Lifeflight: Fentanyl Versus Morphine: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Lifeflight: Fentanyl Versus Morphine (NCT00580489), a randomized na study. The primary outcome is Mean Change in Numeric Pain Score (NPS) From First to Last Dose.

2. Clinical Question

3. Trial Design

The registry describes a randomized, triple-masked, parallel-group study of fentanyl versus morphine in an aeromedical setting. The official title is “Efficacy and Adverse Events of Morphine and Fentanyl in an Aeromedical Setting.” The study is listed as completed, with MetroHealth Medical Center as sponsor. Its recorded start is 2006-08 and its primary completion is 2008-12. The phase is listed as NA.

Trauma patients transported by helicopter were assigned to one of the two medication groups. The brief summary says that the researchers randomized either fentanyl or morphine and recorded pain-scale information while observing for adverse events. It also says the study was exempt from informed consent by the MetroHealth Medical Center institutional review board because two standards of care were used and there was no increased clinical risk to the patient due to the study. Further details about the randomization procedure, masking roles, or allocation concealment are not reported in the registry record.

The registry reports enrollment of 204. For the primary-outcome analysis, 4 subjects were excluded: 1 from the Morphine Group and 3 from the Fentanyl group. The analyzed baseline participants were 103 for morphine and 97 for fentanyl. These analyzed group counts, rather than the overall enrollment, are the denominators associated with the posted primary-outcome results.

The primary endpoint was mean change in numeric pain score from first to final medication dose. Medication was administered over a mean transport time of 37 minutes in the Morphine group and 43 minutes in the Fentanyl group. The registry also lists recording of instances of narcotic side effects as a secondary outcome. The trial's original statistical analysis plan and its own sample-size assumptions are 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

Analysis population for the primary outcome, as defined in the registry: 4 subjects were excluded from analysis, 1 from the Morphine Group and 3 from the Fentanyl group to achieve the baseline participants for data analysis 103 morphine and 97 fentanyl.

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 Mean Change in Numeric Pain Score (NPS) From First to Last Dose, measured over Medication was administered over a mean transport time of 37 minutes in the Morphine group and 43 minutes in the Fentanyl group..

The primary endpoint is the mean difference in numeric pain score from the first dose to the final dose of medication administered. The numeric pain score runs from 0 to 10, with 0 described as least pain and 10 as most pain. The registry defines a significant mean pain-score change as greater than or equal to 2. That threshold is part of the endpoint description; the posted primary result is a group mean change, not a count of participants whose changes crossed the threshold.

A score measured at more than one time point can describe how the recorded pain measure changes during treatment. Using the first and final dose provides a defined interval for the comparison, while a group mean summarizes the changes across analyzed participants. The endpoint is continuous, so its reported group summaries include a mean and standard deviation. The registry reports mean changes of 2.2 for morphine and 2.5 for fentanyl. The exact subtraction convention used to form each participant’s change is not described beyond the wording “from the first to the final dose.”

The recorded mean transport times were 37 minutes in the Morphine group and 43 minutes in the Fentanyl group. Those times provide context for the period over which medication was administered, but the registry does not report an adjusted comparison for transport duration. The endpoint therefore describes the posted mean score changes in the analyzed groups, rather than a result standardized to a common transport time.

7. Results Posted in the Registry

• Fentanyl: mean 2.50 versus 2.20 on control; difference 0.30 (95% CI -0.36 to 0.96), standardized effect d = 0.13; z-test p = 0.374.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is continuous: a numeric score summarized by its mean. The posted comparison reports each group's mean and standard deviation, then gives a mean difference for fentanyl relative to morphine. These quantities describe the location and spread of the analyzed observations. They do not reveal the individual score changes or their distribution.

What does the mean difference represent?

The mean difference is the fentanyl group mean minus the morphine group mean as represented by the posted comparison. Its estimate is 0.3 score points. A difference near zero indicates similar group means in the observed data; a positive or negative value indicates which group's mean is numerically larger, according to the comparison's direction. The estimate is unadjusted, so it is not described as controlling for other participant or transport characteristics.

In general, a mean is sensitive to unusually high or low observations. A standard deviation describes how spread out observations are around the mean, but it does not show the shape of that spread or whether outliers are present. The registry reports standard deviations of 2.0 for morphine and 2.7 for fentanyl. It does not report participant-level data, distribution diagnostics, or an analysis addressing departures from assumptions.

How should the confidence interval be read?

