Spinal Anaesthesia With Levobupivacaine 0.5% and Ropivacaine 0.75% for Lower Limb Orthopaedic Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Spinal Anaesthesia With Levobupivacaine 0.5% and Ropivacaine 0.75% for Lower Limb Orthopaedic Surgery (NCT02201784), a randomized phase 4 study. The primary outcome is Duration of Analgesia.

2. Clinical Question

The clinical question concerns a comparison of two spinal anaesthesia regimens in the context of lower limb surgery. The primary measure is a time in minutes, summarized in the registry record as a mean and standard deviation for each group. The posted outcome summaries give a mean of 309.8 minutes for levobupivacaine and 249.5 minutes for ropivacaine. The recalculated, unadjusted mean difference is -60.33 minutes for ropivacaine relative to levobupivacaine, with a confidence interval from -76.11 to -44.55 minutes.

This outcome is defined by the patient’s first request for analgesia, rather than by a direct measure of pain intensity. The clinical question is therefore about the timing of that request under the study conditions. The record also names sensory and motor block outcomes, which describe other aspects of the spinal block. These measures provide related context but are not interchangeable with the primary endpoint. The registry record does not report additional details about eligibility, clinical setting, analgesic policy, or the reasons a participant might not contribute a primary outcome measurement.

3. Trial Design

The registry record describes a completed, randomized, double-masked, parallel-group phase 4 study sponsored by Aligarh Muslim University. The condition listed is lower limb surgery. The record gives an enrollment of 60. It does not report further details about the study setting, the randomization process, or which people were masked.

The two groups received different intrathecal drug regimens. The levobupivacaine group is described as receiving 15 mg of levobupivacaine 0.5%, and the ropivacaine group as receiving 22.5 mg of ropivacaine 0.75%. The primary outcome summaries list 28 participants for levobupivacaine and 30 for ropivacaine. The registry record does not explain the difference between those outcome counts and the overall enrollment, or describe exclusions, withdrawals, or missing outcome measurements.

The primary outcome was duration of analgesia, measured in minutes and defined as the time to the patient’s first analgesic request. Its stated timeframe is 8 hours. The registry also lists secondary measures concerning sensory block onset, maximum sensory blockade, cephalic spread, motor block onset, and motor block duration. Arm-level summaries are present for three of these secondary measures; results for the other listed measures are not reported in the registry record.

Although the record identifies randomization and double masking, it does not report allocation concealment, the masking procedures, the original statistical analysis plan, or the method used to handle missing data. The record also lists no reported analyses. Those omissions limit the detail available for assessing how the study was conducted and how its outcome comparisons were originally analyzed.

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.

Before assignment: Patients who met any of the exclusion criteria or those who did not gave consent were excluded.

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 Duration of Analgesia, measured over 8 hours.

Duration of analgesia is the primary endpoint. The registry defines it as the time until the patient makes the first request for analgesia, records it in minutes, and gives a timeframe of 8 hours. The arm summaries report means and standard deviations.

This definition gives the endpoint a practical interpretation: it records when a participant first asks for additional analgesia after the spinal anaesthetic. As a general statistical point, an outcome is most interpretable when its measurement rule is clearly stated. Here, the stated rule identifies a specific event and a time scale. It does not, by itself, describe the participant’s pain intensity, the amount of later analgesia used, or whether requests were managed in a uniform way; those details are not reported in the registry record.

The mean is a summary of the recorded times within each group, while the standard deviation describes how dispersed those times were around the group mean. The posted means are 309.8 minutes for levobupivacaine and 249.5 minutes for ropivacaine; the corresponding standard deviations are 36.45 and 22.83 minutes. The group means describe the observed summaries, not a guarantee that every participant had a time close to the mean.

Because the outcome is based on a request, it should be read as an operational measure of analgesia duration under the study conditions. The registry record does not report further measurement instructions, rules for participants who did not request analgesia within the stated timeframe, or details about other analgesic care.

7. Results Posted in the Registry

• Ropivacaine 0.75%: mean 249.50 versus 309.83 on control; difference -60.33 (95% CI -76.11 to -44.55), standardized effect d = -2.00; z-test p = <0.001.

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.

