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 Transfusions and Nitric Oxide Level in Preterm Infants (NCT00787124), a registered phase not stated study. The primary outcome is SNOHgB Levels.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00787124 |
| Phase | Phase not stated |
| Condition | Prematurity, Anemia, Necrotizing Enterocolitis |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Duke University |
| Results posted | Yes |
2. Clinical Question
Population
Extremely preterm infants were the intended population. The listed groups were restricted to infants born before 28 weeks of gestation and distinguished by age and previous transfusion history. The registry lists an enrollment of 8.
Intervention
The study concerned red blood cell transfusions and measurements around transfusion. It aimed to measure nitric oxide bound to hemoglobin, including S-nitrosohemoglobin, in blood to be transfused and in infant samples before and after transfusion. The registry does not describe a randomized intervention or a treatment intended to alter the transfused blood.
Comparator
The listed groups were infants younger than 30 days with fewer than 3 previous transfusions, and infants aged 30 days or older with 3 or more previous transfusions. These groups differ on both age and transfusion history. The registry says allocation was not stated and identifies the arms as not a like-for-like control comparison.
Primary question
The primary endpoint was SNOHgB levels at the beginning and end of the study. The study intended to characterize nitric oxide measures in transfused blood and infant samples before and after transfusion. However, the registry states that the levels were never run by the laboratory. It therefore does not provide a primary-outcome estimate for answering whether these measures differed after transfusion.
3. Trial Design
This completed study, sponsored by Duke University, is titled “Transfusions and Nitric Oxide Level in Preterm Infants.” The registry lists a start of 2008-09, primary completion in 2009-09, and enrollment of 8. It classifies the study as “other,” rather than describing a randomized controlled comparison.
The protocol summary describes two aims. The first was to measure total hemoglobin-bound nitric oxide, hemoglobin iron-bound nitric oxide, and calculated SNO-Hb in blood intended for transfusion and in infant samples collected before and after transfusion. The second was to collect clinical observations, including oxygen saturation and measures of perfusion before and after transfusion. The stated hypotheses anticipated low nitric oxide measures in transfused blood, decreases in infant post-transfusion samples relative to pre-transfusion samples, and a 20% reduction in perfusion after transfusion. These are protocol expectations, not reported findings.
The listed groups distinguish infants born before 28 weeks of gestation by age and previous transfusion history: younger than 30 days with fewer than 3 previous transfusions, or aged 30 days or older with 3 or more previous transfusions. Allocation is not stated. The registry explicitly cautions that the arms are not a like-for-like control comparison, so differences between them cannot be attributed to age or transfusion history separately.
The primary laboratory outcome was not measured because the levels were never run by the laboratory. The registry lists oxygen saturation and perfusion as secondary outcomes, but their results are not reported in the registry record. No statistical analysis is listed.
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 | <30 Days | >=30 |
|---|---|---|
| STARTED | 4 | 4 |
| COMPLETED | 4 | 4 |
| 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 | <30 Days | >=30 | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 4 | 8 | |
| Age, Categorical: <=18 years | Participants | 4 | 4 | 8 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 | 0 | 0 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | days | 20 (SD 45) | 60 (SD 37) | 40 (SD 40) |
| Sex: Female, Male: Female | Participants | 1 | 0 | 1 |
| Sex: Female, Male: Male | Participants | 3 | 4 | 7 |
| Region of Enrollment: United States | participants | 4 | 4 | 8 |
6. Primary Endpoint
The registry lists the primary outcome as SNOHgB Levels, measured over beginning and end of study.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled SNOHgB Levels, with a timeframe of the beginning and end of the study. SNO-Hb is described in the study summary as a calculated measure: total hemoglobin-bound nitric oxide minus hemoglobin iron-bound nitric oxide. The broader measurement aim also included those component measures in blood to be transfused and in infant samples before and after transfusion.
These measures were intended to characterize nitric oxide associated with hemoglobin in the transfused unit and in the infants around transfusion. The study rationale describes interest in variation among packed red blood cell units and among individual infants before and after transfusion. In general, a before-and-after endpoint can describe how a measured quantity changes over time in the same participants. It does not, by itself, establish that transfusion caused a change; other explanations and the study design also matter.
