Treatment Response of Injectafer vs Oral Iron to Baseline Hepcidin Levels in Patients With Iron Deficiency Anemia (IDA) Secondary to Inflammatory Bowel Disease (IBD) or Gastric Bypass: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treatment Response of Injectafer vs Oral Iron to Baseline Hepcidin Levels in Patients With Iron Deficiency Anemia (IDA) Secondary to Inflammatory Bowel Disease (IBD) or Gastric Bypass (NCT02086968), a randomized phase 4 study. The primary outcome is Correlation Between Screening Hepcidin and Change in Hemoglobin From Baseline to Highest Observed Hemoglobin Change (Proportion of Responders)..

2. Clinical Question

The trial examined treatment response among patients with iron deficiency anemia secondary to inflammatory bowel disease or gastric bypass. Its stated primary objective was to evaluate treatment response in relation to baseline hepcidin levels, including whether selected patients might be inappropriate for oral iron therapy. The registry record describes an assessment of the relationship between screening hepcidin and change in hemoglobin, but it does not report a numerical estimate of that relationship. The posted primary outcome gives the number of participants classified as responders in each treatment group.

The registry describes a randomized, open-label comparison. The treatment groups therefore allow a comparison of responder counts under the two assigned regimens, while the stated hepcidin question concerns whether baseline values were associated with response. These are related but distinct questions. The posted group counts address how many participants met the responder definition; they do not, by themselves, show whether response differed by hepcidin level or identify a hepcidin threshold. No such threshold or subgroup result is reported in the registry record.

3. Trial Design

This was a Phase 4, randomized, open-label, parallel-group study sponsored by American Regent, Inc. The condition is listed as iron deficiency anemia secondary to inflammatory bowel disease or gastric bypass. The registry reports an enrollment of 198 and a completed study, with a start date of 2014-01-01 and primary completion on 2016-07-16. The registry record does not state the original sample-size assumptions or provide further detail about the randomization procedure.

Participants were assigned to Injectafer or ferrous sulfate tablets. The Injectafer regimen consisted of two doses on Days 0 and 7, each at 15 mg/kg and subject to a maximum single dose of 750 mg, for a total of up to 1500 mg. The oral regimen was 325 mg ferrous sulfate, one tablet three times a day for 28 days. Because masking was listed as none, the study was open label: participants and study personnel were not masked to treatment assignment according to the registry description.

The primary outcome timeframe was any time between baseline and the end of the study on Day 28 or the time of intervention. The outcome definition classified participants as responders if hemoglobin increased from baseline by at least 2 g/dL at any time between baseline and Day 28. The registry identifies the full analysis set as the population for this outcome. It posts outcome counts for 94 participants in the Injectafer group and 92 in the ferrous sulfate group. Those outcome denominators should be distinguished from the registry’s overall enrollment of 198 and from the separate safety denominators.

The registry record lists one outcome measure and no posted secondary outcomes. It describes regression models for the hepcidin relationship and methods for treatment-group comparisons, but the number of posted analyses is zero. As a result, the available result supports a description of the posted responder counts and their listed comparison, not a reconstruction of the complete analysis or participant flow.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full analysis set population

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.

Population: Of the 198 subjects randomized, two subjects (one in each group) were not treated.

6. Primary Endpoint

The registry lists the primary outcome as Correlation Between Screening Hepcidin and Change in Hemoglobin From Baseline to Highest Observed Hemoglobin Change (Proportion of Responders)., measured over anytime between baseline and end of study (day 28) or time of intervention.

The primary endpoint concerns the relationship between screening hepcidin and the change in hemoglobin, expressed through the proportion of participants who met a responder definition. A responder was a participant with an increase from baseline of at least 2 g/dL in hemoglobin at any time between baseline and the end of the study on Day 28. The registry gives the timeframe as any time between baseline and the end of the study or the time of intervention.

A threshold-based responder outcome turns a continuous measurement, hemoglobin change, into a yes-or-no classification. In general, this can make a result easier to interpret as the number of participants crossing a specified response threshold. It also discards information about the size and timing of changes that do not cross the threshold, and participants with changes close to one another may be assigned to different categories if they fall on opposite sides of the cutoff.

