Local Anesthetics for Pain Reduction Prior to IV Line Placement: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Local Anesthetics for Pain Reduction Prior to IV Line Placement (NCT01759459), a randomized phase 4 study. The primary outcome is Pain Score Following Anesthetic Administration.

2. Clinical Question

The trial asks how reported pain differs among patients receiving lidocaine, buffered lidocaine, or bacteriostatic normal saline before peripheral intravenous catheterization. The registry description identifies two pain experiences of interest: pain when the anesthetic is administered and pain associated with insertion of the catheter. The primary outcome is titled “Pain Score Following Anesthetic Administration,” while its description refers to pain both upon anesthetic administration and upon catheter insertion. Separate scores for those experiences are not reported in the registry record.

The clinical question is therefore a comparison of patient-reported pain across three premedication options, with the interpretation limited to the way the outcome is defined and recorded. The registry describes lidocaine as commonly used for this purpose, notes that its acidity may itself cause discomfort on administration, and explains that buffering with sodium bicarbonate is intended to raise its pH. It also describes bacteriostatic normal saline as an option used in some cases, including for patients with a lidocaine allergy, because it contains benzyl alcohol. These descriptions explain the rationale for comparing the agents; they are not findings from this trial about their comparative effects.

3. Trial Design

The registry describes a randomized, double-masked, parallel-group, phase 4 study. Enrollment is recorded as 150, and the arm-level results list 50 participants for lidocaine, 50 for buffered lidocaine, and 50 for bacteriostatic normal saline. The record marks the study as completed, with a start date of 2013-01 and primary completion in 2013-06. Allina Health System is listed as the sponsor.

The interventions were administered once by the intradermal route in the peripheral forearm. The lidocaine arm received 1% lidocaine for injection, 0.50 mL. The buffered-lidocaine arm received 1% buffered lidocaine for injection, 0.50 mL. The registry describes preparation of the buffered product by adding 2.3 mLs of 8.4% sodium bicarbonate to a vial of 1% lidocaine. The bacteriostatic normal saline arm received 0.50 mL of that solution for injection. The record does not provide further information about administration procedures or masking.

Randomization and masking are stated, but the method used to generate the allocation sequence, conceal assignments, or maintain masking is not reported in the registry record. The people masked, the clinical setting, eligibility criteria, and the handling of treatment deviations are also not reported. These details matter when assessing how well the design limits bias, but their absence from the registry record does not establish that the procedures were absent from the study.

The primary outcome is a pain score on a scale from 0 to 10, with 0 defined as no pain and 10 as the worst pain ever felt. The registry gives Day 1 as the timeframe. It also lists an economic analysis of the cost of compounding buffered lidocaine versus the cost of purchasing regular lidocaine and/or bacteriostatic normal saline as a secondary outcome. Results for that economic outcome 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

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 Pain Score Following Anesthetic Administration, measured over Day 1.

The primary endpoint is the mean pain score following anesthetic administration. The registry describes the score as a patient report on a scale from 0 to 10, where 0 means no pain and 10 means the worst pain ever felt. Its timeframe is Day 1. The arm-level results report means of 2.81 for lidocaine, 1.64 for buffered lidocaine, and 2.05 for bacteriostatic normal saline. The reported range is 0 to 10 in each arm.

A patient-reported pain score is used because pain is a subjective experience: the person receiving the anesthetic is the source of the outcome measurement. In general, a common scale allows responses from different participants and trial arms to be described on a shared metric. The reported mean describes the average score within an arm; it does not show how scores were distributed among individuals.

There is an ambiguity in the registry wording. The outcome title refers to pain following anesthetic administration, while the description says pain is measured both upon administration of the anesthetic and upon insertion of the catheter. The record does not report separate results for those two events or clarify whether the posted mean combines them. The registry also gives only the full range as a dispersion measure; standard deviations, other distribution summaries, and confidence intervals are not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry presents a randomized, double-masked, parallel-group design and arm-level summary results. Those features describe how the trial was organized at a broad level. They do not, on their own, specify the statistical analysis used to compare pain scores. No analysis entries are listed in the registry record, so the statistical approach for the primary comparison is not reported.

What does the mean describe?

In general, a mean is the arithmetic average of the recorded values in a group. It provides a compact description of the group’s typical score, but it can conceal variation among participants. Two groups can have similar means while having different distributions, or different means while still having substantial overlap in individual scores. The posted means are 2.81 for lidocaine, 1.64 for buffered lidocaine, and 2.05 for bacteriostatic normal saline. No new contrast between those means is calculated.

The endpoint is a bounded patient-reported scale from 0 to 10. When interpreting a mean on a bounded scale, it is useful to know not only the average but also how observations are spread and whether values cluster near the endpoints. The registry reports the full range, 0 to 10, for each arm, but no further distribution details. The range confirms that scores at both ends were recorded; it cannot indicate how frequent such scores were.

What would uncertainty measures add?