For this record, the crucial fact is that the laboratory never ran the SNOHgB levels. No endpoint values, summary statistics, or comparison estimates are reported in the registry record. Thus, the stated endpoint describes the intended measurement, not an observed result. The registry also does not provide a separate rationale for selecting this endpoint or explain how its measurements would be analyzed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes an exploratory study of transfusion-related nitric oxide measures and clinical observations in extremely preterm infants. It lists an enrollment of 8 and two groups defined by age and previous transfusion history. The groups are not described as randomized, allocation is not stated, and the registry warns that they are not a like-for-like control comparison. The record therefore does not support a causal comparison between those groups.
Most importantly, the primary SNOHgB levels were never run by the laboratory. There is consequently no reported primary-outcome value or estimate to interpret, and no result in the registry that can confirm or refute the stated hypothesis about nitric oxide measures. The hypothesis of a 20% reduction in perfusion is likewise a planned expectation, not an observed result in the record. Although oxygen saturation and perfusion are listed as secondary outcomes, their results are not reported in the registry record.
The registry lists no analyses. It gives no effect estimates, measures of variability, confidence intervals, or p-values. A confidence interval, in general, represents a range of values compatible with the data and analysis method; without an estimate and its uncertainty, precision cannot be assessed. The absence of reported estimates is not evidence that a measured difference was absent. For the primary endpoint, the registry specifically says the measurements were never performed by the laboratory.
The adverse-event entries report 0 serious events and 0 other events among 4 at risk in each group. These are descriptive counts, not evidence that the groups had equivalent safety or that transfusion caused or prevented any event. Deaths are not reported in the registry record. The record does not provide enough information to evaluate the completeness of adverse-event ascertainment or the observation period for those entries.
Any sample-size figures elsewhere should be understood only as planning illustrations, not observed power or a description of the study’s original design. The stated illustration assumptions include a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a stated fraction of an observed effect. The registry does not report a primary endpoint effect because its laboratory levels were never run. No clinical conclusion about benefit or harm follows from this record.
9. Statistical Methods Explained
What can be estimated from this record?
The registry lists an enrollment of 8, but it reports no analyses. For the primary SNOHgB endpoint, it explicitly states that the laboratory never ran the levels. That means there is no observed primary measurement available in the record from which to calculate a group summary, a before-and-after change, or an uncertainty estimate. The existence of a planned endpoint does not create an analyzable outcome.
The registry also lists oxygen saturation and measures of perfusion as secondary outcomes, but does not report their results. Without reported observations or analysis estimates, readers cannot assess the size, direction, or precision of any change in those measures. A null result would require an analysis that yielded an estimate; no such result is listed. Missing results must not be interpreted as evidence of no effect.
Why does the group structure matter?
The groups differ in both age and previous transfusion history. One group is described as younger than 30 days with fewer than 3 previous transfusions, and the other as aged 30 days or older with 3 or more previous transfusions. The registry states that allocation was not given and that the arms are not a like-for-like control comparison. A difference between the groups, if one had been reported, could reflect either characteristic or other differences between participants. The design does not isolate the contribution of age from the contribution of transfusion history.
More generally, random allocation can help balance measured and unmeasured characteristics across treatment groups. When allocation is not stated and groups are defined by participant characteristics, an observed contrast is descriptive and may be confounded. In this record, no group contrast is reported in any case. It would be inappropriate to treat the groups as randomized arms or as a direct treatment-versus-control comparison.
How should uncertainty be understood?
In general, an effect estimate describes the direction and magnitude of a contrast, while a confidence interval conveys the uncertainty around that estimate under the chosen statistical model. A p-value addresses compatibility of data with a specified null model; it does not measure clinical importance or prove that a hypothesis is true or false. None of these inferential quantities is reported in the registry record. With no primary laboratory values and no listed analyses, there is no basis for describing statistical significance or precision.
Small studies can produce imprecise estimates even when measurements are available. In general, limited information makes estimates more sensitive to individual observations and makes it harder to distinguish a real pattern from random variation. Here, the primary limitation is more fundamental: the primary laboratory outcome was not run, and the registry reports no results for the secondary outcomes. No precision assessment can substitute for missing outcome measurements.
What do the planning assumptions mean?
