This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Prospective, Randomized TrialComparing Oral N-Acetylcysteine and Intravenous Sodium Bicarbonate (NCT00579995), a randomized na study. The primary outcome is Compare the Effectiveness of Two Medications for Prevention of Contrast-induced Nephropathy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00579995 |
| Phase | NA |
| Condition | Nephropathy |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 41 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Nebraska |
| Results posted | Yes |
2. Clinical Question
Population
High-risk patients undergoing cardiac catheterization were the intended population. The registry record identifies nephropathy as the condition and describes the purpose as prevention of contrast-induced nephropathy. It does not report detailed eligibility criteria, how “high-risk” was defined, or the characteristics of enrolled participants. Enrollment was 41.
Intervention
The intervention arm received oral N-acetylcysteine. Its arm description lists 600 mg, without a dosing schedule. The record does not report further details about administration or adherence.
Comparator
The comparison arm received sodium bicarbonate intravenously. The description lists “3 milliliter per kilogram per hour (3 mL/kg/hr) infused at 1 mL/kg/hr for 6 hours post-procedure.” That wording is reproduced as recorded; the registry record does not clarify the dosing description further.
Primary question
The trial asked whether oral N-acetylcysteine and intravenous sodium bicarbonate differed in their effectiveness for preventing contrast-induced nephropathy in this population. The primary measure is described as a mean with standard deviation, in milligrams per deciliter, with a listed timeframe of 2 years. The registry record does not name the measured analyte or provide outcome values, so the size and direction of any difference cannot be determined from the posted results.
3. Trial Design
The registry record describes a randomized, parallel-group trial with no masking. Participants were assigned to oral N-acetylcysteine or intravenous sodium bicarbonate. The listed enrollment was 41: the N-acetylcysteine arm has 18 participants and the sodium bicarbonate arm has 23. These figures describe enrollment by arm; the record does not state how many participants contributed data to the primary outcome.
The trial’s stated purpose was to compare the medications for prevention of contrast-induced nephropathy after cardiac catheterization in high-risk patients. The primary outcome description likewise frames the question as a comparison of the two medications. Its measurement is listed as a mean with standard deviation and a unit of milligrams per deciliter. A timeframe of 2 years is recorded, but the registry record does not explain when or how often the outcome was measured within that timeframe.
The record lists the study status as terminated. It gives a start date of 2005-05-01 and a primary completion date of 2010-04-08. The reason for termination, whether recruitment ended as planned, and whether the termination affected outcome collection are not reported in the registry record. The listed phase is NA.
Random allocation can reduce systematic differences between groups at the point of assignment, but it does not ensure that the groups remain comparable in every respect, especially when enrollment is limited. With no masking, participants and study personnel were not masked according to the registry listing. The record does not describe procedures for outcome assessment or allocation concealment. It also does not provide a protocol or a detailed account of trial conduct, so those features cannot be evaluated.
Although the record lists one primary outcome measure, it reports no analyses and no primary outcome values. As a result, the randomized design and planned comparison can be described, but the comparative result itself cannot be assessed from 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
| Stage | 1, N-Acetylcysteine | 2, Sodium Bicarbonate |
|---|---|---|
| STARTED | 18 | 23 |
| COMPLETED | 18 | 23 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | 1, N-Acetylcysteine | 2, Sodium Bicarbonate | Total |
|---|---|---|---|---|
| Participants analysed | 18 | 23 | 41 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 10 | 15 | 25 |
| Age, Categorical: >=65 years | Participants | 8 | 8 | 16 |
| Age, Continuous | years | 62 (SD 3.8) | 60 (SD 4.4) | 61 (SD 4.2) |
| Sex: Female, Male: Female | Participants | 6 | 5 | 11 |
| Sex: Female, Male: Male | Participants | 12 | 18 | 30 |
| Region of Enrollment: United States | participants | 18 | 23 | 41 |
6. Primary Endpoint
The registry lists the primary outcome as Compare the Effectiveness of Two Medications for Prevention of Contrast-induced Nephropathy, measured over 2 years.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | milligrams per deciliter |
| Endpoint classification | Continuous Endpoint |
The primary outcome is titled “Compare the Effectiveness of Two Medications for Prevention of Contrast-induced Nephropathy.” Its description says the study compares oral N-acetylcysteine with intravenous sodium bicarbonate for prevention of contrast-induced nephropathy in high-risk patients undergoing cardiac catheterization. The record specifies a mean, standard deviation, a unit of milligrams per deciliter, and a timeframe of 2 years.
