2 Doses of Ferrlecit Versus Oral Iron to Treat Iron-deficiency Anemia in Peritoneal Dialysis Patients.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for 2 Doses of Ferrlecit Versus Oral Iron to Treat Iron-deficiency Anemia in Peritoneal Dialysis Patients. (NCT00223977), a randomized phase 2, phase 3 study. The primary outcome is Hemoglobin.

2. Clinical Question

The study record describes a phase 3 investigation, while its phase listing includes PHASE2 and PHASE3. Its title identifies the clinical context as treatment of iron-deficiency anemia in peritoneal dialysis patients. The question is comparative: the two intravenous schedules are each assessed against the 125 mg sodium ferric gluconate schedule, which serves as the comparison reference in the posted results.

The primary outcome is a change from baseline in hemoglobin, rather than a reported percentage of participants reaching a defined response threshold. The record lists the outcome timeframe as baseline to 5 weeks and 9 weeks, and describes measurement at 1 week after the last oral iron dose or 2 weeks after the last sodium ferric gluconate injection. The registry does not report a separate primary contrast between the two active intravenous schedules.

3. Trial Design

This was a randomized, open-label, parallel-group study. The registry record lists enrollment as 146 and says that eligible participants who gave signed informed consent were assigned in a 1:1:1 ratio to one of two sodium ferric gluconate doses or oral iron. Because masking was listed as none, the study was not blinded. The registry does not report further details about how the random sequence was generated or concealed.

The regimens differed in both dose and schedule. One group received sodium ferric gluconate complex 125 mg weekly for 8 weeks; another received 250 mg weekly for 4 weeks. The oral group received ferrous sulfate 325 mg three times daily for 8 weeks. These differences matter when interpreting the comparison: the study contrasts treatment regimens, not simply the same medication at different doses while all other features remain constant.

The primary outcome summaries use 46 participants in the 125 mg group, 55 in the 250 mg group, and 42 in the oral iron group. The registry specifies a modified intent-to-treat population with last observation carried forward imputation for the primary outcome. It does not explain the exact membership rules for that population or how missing observations were handled before the stated imputation.

The study is marked completed. Its start is listed as 2003-12 and its primary completion as 2004-11. These dates and the enrollment figure describe the study record; they do not establish how closely the completed conduct matched the intended design. The registry record does not report a detailed protocol, sample-size justification, allocation concealment method, or statistical analysis plan. It also lists no reported analyses for the primary outcome, so the presented pairwise comparisons should be read as unadjusted comparisons of the posted group summaries rather than as documented results of a specified sponsor analysis.

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: modified intent to treat (mITT) with last observation carried forward (LOCF) imputation

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Hemoglobin, measured over Baseline to 5 weeks and 9 weeks.

Hemoglobin is the primary measure in this record. The outcome is defined as change from baseline, with the registry listing a timeframe of baseline to 5 weeks and 9 weeks. Its description places measurement 1 week after the last oral iron dose or 2 weeks after the last sodium ferric gluconate injection. The stated unit is ng/mL, and the posted values are means with standard deviations.

As a general statistical matter, a continuous measure such as hemoglobin can be summarized by a mean change, which describes the average change in the analyzed group. A mean does not describe how every individual changed: participants may have had changes above or below that average. The standard deviation conveys how dispersed individual values were around the group mean, not how precisely the group mean itself was estimated.

Change from baseline is used to describe how a measurement shifted during follow-up relative to its starting value. Comparing mean changes across randomized groups can characterize differences between the assigned regimens in this study population. It does not, on its own, establish how durable any change was beyond the recorded follow-up or how a change relates to outcomes not measured in the posted results.

The registry does not explain why these particular follow-up times were selected, or provide a clinically important threshold for hemoglobin change. The listed unit should be interpreted as the registry records it, rather than silently converted to another unit.

7. Results Posted in the Registry

• Sodium Ferric Gluconate Complex 250 mg: mean 0.89 versus 1.49 on control; difference -0.60 (95% CI -1.08 to -0.12), standardized effect d = -0.48; z-test p = 0.013.
• Oral Iron: mean 1.02 versus 1.49 on control; difference -0.47 (95% CI -1.03 to 0.09), standardized effect d = -0.35; z-test p = 0.103.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change From Baseline in Hematocrit (Hct)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sodium Ferric Gluconate Complex 250 mg: mean 2.93 versus 4.62 on control; difference -1.69 (95% CI -3.25 to -0.13), standardized effect d = -0.41; z-test p = 0.034.
  • Oral Iron: mean 3.07 versus 4.62 on control; difference -1.55 (95% CI -3.25 to 0.15), standardized effect d = -0.39; z-test p = 0.073.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Sodium Ferric Gluconate Complex 250 mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Oral Iron and the control. The interval gives the range of effects that remain compatible with the data.

