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 Randomized Study of Weekly Erythropoietin Dosing in Preterm Infants (NCT01235923), a randomized phase 2 study. The primary outcome is Baseline Retic Count.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01235923 |
| Phase | Phase 2 |
| Condition | Preterm Infants |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 20 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of New Mexico |
| Results posted | Yes |
2. Clinical Question
Population
Preterm infants were the study population. The registry describes baseline reticulocyte counts as measured for all study subjects, and lists an enrollment of 20.
Intervention
The weekly regimen was 1,200 units/kg of erythropoietin given subcutaneously once a week for 4 weeks.
Comparator
The comparator was 400 units/kg of erythropoietin given subcutaneously three times weekly for 4 weeks.
Primary question
The posted primary outcome compares mean reticulocyte counts at baseline between the dosing groups. It does not report a post-treatment reticulocyte count or a transfusion outcome.
The clinical context in the registry is that preterm infants may require multiple transfusions and that erythropoietin has been used with the aim of decreasing transfusion requirements. The study rationale contrasts the usual three-times-weekly dosing schedule with less frequent dosing schedules that had been used in adults. The question described in the registry was whether weekly dosing could be assessed against three-times-weekly dosing in preterm infants.
The distinction between that clinical rationale and the posted primary outcome matters. The registry record reports baseline reticulocyte counts, measured at study entry. A baseline comparison describes the groups before the scheduled study dosing; it does not directly answer whether either schedule changes reticulocyte counts over time or affects transfusions. Those outcomes are not reported in the registry record as posted results.
The numerical comparison is between the mean baseline count in the weekly group and the mean in the three-times-a-week group. It is a descriptive contrast of a continuous laboratory measure. The result should therefore be read as evidence about the recorded entry values and their statistical uncertainty, not as a direct estimate of a treatment effect on clinical outcomes.
3. Trial Design
The registry identifies this as a phase 2, randomized, parallel-group study with quadruple masking. Its status is completed, and the registry lists enrollment of 20. The sponsor is the University of New Mexico. The registry dates the study start to 2006-04 and primary completion to 2009-03.
The two groups received different schedules of erythropoietin by subcutaneous administration. The weekly group received 1,200 units/kg once a week for 4 weeks. The comparison group received 400 units/kg three times weekly for 4 weeks. The study description frames the comparison as weekly versus standard three-times-weekly dosing. The registry does not report further details about the masking procedures, such as which roles were masked or how masking was maintained.
The primary outcome listed is “Baseline Retic Count,” measured at study entry in x1000 cells/microliter. The outcome is continuous and is summarized as a mean with standard error. The registry states that all study subjects had a baseline reticulocyte count measured. The posted group summaries list 10 participants for the weekly group and 10 for the three-times-a-week group.
The reported comparison is an unadjusted mean difference, with the three-times-a-week group contrasted against the weekly group. The registry reports no posted analyses and no posted secondary outcomes. The registry record does not report the trial’s original sample-size justification, its intended analysis populations, its detailed statistical plan, or whether interim analyses were planned or conducted. Those omissions limit what can be inferred about the study’s original design decisions or the analysis process.
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 | Three Times Weekly Epo | Weekly Epo |
|---|---|---|
| STARTED | 10 | 10 |
| COMPLETED | 10 | 10 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: All study subjects had baseline retic count measured.
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 | Three Times Weekly Epo | Weekly Epo | Total |
|---|---|---|---|---|
| Participants analysed | 10 | 10 | 20 | |
| Age, Customized | days | 15 (SD 4) | 18 (SD 3) | 17 (SD 3) |
| Sex: Female, Male: Female | Participants | 6 | 5 | 11 |
| Sex: Female, Male: Male | Participants | 4 | 5 | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Baseline Retic Count, measured over baseline.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | x1000 cells/microliter |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the reticulocyte count measured at study entry. Reticulocytes are immature red blood cells, and their count is a continuous laboratory measure. The registry records the unit as x1000 cells/microliter and specifies that the outcome is summarized by its mean and standard error. It describes the measurement as a baseline reticulocyte count and says all study subjects had this measurement taken.