The registry describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect; time-to-event illustrations use total events, while other illustrations use participants per arm. These are assumptions for planning calculations, not evidence about what the study observed and not a statement of the trial’s original design.
The registry does not report a primary endpoint effect to use as an observed estimate because the SNOHgB levels were never run. It also reports no analyses. The numerical planning outputs are not included in the registry record for this account, so no participant requirement can be stated. In general, planning estimates depend on the assumed effect, variability, allocation, significance threshold, and analysis method. If assumptions do not match the eventual study, the resulting planning figure may not describe the study’s actual ability to detect an effect. Such figures are never observed power.
Over-dispersion is a general concern when outcome variability exceeds what a chosen model assumes. If ignored, standard errors can be too small and confidence intervals too narrow. The registry does not identify an over-dispersion issue or report a statistical model for the outcomes, so it is not possible to say whether this concern applied to this study.
The registry does not report a statistical analysis plan, a sample-size justification for the original study, or interim analyses. The stated planning illustration should therefore be kept separate from the study’s design and from any interpretation of its posted results.
10. Multiplicity, Missing Data and Analysis Populations
The study summary describes multiple measurements: total hemoglobin-bound nitric oxide, hemoglobin iron-bound nitric oxide, calculated SNO-Hb, oxygen saturation, and measures of perfusion. The registry identifies SNOHgB Levels as the primary outcome and lists oxygen saturation and perfusion as secondary outcomes. It does not report a statistical analysis plan explaining how these measures would be analyzed together or how the primary and secondary questions would be prioritized.
When an analysis tests multiple outcomes or contrasts, the chance of obtaining at least one apparently notable result can increase. General approaches to multiplicity include prespecifying a primary contrast, adjusting inference, or treating secondary findings as exploratory. Which approach was intended is not reported in the registry record. In this study, the registry lists no analyses, so there are no reported p-values or outcome comparisons to assess for multiplicity.
The primary laboratory outcome was never run. The registry does not report participant-level missingness, the number of usable measurements, reasons for missing observations, or a method for handling missing data. It also does not describe analysis populations, such as whether analyses were planned for all enrolled participants or only participants with complete measurements. These details are not reported in the registry record.
The absence of analysis-population and missing-data details limits assessment of how the enrolled participants would have contributed to an outcome estimate. It is not possible to determine whether any unreported observations were collected, excluded, or unavailable. The registry’s statement that the laboratory did not run the primary levels establishes that the primary endpoint cannot be interpreted from the posted record; it does not supply a missing-data method or an analysis result.
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 |
|---|---|---|---|
| <30 Days | 0 | 4 | 0.0% |
| >=30 | 0 | 4 | 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 |
|---|---|
| <30 Days | 0 of 4 |
| >=30 | 0 of 4 |
The registry lists two groups for adverse-event reporting. For each group, it reports 4 participants at risk, 0 serious adverse events, and 0 other adverse events. These counts describe what is entered in the registry; they do not show that the groups had equal risk or that transfusion caused or prevented any event.
Zero recorded events should be read as a count, not as proof that an event could not occur. In general, estimates of uncommon harms are difficult to assess in small studies, and the amount of follow-up and completeness of event collection matter. The registry record does not report the adverse-event observation period, ascertainment procedures, or a statistical comparison between groups. It also does not provide serious adverse-event terms.
Deaths are not reported in the registry record. That is distinct from a reported count of zero deaths. The adverse-event figures are descriptive and do not support a treatment-effect or safety-equivalence conclusion.
12. What the Result Does, and Does Not, Mean
The registry record documents an intended study of nitric oxide measures related to transfusion in extremely preterm infants, together with planned observations of oxygen saturation and perfusion. It identifies SNOHgB Levels as the primary endpoint and describes a hypothesis that perfusion would be reduced by 20% after transfusion. Those details define research questions; they are not evidence that the predicted changes occurred.
The primary laboratory levels were never run, and no analyses are listed. The registry therefore supplies no primary-outcome estimate and no reported secondary-outcome results. It is not possible to say from this record whether nitric oxide measures, oxygen saturation, or perfusion increased, decreased, or remained stable. Nor can the absence of a reported estimate be interpreted as a finding of no difference.