The registry record does not identify the particular measurement represented in milligrams per deciliter. It therefore does not establish whether the outcome is a named laboratory measure, how it was obtained, or what threshold—if any—defined contrast-induced nephropathy. The timing and frequency of measurement are also not reported in the registry record. Those details matter because an interpretable endpoint needs a clear definition and assessment schedule.
General: continuous measurements retain information about the range of observed values, while a mean describes the group’s average and a standard deviation describes the spread of values around that average. Such measures can help compare groups, but their meaning depends on the variable measured, its distribution, and the way observations were collected. Here, neither group’s mean nor standard deviation is reported. No estimate of the between-group difference or its uncertainty is available, so the stated endpoint cannot be interpreted comparatively from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that the trial was designed to compare oral N-acetylcysteine with intravenous sodium bicarbonate in high-risk patients undergoing cardiac catheterization. It does not establish which arm had a higher or lower primary-outcome value, whether the groups differed, or how precise an estimated difference would be. The primary-outcome values and spreads are absent, and the record lists no analyses. There is consequently no reported treatment estimate, confidence interval, or p-value to interpret.
The posted enrollment is 41, with 18 assigned to the N-acetylcysteine arm and 23 to the sodium bicarbonate arm. These counts do not indicate how many participants had outcome data available, whether all randomized participants were included in an analysis, or whether participants were analyzed according to their assigned arm. Those details are not reported in the registry record. Enrollment counts alone cannot establish whether the outcome comparison was adequately precise.
The registry lists the primary outcome as a mean with standard deviation, in milligrams per deciliter, and gives a timeframe of 2 years. The specific measured variable and its assessment schedule are not identified. Without those details, even a reported numerical difference would be difficult to interpret clinically and statistically. In the posted results, however, no group values or estimated difference are available at all.
The record reports zero serious adverse events among the 18 participants at risk in the N-acetylcysteine group and among the 23 participants at risk in the sodium bicarbonate group. It also reports zero other adverse events in each group’s stated at-risk count. These counts are descriptive entries, not a comparison adjusted for follow-up or a demonstration that no events occurred outside the recorded categories. Death counts are not reported in the registry record.
General: a confidence interval, when reported, describes the uncertainty around an estimated effect under the analysis assumptions; a p-value addresses compatibility between data and a specified null hypothesis. Neither replaces the effect estimate or establishes clinical importance. Since no comparative analysis is posted, there is no basis to assess the direction, magnitude, precision, or statistical significance of the primary comparison.
The study status is terminated, but the reason and its implications for data collection are not reported in the registry record. It would be inappropriate to infer from termination alone why the trial stopped or what the unposted results might have been. The available record supports a description of the planned comparison and the limited posted safety counts, but not a conclusion about comparative effectiveness.
9. Statistical Methods Explained
The trial is listed as randomized, parallel-group, and unmasked. Randomization means that assignment to the two treatment groups was intended to be determined by chance. In general, this design aims to make groups comparable at the start with respect to measured and unmeasured characteristics. Randomization does not guarantee identical groups, and its balance can be uncertain in a study with limited enrollment. The registry record does not describe the randomization sequence, allocation concealment, or any stratification.
What does the continuous outcome description mean?
The primary measure is described as a mean with standard deviation and is expressed in milligrams per deciliter. A mean is a summary of the observed values in a group; a standard deviation describes how dispersed those values are around the mean. In general, these summaries are most informative when the variable and its measurement process are clearly defined. The registry record does not name the measured analyte, supply either group’s mean or standard deviation, or explain how the outcome was assessed. It therefore does not allow a reader to reconstruct or interpret a group comparison.
A comparison of group means would ordinarily be expressed as an estimated difference, with an uncertainty interval or another measure of uncertainty. That estimate would need to be interpreted alongside the outcome definition, analysis population, and assumptions of the statistical method. None of those comparative results are reported in the registry record. No inferential method, such as a particular test or model, is specified, and no p-value or confidence interval is posted.
Why does the analysis population matter?
Analysis populations describe which participants and observations contribute to a result. General: an intention-to-treat analysis typically retains participants in the groups to which they were assigned, while other analysis approaches may use a different set of participants or observations. These approaches can answer different questions and may be affected differently by missing measurements or treatment changes. The registry record does not identify an analysis population, report outcome availability by group, or describe how missing values were handled. It is not possible to determine whether the primary analysis included all randomized participants.
The outcome timeframe is listed as 2 years, but the record does not specify the assessment schedule. If a continuous outcome is measured more than once, the analysis may need to account for repeated observations and their dependence within participants. That is a general methodological consideration, not a description of the method used in this trial; the registry record does not say whether repeated measures were collected or analyzed.
What can be said about sample-size planning?