In general, a baseline measure can describe the condition of participants at entry and provide context for comparing groups before the study dosing schedules are delivered. Reticulocyte counts are relevant to the red-cell context underlying the study’s discussion of erythropoietin and transfusion requirements. That relevance does not make a baseline value a measure of subsequent response. The posted endpoint is not a change from baseline, a later reticulocyte count, or a transfusion count.
The group means are 122.0 for weekly dosing and 140.0 for three-times-a-week dosing. The reported mean difference, defined as the three-times-a-week group relative to the weekly group, is 18.0. These entry values describe the recorded baseline endpoint. The registry record does not report follow-up measurements for this endpoint, so the posted result cannot characterize how reticulocyte counts changed after dosing began.
7. Results Posted in the Registry
- Three Times a Week Epo: mean 140.00 versus 122.00 on control; difference 18.00 (95% CI -34.59 to 70.59), standardized effect d = 0.30; z-test p = 0.502.
Mean difference: Three Times a Week Epo
95% CI: -34.59 to 70.59
Recalculated from the posted summary statistics
8. Statistical Interpretation
The weekly group had a reported mean baseline reticulocyte count of 122.0, with a standard error of 12.0. The three-times-a-week group had a reported mean of 140.0, with a standard error of 24.0. The registry’s unadjusted mean difference is 18.0, with the three-times-a-week group as the contrast group relative to weekly dosing. The reported 95% confidence interval extends from -34.59 to 70.59, and the unadjusted p-value is 0.502.
The point estimate is positive: the recorded mean was higher in the three-times-a-week group at baseline. The confidence interval, however, includes negative and positive values. In general, this means the data are compatible with a range of possible underlying differences in either direction, including values close to no difference. The interval is wide relative to the point estimate, so the estimate is not precise. The result does not establish that the underlying baseline means were identical, nor does it establish a meaningful baseline difference.
The p-value of 0.502 is the reported unadjusted value for this comparison. In general, a p-value measures how unusual data at least as inconsistent with a specified null model would be if that model held, under the test’s assumptions. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. The registry record does not report a prespecified significance threshold for the trial’s own analysis, so the p-value should be read as a reported statistic rather than as a complete account of the original decision rule.
This outcome is measured at baseline, before the study dosing schedules described in the registry. It therefore cannot be interpreted as evidence that weekly or three-times-weekly dosing changed reticulocyte counts. Nor does it directly report transfusion requirements, despite transfusions appearing in the clinical rationale. No post-treatment reticulocyte results or transfusion results are reported in the registry record.
The group summaries are based on small listed group sizes, with 10 participants in each arm. As a general statistical matter, estimates from small groups can be imprecise, and the confidence interval conveys that uncertainty more directly than a binary reading of the p-value. The registry record does not report an adjusted analysis; the posted contrast is identified as unadjusted. No discrepancy between the posted result and the recalculated comparison is flagged.
The most bounded interpretation is that the registry reports a higher sample mean at baseline in the three-times-a-week arm, but the uncertainty around the estimated difference is substantial. This is a baseline description only. It does not support a conclusion about comparative efficacy, later blood counts, safety beyond the posted adverse-event counts, or clinical outcomes.
9. Statistical Methods Explained
The primary endpoint is continuous, so the registry summarizes it with a mean for each group and reports a mean difference between groups. A mean gives the arithmetic average of the observed values in a group. It is useful for describing the center of a continuous measure, although it does not show the full distribution of individual measurements. The registry reports the group means as 122.0 for weekly dosing and 140.0 for three-times-a-week dosing.
What does the standard error describe?