A confidence interval expresses uncertainty around an estimate under the statistical method used. The interval for the mean difference extends from -0.362 to 0.962. Because this range includes zero, it does not isolate a direction of difference at the interval's stated confidence level. The confidence level and the method used to calculate this interval are not reported in the registry record. In general, an interval is not a guarantee that the true value lies within its endpoints; it is a measure of statistical uncertainty under the method's assumptions.

What does the p-value add?

The unadjusted p-value is 0.374. In general, a p-value measures how unusual data at least as incompatible with a null hypothesis would be if that null hypothesis and the analysis assumptions were correct. It is not the probability that the null hypothesis is true, and it does not measure the probability that the result is due to chance. The registry does not describe the sponsor's statistical test or analysis model. The reported p-value should therefore be read as an unadjusted comparison, not as a fully specified account of the trial's original analysis.

There are two outcome groups with analyzed counts of 103 and 97. The group means and standard deviations provide a basis for an unadjusted summary comparison, but those summaries cannot show whether the randomization achieved balance on other characteristics. No adjusted outcome analysis is posted. The registry reports no posted analyses, so details such as model covariates, handling of repeated measurements, and sensitivity analyses are not reported in the registry record.

What does the standardized effect describe?

The reported standardized effect, 0.127, relates the group mean difference to the pooled standard deviation, which is 2.365. In general, standardizing an effect can make outcomes measured on different scales easier to compare, but it removes the original score units and relies on the variability estimate. It is not a probability of benefit or a measure of clinical importance. The score-unit estimate and interval remain important for understanding the actual endpoint.

The endpoint's description says that a significant mean pain-score change is greater than or equal to 2. This definition concerns a change threshold, whereas the reported comparison is between group means. A threshold applied to each participant would require the distribution of individual changes or a reported count meeting the threshold. Such a participant-level threshold analysis is not reported in the registry record.

What do planning calculations mean?

The planning illustrations use fractions of the observed effect and list participants per arm for 80% and 90% power. Their stated assumptions are a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. In general, power is the probability that a planned analysis will detect an effect of a specified size under the assumptions used. Planning calculations describe hypothetical future study requirements; they are distinct from the analysis of the enrolled participants. The registry's original sample-size justification, design assumptions, and any protocol-based target are not reported.

These calculations use the observed effect as their starting point, so their interpretation depends on that estimate and the stated planning assumptions. They do not describe a confirmed requirement for a future trial, and they cannot establish what effect would be clinically important. General statistical concepts in this explanation describe how these methods are commonly interpreted; they do not supply missing details about the trial's original analysis plan.

10. Confidence Intervals and Precision

The unadjusted mean difference in numeric pain score is 0.3 for fentanyl relative to morphine. Its confidence interval runs from -0.362 to 0.962. The interval includes zero and spans values favoring either direction of the numerical comparison. It therefore indicates that the estimate is not precise enough to distinguish a small positive difference from a small negative difference using this interval alone.

In general, a confidence interval combines an estimate with uncertainty under a statistical method. A narrower interval indicates greater precision, while a wider interval indicates less precision. Precision is not the same as clinical importance: an estimate can be precise but small, or uncertain while including potentially meaningful values. The registry defines a significant mean change as greater than or equal to 2, but that threshold is not a threshold for the between-group mean difference, and the posted interval should not be compared with it as if the two quantities were interchangeable.

The confidence level and calculation method for the posted interval are not reported in the registry record. The interval should therefore be read as the registry's reported uncertainty range, without assuming an undocumented analysis procedure. The unadjusted p-value is 0.374, a related summary that also does not establish equality or prove that an effect is absent.

The analyzed group sizes are 103 for morphine and 97 for fentanyl. The interval reflects uncertainty in the comparison based on the posted results; it does not account for unreported sources of uncertainty such as the reasons for exclusions or any missing-data handling. The registry does not report participant-level data, an adjusted estimate, or a sensitivity analysis that could clarify how those choices affect precision.

11. 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.

For this continuous pain-score outcome, the planning figures are participants per arm, not total events. The planning assumptions are a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario uses the stated fraction of the observed effect. The registry's original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the planned number of participants per arm under which the calculation has 80% power to detect the specified effect, assuming the planning model and assumptions hold. The 90% power column gives the corresponding number per arm for 90% power. Power describes a planned study's probability of detecting a specified effect under its assumptions; it is not the probability that the observed result is correct. These planning figures are not observed power.

