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 Observational Study of Deferiprone (Ferriprox®) in the Treatment of Superficial Siderosis (NCT01284127), a registered phase not stated study. The primary outcome is Number of Participants Who Show Stability, Improvement or Decline in Self Reported Hearing.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01284127 |
| Phase | Phase not stated |
| Condition | Superficial Siderosis |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 38 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
People with superficial siderosis who had MRI evidence of the condition and were taking deferiprone. The registry record reports enrollment of 38 participants.
Intervention
Deferiprone, described in the registry as chelation therapy given according to standard-of-care guidelines. Participants were treated and monitored locally by participating neurologists.
Comparator
No control group or randomized comparator is reported. The record identifies a deferiprone group and does not state an allocation method.
Primary question
At the end of the 2-year period, how many participants showed stability, improvement, or decline in self-reported hearing?
The registry describes superficial siderosis as a neurological disease associated with iron deposition in the central nervous system following chronic subarachnoid bleeding. It presents this study as documenting the clinical course of people with superficial siderosis taking deferiprone. The primary outcome focuses on hearing, one of the clinical concerns named in the registry summary.
This is an observational question about outcomes among people receiving deferiprone in clinical care, rather than a randomized comparison of treatment against a control. The record does not report a comparator group or a method for assigning participants to treatment. Therefore, the question is descriptive: what hearing status was reported for the enrolled participants at the specified endpoint? The registry record does not report the counts in the stability, improvement, or decline categories, so those outcomes cannot be characterized from the posted results.
3. Trial Design
The record describes a Phase IV observational study of deferiprone for superficial siderosis. It lists Johns Hopkins University as the sponsor, an enrollment of 38, and a completed status. The study start is listed as 2012-03, and primary completion as 2018-01-08. Those dates describe the record; they do not establish that each participant was followed for the same length of time.
Participants were people with superficial siderosis who were taking deferiprone for chelation therapy and were offered enrollment. The arm description specifies MRI evidence of superficial siderosis and treatment with deferiprone according to standard-of-care guidelines. The registry summary says participating neurologists treated and monitored patients locally and helped collect study information. The primary outcome is framed at the end of a 2-year period, but the registry record does not report individual follow-up duration or completeness.
The registry identifies a deferiprone group, with no separate control group reported. It does not state an allocation method. The record therefore does not describe a like-for-like treatment comparison, and the results cannot be read as a randomized contrast. The registry record does not report the detailed eligibility criteria, procedures for assessing hearing, visit schedule, or statistical analysis plan. The record lists six outcome measures, but detailed results for the primary endpoint are not reported. It lists one secondary outcome concerning MRI changes in hemosiderin deposition.
Because treatment was given in clinical care rather than assigned through a reported randomized allocation, the study describes outcomes in an enrolled group, not the effect of treatment relative to an untreated or alternative-treatment group. Any differences among participants could reflect clinical and other factors not documented in the registry record.
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 | Deferiprone |
|---|---|
| STARTED | 38 |
| COMPLETED | 31 |
| NOT COMPLETED | 7 |
Reasons for not completing this period:
| Reason | Deferiprone |
|---|---|
| Adverse Event | 2 |
| Withdrawal by Subject | 4 |
| Physician Decision | 1 |
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 | Deferiprone |
|---|---|---|
| Participants analysed | 38 | |
| Age, Continuous | years | 64 (37 to 86) |
| Sex: Female, Male: Female | Participants | 18 |
| Sex: Female, Male: Male | Participants | 20 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 36 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Region of Enrollment: United States | Participants | 38 |
| Cause of Bleed: Dural Tear | Participants | 11 |
| Cause of Bleed: Prior Neurosurgical Procedure | Participants | 8 |
| Cause of Bleed: Central Nervous System (CNS) Tumor/Cyst | Participants | 4 |
| Cause of Bleed: Undetermined | Participants | 15 |
| Duration of Clinical Disease | years | 7 (1 to 33) |
| Participants with Repair of Bleed | Participants | 7 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants Who Show Stability, Improvement or Decline in Self Reported Hearing, measured over At the end of the 2-year period.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants who show stability, improvement, or decline in self-reported hearing at the end of the 2-year period. It is a count outcome: it concerns how many participants fall into the reported hearing-status categories, rather than a mean score or a time-to-event measure. The registry gives the unit as participants and describes the endpoint as self-reported.