The endpoint has two components in the registry description: the responder proportion and its relation to screening hepcidin. The posted results report 60 responders among 94 participants assigned to Injectafer and 34 among 92 assigned to ferrous sulfate. The registry description states that regression models assessed the relationship between baseline hepcidin and hemoglobin change, with baseline hepcidin and treatment group as independent factors. However, a coefficient, association estimate, or other numerical result for hepcidin is not reported in the registry record. The responder counts therefore describe the treatment-group outcome, but do not establish how response varied with baseline hepcidin.

7. Results Posted in the Registry

• Ferrous Sulfate Tablets: 37.0% (34/92) versus 63.8% (60/94) on control; risk difference -26.9 percentage points (95% CI -40.7 to -13.0), risk ratio 0.58 (0.43–0.79); unadjusted two-proportion z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes several statistical approaches for the primary outcome. In general, a statistical method summarizes data under stated assumptions; its result is meaningful only in relation to the endpoint definition, the analysis population, and the information actually reported. Here, the posted result includes responder counts by treatment group and an unadjusted comparison, while the registry’s stated analysis description also refers to regression and covariance models.

What does the responder comparison measure?

The endpoint classifies participants as responders or nonresponders using a threshold: an increase from baseline of at least 2 g/dL in hemoglobin at any time through Day 28. For a binary endpoint, the basic information is the number meeting the definition and the number included in each group. The posted counts are 60 of 94 for Injectafer and 34 of 92 for ferrous sulfate. The comparison estimates how the responder outcome differs between the groups. A risk difference is an absolute contrast between the groups’ outcome probabilities, so zero represents no absolute difference. Its sign depends on which group is subtracted from which; the reported estimate is for ferrous sulfate relative to Injectafer.

The registry gives the risk difference as -0.269 and its 95% confidence interval as -0.407 to -0.130. It also gives a risk ratio and an odds ratio. In general, the risk ratio compares probabilities, while the odds ratio compares odds. The two measures can differ in size and interpretation, particularly when an outcome is not rare. They answer related but distinct questions, and the scale should be kept in mind when interpreting them. No conversion of one measure into another is needed to read the posted estimates.

What does the confidence interval contribute?

In general, a confidence interval describes the range of estimates reasonably compatible with the data under a specified statistical procedure and its assumptions. It conveys uncertainty around an estimate and can show which values are less compatible with the observed data. It does not guarantee that the true value lies inside the particular interval, nor does it describe the range of individual participant outcomes. For the risk difference, the interval lies on the negative side of zero. That is consistent with the reported direction of the comparison and with the unadjusted p-value of <0.001. The width of the interval also matters: estimates across the interval represent a range of possible magnitudes, not just a single point estimate.

How was hepcidin intended to be assessed?

The registry description says that regression models used baseline hepcidin and treatment group as independent factors to assess the relation between screening hepcidin and hemoglobin change. In general, regression models estimate how an outcome varies with one or more explanatory variables while accounting for the variables included in the model. A model with baseline hepcidin and treatment group can examine their associations with the outcome as specified, but interpretation depends on the exact model form, outcome scale, coding, and any interaction terms. Those details, along with model coefficients and uncertainty estimates, are not reported in the registry record. The posted responder counts cannot substitute for those model results or show whether the relationship with hepcidin differs between groups.

The registry also states that treatment-group differences for mean changes in endpoints were assessed with analysis of covariance, using a fixed factor for treatment and the baseline value as a covariate. In general, analysis of covariance compares group outcomes while accounting for a baseline measurement in the model. This description concerns mean changes, whereas the posted primary result is a count of participants meeting a binary threshold. The registry does not report numerical results from the stated covariance analysis, so its estimates cannot be evaluated from the posted result.

What does the proportion test mean?

For treatment-group differences in proportions, the registry describes a normal approximation to the binomial distribution. In general, this approach uses an approximate sampling distribution to test or estimate a difference in proportions. Its accuracy depends on whether the data support the approximation and on the analysis details. The reported unadjusted p-value is <0.001. The registry record does not provide a fuller account of the test implementation or any adjusted analysis for the posted responder comparison.

The outcome is binary, but the underlying hemoglobin measurement is continuous. In general, thresholding can simplify communication but can obscure the range of measurements and the magnitude of changes among participants. The registry reports the responder counts rather than a distribution of individual hemoglobin changes. It therefore permits interpretation of the threshold-defined result, but not a fuller assessment of the continuous outcome from these figures alone.

