assess the completeness of adverse-event collection.

Death counts are not reported in the registry record. The trial's termination reason is also not reported, and should not be inferred from the adverse-event figures. These safety summaries are separate from the primary temperature comparison and do not replace assessment of the other listed outcomes.

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

The posted primary data show a higher mean temperature at incision in the Pre-Warming group than in the Control group. The recalculated unadjusted difference is 0.3 degrees Celsius, and its confidence interval excludes zero. This is evidence of a difference in the average recorded endpoint for the analyzed groups under the assumptions of that comparison.

The result does not show that every participant in Pre-Warming had a higher temperature, or that the group difference applies at all points in the perioperative period. It also does not establish a change in a specific clinical event rate. The primary endpoint is a continuous temperature measurement, and the registry record does not report a threshold analysis or a clinically meaningful difference threshold.

The randomized parallel design is relevant when interpreting a between-group comparison, but the record lacks details on allocation concealment, participant flow, adherence, missing observations, and analysis populations. The posted comparison is an unadjusted recalculation from summary statistics, and no sponsor analysis is reported. These limits matter when judging how fully the available result represents the intended randomized comparison.

The secondary temperature results are directionally consistent with the primary comparison at later measurement times, while the pre-operating-room comparison is less conclusive by its interval and unadjusted p-value. Other listed secondary outcomes do not have numeric results reported in the registry record. The record therefore does not provide a full picture across all questions named in the trial.

In general, statistical evidence about an average difference is not, by itself, a recommendation about care. Practical interpretation depends on clinical context, outcome relevance, measurement properties, and the balance of benefits and harms. Those judgments cannot be settled by the posted mean difference alone. The safety summaries report no adverse events in the listed categories for either arm, but the recorded counts do not establish absence of risk.

17. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation should begin with the endpoint definition. The primary outcome is a temperature reading at incision, while the study description also refers to repeated operating-room measurements and the registry lists outcomes at other perioperative times. Keeping those measurement times distinct prevents a single comparison from being mistaken for an overall trajectory.

The results also demonstrate the difference between an estimate and its uncertainty. A mean difference gives the direction and scale of the average contrast; a confidence interval conveys the precision of that contrast under the calculation method. Neither alone determines clinical importance. The registry record does not state a threshold for meaningful temperature change, so statistical evidence should not be substituted for that missing context.

Documentation affects what can be assessed. The record identifies randomization and a parallel design, but does not report the sequence-generation method, a sample-size justification, handling of missing data, an analysis population, or procedures for multiplicity. The listed termination status has no accompanying reason. These omissions do not prove that methods were absent, but they constrain independent evaluation of the analysis and its scope.

Finally, planning calculations derived from the observed effect are useful for illustrating how assumptions about target effect size influence design size. They are not evidence about the trial's original planning process or its achieved power. Distinguishing such planning illustrations from trial-design documentation is an important part of 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 to evaluate the primary comparison are not reported in the registry record. The arm descriptions are empty, and the record names two warming devices without mapping them to the Pre-Warming and Control arms. It also does not describe what the control group received. The precise implementation of the contrast therefore cannot be reconstructed from the registered descriptions.

The record does not report participant eligibility criteria, participant flow, reasons for missing outcome measurements, adherence, or the analysis population. Although the primary outcome summaries include 47 and 51 participants, the registry does not explain the relationship of those counts to the enrollment figure of 100. The handling of missing data is not reported.

The endpoint description includes temperature readings every 30 minutes in the operating room, but the reported primary result concerns the reading at incision. The record does not report how repeated measurements were analyzed or whether any other time-point measurements were incorporated into a longitudinal analysis. It also does not report a clinically meaningful threshold for interpreting the magnitude of a temperature difference.

The study is marked terminated, but the reason is not reported. The registry does not report the original sample-size assumptions, the analysis plan, interim analyses, multiplicity handling, or a sponsor analysis for the posted primary comparison. These gaps limit assessment of whether the posted summary-statistic comparison matches the intended analysis. Numeric results for several listed non-temperature secondary outcomes are not reported in the registry record, leaving those parts of the trial question unanswered by the posted results.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Prospective Trial of the Effect of Preoperative Forced-air Warming on Perioperative Body Temperature Following Neuraxial Anesthesia in Total Hip Arthroplasty Patients — NCT01626690.
• Registry record last updated 2016-08-15; status last verified 2016-07.
• Results first posted 2016-08-15.
• 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

NCT01626690 is a Phase 4, randomized, unmasked, parallel-group trial of preoperative forced-air warming in total hip arthroplasty patients following neuraxial anesthesia. Enrollment was 100; the record lists the trial as terminated, with a start of 2012-05 and primary completion of 2014-12. The reason for termination is not reported in the registry record.

The primary endpoint was mean temperature at incision measured with the SpotOn (3M) system. The posted group means were 35.7 degrees Celsius for Pre-Warming and 35.4 degrees Celsius for Control. The unadjusted recalculated mean difference was 0.3 degrees Celsius, with a 95% confidence interval from 0.110 to 0.490 and an unadjusted p-value of 0.002. The registry record does not report a sponsor analysis or details of the analysis population, missing-data handling, or multiplicity procedures.