Hearing is used as the primary clinical focus because the registry summary identifies hearing as an area of interest in documenting the clinical course of superficial siderosis. Tracking whether hearing is reported as stable, improved, or declined can describe the direction of participants’ experiences over the stated period. However, the registry record does not report the criteria used to classify these categories, the questionnaire or assessment method, or whether the categories are exhaustive and mutually exclusive.
The endpoint’s participant counts are not reported in the registry record. Consequently, the posted results do not establish how many participants were classified in any category, whether some participants lacked an assessment, or how the endpoint was analyzed. A count without the category definitions and the number assessed would also be difficult to interpret in relation to missing follow-up. The endpoint describes reported hearing status; by itself, it does not compare deferiprone with another treatment or establish why a participant’s hearing status changed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary outcome and a completed study, but it does not report the primary endpoint counts. In particular, the numbers of participants with stable, improved, or declined self-reported hearing are not reported in the registry record. There is therefore no reported primary-outcome result to describe, and no basis in the posted results for estimating the distribution of hearing outcomes in the enrolled group.
The record lists enrollment of 38 participants. Enrollment is not necessarily the number with an observed endpoint: the registry record does not report the number assessed at the end of the 2-year period, the amount of missing outcome data, or how missing assessments were handled. Without those details, the completeness of the primary endpoint cannot be assessed.
No effect estimate, confidence interval, or p-value for the primary outcome is reported in the registry record. General statistical interpretation: a confidence interval describes the range of values compatible with the data and the method used, and helps convey precision. Without an estimate and its uncertainty, it is not possible to assess precision or distinguish a stable pattern from a highly uncertain one. The registry record lists zero analyses, so it does not provide an analysis result to interpret.
The observational design also limits what a reported outcome could establish. There is no reported control group or randomized comparison, and allocation is not stated. An outcome among people receiving deferiprone would describe this enrolled group; on its own, it would not show what would have happened to comparable people without deferiprone or under another treatment. General statistical interpretation: differences in prognosis, care, or participant characteristics can affect outcomes in observational studies, so an uncontrolled description does not isolate a treatment effect.
The record lists one secondary outcome concerning MRI changes in hemosiderin deposition, but no result for that outcome is reported in the registry record. It lists six outcome measures overall, while the other detailed measures and any associated results are not reported in the registry record. The record also reports adverse-event counts, which are separate from the primary hearing endpoint and should not be taken as evidence about hearing outcomes.
Accordingly, the available registry information establishes the study’s question, enrollment, design description, and selected safety counts. It does not establish the observed primary outcome pattern, its statistical precision, or a causal effect of deferiprone.
9. Statistical Methods Explained
The registry describes a count outcome: the primary endpoint is the number of participants in each self-reported hearing-status category. Counts answer how many participants were classified in a group. They do not, by themselves, convey how many participants had an assessment or how missing observations were treated. The registry record does not report category counts, denominators for the endpoint, or an analysis method.
What does a count outcome describe?
General statistical explanation: a count is a direct summary of observed cases or participants. For a categorical outcome such as stability, improvement, or decline, interpretation depends on knowing the definition of each category and the number of participants assessed. If some participants have no outcome assessment, counts alone can give an incomplete picture unless the missingness and denominator are also described. Those details are not reported in the registry record.
The endpoint is explicitly self-reported. General statistical explanation: self-reported outcomes can capture a participant’s experience, but the interpretation depends on how the question was asked, how responses were classified, and whether the method was consistent across participants. The registry record does not report an instrument, thresholds, validation information, or procedures for handling uncertain responses. No claim can therefore be made about the measurement properties of this endpoint.
What does the observational design imply?
General statistical explanation: random assignment can help balance both measured and unmeasured factors between treatment groups. In an observational study, treatment is not assigned by a reported random process, so treatment groups may differ in ways that affect outcomes. Here, the registry record identifies a deferiprone group and does not report a control group; allocation is not stated. The record therefore supports a description of outcomes among participants enrolled while taking deferiprone, not a randomized estimate of treatment effect.
The registry summary says participants were treated and monitored locally by participating neurologists. General statistical explanation: local clinical monitoring may involve differences in care or outcome assessment, but the registry record does not describe whether or how such differences were standardized. It also does not report covariate adjustment, stratification, or other methods that might address differences among participants. Whether any such procedures were used is not reported in the registry record.
How should uncertainty be considered?