Onset of Sensory Block at T10

• 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:
  • Ropivacaine 0.75%: mean 7.33 versus 13.50 on control; difference -6.17 (95% CI -8.21 to -4.13), standardized effect d = -1.59; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Ropivacaine 0.75% than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Time to Maximum Cephalic Spread of Sensory Block

• 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:
  • Ropivacaine 0.75%: mean 13.17 versus 20.33 on control; difference -7.16 (95% CI -9.40 to -4.92), standardized effect d = -1.67; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Ropivacaine 0.75% than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Onset of Motor Block to Bromage3

• 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:
  • Ropivacaine 0.75%: mean 7.83 versus 12.17 on control; difference -4.34 (95% CI -6.16 to -2.52), standardized effect d = -1.24; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Ropivacaine 0.75% than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The available secondary results follow a broadly consistent direction: the reported means for sensory block onset, time to maximum cephalic spread, and motor block onset are lower in the ropivacaine group than in the levobupivacaine group. The recalculated unadjusted comparisons for those outcomes have confidence intervals that lie below zero and unadjusted p-values of <0.001. This pattern is related to, but distinct from, the primary comparison of time to first analgesic request.

These outcomes describe features of sensory and motor block rather than the timing of a request for analgesia. A consistent direction across related measures can help readers understand the overall pattern of the posted summaries, but it does not make the outcomes interchangeable or demonstrate that one outcome explains another. The registry record does not report an analysis linking the secondary measures to the primary endpoint.

Secondary results generally carry less weight when the number of outcomes considered, prespecification, and multiplicity handling are unclear. Each additional comparison creates another opportunity for a result to appear notable by chance. As a general statistical principle, a multiplicity strategy can help control that risk, but the registry record does not report whether any such strategy was used. The unadjusted secondary p-values should therefore be read as individual comparisons, not as a set of confirmatory tests.

The record lists other secondary outcome titles, including median maximum level of sensory blockade and duration of motor block, but their arm-level results are not reported in the registry record. The registry record also does not report a complete secondary analysis plan, missing-data approach, or analysis population for these outcomes. The available pattern is thus descriptive and should not be extended to unreported measures or interpreted as evidence about outcomes not presented.

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

• Onset of Sensory Block at T10
• Median Maximum Level of Sensory Blockade
• Time to Maximum Cephalic Spread of Sensory Block
• Onset of Motor Block to Bromage3
• Duration of Motor Block

9. Statistical Interpretation

10. Statistical Methods Explained

The reported outcome is continuous: duration of analgesia is measured in minutes, and the registry summarizes it using a mean and standard deviation. A mean gives the arithmetic average of the recorded values in a group. A standard deviation describes the spread of those values around the mean. These summaries are useful for comparing group averages, but they do not show the full distribution or reveal whether a small number of observations strongly influenced the average.

What does the mean difference represent?

The comparison is expressed as a mean difference for ropivacaine relative to levobupivacaine. The recalculated estimate is -60.33 minutes. The sign depends on the order of subtraction: a negative value means the ropivacaine group’s mean is lower than the levobupivacaine group’s mean. The estimate is a difference between group averages, not a statement that every participant in one group differed from every participant in the other by that amount.

The recalculated comparisons use the posted summary statistics and are unadjusted. An unadjusted comparison does not account for additional covariates or other model terms. This is not evidence that the investigators used the same method in their original analysis. The registry record lists no reported analyses and does not describe the trial’s statistical analysis plan, so details such as the original test, model, or covariate adjustment are not reported in the registry record.

How should the confidence interval be read?

A confidence interval gives a range of estimates compatible with the observed data under the method’s assumptions. For the primary comparison, the recalculated interval is -76.11 to -44.55 minutes. Because the interval lies on one side of zero, it is consistent with a lower group mean for ropivacaine relative to levobupivacaine. The interval’s width also matters: it reflects uncertainty in the estimated difference. A confidence interval is not an interval containing a stated proportion of individual participant outcomes, and it does not account for uncertainty from every design or reporting limitation.

The unadjusted p-value for the primary comparison is <0.001. In general, a p-value describes how unusual data at least as incompatible with a null comparison would be if the null and the test assumptions held. It does not measure the size or clinical importance of the difference, and it is not the probability that the null is true. It also does not resolve questions about bias, missing data, outcome selection, or whether an analysis was prespecified.

Why do the registry’s analysis details matter?

Randomization is intended, in general, to support a fair comparison by assigning participants to groups without choosing their allocation based on their characteristics. The registry identifies this study as randomized and double-masked, but does not describe the allocation sequence, concealment, or masking procedures. The design labels therefore identify the stated design but do not permit a detailed appraisal of how those procedures were implemented.