Finally, a p-value and a confidence interval address sampling uncertainty under a statistical model; neither resolves questions about missing data, selection into the analysis set, or clinical importance. The registry identifies the full analysis set for the primary endpoint but does not describe missing-data handling. The reported estimates should therefore be interpreted with the endpoint and reported analysis population in view, while recognizing that unreported analytic details limit independent assessment.

10. Confidence Intervals and Precision

The risk difference for ferrous sulfate relative to Injectafer is -0.269, with a 95% confidence interval from -0.407 to -0.130. The interval is entirely negative, so the estimated contrast is consistently in the direction of fewer responders in the oral group under the stated comparison orientation. Its endpoints indicate that the data are compatible with a range of negative differences, rather than only the point estimate. The interval does not express the probability that a future participant will respond, and it is not an interval for individual hemoglobin change.

The registry also reports a risk ratio of 0.579, with a 95% confidence interval from 0.426 to 0.787, and an odds ratio of 0.332, with a 95% confidence interval from 0.183 to 0.603. These are relative measures for the oral group compared with Injectafer. Their intervals remain below the no-difference value for a ratio, which is 1. In general, the confidence interval’s width reflects both the observed estimate and the amount of information available, along with the method used to calculate it. The different scales have different meanings; the odds ratio is not an absolute probability difference.

The unadjusted p-value is <0.001. It is evidence against a no-difference null hypothesis within the test framework, but it does not measure the magnitude or practical importance of the result. Precision is better judged by considering the estimate and its interval together, while keeping the endpoint definition and analysis population in mind. The registry does not report a confidence interval for the hepcidin relationship, because its numerical model result is not reported in the registry record. Thus, the precision of the responder-group comparison can be described, but the precision of the hepcidin association cannot be assessed from the posted results.

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.

The planning figures are participants per arm, not total participants, because the illustration concerns a two-arm binary outcome. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is defined as a stated fraction of the observed effect. The original trial’s own design assumptions and sample-size justification are not reported in the registry record. These figures are a planning illustration based on the observed result, not observed power.

The 80% power column gives the number of participants per arm that the planning calculation would require to have an 80% chance of detecting the specified effect under the listed assumptions, if that effect were the true one. The 90% power column gives the corresponding number per arm for a 90% chance. Power is a feature of a design under assumed conditions; it does not tell whether a particular finding is true, and it should not be read as a measure of the strength of the observed evidence.

The illustration gives 54 participants per arm for planning for 100% of the observed effect at 80% power, and 71 participants per arm at 90% power. For planning for 75% of the observed effect, the figures are 95 participants per arm for 80% power and 127 for 90% power. For planning for 50% of the observed effect, they are 212 participants per arm for 80% power and 284 for 90% power. The general pattern is that smaller effects require more participants to detect under otherwise unchanged assumptions. This is because smaller contrasts are harder to distinguish from sampling variation.

These are not the trial’s observed enrollment counts or a retrospective assessment of its power. The record gives overall enrollment as 198, while the primary outcome denominators are 94 and 92. The planning values are hypothetical and should not be treated as evidence that the trial was designed around the observed effect.

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 z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.638; treatment proportion p₁ = 0.370; average p̄ = 0.504.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7071 = 1.3859.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6811 = 0.5732.
4. n = (1.3859 + 0.5732)² / (-0.2687)² = 53.1, rounded up to 54 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
p0 <- 0.638297872340426                          # control proportion
p1 <- 0.369565217391304                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2086968)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 54 (80% power), 71 (90% power)
 75% of observed effect: n per arm = 95 (80% power), 127 (90% power)
 50% of observed effect: n per arm = 212 (80% power), 284 (90% power)
power.prop.test: 53.1 
Simulated power at n = 54 per arm: 0.796 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 outcome measure and no posted secondary outcomes. It records zero posted analyses. The primary outcome description includes a hepcidin relationship and treatment-group comparisons, but the registry does not provide a complete list of analyses performed or a numerical result for the hepcidin model. The existence of more than one statistical question within the endpoint description does not establish how the analyses were prioritized or whether any correction for multiple testing was used.