The reported dispersion is the standard error, not the standard deviation. In general, a standard error describes the uncertainty in an estimated quantity, such as a sample mean, across repeated samples under a statistical model. It is not a direct description of how far individual participants’ measurements tend to vary from the group mean. The standard errors are 12.0 for the weekly group and 24.0 for the three-times-a-week group. Because these are standard errors, they should not be interpreted as ranges containing most individual values.
The registry also reports a pooled standard deviation of 60.0 for the comparison. In general, a pooled standard deviation combines information about within-group variability under assumptions appropriate to the comparison. It is a different quantity from either group’s standard error. The standardized effect listed for the comparison is 0.3. Such a standardized effect expresses a contrast relative to a variability scale, which can make effects measured on different scales easier to compare in general. It does not replace the original-unit estimate, and it should be interpreted cautiously when the underlying study groups are small.
How should the mean difference be read?
The comparison is a mean difference of 18.0, formed in the direction of the three-times-a-week group relative to the weekly group. The registry also lists the two group means used in that comparison. In general, a mean difference retains the measurement’s original scale, making its direction and units more directly interpretable than a standardized effect. Here the unit is x1000 cells/microliter. Since the endpoint was measured at baseline, this contrast describes entry values rather than an effect of the dosing schedules.
The posted confidence interval is -34.59 to 70.59. In general, a confidence interval is an uncertainty range calculated by a method designed to have a stated coverage rate over repeated applications when its assumptions hold. It reflects both the estimated difference and its uncertainty. The interval does not mean that each participant’s value lies within those limits, and it is not a guarantee that the true difference is inside the particular interval. Its inclusion of values on both sides of zero indicates that the estimate is compatible with differences in either direction under the reported method.
What does the p-value add?
The unadjusted p-value is 0.502. In general, a p-value is calculated under a null hypothesis and model assumptions; it describes the compatibility of the observed data with that null model. It does not quantify the probability that the null is true, the probability that the result will replicate, or the clinical importance of the estimated contrast. It is most informative alongside the effect estimate and confidence interval, rather than on its own. The registry record does not report the exact test or a fuller statistical analysis plan for this endpoint.
The comparison is described as unadjusted. In general, an unadjusted estimate is calculated without accounting for other variables through a covariate-adjustment model. Randomization can support comparability in expectation, but it does not ensure that every measured baseline characteristic will be identical in a particular trial. The registry record does not report covariates used in an adjusted analysis, and it lists no posted analyses beyond the endpoint result.
Why can over-dispersion matter?
Over-dispersion is a general concern when observed variability exceeds what a model assumes. If a method underestimates variability, its standard errors may be too small and its confidence intervals too narrow. This concept is often important for count outcomes or clustered observations, but the posted primary endpoint is a continuous reticulocyte count summarized by a mean. The registry record does not report an over-dispersion assessment or a model-based adjustment for it. It would therefore be inappropriate to claim that over-dispersion was tested or corrected in this analysis.
The registry identifies the study as randomized, parallel, phase 2, and quadruple masked. Those design labels describe important features, but they do not specify the details of the statistical test, the handling of missing data, or the analysis population. Those elements are not reported in the registry record. The reported comparison should consequently be understood on the terms that are available: an unadjusted mean difference for a continuous baseline measure, accompanied by a confidence interval and p-value.
10. Confidence Intervals and Precision
The estimated mean difference in baseline reticulocyte count is 18.0, with a 95% confidence interval from -34.59 to 70.59. The interval is broad and extends from a negative difference to a positive one. This indicates substantial uncertainty about the direction and size of the underlying difference. It does not establish that the groups had the same baseline mean, and it does not establish a definite difference in either direction.
In general, a confidence interval represents a range of estimates compatible with the observed data under the method and assumptions used. Its width is informative about precision: a narrower interval indicates a more precise estimate, while a wider interval indicates less precision. The reported interval includes values that differ considerably from the point estimate of 18.0. The point estimate alone therefore gives an incomplete picture of the result.