In general, a confidence interval describes a range of values compatible with the data and a stated statistical procedure. Its width helps readers judge the precision of an estimate. A standard deviation describes variation among observations, while a standard error describes uncertainty in an estimated statistic under a specified model. These measures answer different questions and are not interchangeable. None of these quantities is reported for the arm means in the registry record, and no confidence intervals for between-arm comparisons are reported.

A formal comparison could be designed to estimate differences among the three arm means, but the registry record does not identify the test, model, or contrast definitions used. It also does not report whether an analysis adjusted for other variables, how assumptions were assessed, or how the bounded scale was handled. Without those details and the underlying uncertainty estimates, the numerical ordering of means should not be treated as a test result.

Why can score distributions matter?

In general, statistical methods that assume a particular distribution can be affected when the data depart from that assumption. A mean-based analysis may be reasonable in some settings, but the choice depends on the design, score distribution, and analysis objective. Over-dispersion, in general, means that observed variation is greater than a model assumes; ignoring it can make uncertainty appear too small. The registry does not report distributional diagnostics or a method for handling over-dispersion, so it is not possible to say whether either issue arose in this trial.

The score is bounded, so methods intended for unbounded continuous outcomes may need careful consideration. General statistical practice is to assess whether the chosen model fits the observed outcome and to report estimates with uncertainty. The registry does not state the model or provide enough distributional information to evaluate its suitability. This does not establish that the analysis was inappropriate; the relevant analysis details are simply not reported in the registry record.

How should planning illustrations be read?

Any sample-size figures associated with planning are illustrations based on the observed effect, not results of a prospective design justification for this trial. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such calculations ask, in general, how many participants per arm a future comparison might require under specified assumptions. They do not show the probability that this completed trial detected an effect, and they are not observed power.

These illustrations are distinct from the trial’s recorded enrollment and arm counts. They should not be used to infer that the original trial was designed around the observed means or that its sample-size rationale is known. The registry record does not report the trial’s own sample-size justification, target effect, or planning assumptions. No calculation beyond the posted planning assumptions is warranted from the record.

What can be concluded from the available summaries?

The summaries permit a descriptive account of the mean scores, arm counts, and observed ranges. They do not provide a formal estimate of the uncertainty in the comparisons. No p-values, confidence intervals, adjusted estimates, or analysis populations are reported. General statistical interpretation distinguishes a descriptive difference from evidence that a population-level difference exists. Here, only the descriptive summaries are available in the registry record, so claims about statistical significance or comparative effect are not supported by the reported analysis information.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and identifies the pain score following anesthetic administration as the primary outcome. It also lists an economic analysis of compounding buffered lidocaine versus purchasing regular lidocaine and/or bacteriostatic normal saline as a secondary outcome. The registry record does not describe a multiplicity strategy, such as how the chance of false-positive findings would be handled across multiple outcomes or comparisons. No statistical analysis entries are listed.

With three treatment arms, a complete comparison plan could define which pairwise or overall comparisons are primary and how they are interpreted. The record does not specify such a plan, identify planned contrasts, or state whether any adjustment for multiple comparisons was intended. This absence means the reader cannot determine from the registry record how the analysis controlled or prioritized multiple statistical questions. It does not establish what analyses may have been conducted outside the registry record.

Missing-data methods are not reported. The record does not give counts of missing pain scores, reasons for missingness, imputation procedures, or sensitivity analyses. Although each arm’s outcome summary lists 50 participants, that alone does not explain whether the listed count is the number randomized, treated, assessed, or included in the mean calculation. A participant-flow account and analysis-population definitions are not reported in the registry record.

The registry does not identify an intention-to-treat, per-protocol, or other analysis population. It also does not describe handling of deviations from assigned treatment or the timing of outcome assessment beyond the Day 1 timeframe. Without these details, the completeness and comparability of the analyzed groups cannot be evaluated from the registry record. These omissions limit interpretation of the posted summaries; they are not evidence that data were missing or that a particular analysis population was used.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports no serious adverse events, other adverse events, or deaths for any of the three arms. For lidocaine, the listed number at risk is 50 for serious and other adverse events, with 0 serious events, 0 other events, and 0 deaths. For buffered lidocaine, the corresponding listed number at risk is 50, with 0 serious events, 0 other events, and 0 deaths. For bacteriostatic normal saline, the listed number at risk is also 50, with 0 serious events, 0 other events, and 0 deaths.

These figures describe the events recorded in the registry. Zero recorded events should not be interpreted as proof that an intervention has no risk. The record does not provide event definitions, collection procedures, follow-up details for safety, or information about how adverse events were assessed. It also does not report non-serious event terms; the registry lists no top serious-event terms.

Safety counts are separate from the pain-score outcome and do not explain the comparative pain results. The registry’s event counts can be read as the reported safety record for these arms, with the limitations that follow from the absence of further ascertainment details. They do not support broader conclusions about safety in other settings or populations.

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

The registry provides a descriptive snapshot of pain scores after local anesthetic administration for peripheral intravenous catheterization. The mean scores are 2.81 for lidocaine, 1.64 for buffered lidocaine, and 2.05 for bacteriostatic normal saline, with a reported range of 0 to 10 in each arm. The record also reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each arm. These are the results recorded for the trial; they do not by themselves establish comparative efficacy or safety.

