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 Potential Effect of Dialyzer Leaching of BPA From the Fresenius Optiflux 160NR Compared to the Nipro ELISIO-15H (NCT02627118), a na na study. The primary outcome is BPA Level Following 2 Months of Dialysis.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02627118 |
| Phase | NA |
| Condition | End Stage Renal Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 10 |
| Arms in the primary outcome | n/a |
| Lead sponsor | UConn Health |
| Results posted | Yes |
2. Clinical Question
The study asks whether blood BPA levels differ after patients with end-stage renal disease receive dialysis with the Fresenius 160NR and the Nipro ELISIO-15H. Its stated focus is the potential effect of BPA leaching from the Fresenius dialyzer, compared with a dialyzer described as non-BPA-containing. The primary outcome is blood BPA concentration, measured in ng/mL after 2 months of treatment with each dialyzer.
Population
Patients with end-stage renal disease receiving dialysis. The registry lists enrollment of 10. One patient's BPA measurement was not measurable because the laboratory reported an unidentified interfering substance, and that patient's data was removed from the final analysis. The analyzed population is not otherwise reported in the registry record.
Intervention
Two months of dialysis with the Fresenius 160NR, described in the record as the dialyzer of interest because of potential BPA leaching.
Comparator
Two months of dialysis with the Nipro ELISIO-15H, described in the study summary as a non-BPA-containing dialyzer. The record says this treatment followed the Fresenius period.
Primary question
What blood BPA level was measured after 2 months of dialysis with each device, and how do the recorded levels compare? The registry record does not report the outcome values or a comparative estimate.
This question is about a measured biochemical concentration under two treatment conditions. The registry description also refers to hepatic enzyme and estrogen-dependent biochemical changes, but the listed primary outcome is BPA level. Results for those other biochemical measures are not reported in the registry record.
3. Trial Design
The registry describes a completed clinical study sponsored by UConn Health, with enrollment of 10 and a single-group model. The study started in 2015-04 and had a primary completion date of 2016-07-11. It is listed as not applicable for phase. The registry lists the allocation as not applicable and masking as none.
The treatment sequence is described as 2 months of dialysis with the Fresenius 160NR followed by 2 months with the Nipro ELISIO-15H. Thus the record describes a sequential dialyzer comparison, not a randomized comparison with independently assigned groups. The fixed order matters: differences in measurements could reflect the device condition, but the sequence also means treatment condition is linked to time and order. The registry record does not report a randomized order or a method for separating device effects from period or order effects.
The study summary says patient chemistries were evaluated before and after 2 months of standard dialysis treatments with each dialyzer. The primary outcome is specified as BPA level following 2 months of dialysis. Details about the timing and handling of blood samples beyond that description are not reported in the registry record.
One patient's BPA level was not measurable because the laboratory reported an unidentified interfering substance; the patient's data was removed from the final analysis. Although enrollment is listed as 10, the final analyzed count is not otherwise reported in the registry record. The record does not describe further details of adherence, treatment changes, withdrawals, or whether every enrolled participant completed both treatment periods.
One outcome measure and one analysis are listed. A detailed statistical analysis plan, including the intended comparison method, is not reported in the registry record. The design information therefore supports describing the treatment sequence and the listed endpoint, but it does not establish how the investigators intended to account for the paired, sequential nature of measurements.
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 | Dialyzer Comparison |
|---|---|
| STARTED | 10 |
| COMPLETED | 10 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: When data was collected, BPA level was not measureable in one patient (lab reported the presence of unidentified "interfering substance") and that patient's data was removed from final analysis.
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 | Dialyzer Comparison |
|---|---|---|
| Participants analysed | 10 | |
| Age, Continuous | years | 56.1 (SD 16.6) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 10 |
| Race/Ethnicity, Customized: White Non-Hispanic/Latino | Participants | 3 |
| Race/Ethnicity, Customized: Hispanic | Participants | 5 |
| Race/Ethnicity, Customized: African American | Participants | 1 |
| Race/Ethnicity, Customized: Other | Participants | 1 |
6. Primary Endpoint
The registry lists the primary outcome as BPA Level Following 2 Months of Dialysis, measured over 2 MONTHS OF TREATMENT.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | ng/mL |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is blood BPA concentration, expressed in ng/mL, following 2 months of dialysis with the Fresenius 160NR or the Nipro ELISIO-15H. The registry specifies a mean as the summary measure and standard error as the dispersion measure. The endpoint is intended to quantify BPA in blood after exposure to each dialyzer condition, matching the study's stated concern about possible BPA leaching.