The standard errors are 12.0 in the weekly arm and 24.0 in the three-times-a-week arm. Standard errors describe uncertainty in estimates, rather than the spread of individual participants’ values. The registry reports 10 participants in each arm, and the endpoint is described as measured for all study subjects. The registry does not provide individual-level data or a separate account of missing measurements, so further evaluation of the observed variability or missingness is not possible from this record.
Precision also depends on the study question. This interval pertains to a baseline difference, not a treatment effect on a later outcome. Even a more precise estimate of baseline values would not answer whether either dosing schedule changes reticulocyte counts or affects transfusion requirements. Those results are not reported in the registry record.
11. Planning a Similar Trial: Sample Size
This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.
| Effect to detect | Participants per arm, 80% power | Participants per arm, 90% power |
|---|---|---|
| 100% of the observed effect | 175 | 234 |
| 75% of the observed effect | 311 | 416 |
| 50% of the observed effect | 698 | 934 |
The planning figures are participants per arm, not total event counts. The registry’s planning illustration uses the observed effect as its reference and gives scenarios for detecting 100%, 75%, or 50% of that observed effect. For 100% of the observed effect, the listed requirements are 175 participants per arm for 80% power and 234 participants per arm for 90% power. For 75% of the observed effect, the corresponding figures are 311 and 416 participants per arm. For 50% of the observed effect, they are 698 and 934 participants per arm.
In general, power is the probability that a statistical test will reject its null hypothesis under a specified alternative, assuming the planning model and its parameters hold. The 80% power column gives the per-arm planning size for the stated power target; the 90% power column gives the per-arm planning size for the higher target. A higher target generally requires more participants under otherwise unchanged assumptions. The scenarios also illustrate that smaller effects need more participants: the listed requirements rise as the assumed fraction of the observed effect declines.
The stated 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. These are planning illustrations computed from the observed effect, not the trial’s original design assumptions; the trial’s own sample-size justification is not reported in the registry record. These figures are not observed power. They are prospective planning calculations based on assumptions, not a measure of whether the completed trial had a high or low probability of detecting its actual result.
12. How the Sample Size Is Derived
Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z1−α/2 = 1.960) and the desired power (z1−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
- Observed difference Δ = 18.000; pooled standard deviation σ = 60.000.
- n = 2 × (1.96 + 0.842)2 × 60.0002 / 18.0002 = 174.4, rounded up to 175 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 <- 18 # observed difference in means
sigma <- 60 # 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(1235923)
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 = 175 (80% power), 234 (90% power)
75% of observed effect: n per arm = 311 (80% power), 416 (90% power)
50% of observed effect: n per arm = 698 (80% power), 934 (90% power)
power.t.test: 175.4
Simulated power at n = 175 per arm: 0.797 (20000 replicates)The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.
13. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, baseline reticulocyte count, and no posted secondary outcomes. It also lists no posted analyses. The record does not describe a multiplicity plan, such as how the trial would handle interpretation of several endpoints or repeated statistical tests. With no posted secondary results, the extent to which multiplicity would have affected the interpretation of a broader outcome set cannot be assessed.
In general, multiplicity arises when several hypotheses are tested or several outcomes are examined. Repeated testing can increase the chance of obtaining at least one apparently unusual result even when no underlying effect exists. Statistical plans may address that issue through prespecified outcome hierarchies or adjustment methods. The registry record does not report whether such procedures were planned or used, so none should be assumed for this result.
Missing-data handling is also not reported in the registry record. The outcome description says all study subjects had a baseline reticulocyte count measured, but the record does not provide a detailed accounting of analysis exclusions, any imputation method, or how missingness was assessed. The group summaries list 10 participants in each arm; that does not supply details about the analysis population beyond the information recorded for this endpoint.