Change From Baseline in Transferrin Saturation (TSAT).

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sodium Ferric Gluconate Complex 250 mg: mean 8.20 versus 8.13 on control; difference 0.07 (95% CI -3.46 to 3.60), standardized effect d = 0.01; z-test p = 0.969.
  • Oral Iron: mean 1.84 versus 8.13 on control; difference -6.29 (95% CI -9.50 to -3.08), standardized effect d = -0.81; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sodium Ferric Gluconate Complex 250 mg and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Oral Iron than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline in Serum Ferritin.

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sodium Ferric Gluconate Complex 250 mg: mean 368.67 versus 259.88 on control; difference 108.79 (95% CI 14.59 to 202.99), standardized effect d = 0.44; z-test p = 0.024.
  • Oral Iron: mean 26.98 versus 259.88 on control; difference -232.90 (95% CI -299.72 to -166.08), standardized effect d = -1.41; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Sodium Ferric Gluconate Complex 250 mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Oral Iron than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes cover hematocrit, transferrin saturation, serum ferritin, and responders by treatment group. The record posts continuous summaries and pairwise comparisons for the first three. Although responders are listed as an outcome, its results are not among the posted secondary summaries described in the record. The registry lists five outcome measures overall but only four secondary outcomes in the outcome list.

Across the posted secondary measures, the pattern is not uniform. The comparisons involving the 250 mg regimen and the 125 mg regimen differ in direction and apparent precision across measures. The oral iron comparisons also vary: some estimates indicate a difference from the reference group, while others are less precise and include no difference. This variation means that no single broad statement about all secondary endpoints captures the posted results.

These outcomes add context to the primary hemoglobin comparison because they describe other measures related to anemia and iron status. They do not replace the primary endpoint or establish that a change in one measure necessarily produces a corresponding change in another. The registry does not report participant-level relationships among these outcomes, a composite analysis, or a formal hierarchy for interpreting them.

Unadjusted secondary comparisons carry less weight when many outcomes and pairwise comparisons are examined. In general, making multiple comparisons increases the chance that some results will appear notable by chance, even if no underlying difference exists. The registry does not report a multiplicity adjustment or a prespecified hierarchy that would indicate how the secondary findings were intended to be interpreted. The findings are therefore best treated as descriptive or exploratory signals rather than as a set of independent confirmatory conclusions.

The record also lists no reported analyses for these secondary endpoints. The comparisons are therefore unadjusted calculations from the posted summaries, and their interpretation is limited by the same issues affecting the primary results: group sizes, variability, missing-data handling, and the lack of a documented analysis plan. No conclusion about the unposted responder outcome can be drawn from its name alone.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change From Baseline in Hematocrit (Hct)
• Change From Baseline in Transferrin Saturation (TSAT).
• Change From Baseline in Serum Ferritin.
• Responders by Treatment Group

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result is a continuous-outcome comparison. Each group is described by its mean change and standard deviation. The mean is the arithmetic average of the observed changes in the analyzed group. The standard deviation describes the spread of participant-level changes around that average. A larger standard deviation indicates more variation among the observed values, but it is not itself a confidence interval for the mean.

What does the mean difference represent?

The pairwise mean difference compares an intervention group's average change with the 125 mg sodium ferric gluconate group's average change. A negative estimate indicates a lower average change in the compared group under the subtraction direction used in the posted results; a positive estimate indicates a higher one. For hemoglobin, the estimate for the 250 mg group is -0.6 and the estimate for oral iron is -0.47. These estimates are expressed in the registry's stated unit, ng/mL.

Randomization is intended to make treatment groups comparable on average at assignment, but the registry does not report the randomization procedure or allocation concealment. The study is open label, so participants and study personnel were not masked according to the record. The posted endpoint is a measured continuous outcome; no specific concern about measurement bias can be established from the record alone.

How should confidence intervals be read?