The two listed groups differ in age and previous transfusion history, and the registry says the arms are not a like-for-like control comparison. Allocation is not stated. Thus, even if group results were available, a contrast between these groups would not automatically identify the effect of transfusion, age, or transfusion history. The registry does not provide a randomized comparison.
The adverse-event record reports zero serious events and zero other events among four participants at risk in each group; deaths are not reported. Those entries do not establish that the groups are equivalent in safety or that no risk exists. The small enrollment and lack of outcome analyses sharply limit what can be learned about patterns and uncertainty.
The record’s contribution is therefore primarily descriptive of the study’s aims, grouping, and measurement status. It indicates that the planned primary laboratory measurements were not completed as recorded. It cannot answer the clinical or mechanistic questions the study set out to explore, and it does not establish whether any transfusion-related measure changed.
13. Why This Trial Matters Statistically
This record is statistically important because it distinguishes an intended endpoint from an observed one. A protocol hypothesis, even when it gives a precise expectation such as a 20% reduction in perfusion, is not a result. The registry states that the primary SNOHgB levels were never run by the laboratory and lists no analyses. That makes it essential to avoid drawing conclusions from the aims alone.
The study also illustrates why comparator structure matters. The groups are defined by both age and previous transfusion history, while allocation is not stated. The registry explicitly warns that they are not a like-for-like control comparison. A simple contrast between them would not separate those characteristics, even if outcome results were available. This is a design issue, not something that can be resolved by choosing a more elaborate statistical test after the fact.
Planning calculations and observed evidence answer different questions. The registry describes planning assumptions, including a two-sided significance level of 0.05 and equal allocation, but those assumptions do not establish that the study was designed around those calculations. Planning illustrations are not observed power and cannot replace reported outcome estimates or measures of uncertainty.
Finally, the safety entries show why counts need context. Zero recorded events in each group is a descriptive registry entry; it does not demonstrate equal risk, rule out uncommon events, or establish causation. Interpretation depends on complete ascertainment and appropriate follow-up, neither of which is described in the record. Careful reading therefore requires separating the study’s stated questions, the measurements actually run, and the results that the registry reports.
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 central limitation is that the primary SNOHgB levels were never run by the laboratory. Without those measurements, the primary endpoint cannot yield an estimate or an uncertainty assessment. The registry lists no analyses and does not report results for oxygen saturation or perfusion, so the secondary questions also cannot be evaluated from the record.
Enrollment was 8. That is limited information for describing variability or comparing groups, even if the relevant outcomes had been reported. The registry’s adverse-event entries list four participants at risk in each group, but these counts do not supply outcome results or establish the completeness of follow-up.
The groups differ simultaneously by age and previous transfusion history. Allocation is not stated, and the registry says the arms are not a like-for-like control comparison. Any contrast would therefore have limited interpretability as a causal comparison, even if results were available. The record does not describe adjustment for participant characteristics or a strategy for separating the effects of age and transfusion history.
The registry does not report a statistical analysis plan, the original sample-size justification, interim analyses, missing-data methods, or analysis populations. It does not specify the observation period or procedures for adverse-event collection, and deaths are not reported. The stated planning illustration does not fill these gaps: it is a calculation description, not evidence of the study’s original design or its observed findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Transfusions and Nitric Oxide Level in Preterm Infants — NCT00787124.
- Registry record last updated 2018-09-28; status last verified 2018-08.
- Results first posted 2014-01-15.
- 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.
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18. Record Summary
The registry record describes a completed study titled “Transfusions and Nitric Oxide Level in Preterm Infants,” sponsored by Duke University. It lists a start of 2008-09, primary completion in 2009-09, and enrollment of 8. The study aimed to measure hemoglobin-bound nitric oxide and SNO-Hb in transfused blood and infant samples, and to collect oxygen saturation and perfusion measures around transfusion.
The primary endpoint was SNOHgB Levels, with a timeframe of the beginning and end of the study. The laboratory never ran those levels, and the registry lists no analyses. Results for the secondary outcomes are not reported in the registry record. The groups differ by age and prior transfusion history; allocation is not stated, and the registry cautions that they are not a like-for-like control comparison.
Adverse-event entries report zero serious and zero other events among four at risk in each group. Deaths are not reported. The record supports description of the study’s aims and reporting gaps, but not an estimate of the primary outcome or a causal conclusion.