The record does not identify an intention-to-treat, per-protocol, or other named analysis population. It does not report whether participants were analyzed according to randomized assignment, whether deviations from the dosing schedules occurred, or how such deviations would have been handled. In general, the chosen analysis population and missing-data strategy can affect the interpretation of a randomized comparison. Without these details, the reported estimate can be described, but its alignment with a prespecified analysis strategy cannot be verified.
The registry also does not report a detailed statistical analysis plan, the exact test for the primary comparison, or whether there were interim analyses. This absence is not evidence that such procedures were absent from the study; it means they are not reported in the registry record. Interpretations should remain limited to the posted baseline summary and its reported uncertainty.
14. 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 |
|---|---|---|---|
| Weekly Epo | 1 | 10 | 10.0% |
| Three Times Weekly Epo | 1 | 10 | 10.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Weekly Epo | 5 of 10 |
| Three Times Weekly Epo | 6 of 10 |
Most frequent serious adverse event terms
| Event term | Organ system | Weekly Epo | Three Times Weekly Epo |
|---|---|---|---|
| Death | Gastrointestinal disorders | 1 of 10 | 1 of 10 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Weekly Epo | Three Times Weekly Epo |
|---|---|---|---|
| bronchopulmonary dysplasia | Respiratory, thoracic and mediastinal disorders | 5 of 10 | 6 of 10 |
| interventricular hemorrhage greater than grade 2 | Nervous system disorders | 1 of 10 | 3 of 10 |
Serious events with the highest arm-level rate: death (10.0%).
The registry reports serious adverse events in 1 participant at risk of 10 in the weekly group and 1 participant at risk of 10 in the three-times-weekly group. For other adverse events, it reports 5 affected participants among 10 at risk in the weekly group and 6 among 10 at risk in the three-times-weekly group. These are separate recorded categories; the registry does not explain whether participants could appear in both categories or give event-level details.
The top serious adverse-event term is listed as Death, with 10.0%. The group-level deaths field is not reported in the registry record. The term and percentage should therefore be reported as the registry lists them, without inferring which group or individual it refers to. The record does not provide further detail about timing, severity descriptions beyond the serious classification, relatedness to study dosing, or the number of events per affected participant.
These counts describe reported adverse events and are not, by themselves, a complete comparative safety analysis. The registry record does not provide statistical uncertainty for the adverse-event comparisons. The small listed group sizes and limited event detail constrain interpretation; these figures should not be used to infer a causal relationship or to make treatment recommendations.
15. What the Result Does, and Does Not, Mean
The posted result establishes what the registry reports about the baseline measure: the mean reticulocyte count was 122.0 in the weekly group and 140.0 in the three-times-a-week group. The unadjusted mean difference, in the direction of three-times-a-week dosing relative to weekly dosing, was 18.0. Its 95% confidence interval ranged from -34.59 to 70.59, and the unadjusted p-value was 0.502. The interval indicates considerable uncertainty about the size and direction of a baseline difference.
The result does not establish that the groups were equivalent at baseline. A failure to obtain a small p-value is not proof of equality, and the registry does not report an equivalence margin or an equivalence analysis. Conversely, the positive point estimate does not establish a meaningful difference between the groups. Its uncertainty must be considered alongside its direction.
Most importantly, the endpoint is a measurement at study entry. It is not a post-treatment response and does not compare changes in reticulocyte counts after weekly or three-times-weekly erythropoietin. The registry describes transfusion requirements as part of the clinical rationale, but it does not report transfusion results among the posted outcomes. The result therefore cannot answer whether either schedule changed transfusion requirements.
The registry’s adverse-event counts provide a limited description of events recorded in each group. They do not resolve questions about causality, timing, or comparative risk, and the group-level deaths field is not reported in the registry record. The baseline endpoint and adverse-event counts should not be combined into a broader claim about benefit or harm.
The trial is identified as randomized, masked, parallel, and phase 2, but the registry does not report enough detail to reconstruct the full analysis plan or the original sample-size justification. The most defensible conclusion is descriptive: the posted baseline means differ by the reported estimate, with an interval broad enough to leave substantial uncertainty. The record does not report the later clinical outcomes needed to assess the dosing schedules’ effects.
