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 Stem Cell Transplantation for Hurler (NCT00176917), a na phase 2 study. The primary outcome is Mean Percentage of Donor Cells in Study Population (Chimerism)..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00176917 |
| Phase | Phase 2 |
| Condition | Mucopolysaccharidosis I, Mucopolysaccharidosis VI, Mannosidosis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 41 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Masonic Cancer Center, University of Minnesota |
| Results posted | Yes |
2. Clinical Question
Population
Patients undergoing hematopoietic stem cell transplantation for Hurler syndrome, Maroteaux Lamy syndrome, Mannosidosis, or I-cell disease. The registry lists Mucopolysaccharidosis I, Mucopolysaccharidosis VI, Mannosidosis, and Mucolipidosis Type II (I-cell Disease) as conditions. Enrollment was 41.
Intervention
Hematopoietic stem cell transplantation with chemotherapy conditioning. The listed interventions are Stem Cell Transplant and Busulfan, Cyclophosphamide, ATG.
Comparator
There was a single treatment group, in which all patients received chemotherapy and transplantation. No separate comparison group is described.
Primary question
What was the mean percentage of donor cells, measured as chimerism, at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year?
The clinical question is about donor-cell engraftment after transplantation under the conditioning regimen, alongside the regimen’s safety. The registry describes engraftment as determined by restriction fragment length polymorphism (RFLP). It also lists secondary outcomes concerning survival on study, failed engraftment, and Grade III-IV acute graft-versus-host disease.
Because this is a single-group study, its design does not provide a concurrent untreated or alternative-treatment group for estimating a comparative treatment effect. The stated question is therefore descriptive: it concerns the observed donor-cell percentages at specified follow-up times in the study population. The registry record does not report the observed means, their standard deviations, or analyses comparing time points. It also does not report outcome results for the listed secondary outcomes. The record identifies the population and intended measurements, but it does not establish how results differed across patient subgroups or how they compare with outcomes under another regimen.
3. Trial Design
This is a completed Phase 2 study with a single-group model and no allocation to multiple groups. The registry describes one Treatment Arm: all patients were treated with chemotherapy and transplantation. Masking is listed as none. Enrollment was 41. The study start is listed as 1999-05 and primary completion as 2008-05.
The listed procedures and drugs are Stem Cell Transplant and Busulfan, Cyclophosphamide, ATG. The study’s stated purpose was to determine the safety and engraftment of donor hematopoietic cells using the conditioning regimen among patients undergoing transplantation for the named disorders. The registry’s condition list includes Mucopolysaccharidosis I, Mucopolysaccharidosis VI, Mannosidosis, and Mucolipidosis Type II (I-cell Disease).
The primary outcome is the mean percentage of donor cells in the study population, described as chimerism. It is specified at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year. The registry gives different numbers of patients included at these measurement times: 24 patients at Day 21, 15 pts at Day 42, 29 pts at Day 60, 25 pts at Day 100, 18 pts at 6 Months, and 16 pts at 1 Year. The record does not explain why these counts differ.
There is no like-for-like control comparison in the registry design. Any description of outcomes should therefore distinguish observations in this treated group from evidence of a difference between treatments. The registry record does not report a statistical analysis plan, a sample-size justification for the enrolled study, or methods for accounting for repeated 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 | Transplant Patients |
|---|---|
| STARTED | 41 |
| COMPLETED | 41 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Day 21 (24 patients included), Day 42 (15 pts), Day 60 (29 pts), Day 100 (25 pts), 6 Months (18 pts), 1 Year (16 pts).
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 | Transplant Patients |
|---|---|---|
| Participants analysed | 41 | |
| Age, Categorical: <=18 years | Participants | 41 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 1.8 (SD 1.4) |
| Sex: Female, Male: Female | Participants | 23 |
| Sex: Female, Male: Male | Participants | 18 |
| Region of Enrollment: United States | participants | 41 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Percentage of Donor Cells in Study Population (Chimerism)., measured over at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Percentage |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean percentage of donor cells in the study population, called chimerism in the registry. It is measured at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year. Donor-derived engraftment is described as determined by restriction fragment length polymorphism (RFLP).
In general, a mean gives a central summary of a continuous measurement across the participants with available measurements. Chimerism expresses the donor-cell contribution as a percentage, so the endpoint is intended to describe the extent of donor-derived cell presence at the specified follow-up times. The registry specifies standard deviation as the measure of dispersion. In general, standard deviation describes how spread individual observations are around the mean; it is not itself a measure of how precisely the mean has been estimated.
Repeated measurements at specified follow-up times can describe the course of observed chimerism in the study population. However, comparing group means across time would require results and an analysis that account for the actual data structure. The registry record does not report the endpoint’s observed means or standard deviations, confidence intervals, or tests. It therefore does not permit a numerical assessment of the level or precision of chimerism at any listed time.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clear descriptive endpoint: mean donor-cell percentage at scheduled follow-up times. It also gives the number of patients included at each time point. But the observed endpoint values are not reported in the registry record. There is no mean or standard deviation listed for any of the scheduled assessments, and no confidence interval or statistical test is reported. Consequently, the posted information cannot establish the size or precision of the observed chimerism values.