The arm-level outcome counts are 28 for levobupivacaine and 30 for ropivacaine. The registry’s overall enrollment is 60. The record does not explain why the outcome counts differ from the enrollment information, whether any measurements were missing, or how participants without outcome measurements were treated. In general, missing observations can affect both the group summaries and the comparison, especially if the reasons for missingness differ between groups or relate to the outcome. No specific missing-data assumption can be inferred from this record.

The posted standard deviations describe variability within each group. They are not standard errors or confidence intervals. A standard error, in general, describes the uncertainty of an estimated statistic; a confidence interval uses that uncertainty to express a range of plausible values. The posted arm summaries include standard deviations, while the comparison results include recalculated confidence intervals. These quantities answer different questions and should not be used interchangeably.

The study also reports secondary outcome summaries, but the registry record lists no reported analyses and does not describe whether the secondary outcomes were prespecified, whether any correction for multiple comparisons was used, or how secondary results were selected for reporting. General statistical reasoning treats multiple unadjusted comparisons cautiously because examining several outcomes can make apparently strong findings more likely by chance. The available results can be described, but the record does not support an assumption that multiplicity was addressed.

What does the reported analysis not establish?

The registry’s posted results do not supply a full analysis plan, participant-level data, or information about the distribution of each continuous measure. The unadjusted calculations are consequently limited to comparisons that can be made from the posted means, standard deviations, and group counts. They do not adjust for possible baseline differences, explore alternative distributional assumptions, or establish whether other reasonable analytic choices would produce the same result.

These methods explain how to read the displayed summaries and recalculated comparisons. They do not reconstruct unreported trial procedures. Where a design or analysis detail is absent, it is not reported in the registry record.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data estimate a group difference. For the primary outcome, the recalculated mean difference is -60.33 minutes, with a confidence interval from -76.11 to -44.55 minutes. The interval excludes zero and is bounded on both sides, giving a range of estimates under the recalculation’s assumptions. It is not a range of individual durations, nor does it account for possible bias or missing outcome information.

The group means and standard deviations provide additional context. Levobupivacaine has a mean of 309.8 minutes and a standard deviation of 36.45; ropivacaine has a mean of 249.5 minutes and a standard deviation of 22.83. Standard deviations describe variation among observations in each group. They do not directly measure the precision of the difference, which also depends on the amount of outcome information and the method used to estimate uncertainty.

The confidence interval for the primary comparison is a recalculated, unadjusted interval based on the posted summaries. The registry record does not report an original analysis or its uncertainty calculation. The interval should therefore be interpreted as a result of the stated recalculation, not as confirmation of a particular prespecified analysis. Its apparent precision does not address limitations such as unreported missing-data handling, study conduct details, or multiplicity across outcomes.

The secondary comparisons also have confidence intervals that do not include zero, but those estimates are unadjusted and arise among multiple outcomes. Precision within an individual comparison does not remove the broader uncertainty introduced when several outcomes are considered without a reported multiplicity plan. The registry record does not report such a plan.

Confidence intervals are most informative when read alongside the outcome definition, group summaries, study design, and analysis assumptions. In this case, the interval indicates the range of recalculated differences compatible with the posted primary summaries under the calculation’s assumptions. It does not by itself establish clinical importance, generalizability, or the absence of systematic error.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size table and curve are planning illustrations based on fractions of the observed effect, rather than a record of the trial’s original design calculation. For these continuous outcomes, the figures are participants per arm. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The trial’s own original sample-size assumptions are not reported in the registry record.

For the primary outcome, planning for 100% of the observed effect gives 4 participants per arm for 80% power and 6 participants per arm for 90% power. Planning for 75% of the observed effect gives 7 participants per arm for 80% power and 10 participants per arm for 90% power. Planning for 50% of the observed effect gives 16 participants per arm for 80% power and 22 participants per arm for 90% power.

In general, the 80% power column describes the planned chance of detecting the specified effect under the stated assumptions if that effect is real; the 90% column uses a higher target chance of detection. These planning values are not observed power. Smaller effects require more participants under the same assumptions, as illustrated by the larger per-arm figures for smaller fractions of the observed effect.

The values depend on the observed effect used as the planning reference. They should not be read as a justification for the study’s enrollment or as proof that the study was designed around these assumptions. The registry record does not report the investigators’ original sample-size calculation. Planning estimates also do not account for details absent from the record, such as the original analysis model or how missing outcomes were anticipated.