16. Why This Trial Matters Statistically
This trial raises a useful statistical distinction between a clinical question and the outcome actually reported. The registry’s rationale concerns dosing frequency and transfusion requirements in preterm infants, while its posted primary result is a reticulocyte count measured at baseline. Keeping those questions separate prevents a baseline comparison from being mistaken for evidence about treatment response or clinical benefit.
The reported mean difference is accompanied by a confidence interval that crosses from negative to positive values. This makes the uncertainty visible: the point estimate alone suggests one direction, but the data are compatible with a range of underlying differences. Reading the interval alongside the p-value avoids reducing interpretation to whether a result passes a threshold that is not reported as part of the trial’s original analysis plan.
The sample-size illustration also demonstrates a general planning principle. Smaller target effects require larger per-arm sample sizes under the stated planning assumptions. These illustrations are based on the observed effect and do not establish the trial’s original design rationale or its achieved power. Separating planning calculations from observed results is important when evaluating a completed study.
Finally, the registry record shows why completeness of reporting affects statistical interpretation. The endpoint result is posted, but a detailed analysis plan, missing-data procedures, analysis populations, multiplicity methods, and secondary outcomes are not reported. The available result can still be described precisely, while questions that depend on those absent details remain unresolved. That distinction supports careful interpretation without extending the evidence beyond the outcome and information recorded.
17. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal limitation for interpreting the primary result is that it concerns a baseline measure rather than a post-treatment endpoint. It cannot show how reticulocyte counts changed during or after the dosing schedules, and it does not report the transfusion outcome discussed in the study rationale. The posted result is therefore limited to describing entry values.
The group sizes listed for the primary endpoint are 10 participants in each arm. The confidence interval is broad, and the registry does not provide individual-level observations that would permit further checks of the distribution or influential values. The group summaries report standard errors, not standard deviations, so the listed dispersion does not directly convey the spread of individual measurements.
Important analytical details are not reported in the registry record. These include the detailed statistical plan, the precise test used for the primary comparison, the analysis population, missing-data procedures, multiplicity handling, and interim-analysis plans. The trial’s original sample-size justification is also not reported. The planning illustration based on the observed effect cannot fill in those design details.
The safety information is limited to affected-participant counts and a top serious adverse-event term. The record does not give event-level detail, timing, attribution, or a reported group-level deaths count. The adverse-event counts therefore cannot establish causality or provide a complete comparison of safety.
The registry identifies randomization and quadruple masking but does not report operational details about allocation procedures or masking. These limitations do not invalidate the posted values, but they restrict evaluation of how the study was conducted and analyzed. Conclusions should remain confined to the recorded baseline comparison and the adverse-event summaries.
18. Related Tutorials
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: Randomized Study of Weekly Erythropoietin Dosing in Preterm Infants — NCT01235923.
- Registry record last updated 2022-06-21; status last verified 2012-06.
- Results first posted 2013-07-29.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
21. Record Summary
The registry record describes a completed phase 2 randomized, quadruple-masked, parallel study sponsored by the University of New Mexico. It lists enrollment of 20 and compares weekly erythropoietin with three-times-weekly erythropoietin in preterm infants. The schedules were administered subcutaneously for 4 weeks.
The posted primary outcome is baseline reticulocyte count, measured at study entry and summarized as a mean with standard error. The reported mean difference is 18.0 for three-times-a-week dosing relative to weekly dosing, with a 95% confidence interval from -34.59 to 70.59 and an unadjusted p-value of 0.502. The result is a baseline comparison, not a reported treatment response.
The record lists adverse-event counts but does not report secondary outcomes or analyses. Details of the trial’s original statistical plan, sample-size justification, analysis populations, and missing-data procedures are not reported in the registry record.