General statistical explanation: an estimate is more informative when accompanied by an uncertainty measure, such as a confidence interval. The interval communicates the precision of an estimate under the stated statistical method; it does not remove limitations from missing data, measurement, or study design. No primary-outcome estimate, confidence interval, or p-value is reported in the registry record, so precision and statistical evidence for the hearing outcome cannot be assessed.
General statistical explanation: over-dispersion matters when count data vary more than a chosen model expects. A model that assumes too little variability may understate uncertainty. The record identifies a count outcome, but it does not report a count model or any distributional assumptions. There is no basis for saying whether over-dispersion was assessed or relevant to a fitted model.
What do planning illustrations represent?
The study’s enrollment and its outcome counts are different quantities. General statistical explanation: sample-size planning estimates a number of participants or events for a future design under specified assumptions; it is not a summary of observed outcomes and is not observed power. The planning assumptions described for illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They define the effect to detect as a stated fraction of the observed effect. For time-to-event illustrations, the total number of events is used; other illustrations are expressed as participants per arm.
Those are planning assumptions, not a reported design justification for this observational study. The registry record does not report the study’s own sample-size justification, and no numerical planning results are reported in the registry record. A two-arm equal-allocation assumption does not describe the reported study design, which identifies a deferiprone group without a reported comparator. Any planning illustration should therefore be kept separate from the study’s enrollment of 38 and from observed endpoint results.
What analyses are reported?
The registry record lists zero analyses. It does not report a statistical analysis plan, adjusted or unadjusted endpoint estimates, interim analyses, or methods for repeated measurements. General statistical explanation: a prespecified analysis plan helps clarify which outcomes and comparisons are primary and how uncertainty is quantified. Without a reported plan or results, the analysis choices and their implications cannot be evaluated. The absence of listed analyses in the record should not be interpreted as proof that no analysis was conducted outside the registry; it means analyses are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists six outcome measures and one secondary outcome concerning MRI changes in hemosiderin deposition. It does not report detailed results for the primary hearing endpoint or the MRI outcome, and details for the remaining outcome measures are not reported in the registry record. The record lists zero analyses. A multiplicity adjustment or a plan for prioritizing outcomes is not reported in the registry record.
General statistical explanation: when multiple outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. A prespecified hierarchy, adjustment, or other multiplicity strategy can help readers interpret a collection of results. Since no analysis results or multiplicity approach are reported, it is not possible to assess whether multiplicity was addressed or how it would affect interpretation.
Missing-data methods are not reported in the registry record. The record does not state how many participants completed the hearing assessment, how incomplete or unclassifiable responses were handled, or whether any participants were excluded from an analysis. Enrollment of 38 does not establish the number included in an endpoint analysis. The analysis population is not reported in the registry record.
Interim analyses and stopping rules are also not reported in the registry record. These omissions mean that the available information does not establish how the reported study outcomes, if analyzed outside the registry, were selected or handled. No particular missing-data or multiplicity method should be assumed.
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 |
|---|---|---|---|
| Deferiprone | 0 | 38 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Deferiprone | 0 of 38 |
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 |
|---|---|
| Deferiprone | 10 of 38 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Deferiprone |
|---|---|---|
| Fatigue | Nervous system disorders | 10 of 38 |
| Joint Pain | Musculoskeletal and connective tissue disorders | 2 of 38 |
| Mouth sores | Skin and subcutaneous tissue disorders | 2 of 38 |
For the deferiprone group, the registry reports 38 participants at risk for serious adverse events and zero affected participants. It reports 38 participants at risk in the other adverse-event category and 10 affected participants. Deaths are reported as zero. These are counts of participants, not a measure of event frequency per unit of follow-up time.
The registry record lists no top serious adverse-event terms. The safety counts do not establish whether events were judged related to deferiprone, and a causal relationship is not reported. The categories should also be kept distinct: the zero count for serious adverse events does not mean that no other adverse events were recorded, since 10 participants are listed as affected in the other category.
General statistical explanation: observing no serious adverse events in a study does not prove that the risk is zero. The count is limited to the participants and observation captured in the record, and the registry does not report exposure duration or the completeness of safety follow-up. These safety figures should be read as the registry’s reported counts, not as a comprehensive estimate of risk or as a comparison with another treatment.
12. What the Result Does, and Does Not, Mean
The record establishes that an observational study of deferiprone in superficial siderosis enrolled 38 participants and is marked completed. Its primary question concerns how many participants reported stable, improved, or declined hearing at the end of the 2-year period. The actual counts for those categories are not reported in the registry record. As a result, the posted information does not show the observed pattern of hearing outcomes.