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 = -60.330; pooled standard deviation σ = 30.174.
2. n = 2 × (1.96 + 0.842)² × 30.174² / -60.330² = 3.9, rounded up to 4 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 <- -60.33                      # observed difference in means
sigma <- 30.1742929849708                     # 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(2201784)
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 = 4 (80% power), 6 (90% power)
 75% of observed effect: n per arm = 7 (80% power), 10 (90% power)
 50% of observed effect: n per arm = 16 (80% power), 22 (90% power)
power.t.test: 5.1 
Simulated power at n = 4 per arm: 0.661 (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 does not report whether the investigators adjusted for multiple comparisons, ranked outcomes for testing, or specified a confirmatory sequence. It lists a primary outcome and multiple secondary outcome titles, while the posted secondary comparisons include unadjusted p-values. Without a reported multiplicity plan, the secondary p-values should not be treated as if they had been adjusted for the number of outcomes examined.

As a general statistical matter, testing multiple outcomes can increase the chance of at least one apparently strong result even when no corresponding effect exists. Adjustment procedures or a prespecified hierarchy can address this issue, but neither should be assumed in the absence of documentation. The primary outcome is distinct in the registry listing, yet the record does not provide an analysis plan showing how it was selected, whether it was the sole primary measure, or how secondary testing was intended to be interpreted.

The registry record lists no reported analyses. It does not state whether the analysis followed an intention-to-treat principle, whether any per-protocol or other population was used, or how randomized participants were included in each outcome analysis. The primary outcome summaries list 28 participants for levobupivacaine and 30 for ropivacaine, while the enrollment is 60. The record does not explain the relationship between these counts or report exclusions and withdrawals.

Missing-data handling is also not described. The record does not say whether all participants had an outcome measurement, how an unavailable measurement was treated, or whether the analysis made assumptions about missingness. In general, missing data can affect estimates and their uncertainty when the likelihood of a missing value is related to group assignment or outcome status. The available summaries do not permit an assessment of that possibility.

These omissions do not show that the investigators failed to use an analysis plan or appropriate methods. They mean that such methods are not reported in the registry record and cannot be evaluated from the posted information. The unadjusted recalculations should be understood within that reporting limit.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record reports serious adverse events for groups with 30 participants at risk in each group. It records zero participants affected by a serious adverse event in the levobupivacaine group and zero in the ropivacaine group. The serious-event terms list is empty. The death counts are not reported in the registry record.

These figures describe what was recorded in the registry for the stated groups and at-risk counts. A recorded zero means no serious adverse events were listed as affecting participants in that group; it does not establish that the risk of serious events is absent. Safety estimates from a study of this size can be limited in their ability to characterize uncommon events, and the record does not provide further detail about event definitions, monitoring, reporting procedures, or the observation period for adverse events.

The registry also gives counts for other adverse events: 11 participants affected in the levobupivacaine group and 13 in the ropivacaine group, each with 30 at risk. These are distinct from the serious adverse event figures and should not be combined with them. The record does not provide descriptions of those other events in the information available for this comparison. These summaries support a descriptive account of recorded events, not a conclusion that either regimen is safer.

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

The primary outcome data show a difference in the reported group means for time to first analgesic request. The mean was 309.8 minutes for levobupivacaine and 249.5 minutes for ropivacaine. The recalculated unadjusted mean difference for ropivacaine relative to levobupivacaine is -60.33 minutes, with a confidence interval from -76.11 to -44.55 minutes and an unadjusted p-value of <0.001. This is a statistical description of the posted summaries under the recalculation’s assumptions.

The result does not mean that every participant in one group had a shorter duration than every participant in the other. Group means summarize distributions that can overlap, and the standard deviations indicate variation among recorded values. The registry does not provide participant-level data or distribution plots in the registry record for this interpretation, so the individual pattern cannot be reconstructed from the mean difference alone.

The endpoint is defined as the time to the patient’s first analgesic request. It does not directly measure pain intensity or describe later analgesic use. The registry record does not report enough detail about additional analgesic care or the rules for participants without a recorded request to extend the interpretation beyond that operational definition.

The result also does not establish what would occur in other populations, settings, or clinical protocols. Although the record identifies randomization and double masking, it does not report implementation details, an original analysis plan, or missing-data handling. The recalculated comparison is unadjusted and should not be mistaken for a fully documented original trial analysis.