A concentration is a continuous measurement: it can take a range of numerical values rather than representing only an event such as a diagnosis or hospitalization. A mean describes the central level across the analyzed observations. A standard error describes the statistical precision of an estimated mean, rather than the spread of individual patients' measurements. These are general statistical meanings; the actual mean and standard error for this endpoint are not reported in the registry record.
The endpoint is relevant to the stated study question because it measures BPA directly rather than relying only on a device description or a hypothesized exposure pathway. However, a measurement after treatment does not by itself establish the source of BPA or distinguish a dialyzer-related change from other influences. The registry specifies the timing of measurement after 2 months of treatment but does not report a numerical baseline value, a change-from-baseline result, or a comparative effect estimate.
The outcome description notes that one patient's BPA measurement could not be measured because of an unidentified interfering substance, and the patient's data was removed from the final analysis. The record does not report the assay's detection limit, how unmeasurable readings were otherwise handled, or numerical BPA results for either treatment condition.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the outcome the study set out to measure, but it does not report the numerical BPA levels after either dialyzer condition. It also does not report a difference between conditions, an uncertainty interval, or a p-value. As a result, the posted record does not permit a statistical assessment of the direction, magnitude, or precision of the observed BPA comparison. The study's title and rationale are not substitutes for outcome results.
The reported mean and standard error are the planned summary format for a continuous outcome. In general, the mean gives a central summary of the measured values, while the standard error indicates the precision of the estimated mean. Without the actual estimates, neither the average level nor its precision can be evaluated. The registry's specification of a summary method should not be mistaken for a reported finding.
The design sequence is also important to interpretation. The record states that participants received 2 months with the Fresenius 160NR followed by 2 months with the Nipro ELISIO-15H. It does not describe random assignment or a counterbalanced sequence. In a sequential comparison, treatment and period are linked: measurements taken during the later period may differ for reasons related to time, treatment history, or other changes, as well as to the device condition. This is a general design consideration, not evidence that any such influence occurred in this study. A method for addressing these issues is not reported in the registry record.
The record lists enrollment of 10, and notes that one patient's measurement was removed from final analysis because it was not measurable. It does not report the final analysis count otherwise, nor individual measurements or the amount of variation among patients. With no numerical endpoint results, the influence of that exclusion on the reported comparison cannot be assessed.
Consequently, the record supports a description of the study question, sequence, outcome definition, and one excluded measurement. It does not support a conclusion about whether the dialyzers produced different BPA levels, how large any difference might have been, or how precisely a difference was estimated. No clinical conclusion follows from the absence of numerical results in the registry record.
9. Statistical Methods Explained
The registry identifies the primary outcome as a continuous measure summarized by a mean and standard error. It lists one outcome measure and one analysis. The detailed statistical methods used for that analysis are not reported in the registry record, so the intended estimator, comparison procedure, and handling of within-participant measurements cannot be confirmed.
What does a mean describe?
In general, a mean is an arithmetic summary of a set of measurements. It can help describe a typical level when considered alongside the distribution of the observations and the study design. For BPA concentration, the registry names the mean as the parameter of interest after 2 months of treatment with each dialyzer. The numerical means are not reported in the registry record, so they cannot be interpreted or compared.
A mean alone does not show whether observations are tightly clustered or widely spread. It can also be influenced by unusually high or low measurements. For this reason, statistical interpretation usually considers both the estimate and its uncertainty, as well as how the data were collected. Individual values, distributional summaries, and the numerical estimates for this study are not reported in the registry record.
What does the standard error mean?
In general, the standard error describes the precision of an estimated quantity, such as a sample mean. It is not the same as the standard deviation, which describes variation among observations. A smaller standard error typically corresponds to a more precise estimate under the assumptions of the analysis; it does not mean that individual measurements vary little. The registry names standard error as the dispersion measure, but does not report its value for either condition.
A confidence interval is a general way to express uncertainty around an estimate. Its width depends on the estimate's uncertainty and the method used to construct it. A confidence interval for a difference could help readers assess which values are compatible with the observed data under the analysis assumptions. No confidence interval or other uncertainty interval is reported in the registry record, and none can be reconstructed from the information available there.
How does the sequence affect comparison?
The registry describes a single group receiving the Fresenius 160NR first and the Nipro ELISIO-15H second. This sequence means measurements from the two conditions are not described as coming from separately randomized groups. If the same participant contributes measurements under both conditions, a paired analysis can account for the fact that two measurements from one person may be related. However, the registry record does not report the analysis method or explicitly describe how participant-level pairing was handled.