A confidence interval gives a range of values compatible with the data and the calculation procedure, under its assumptions. A narrower interval indicates more precision about the estimated mean difference; a wider interval indicates greater uncertainty. For the 250 mg versus 125 mg hemoglobin comparison, the interval is -1.076 to -0.124. For oral iron versus the 125 mg regimen, it is -1.035 to 0.095. The second interval includes zero, while the first does not. An interval is not a range containing a known proportion of individual participant responses, and it does not measure the probability that a particular fixed effect lies inside the interval.

What does an unadjusted p-value say?

A p-value assesses how compatible the observed data are with a specified null comparison, under the assumptions of the calculation. Smaller values indicate less compatibility with that null, but a p-value is not the probability that the null is true, nor a measure of clinical importance. The registry lists unadjusted values of 0.013 and 0.103 for the two primary pairwise comparisons. Since no multiplicity adjustment is reported, these should be understood as unadjusted results, not as family-wise error-controlled evidence across all outcomes and comparisons.

The registry gives the primary population as modified intent to treat with last observation carried forward imputation. In general, last observation carried forward fills a missing follow-up value using an earlier recorded value. This approach can be questionable if measurements would have changed after the last observation, and it can understate uncertainty because the imputed value is treated differently from an observed follow-up value. The record does not report how many observations were missing, the timing of missingness, or sensitivity analyses using other assumptions. The meaning of the modified intent-to-treat population is also not described in detail.

The comparison estimates are unadjusted recalculations from posted summary statistics. Such recalculations do not reproduce an analysis using participant-level data, covariate adjustment, or a model that accounts for additional design features. The registry record lists no reported analyses for these endpoints. No inferential method, covariance structure, or adjustment strategy from a sponsor analysis is documented in the record, so none should be assumed.

As a general statistical concept, variability affects precision: when participant outcomes vary substantially, a group mean is less precisely estimated for a given amount of information. The standard deviations for the primary outcome are 1.09, 1.35, and 1.55 across the posted groups. Those values describe spread; they do not explain why participants differed, and they do not resolve limitations from missing data, outcome timing, or the open-label design.

11. Confidence Intervals and Precision

The confidence intervals convey how precisely the mean differences are estimated from the posted summaries. For the 250 mg sodium ferric gluconate group compared with the 125 mg group, the estimated difference in hemoglobin change is -0.6, and the interval extends from -1.076 to -0.124. The interval is entirely below zero, indicating that the posted unadjusted estimate is more compatible with a lower mean change in the 250 mg group than in the 125 mg group than with no difference under the calculation assumptions.

For oral iron compared with the 125 mg group, the estimated difference is -0.47, with an interval from -1.035 to 0.095. Because this interval includes zero, the data are compatible with a range of differences that includes no difference as well as values in either direction. That does not establish equivalence. Equivalence would require a prespecified margin and an analysis designed to test it; neither is reported in the registry record.

The intervals are not especially narrow relative to the range of estimates they permit. They therefore leave meaningful uncertainty about the size of the underlying mean differences. The posted point estimates are single best estimates under the calculation, not exact descriptions of the population effect. Interpretation should consider both the direction and the span of plausible values, rather than treating the p-value as a complete summary.

Confidence intervals address sampling uncertainty under the calculation assumptions. They do not incorporate every possible source of uncertainty, such as outcome measurement differences, the consequences of missing data, or limitations in how the analysis population was defined. The registry does not report a sensitivity analysis that would show how conclusions change under alternative missing-data assumptions. The intervals should therefore be read as precision for the reported comparison, not as a guarantee that all design and analysis uncertainties have been captured.

12. 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 sample-size figures are planning illustrations based on the observed effect, not the trial's own design assumptions. They use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row considers detecting a stated fraction of the observed effect. For these continuous outcomes, the figures are participants per arm, not total participants. The registry's planning description notes that time-to-event calculations would instead give total events; that distinction does not apply to these mean comparisons.

The 80% power column describes the planned number of participants per arm for a design that, under the planning assumptions and if the selected effect were the true effect, would have an 80% chance of detecting that effect using the specified test procedure. The 90% column makes the analogous illustration for a 90% chance. Power is a property of a planned design under assumptions; it is not a measure of whether the observed finding is true.

Rows that plan for 75% or 50% of the observed effect assume a smaller target difference than the full observed effect. Smaller effects are harder to distinguish from random variation, so the planning figures rise as the target effect becomes smaller. This relationship is general, and the actual figures also depend on the assumed variability and other planning choices.