The record includes assumptions for a planning illustration: two-sided significance level 0.05, equal allocation, and a normal approximation, with an effect defined as a stated fraction of the observed effect. Such an illustration is a planning exercise, not observed power and not necessarily the trial’s original design calculation. The observed primary effect is unavailable because the group outcome values and comparative analysis are not reported. Thus, no planning sample size based on that effect can be interpreted from the posted results. The trial’s own sample-size justification is not reported in the registry record.
General: over-dispersion means that observed variability is greater than a model assumes. When present, a model that fails to account for it can understate uncertainty and make results appear more precise than they are. Whether over-dispersion is relevant depends on the outcome and model. Because the outcome’s specific measurement and analysis method are not reported, there is no basis to assess over-dispersion or the use of a model that addresses it.
What does the absence of analyses imply?
The registry lists no analyses for the primary outcome. This is distinct from a reported null result: no estimate is posted, so there is no statistical result to characterize as positive, negative, or inconclusive. General statistical interpretation requires both an effect estimate and its uncertainty. A significance test alone would not show the size or practical importance of a difference; here, neither a test nor an estimate is available.
The record also does not describe interim analyses, stopping rules, model diagnostics, covariate adjustments, or handling of protocol deviations. These matters are not assumed to have occurred or not occurred. They are simply not reported in the registry record, limiting the ability to evaluate the analysis plan or the robustness of any comparative conclusion.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure and no secondary outcome measures. It also lists no analyses. Although the number of listed outcomes is limited, the record does not report whether multiple endpoints, time points, subgroup comparisons, or interim analyses were planned or examined. Any multiplicity strategy, including whether statistical testing was adjusted for multiple comparisons, is not reported in the registry record. Without an analysis report, it is not possible to assess how multiplicity may have affected interpretation.
Missing-data information is also unavailable. The record gives enrollment by arm, but does not state the number of participants with primary-outcome measurements, the reasons measurements might be missing, or the method used to handle missing values. It does not say whether outcome data were collected for all enrolled participants or whether any participants withdrew or were excluded from analysis. Those details should not be inferred from the enrollment counts.
The analysis population is not reported in the registry record. In general, including participants according to randomized assignment and analyzing only those with complete outcome data can lead to different interpretations, particularly if missingness is related to participant characteristics or outcomes. The record does not identify which approach was used. It also does not report protocol deviations, crossover, treatment adherence, or sensitivity analyses addressing missing data.
These omissions leave uncertainty about the completeness of outcome ascertainment and the population represented by any analysis. Since no primary analysis is posted, it is not possible to assess whether missing data or multiplicity influenced a comparative estimate.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| 1, N-Acetylcysteine | 0 | 18 | 0.0% |
| 2, Sodium Bicarbonate | 0 | 23 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| 1, N-Acetylcysteine | 0 of 18 |
| 2, Sodium Bicarbonate | 0 of 23 |
The registry reports zero serious adverse events in the N-acetylcysteine group, with 18 participants listed as at risk, and zero in the sodium bicarbonate group, with 23 listed as at risk. It also reports zero other adverse events in each group, using the same respective at-risk counts. These are the posted event counts for the categories recorded; they do not supply event descriptions or a detailed account of how safety events were collected.
The death counts are not reported in the registry record. A missing death count should not be read as zero. The record also does not provide timing, duration of observation for safety, event severity beyond the serious-event category, or comparative statistical analyses. The at-risk counts are not necessarily evidence that every participant had the same duration or completeness of safety follow-up.
General: an observed count of zero does not establish that the underlying risk is zero. Interpretation depends on the number of people observed, how long they were observed, the definitions used, and completeness of reporting. These registry entries are descriptive and do not establish a safety advantage for either group.
12. What the Result Does, and Does Not, Mean
The available record describes a randomized comparison of oral N-acetylcysteine and intravenous sodium bicarbonate for prevention of contrast-induced nephropathy in high-risk patients undergoing cardiac catheterization. It records enrollment of 41 and identifies the assigned group counts. It also records zero serious and zero other adverse events in each group’s stated at-risk population. These details characterize the trial record, but they do not answer the primary comparative question.
The primary outcome is described as a mean with standard deviation in milligrams per deciliter, with a timeframe of 2 years. The specific variable is not named, and neither group’s outcome values nor a comparative estimate is reported. No analyses are listed. Therefore, the posted results do not show whether the outcome differed between groups, how large any difference may have been, or how precisely it could be estimated. They also do not support a conclusion that the treatments are equivalent or that there is no difference.