More generally, a paired comparison focuses on within-person changes or differences, while an independent-groups comparison treats measurements from the groups as unrelated. Choosing between these approaches depends on the design and data structure. The record does not provide enough detail about the analysis to identify which method was used. The fixed treatment order also raises a general possibility of period or order effects; whether and how these were addressed is not reported in the registry record.
What do the planning assumptions mean?
The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. The specific illustration results and the fractions are not reported in the registry record. These assumptions describe an illustrative planning calculation, not the study's own design justification or observed evidence about treatment differences. A sample-size illustration is not observed power, and it does not establish that the study could reliably detect an effect.
The registry does not report the trial's sample-size justification. The planning assumptions therefore should not be read as confirmation that the enrollment target was selected through those calculations. A statistical plan, including any interim analyses, is not reported in the registry record.
Why can over-dispersion matter?
In general, over-dispersion means that variability in observed data is greater than a statistical model assumes. When a model understates variability, uncertainty estimates can be too small and inferential conclusions can be overconfident. This concept is relevant to statistical modeling generally, but the registry does not identify an over-dispersed outcome or a model requiring a dispersion adjustment. It is not possible to determine whether over-dispersion was assessed in this study.
Overall, the registry supplies the endpoint definition and the intended descriptive summary but not the numerical estimates or the methods needed to evaluate the comparison. The design and analysis details should therefore be interpreted as limited to what the record explicitly describes.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and one analysis. It does not report whether other outcomes were analyzed for this report, whether the listed endpoint was selected in advance, or whether any multiplicity adjustment was used. A multiplicity strategy is not reported in the registry record. The listing of one outcome measure does not by itself establish that no other comparisons or analyses were conducted.
For the primary endpoint, the record identifies one patient's BPA level as not measurable because the laboratory reported an unidentified interfering substance. That patient's data was removed from the final analysis. The record does not report the final analyzed count beyond this exclusion, whether other data were missing, or whether any imputation or sensitivity analysis was performed. It also does not report a prespecified rule for handling measurements that could not be measured.
The number enrolled is 10, but the analysis population is not otherwise defined in the registry record. There is no reported description of an intention-to-treat population, a per-protocol population, or another population used for analysis. The record does not state how protocol deviations, incomplete treatment periods, or missed measurements were handled.
These omissions matter because exclusions and missing measurements can affect which participants contribute to a result and how representative the analyzed measurements are of those enrolled. The record identifies one specific exclusion, but does not provide enough information to assess the impact of that exclusion or the overall completeness of the outcome data. No conclusion about bias from missing data can be drawn from the registry description alone.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| FRESENIUS OPTIFLUX 160NR | 0 | 10 | 0.0% |
| NIPRO ELISIO-15H | 0 | 10 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| FRESENIUS OPTIFLUX 160NR | 0 of 10 |
| NIPRO ELISIO-15H | 0 of 10 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| FRESENIUS OPTIFLUX 160NR | 0 of 10 |
| NIPRO ELISIO-15H | 0 of 10 |
The registry lists serious adverse events for the Fresenius Optiflux 160NR group as 0 affected among 10 at risk, and for the Nipro ELISIO-15H group as 0 affected among 10 at risk. It also lists other adverse events as 0 affected among 10 at risk for each group, with 0 deaths in each. No serious adverse event terms are listed.
These figures describe the events recorded in the registry for the stated groups and risk counts. They do not show that the possibility of an adverse event is absent. In general, a zero count in a small study means that no event was recorded in the listed observations; it does not establish that an event could never occur or that the conditions have identical safety profiles.
The record does not provide further detail about how adverse events were collected, their observation period, event definitions, or whether the same participants contributed to both groups' risk counts. The sequential design makes those details relevant to interpreting group labels. The figures should therefore be read as registry-reported counts, not as a definitive comparison of safety between devices.
12. What the Result Does, and Does Not, Mean
The registry record establishes that investigators planned to measure blood BPA after 2 months of dialysis with each of two dialyzers, in a sequence beginning with the Fresenius 160NR and followed by the Nipro ELISIO-15H. It also describes enrollment of 10, one measurement excluded because it was not measurable, and the intended use of means and standard errors for the primary endpoint.
The record does not report numerical BPA results. It therefore does not establish whether the measured levels were higher after one condition, whether they differed, or how large or precise any difference was. The study title and stated concern about potential BPA leaching describe the motivation and question; they are not evidence of an observed result. No conclusion that either dialyzer did or did not change BPA levels is supported by the posted results in the registry record.