The registry record does not report the trial's original sample-size justification or the assumptions used to design the study. The figures should not be read as evidence that the completed trial had a particular probability of detecting its observed results. This is not observed power. The planning calculations are illustrations of what future designs might require under their stated assumptions, rather than a retrospective score of this trial's success.

13. 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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.600; pooled standard deviation σ = 1.239.
2. n = 2 × (1.96 + 0.842)² × 1.239² / -0.600² = 66.9, rounded up to 67 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 <- -0.6                      # observed difference in means
sigma <- 1.23860258502732                     # 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(223977)
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 = 67 (80% power), 90 (90% power)
 75% of observed effect: n per arm = 119 (80% power), 160 (90% power)
 50% of observed effect: n per arm = 268 (80% power), 359 (90% power)
power.t.test: 67.9 
Simulated power at n = 67 per arm: 0.793 (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.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists several outcomes and comparisons, but it does not report a multiplicity strategy. The primary outcome is compared between the 125 mg sodium ferric gluconate group and each of the other two groups, and secondary measures also have pairwise comparisons. As a general statistical matter, evaluating many hypotheses increases the chance that at least one result will look unusual by chance. An adjustment or a prespecified hierarchy can address how evidence is assessed across multiple tests. Neither an adjustment nor a hierarchy is reported.

The p-values presented for the pairwise comparisons are unadjusted. They do not account for testing multiple treatment contrasts or outcomes. This does not erase the estimates or their confidence intervals, but it means the p-values should not be treated as if they were adjusted for all comparisons in the study. The registry record lists no reported analyses and does not give a statistical analysis plan, so the intended primary testing procedure and handling of secondary hypotheses are not reported in the registry record.

For the primary endpoint, the analysis population is described as modified intent to treat with last observation carried forward imputation. The exact definition of modified intent to treat is not reported in the registry record. Nor are the number of missing measurements, reasons for missingness, or the timing of missingness reported. Last observation carried forward uses a participant's earlier recorded value in place of a missing later value. As a general method, this can be misleading if the outcome would have continued to change, and it may fail to represent uncertainty about the missing value.

The record does not report sensitivity analyses, alternative imputation methods, or results from an analysis of observed outcomes without imputation. It is therefore not possible to assess whether the estimated differences would remain similar under other missing-data assumptions. The registry also does not specify whether the secondary outcomes used the same analysis population and imputation approach as the primary endpoint. These details matter because the interpretation of a group difference depends on who was included and how missing follow-up measurements were addressed.

15. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hypotens (8.6%), peritonitis (8.6%), anemia (4.8%), infarct myocard (4.8%), cellulitis (2.4%).

The registry lists serious adverse events for 46 participants at risk in the 125 mg sodium ferric gluconate group, 58 in the 250 mg group, and 42 in the oral iron group. The corresponding numbers with a serious adverse event are 3, 13, and 7. The record also lists other adverse events affecting 16, 20, and 12 participants, respectively, using those same group-specific risk counts. These are participant counts, not event totals; a participant may have experienced more than one event, and the record does not explain how repeat events were counted.

The listed serious event terms include HYPOTENS and PERITONITIS at 8.6% each, ANEMIA and INFARCT MYOCARD at 4.8% each, and CELLULITIS and EDEMA LUNG at 2.4% each. The terms are recorded as presented in the registry, without additional detail about severity, timing, relatedness, or the number of distinct participants for each term.

Deaths are not reported in the registry record. The safety counts describe events recorded in this study; they do not establish that a treatment caused or prevented an event. Differences in group counts should be interpreted cautiously because the group denominators differ and the registry does not provide adjusted safety analyses or further event-level detail.

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

The posted results describe average changes in hemoglobin during the recorded follow-up among participants included in the modified intent-to-treat analysis with last observation carried forward imputation. The 250 mg sodium ferric gluconate group had a lower mean change than the 125 mg group in the unadjusted comparison, and its confidence interval did not include zero. The oral iron comparison also estimated a lower mean change than the 125 mg group, but its confidence interval included zero. These statements describe the posted statistics and their precision, not a treatment recommendation.

A statistically distinguishable estimate is not automatically clinically important. The registry does not state a threshold for a meaningful hemoglobin change, and the unit is recorded as ng/mL. Without a clinical-importance criterion, the size of a statistical difference cannot by itself establish its relevance to patients. Conversely, an interval that includes zero does not prove that two regimens have the same effect; it indicates that the estimate remains uncertain over values that include no difference.