General: absence of a statistically significant finding, if one were reported, would not by itself establish equivalence. Equivalence or non-inferiority conclusions require an appropriate design, prespecified margins, and analyses that address those questions. Such margins and analyses are not reported in the registry record. In this case, there is no reported primary statistical test or estimate to assess in the first place.
The listed status is terminated, but no reason for termination is given. It cannot be inferred whether termination was related to recruitment, logistics, safety, efficacy, or another circumstance. The record also does not provide enough information to judge the completeness of follow-up or the representativeness of participants beyond describing them as high-risk patients undergoing cardiac catheterization.
The most defensible reading is therefore narrow: the registry documents the study design, enrollment, planned outcome description, and posted adverse-event counts, but not the primary outcome result. Any conclusion about comparative effectiveness, precision, or clinical importance would go beyond the results reported in the registry record.
13. Why This Trial Matters Statistically
This trial illustrates an important distinction between a registered comparison and a reported statistical result. Random assignment and a clearly stated clinical question describe how a study was intended to compare groups. They do not, by themselves, reveal the observed difference or its uncertainty. For this trial, the registry identifies the treatment arms, enrollment, and a continuous primary-outcome format, but no group values or analyses are posted.
That absence matters because statistical interpretation depends on more than knowing which treatments were compared. Readers need an outcome definition, the number of participants contributing data, an effect estimate, and information about its precision. A mean and standard deviation can describe continuous outcomes, but without the measured variable and the reported values, those summaries cannot answer the clinical question. The listed timeframe of 2 years does not resolve uncertainty about when assessments occurred.
The enrollment counts also show why design details and analysis reporting matter. The record lists 18 participants in one arm and 23 in the other, but does not report the analysis population or outcome completeness. Randomization is valuable, yet it cannot compensate for unknown missingness or an unavailable analysis. Nor can a planning illustration based on an observed effect substitute for the trial’s own sample-size justification or a result estimate.
Finally, the safety entries are counts, not a full safety analysis. Zero recorded events in the listed categories should be read alongside the available at-risk counts and the missing death information, rather than as proof of no risk. The statistical lesson is that registry entries can describe design and reporting status while leaving the main treatment comparison unanswered. Transparent outcome definitions, analysis methods, and results are necessary for readers to judge magnitude, precision, and limitations.
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.
The most important limitation for interpretation is that the primary outcome values and analyses are absent. The record does not provide a group mean or standard deviation, a treatment-effect estimate, a confidence interval, or a p-value. The trial’s main comparative question therefore remains unanswered in the posted results.
The endpoint is not fully specified. Although it is described in milligrams per deciliter and as a mean with standard deviation, the measured variable is not named. The timeframe is listed as 2 years, but the assessment schedule and outcome definition are not reported in the registry record. The eligibility criteria and the basis for classifying participants as high-risk are also not reported, limiting assessment of who the results would represent even if results were available.
The registry identifies enrollment of 41 and group counts of 18 and 23, but does not state how many contributed outcome data. It does not describe missingness, withdrawals, exclusions, adherence, treatment changes, or the analysis population. The absence of these details prevents assessment of attrition and whether the analysis preserved the randomized comparison.
The record lists the study as terminated without reporting why. It does not provide a sample-size justification, analysis plan, interim-analysis information, stopping rules, or the methods used for outcome analysis. These are uncertainties in the available record, not evidence that any particular method or event occurred.
Safety interpretation is limited as well. The record gives zero serious and zero other adverse-event counts for the stated at-risk groups, but does not report deaths, event timing, or detailed ascertainment procedures. Overall, the posted information is insufficient to estimate comparative effectiveness or to characterize the precision and completeness of the primary result.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Prospective, Randomized TrialComparing Oral N-Acetylcysteine and Intravenous Sodium Bicarbonate — NCT00579995.
- Registry record last updated 2023-09-21; status last verified 2023-08.
- Results first posted 2023-09-21.
- 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.
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18. Record Summary
The registry record describes a randomized, unmasked, parallel-group trial comparing oral N-acetylcysteine with intravenous sodium bicarbonate for prevention of contrast-induced nephropathy in high-risk patients undergoing cardiac catheterization. Enrollment was 41, with 18 listed in the N-acetylcysteine arm and 23 in the sodium bicarbonate arm. The status is terminated; the reason is not reported in the registry record.
The primary outcome is described as a mean with standard deviation in milligrams per deciliter, with a listed timeframe of 2 years. The measured variable is not named, and no primary-outcome values or analyses are reported. The registry records zero serious and zero other adverse events in each arm’s stated at-risk group; death counts are not reported. The available record describes the trial design and limited safety counts, but does not provide a comparative effectiveness estimate or its precision.