The secondary measures show a generally similar direction among the available summaries, but they assess different aspects of sensory and motor block. Their unadjusted status and the absence of a reported multiplicity plan limit the strength of conclusions drawn from them. Statistical evidence does not by itself establish clinical importance, and no conclusion about an individual patient’s care follows from these group-level summaries.

17. Why This Trial Matters Statistically

This trial illustrates why the difference between a group summary and an individual outcome matters. A mean difference can provide a compact comparison of continuous outcomes, while the confidence interval communicates uncertainty about that estimate. Reading the mean, standard deviation, and interval together gives more context than relying on a single p-value.

It also highlights the importance of a clearly defined endpoint. Duration of analgesia is defined in the registry as time to the first analgesic request, which gives the measure a specific event and time scale. That definition supports interpretation of the reported means, but it also sets a boundary: the result concerns request timing, not every aspect of pain or subsequent analgesic use.

The record identifies a randomized, double-masked, parallel design, yet does not report several details that are important for a full statistical appraisal. The original analysis plan, missing-data approach, analysis population, multiplicity handling, and reasons for the primary outcome counts are not reported in the registry record. Such details help readers distinguish an originally planned analysis from an exploratory or reconstructed comparison.

The secondary results offer a consistent descriptive pattern across available sensory and motor outcomes, while also demonstrating why multiple unadjusted comparisons warrant caution. A pattern across outcomes can be informative, but it should not substitute for a prespecified testing strategy or a transparent account of analysis decisions. The registry record does not supply those details.

Finally, the planning illustrations show how sample-size requirements depend on the assumed effect to detect. They are based on fractions of the observed effect and stated planning assumptions, not on the trial’s original design rationale. Keeping that distinction clear prevents a retrospective planning calculation from being mistaken for evidence about how the study was planned or powered.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The outcome summaries are based on 28 participants in the levobupivacaine group and 30 in the ropivacaine group, while the registry lists an enrollment of 60. The record does not explain why the primary outcome counts differ from enrollment, whether measurements were missing, or how exclusions or withdrawals were handled. This limits assessment of the analysis population and possible effects of missing outcome data.

The registry identifies the study as randomized and double-masked, but does not describe the randomization procedure, allocation concealment, or masking implementation. It also does not report the study setting, further eligibility criteria, or details of the clinical care surrounding analgesic requests. These omissions make it difficult to assess how closely the posted summaries reflect a specific care context or how the design features were implemented.

The posted comparisons are unadjusted recalculations from summary statistics, and no reported analyses are listed. The original statistical plan, test or model, covariate use, and analysis population are not reported in the registry record. The recalculated estimates therefore cannot be assumed to reproduce the investigators’ original analysis.

Several secondary outcomes are named, but the registry record does not include arm-level summaries for all of those listed outcomes. It also does not report whether secondary hypotheses were prespecified or whether multiple comparisons were addressed. The available secondary findings should accordingly be interpreted as unadjusted evidence rather than as a fully documented confirmatory analysis.

Safety reporting is limited to event counts and at-risk groups in the registry information. The record does not provide event descriptions for the other adverse events, and deaths are not reported in the registry record. These reporting limits restrict interpretation of the safety summaries. The absence of reported serious events is not evidence that serious events cannot occur.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Spinal Anaesthesia With Levobupivacaine 0.5% and Ropivacaine 0.75% for Lower Limb Orthopaedic Surgery — NCT02201784.
• Registry record last updated 2015-01-21; status last verified 2015-01.
• Results first posted 2015-01-21.
• 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, randomized, double-masked, parallel-group phase 4 study of spinal anaesthesia for lower limb orthopaedic surgery. It compares intrathecal levobupivacaine 0.5% at 15 mg with intrathecal ropivacaine 0.75% at 22.5 mg and lists enrollment of 60.

The primary outcome is duration of analgesia, defined as time to the first analgesic request and measured in minutes over a stated timeframe of 8 hours. The posted arm means are 309.8 minutes for levobupivacaine and 249.5 minutes for ropivacaine. The recalculated unadjusted mean difference for ropivacaine relative to levobupivacaine is -60.33 minutes, with a confidence interval from -76.11 to -44.55 minutes and p < 0.001.

The available secondary summaries show a generally similar direction, but the registry record does not report a multiplicity strategy, missing-data approach, or original analysis plan. Serious adverse events are recorded as affecting zero participants in each group; deaths are not reported in the registry record. Interpretation is limited to the posted summaries and the information recorded about the trial.