In general, multiplicity arises when several hypotheses or outcomes are tested. As the number of tests increases, the chance of obtaining at least one apparently unusual result by chance can increase, depending on how the tests relate and how results are selected. Statistical plans may address multiplicity by defining a primary test, adjusting significance thresholds, or using another prespecified strategy. The registry record does not report a multiplicity adjustment or enough detail to determine how multiple analyses were handled. The unadjusted p-value should therefore be read as the reported comparison’s unadjusted result, not as evidence that all possible testing concerns were addressed.

The primary endpoint population is identified as the full analysis set. The outcome counts are 94 participants for Injectafer and 92 for ferrous sulfate. The registry’s overall enrollment is 198. Safety denominators are separately listed as 99 and 97. The record does not explain how participants moved from enrollment to these analysis denominators, or why the endpoint and safety populations differ. Reasons for exclusion or non-evaluation are not reported in the registry record.

Missing-data handling is also not reported in the registry record. The endpoint relies on observing hemoglobin change at some point through the stated timeframe. Without details about missing measurements, withdrawals, or how incomplete follow-up was handled, it is not possible to determine from the registry record whether the analysis used a particular imputation method, a complete-case approach, or another procedure. These omissions limit assessment of the risk that missing outcome data affected the responder comparison. They do not, by themselves, establish that missingness occurred or biased the result.

The registry says the study was randomized and open label, but the randomization sequence, allocation concealment, and detailed analysis population rules are not reported in the registry record. These details matter for evaluating how treatment assignment and participant inclusion were implemented. The available description supports a basic account of the planned statistical approach, but not a complete independent audit of the analysis.

14. 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 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: crohn's disease (1.0%), small intestinal obstruction (1.0%), colitis ulcerative (1.0%), large intestinal obstruction (1.0%), clostridium difficile colitis (1.0%).

The safety record lists serious adverse events among 99 participants at risk in the Injectafer group and 97 in the ferrous sulfate group. Three participants in the Injectafer group and one in the ferrous sulfate group were affected. Deaths are listed as zero in each group. The record also lists other, non-serious adverse events among 33 participants in the Injectafer group and 24 in the ferrous sulfate group, with 99 and 97 participants at risk, respectively.

The serious-event terms listed include Crohn's disease, small intestinal obstruction, colitis ulcerative, large intestinal obstruction, and Clostridium difficile colitis, each recorded as 1.0%. These terms describe events in the registry safety record; they do not establish that treatment caused an event. The event figures are counts and denominators, not a randomized statistical comparison with an uncertainty interval. The safety denominators differ from the primary endpoint denominators, and the registry does not explain the difference. In general, safety counts are interpreted in the context of the people at risk, how events were collected, and the study’s duration. Further details on event timing, severity beyond the serious classification, attribution, and statistical testing are not reported in the registry record.

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

The posted results establish that the registry recorded 60 responders among 94 participants assigned to Injectafer and 34 among 92 assigned to ferrous sulfate, using a hemoglobin increase of at least 2 g/dL as the response threshold. The reported risk difference for ferrous sulfate relative to Injectafer is -0.269, with a 95% confidence interval from -0.407 to -0.130 and an unadjusted p-value of <0.001. In statistical terms, the posted comparison indicates a difference in the proportion meeting this particular endpoint during the specified timeframe, with the estimate favoring the Injectafer group in the direction of more threshold-defined responders.

That finding does not answer every question raised by the study’s title or objective. In particular, the posted results do not quantify the association between baseline hepcidin and response, identify a hepcidin value at which oral treatment is unsuitable, or show whether the treatment-group contrast changes across hepcidin levels. The registry describes a regression approach for assessing hepcidin, but the estimates and their uncertainty are not reported in the registry record. The treatment-group counts cannot be used to infer an individual participant’s response from a hepcidin measurement.

The responder definition also has limits. It reduces hemoglobin change to a yes-or-no outcome, so these counts do not show the magnitude of changes among responders or nonresponders, the distribution of all changes, or when participants crossed the threshold. The registry gives a timeframe ending on Day 28 or intervention time, and the finding should be understood within that recorded endpoint and period.

The study was randomized and open label, with a parallel-group design. The registry does not give enough detail to assess all elements of trial conduct, including missing-data handling and the full analysis plan. The result is a statistical description of the posted outcome comparison; it is not a complete account of benefits and harms, a statement about all relevant outcomes, or medical advice. No treatment recommendation follows from the responder comparison alone.