The sequential, nonrandomized design also limits what a comparison could establish without additional design and analysis details. Because one condition preceded the other, device condition is tied to treatment order and time. In general, this can make it difficult to separate a device-associated difference from other changes across periods. The record does not report a method for resolving that issue.
The reported adverse-event counts are zero for the listed serious events, other events, and deaths in both groups. These are descriptive counts and do not establish that no risk exists. The study's small enrollment and the absence of additional safety detail limit the conclusions that can be drawn from them.
More broadly, registry information can clarify what a study set out to measure and how the intervention periods were arranged. Here, the missing numerical outcome results and limited analysis details prevent evaluation of the primary statistical finding. The record should be understood as describing the study framework, not as demonstrating a comparative BPA result.
13. Why This Trial Matters Statistically
This study is statistically interesting because it illustrates how a clearly stated biochemical question can still be difficult to evaluate when the outcome estimates are not reported. The registry identifies BPA concentration, the measurement unit, the post-treatment timing, and the planned summary as a mean with standard error. Those details define what a reader would need to interpret, but without the values they do not show the observed level or the uncertainty around it.
The treatment order also raises a central design issue. The record describes the Fresenius 160NR period followed by the Nipro ELISIO-15H period rather than randomized treatment order. In general, randomization can help balance other influences across conditions; a fixed sequence can leave device condition intertwined with period and order. This does not prove that the comparison is biased, but it identifies a limitation that a statistical analysis would need to consider. The registry does not describe such an adjustment or analysis.
The exclusion of one unmeasurable result is another practical issue. Laboratory interference can prevent a planned measurement from being used, but interpretation depends on how often this occurs, why it occurs, and whether the missing measurement is related to the outcome. The record gives the stated reason for this exclusion but does not report additional missing-data information or sensitivity analyses.
Finally, the adverse-event counts show how registry summaries can be informative while still being limited. The record lists zero events in the stated categories, but the enrollment is small and details of ascertainment are not reported. Counts should be read in their study context rather than as proof of no risk. Taken together, the study highlights the value of reporting numerical results, uncertainty, participant flow, and analysis methods alongside endpoint definitions and design descriptions.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most consequential limitation for interpreting the primary outcome is that the registry record does not report numerical BPA results. It provides no mean, standard error, comparison estimate, or uncertainty interval. Readers therefore cannot assess the size, direction, or precision of the measured comparison from this record.
The study is described as a single-group sequential comparison, with 2 months using the Fresenius 160NR followed by 2 months using the Nipro ELISIO-15H. Allocation is listed as not applicable, and masking as none. The fixed order makes treatment condition inseparable from period in the design description. The record does not report a method for accounting for period effects or other changes over time.
Enrollment is listed as 10, and one participant's unmeasurable result was removed from final analysis. The final analysis count is not otherwise reported. The registry does not provide participant-level measurements, additional missing-data information, or sensitivity analyses to show how the exclusion might affect the result.
The record's outcome description focuses on BPA, although the study summary also mentions hepatic enzyme and estrogen-dependent biochemical changes. Results for those other measures are not reported in the registry record. The statistical analysis plan, sample-size justification, and any interim analyses are also not reported. Although planning assumptions are described, the record does not report the resulting sample-size illustrations or establish that they were used to design the study.
Safety information is limited to the listed event counts and risk totals. Further detail about event ascertainment and observation is not reported. These limitations restrict assessment of both the primary comparison and the broader interpretation of the study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Potential Effect of Dialyzer Leaching of BPA From the Fresenius Optiflux 160NR Compared to the Nipro ELISIO-15H — NCT02627118.
- Registry record last updated 2018-06-11; status last verified 2018-04.
- Results first posted 2018-06-11.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry record describes a completed study of dialysis with the Fresenius 160NR followed by the Nipro ELISIO-15H in patients with end-stage renal disease. Enrollment was 10. The primary outcome was blood BPA level in ng/mL after 2 months of treatment with each device, intended to be summarized as a mean and standard error.
One patient's BPA measurement was not measurable because of an unidentified interfering substance, and the patient's data was removed from final analysis. Numerical BPA results and a comparative estimate are not reported in the registry record. Allocation is listed as not applicable and masking as none. The record lists zero serious adverse events, zero other adverse events, and zero deaths for each device group.
The sequential design, missing numerical results, and limited analysis details mean that the registry record describes the study question and conduct but does not establish the outcome of the BPA comparison.