The scenarios are planning for 100% of the observed effect, planning for 75% of the observed effect, and planning for 50% of the observed effect. For 100% of the observed effect, the figures are 976 participants per arm for 80% power and 1,307 participants per arm for 90% power. For 75% of the observed effect, they are 1,735 and 2,323 participants per arm, respectively. For 50% of the observed effect, they are 3,904 and 5,226 participants per arm, respectively.

Smaller effects require more participants to detect under the same planning assumptions. These values are illustrations derived from the observed comparison, not the original trial's design requirements. The registry does not report whether the original enrollment target was based on a different assumed effect, a different power target, or another design consideration.

12. 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 = 2.365.
2. n = 2 × (1.96 + 0.842)² × 2.365² / 0.300² = 975.9, rounded up to 976 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 <- 0.3                      # observed difference in means
sigma <- 2.36540726200617                     # 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(580489)
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 = 976 (80% power), 1,307 (90% power)
 75% of observed effect: n per arm = 1,735 (80% power), 2,323 (90% power)
 50% of observed effect: n per arm = 3,904 (80% power), 5,226 (90% power)
power.t.test: 976.9 
Simulated power at n = 976 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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary outcome as mean change in numeric pain score from the first to the final dose. It also lists one secondary outcome: recording of instances of narcotic side effects. The registry reports two outcome measures and one posted secondary outcome. It does not report a multiplicity strategy, such as whether or how the analysis accounted for testing more than one outcome or multiple comparisons.

No analyses are posted in the registry record. The mean difference, confidence interval, and p-value available for the primary outcome are unadjusted recalculations from posted summary statistics. The registry does not describe an original sponsor analysis, its statistical model, or whether any planned analyses were changed. The discrepancy indicator is false, so there is no recorded discrepancy between a recalculation and a sponsor analysis.

For the primary outcome, 4 subjects were excluded from analysis: 1 from the Morphine Group and 3 from the Fentanyl group. The analysis population is described as 103 morphine and 97 fentanyl participants. Reasons for exclusion, the timing of those exclusions, and whether excluded participants had missing scores or another reason for exclusion are not reported in the registry record. No imputation method or other missing-data procedure is reported.

The registry identifies the study as randomized, but the outcome record does not provide a detailed analysis-population definition or a participant flow by randomized assignment. Whether the analysis followed an intention-to-treat principle, a per-protocol principle, or another approach is not reported in the registry record. No sensitivity analyses addressing missing outcomes or exclusions are posted. These omissions limit assessment of how the analyzed groups relate to all enrolled participants and how robust the result is to alternative handling of unavailable data.

14. 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 serious adverse-event record lists 103 participants at risk in the Morphine 4 mg iv group and 97 at risk in the Fentanyl 50mcg IV group. The registry records zero affected participants for serious adverse events in each group. It also records zero affected participants for other adverse events in each group. No serious adverse-event terms are listed. Death counts are not reported in the registry record.

These figures describe the entries posted for the analyzed safety groups; they do not establish that no adverse events of any kind occurred beyond the recorded categories, nor can zero recorded events rule out uncommon events. The record does not provide additional details about event definitions, monitoring procedures, timing, or how many events occurred when one participant experienced more than one event. It lists recording of instances of narcotic side effects as a secondary outcome, but a separate detailed set of side-effect results is not reported in the registry record.

The at-risk counts are denominators for the posted adverse-event entries. They should not be confused with the total enrollment of 204 or interpreted as evidence that the groups have identical safety outcomes. The registry entries are descriptive counts, not a statistical comparison of adverse-event risk.

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

The posted primary-outcome estimate describes a small numerical difference between the group means: 2.5 for fentanyl and 2.2 for morphine, with an unadjusted mean difference of 0.3. The confidence interval, from -0.362 to 0.962, includes zero and leaves uncertainty about the direction and size of the difference. The p-value is 0.374. Taken together, these statistics do not establish that the groups differ, but they also do not demonstrate that the groups are equivalent.

The registry's endpoint is a mean change in numeric pain score from the first dose to the final dose. Its stated threshold for a significant mean change is greater than or equal to 2. The posted group-level means do not show how many individual participants met that threshold, and the registry does not report a separate threshold-based comparison. The endpoint is therefore best understood as a comparison of average changes, not as a report of individual response rates.

The trial also records zero affected participants for serious adverse events and zero affected participants for other adverse events in both groups. These are the posted counts, not proof that the treatments have identical safety or that events cannot occur. The registry does not report death counts or detailed event terms. In addition, the record describes a secondary outcome for narcotic side effects but does not post a separate detailed analysis of that outcome.