There is also no reported effect estimate or uncertainty measure for the primary endpoint. The registry record lists zero analyses, so statistical significance and precision cannot be assessed. Enrollment alone is not evidence of a particular outcome, and the completed status does not supply missing endpoint results.
The observational design is important to interpretation. The registry does not report a control group or random allocation. Even if a descriptive hearing result were available, an outcome among participants taking deferiprone would not by itself establish that the treatment caused a change. A comparison with a suitable group and methods addressing differences between groups would be needed to support a causal interpretation; such a comparison is not reported.
The record also lists safety counts: zero participants affected in the serious adverse-event category, 10 affected in the other adverse-event category, and zero deaths, each among 38 at risk. Those figures describe what the registry reports and do not establish comparative safety or causation. The MRI outcome is named as a secondary outcome, but its result is not reported in the registry record.
In short, the registry record documents the study question, enrolled group, observational design, and selected safety counts. It does not provide enough outcome or analysis information to characterize the primary hearing result, quantify its precision, or conclude that deferiprone did or did not alter the clinical course.
13. Why This Trial Matters Statistically
This study is statistically important as an example of the difference between a clearly stated clinical question and a reported analysis result. The registry defines a primary outcome focused on self-reported hearing status at the end of the 2-year period, but the category counts are not reported in the registry record. Without those counts and the number assessed, readers cannot describe the observed endpoint distribution or judge its completeness.
The observational design also matters. The record describes people receiving deferiprone in clinical care, without a reported randomized comparator. Descriptive outcomes can characterize an enrolled group, but they do not isolate the effect of treatment from other influences. The distinction is central when interpreting results from studies intended to document clinical course.
Statistical interpretation depends not only on an outcome definition but also on reporting the analysis, uncertainty, and handling of missing observations. Those details are not reported in the registry record. The record lists six outcome measures and zero analyses, so the relationship between the outcome set and any statistical testing cannot be assessed.
The registry’s safety counts also illustrate why denominators and categories matter. Zero participants are listed as affected by serious adverse events, while 10 are listed in the other adverse-event category, with 38 at risk in each. These counts describe separate categories and do not supply a comparative safety estimate.
The record is therefore informative about the intended endpoint and basic study structure, while also illustrating how absent outcome and analysis reporting constrains conclusions. It cannot support a judgment about the magnitude or precision of the hearing outcome, nor a causal treatment conclusion.
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 direct limitation is that the primary endpoint counts are not reported in the registry record. The record does not report the number of participants assessed at the end of the 2-year period or the number missing an assessment. It also does not report the criteria for classifying hearing as stable, improved, or declined, or the instrument used for self-report. These omissions limit interpretation of both the endpoint and its completeness.
The registry describes an observational study and reports a deferiprone group without a control group. Allocation is not stated. Consequently, no like-for-like comparison is available in the record, and outcomes cannot be separated from differences in participant characteristics, clinical care, or other influences. The registry summary describes local treatment and monitoring by participating neurologists, but procedures for standardizing assessments are not reported in the registry record.
The record lists six outcome measures but gives no analyses. It does not report a statistical analysis plan, missing-data methods, analysis population, interim analyses, or multiplicity handling. Results for the named MRI outcome are also not reported in the registry record. The exact duration and completeness of follow-up for individual participants are not reported.
Safety information is limited to the registry’s participant counts; event attribution and exposure duration are not reported. The completed status and enrollment count do not resolve these limitations. These are limits of what can be learned from the registry record, rather than evidence that particular procedures or analyses were absent from the study itself.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Observational Study of Deferiprone (Ferriprox®) in the Treatment of Superficial Siderosis — NCT01284127.
- Registry record last updated 2019-09-23; status last verified 2019-08.
- Results first posted 2019-09-23.
- 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 describes a completed Phase IV observational study of deferiprone for superficial siderosis, sponsored by Johns Hopkins University. Enrollment was 38. The study start is listed as 2012-03, and primary completion as 2018-01-08.
The primary outcome is the number of participants with stable, improved, or declined self-reported hearing at the end of the 2-year period. Its category counts are not reported in the registry record. One secondary outcome concerns MRI changes in hemosiderin deposition; its result is not reported. The registry lists six outcome measures and zero analyses.
For the deferiprone group, the record reports zero participants affected by serious adverse events, 10 affected in the other adverse-event category, and zero deaths, with 38 at risk for each category. The record does not report a comparator group or an allocation method.