The lower recorded mean in the buffered-lidocaine arm than in the lidocaine arm is a descriptive observation, not proof of a statistically reliable difference. The registry does not provide confidence intervals, p-values, variability estimates beyond the full range, or an analysis method. Without those, the precision of the means and uncertainty around comparisons cannot be assessed. The same caution applies to the numerical ordering of all three arm means.

The endpoint description leaves uncertainty about whether the reported score concerns pain from anesthetic administration, catheter insertion, or both. Separate results for these experiences are not reported. The record also does not provide the statistical analysis, participant flow, missing-data handling, or analysis populations. Thus the results cannot be read as evidence that one agent is superior for either pain experience considered separately.

The registry lists an economic analysis as a secondary outcome, but economic findings are not reported in the record. The posted pain summaries do not establish differences in cost, overall benefit, or clinical importance. The trial’s status is recorded as completed, but completion does not resolve the limits of the available outcome and analysis information.

In general, interpretation of a randomized comparison depends on both the observed estimates and their uncertainty, as well as transparent information about outcome measurement and analysis. Here, the available results support a factual description of the reported means, ranges, arm counts, and event counts. Broader conclusions about treatment effects are not supported by the registry record alone.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it compares three agents for a patient-reported outcome within a randomized, double-masked, parallel-group design. Randomization can help make treatment groups comparable on average, while masking can reduce some forms of influence on outcome reporting or assessment. The registry states that these design features were used, but does not report how randomization or masking was implemented, so their execution cannot be assessed from the record.

The pain outcome is a bounded scale from 0 to 10. In general, choosing how to summarize and compare such an outcome calls for attention to both the mean and the distribution of individual scores. The record reports arm means and the complete observed range, but not standard deviations or other distribution summaries. This illustrates why a mean alone is not a complete account of patient-level variation or the precision of a treatment comparison.

The three-arm structure also makes the analysis plan important. Multiple possible comparisons can be made among three groups, and the interpretation of results depends on which comparisons were planned and how multiplicity was handled. Those details are not reported, and no statistical analysis entries are listed. The numerical ordering of means therefore remains descriptive rather than a documented inferential conclusion.

The registry’s outcome wording highlights another general lesson: precise endpoint definitions are essential. A measure described as pain after anesthetic administration is also described as covering pain at catheter insertion. Without separate scores or clarification, readers cannot identify which experience the arm summaries represent.

Finally, planning illustrations and observed trial summaries answer different questions. A sample-size illustration based on an observed effect is not evidence of the trial’s original design rationale or its probability of detecting an effect. The registry record does not report that rationale. Taken together, the record demonstrates why transparent outcome definitions, analysis plans, uncertainty estimates, and participant-flow information are central to statistical interpretation.

14. 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 limitations of interpretation arise from what the registry record does not report. The primary outcome title refers to pain following anesthetic administration, but the outcome description includes pain upon both anesthetic administration and catheter insertion. Separate scores for these events and clarification of the posted mean are not reported. This makes it difficult to determine precisely which pain experience the arm-level summaries represent.

The registry reports means and full ranges, but no standard deviations, standard errors, confidence intervals, or formal comparison results. The distributions of scores therefore cannot be reconstructed, and the precision of the arm means cannot be assessed. No analysis entries are listed, so the statistical model, comparison strategy, and handling of the bounded scale are not reported in the registry record.

Participant eligibility, baseline characteristics, study setting, and participant flow are not reported in the registry record. The record does not clarify whether arm counts represent those randomized, treated, assessed, or included in the outcome summaries. Missing outcome data, deviations from assigned treatment, and analysis-population definitions are also not reported.

The registry identifies the study as randomized and double-masked, but the sequence-generation method, allocation concealment, masking procedures, and identities of masked individuals are not reported. The trial’s own sample-size justification is not reported. Although an economic analysis is listed as a secondary outcome, its findings are not reported in the registry record. These gaps limit what can be concluded from the posted summary; they do not establish that the study lacked procedures or analyses beyond what is recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Local Anesthetics for Pain Reduction Prior to IV Line Placement — NCT01759459.
• Registry record last updated 2022-07-15; status last verified 2022-07.
• Results first posted 2022-07-15.
• 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.

18. Record Summary

The registry record describes NCT01759459, “Local Anesthetics for Pain Reduction Prior to IV Line Placement,” as a completed, randomized, double-masked, parallel-group, phase 4 trial sponsored by Allina Health System. It lists enrollment as 150, a start date of 2013-01, and primary completion in 2013-06.

The three arms received one-time intradermal lidocaine, buffered lidocaine, or bacteriostatic normal saline in the peripheral forearm. The primary outcome is a pain score on a scale from 0 to 10, with a Day 1 timeframe. The reported arm means are 2.81, 1.64, and 2.05, respectively; the reported range is 0 to 10 in each arm. Each arm lists 50 participants.

The registry reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each arm. An economic analysis is listed as a secondary outcome, but its results are not reported. Statistical analysis details, uncertainty estimates, missing-data handling, and analysis populations are not reported in the registry record.