These findings apply to the analyzed groups of trauma patients transported by helicopter, with mean transport times of 37 minutes for morphine and 43 minutes for fentanyl. Four subjects were excluded from the primary-outcome analysis, and the reasons are not reported. The comparison does not provide an adjusted analysis or a cost outcome. Although the study summary mentions the relative expense of fentanyl and morphine, the posted result does not quantify costs or establish a cost-effectiveness conclusion.

In general, a non-significant comparison should not be treated as proof of no effect. The uncertainty interval and the limits of the registry record matter when interpreting what the data can support. No treatment recommendation follows from these posted statistics.

16. Why This Trial Matters Statistically

This trial illustrates why an estimate should be considered together with its uncertainty. The mean difference of 0.3 gives a direct comparison in the original pain-score units, while the confidence interval from -0.362 to 0.962 shows that the estimate does not pin down a single direction or size with precision. A p-value alone would not communicate that range of plausible values.

It also highlights the distinction between an outcome threshold and a group-average comparison. The registry defines a significant mean score change as greater than or equal to 2, while the posted comparison concerns the difference between group means. Those are not the same statistical question. Without a reported count of individual participants reaching the threshold, the group mean cannot answer how frequently that threshold was reached.

The registry's planning illustrations show how sample-size requirements can depend on the effect selected for planning. Smaller effects need more participants under the stated assumptions. Because the illustrations start from the observed effect, they should be read as planning scenarios rather than as evidence that the original study was designed to detect that effect. The original design justification is not reported in the registry record.

Finally, transparent interpretation depends on knowing who was analyzed, how missing outcomes were handled, and which analyses were prespecified. The record reports exclusions and analyzed group sizes, but does not report reasons for exclusion, a detailed analysis plan, or a missing-data method. Recognizing these gaps is part of evaluating the strength and limits of a registry result, particularly when no adjusted or sensitivity analyses are posted.

17. 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 registry record has several limitations for interpreting the primary result. It does not describe the original statistical analysis plan, the method used for the confidence interval, the test underlying the p-value, or any covariate adjustment. No analyses are posted. The available comparison is an unadjusted recalculation from summary statistics, so it cannot provide details that require participant-level data.

Four subjects were excluded from the primary-outcome analysis, including 1 from the Morphine Group and 3 from the Fentanyl group. The reasons for exclusion and the handling of any unavailable outcome data are not reported in the registry record. The record does not identify whether the analysis population followed an intention-to-treat or another principle. These details matter when assessing how well the analyzed groups represent all enrolled participants.

The outcome is a mean change between first and final medication doses. The registry does not report the distribution of individual changes, the number meeting the stated threshold of greater than or equal to 2, or an adjusted comparison of that threshold. Transport times are reported as group means of 37 minutes and 43 minutes, but the record does not report an analysis accounting for transport time.

The adverse-event entries report zero affected participants for both serious and other adverse events in each group, while deaths are not reported in the registry record. Event definitions, monitoring details, and a separate detailed analysis of the listed secondary side-effect outcome are not reported. The registry also does not post a cost analysis, despite noting relative medication expense in the study summary. These limitations restrict what can be concluded from the posted outcomes; they do not establish that unreported analyses or events were absent from the conduct of the study.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Lifeflight: Fentanyl Versus Morphine — NCT00580489.
• Registry record last updated 2022-08-16; status last verified 2022-07.
• Results first posted 2022-08-16.
• 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.

21. Record Summary

NCT00580489 is a completed randomized, triple-masked, parallel-group comparison of morphine and fentanyl in trauma patients transported by helicopter. MetroHealth Medical Center is listed as sponsor. The registry reports enrollment of 204 and analyzed primary-outcome groups of 103 for morphine and 97 for fentanyl after 4 subjects were excluded.

The primary endpoint is mean change in numeric pain score from first to final dose. The posted means are 2.2 for morphine and 2.5 for fentanyl; the unadjusted mean difference is 0.3, with a confidence interval from -0.362 to 0.962 and p = 0.374. The registry also lists narcotic side effects as a secondary outcome and records zero affected participants for serious and other adverse events in both groups. Death counts are not reported in the registry record.

The registry does not report the original sample-size justification, a detailed analysis plan, reasons for primary-outcome exclusions, or a missing-data method. The planning illustrations are based on the observed effect and stated assumptions, rather than the trial's reported original design.