16. Why This Trial Matters Statistically

This trial raises a statistical question that is more specific than a simple comparison of two treatments: whether baseline hepcidin is related to hemoglobin response and could help characterize response in patients with iron deficiency anemia secondary to inflammatory bowel disease or gastric bypass. That makes the distinction between an overall treatment-group comparison and a biomarker relationship important. The posted responder counts address the former. They do not provide the numerical evidence needed to assess the latter.

The endpoint also illustrates the tradeoff involved in turning a continuous measure into a binary outcome. A threshold such as an increase from baseline of at least 2 g/dL creates an outcome that can be expressed as a responder count and proportion. In general, that format is straightforward to communicate, but it removes information about how far individual measurements changed and can make participants with similar values fall into different categories. The count-based result is therefore informative about the specified threshold, but it is not a complete description of hemoglobin response.

Statistically, the record provides several complementary comparison scales: a risk difference, a risk ratio, and an odds ratio, each with a confidence interval. Reading them together reinforces the importance of specifying the comparison direction and the scale. The risk difference expresses an absolute contrast, while the ratio measures express relative contrasts. The confidence intervals show uncertainty around each reported estimate; the p-value alone would not convey that range or the magnitude of the contrast.

The registry also illustrates why reporting completeness matters. It describes regression and covariance methods, yet does not post the numerical hepcidin association or the mean-change analysis. Missing-data procedures, multiplicity handling, and the original design assumptions are not reported in the registry record. Those omissions constrain how fully readers can assess the stated biomarker question or reproduce the analysis. A clear separation between the outcome that is numerically available and the analyses only described in the methods is essential for a careful interpretation.

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.

Several limitations are specific to the record and endpoint. First, the study’s stated focus includes baseline hepcidin, but the registry posts responder counts by treatment group rather than a numerical hepcidin-response association. The regression approach is described, but its estimates, uncertainty, and any evidence of variation in treatment response across hepcidin values are not reported in the registry record. The central biomarker question therefore cannot be evaluated from the posted numerical results.

Second, the endpoint classifies participants by whether they achieved an increase from baseline of at least 2 g/dL. The registry does not provide the distribution of hemoglobin changes or the continuous mean-change result. The binary outcome can conceal differences in the amount of change within each responder category and does not describe the timing of response beyond the stated timeframe.

Third, the study was open label. The registry does not report whether lack of masking influenced outcome measurement, treatment adherence, or other aspects of conduct, so the magnitude or direction of any such influence cannot be assessed from the record. The registry also does not report the randomization procedure or allocation concealment details.

Fourth, the primary outcome denominators are 94 and 92, while the safety denominators are 99 and 97, and overall enrollment is 198. The registry does not explain the participant flow or the difference between these denominators. Missing-data rules, reasons for any missing outcomes, and analysis-set inclusion details beyond naming the full analysis set are not reported in the registry record. The original sample-size justification and multiplicity approach are also not reported in the registry record. These limits reduce the amount of independent assessment possible, without establishing that any particular bias occurred.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Treatment Response of Injectafer vs Oral Iron to Baseline Hepcidin Levels in Patients With Iron Deficiency Anemia (IDA) Secondary to Inflammatory Bowel Disease (IBD) or Gastric Bypass — NCT02086968.
• Registry record last updated 2020-09-17; status last verified 2020-09.
• Results first posted 2020-09-17.
• 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.

21. Record Summary

NCT02086968 is a completed, randomized, open-label, Phase 4, parallel-group study of Injectafer versus oral ferrous sulfate in iron deficiency anemia secondary to inflammatory bowel disease or gastric bypass. The registry reports enrollment of 198 and identifies the full analysis set as the primary outcome population.

The primary responder definition was an increase from baseline hemoglobin of at least 2 g/dL at any time through Day 28. The posted counts are 60 of 94 for Injectafer and 34 of 92 for ferrous sulfate. The risk difference for ferrous sulfate relative to Injectafer is -0.269, with a 95% confidence interval from -0.407 to -0.130 and an unadjusted p-value of <0.001.

The registry describes analysis of the relationship between screening hepcidin and hemoglobin change, but does not post a numerical hepcidin association. It lists no secondary outcomes and no posted analyses. Missing-data handling, multiplicity procedures, and the study’s original sample-size assumptions are not reported in the registry record.