The registry record does not support conclusions about effects beyond the specified follow-up, outcomes not posted, or how results might apply to populations other than the recorded study population. It also does not provide a detailed protocol, a sponsor analysis report, or a full account of missing observations. The open-label design and imputation approach are relevant context, but the record does not provide enough detail to quantify their influence on the estimates.

The randomized design establishes that treatment assignment was intended to be randomized, but the posted summaries alone cannot resolve every question about trial conduct or analysis. In particular, there is no reported adjusted analysis or multiplicity plan. The comparisons should therefore be understood as estimates from the posted summaries with their stated uncertainty, rather than as definitive evidence about the relative clinical value of the regimens.

17. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation requires more than comparing group means or reading a p-value. The primary outcome is continuous, and the registry supplies a mean change and standard deviation for each treatment group, along with pairwise estimates and confidence intervals. Together, these quantities show both the direction of the estimated differences and how much uncertainty remains about their size.

The randomized, parallel-group structure supports comparisons among assigned regimens, while the open-label designation and differing treatment schedules are important features of the study context. The two intravenous regimens differ in dose and duration, and the oral regimen differs in route and schedule. The comparison is therefore between complete treatment strategies, rather than a controlled test of dose alone.

The record also demonstrates the importance of checking analysis populations and missing-data methods. The primary result uses a modified intent-to-treat population with last observation carried forward, but the membership rules and amount of missing data are not reported. Such omissions make it difficult to assess how robust the result is to alternative assumptions. Similarly, unadjusted secondary comparisons need a cautious reading when multiple outcomes and contrasts are examined.

Finally, the planning illustrations show how assumptions about the effect size influence a future sample-size plan, but they are distinct from the trial's own design justification. The original design assumptions are not reported in the registry record. Keeping planning calculations separate from observed results prevents a hypothetical power calculation from being mistaken for evidence about what this completed study was capable of detecting.

18. 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 registry record leaves several trial-specific questions unanswered. It does not report the original sample-size justification, the detailed randomization procedure, or whether allocation was concealed. It also does not give the protocol or a complete statistical analysis plan. These omissions limit assessment of how the study was designed to handle the outcomes and comparisons.

The primary endpoint population is described as modified intent to treat, but the exact inclusion rules are not reported. Last observation carried forward is specified, yet the number of missing measurements, reasons for missingness, and results under alternative approaches are not reported. As a result, the effect of missing-data assumptions on the estimates cannot be evaluated from the registry record.

The registry lists no reported analyses for the primary or posted secondary outcomes. The pairwise estimates are unadjusted calculations from group summaries and do not incorporate participant-level covariates or other modeling features that might have been specified in a full analysis. The record also does not report a multiplicity adjustment, although multiple comparisons are presented.

Other limitations include the open-label design, the different schedules and routes of treatment, and the endpoint timing described relative to the last dose or injection. The registry does not explain the rationale for these timing choices or provide a clinical threshold for important change in hemoglobin. Safety reporting is also limited: deaths are not reported in the registry record, and details about event timing, relatedness, recurrence, and group-level analyses are not provided.

These limitations do not invalidate the posted numbers, but they constrain what can be inferred from them. The estimates describe the recorded groups and analysis approach, with uncertainty that may not capture every design, measurement, or missing-data concern.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: 2 Doses of Ferrlecit Versus Oral Iron to Treat Iron-deficiency Anemia in Peritoneal Dialysis Patients. — NCT00223977.
• Registry record last updated 2013-07-08; status last verified 2013-05.
• Results first posted 2009-09-28.
• 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.

22. Record Summary

The record describes a randomized, open-label, parallel-group study of sodium ferric gluconate complex at 125 mg weekly for 8 weeks, sodium ferric gluconate complex at 250 mg weekly for 4 weeks, and oral ferrous sulfate 325 mg three times daily for 8 weeks. The study enrolled 146 participants and is marked completed.

The primary outcome is change in hemoglobin from baseline to the listed follow-up, analyzed in a modified intent-to-treat population with last observation carried forward imputation. The posted unadjusted comparison estimates show a lower mean change for the 250 mg regimen than the 125 mg regimen, while the oral iron comparison is less precise and its confidence interval includes zero.

The record also includes secondary outcome summaries and adverse-event counts. It does not report the original sample-size justification, detailed analysis plan, multiplicity adjustment, or sensitivity analyses for missing data. The statistical interpretation is therefore limited to the posted summaries and their uncertainty.