The counts included at the measurement times vary: Day 21 (24 patients included), Day 42 (15 pts), Day 60 (29 pts), Day 100 (25 pts), 6 Months (18 pts), and 1 Year (16 pts). These counts indicate that the number of observations contributing to the endpoint was not the same at each time. They do not, by themselves, explain why measurements were unavailable or whether the participants assessed at different times represent comparable subsets of the enrolled group. Reasons for differing counts are not reported in the registry record.
This is a single-group study. Its design can describe outcomes in patients who received the listed chemotherapy and transplantation, but it does not provide a randomized or concurrent comparison with another regimen. The registry lists allocation as NA, masking as NONE, and a SINGLE GROUP model. Therefore, the record does not support a treatment-versus-control effect estimate. Even if time-specific values were available, changes across follow-up would not by themselves identify what caused those changes.
The registry also lists secondary outcomes for survival on study, failed engraftment, and Grade III-IV acute graft-versus-host disease. Their results are not reported in the registry record. The serious adverse event information lists 41 patients at risk and 0 affected in each of the serious and other adverse-event categories. This is a posted count, not a complete account of the types, timing, severity, or duration of all events. Deaths are listed as null, which is not a numerical death count.
In general, interpreting a study requires matching the statistical claim to the design, observed results, and analysis. Here, the registry record supplies design information and endpoint definitions, but not the numerical primary outcome results or inferential analyses. It supports describing what was planned to be measured and the available patient counts; it does not support a conclusion about the magnitude, precision, or comparative effect of the transplant regimen.
9. Statistical Methods Explained
What does the mean describe?
The endpoint is a continuous measurement summarized by its mean. In general, a mean combines the observed values into a central summary for the participants with measurements at that time. The registry states that the measure is a percentage of donor cells, and that standard deviation is the accompanying measure of dispersion. Standard deviation describes variability among individual measurements; it does not provide the same information as a confidence interval for the mean.
The registry does not post the mean or standard deviation at any follow-up time. It also does not report confidence intervals, p-values, or other inferential results for the primary endpoint. Without those values, neither the observed level of chimerism nor its statistical precision can be assessed from the registry record.
How should the follow-up times be understood?
Chimerism was specified at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year. These are repeated follow-up assessments of the outcome, not separate treatment groups. The number of patients included at each assessment differs: 24 patients at Day 21, 15 pts at Day 42, 29 pts at Day 60, 25 pts at Day 100, 18 pts at 6 Months, and 16 pts at 1 Year.
In general, repeated measurements from the same person may be statistically related. A method that treats all observations as independent may not represent that relationship appropriately. The statistical approach used for repeated measures is not reported in the registry record. Nor does the record explain the varying numbers of patients included at each follow-up time or specify how unavailable measurements were handled.
What can a single-group design estimate?
The study model is SINGLE GROUP, with one treatment arm and no allocation to a concurrent comparison arm. In general, a single-group study can summarize outcomes observed among participants who received the intervention. It cannot directly estimate how those outcomes differ from outcomes under a separate treatment or control condition. Changes in an outcome over follow-up are descriptive unless the analysis and design justify a stronger interpretation; a change alone does not identify its cause.
The registry lists allocation as NA and masking as NONE. It does not report a comparator arm, a randomized comparison, or an adjusted treatment-effect analysis. The record therefore describes a study of transplantation and chemotherapy in the enrolled population, rather than a comparative trial between two assigned regimens.
What do the planning illustrations mean?
Any sample-size figures associated with planning are illustrations based on an observed effect, not the trial’s own design or an observed measure of power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect set as a stated fraction of the observed effect. For time-to-event outcomes, the stated convention is total events using Schoenfeld; for other outcomes, it is participants per arm.
Those assumptions describe a hypothetical planning calculation and do not match this registry’s single-group design. The record does not report the trial’s own sample-size justification. A planning illustration is not evidence that the trial had a particular probability of detecting an effect, and it should not be interpreted as observed power. Since the observed primary endpoint values are not reported, the registry record also does not provide the observed effect needed to understand such an illustration in context.
What statistical analysis is reported?
The record lists 4 outcome measures and 0 analyses. It gives the primary endpoint definition and follow-up times but no statistical model, test, adjustment, or analysis population for the primary outcome. It also does not report an inferential analysis of the listed secondary outcomes. The statistical plan, including any interim analyses, is not reported in the registry record.
In general, a confidence interval conveys a range of values compatible with the data and the analysis, and its width reflects statistical precision under that method. A p-value, when reported, addresses compatibility between data and a specified null model; it does not give the size or clinical importance of an effect. Neither type of inferential result is available for the primary endpoint in this record. Interpretation must therefore remain descriptive and limited to the design and counts that the registry reports.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint is scheduled at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year. Examining an outcome at multiple times creates a need to clarify whether each time point is a separate inferential question, whether one time point is primary for testing, and whether any adjustment is used when interpreting multiple tests. The registry record names the primary outcome and its measurement times but does not report a multiplicity strategy or inferential tests.
The record lists 4 outcome measures, including the primary chimerism outcome and secondary outcomes concerning survival on study, failed engraftment, and Grade III-IV acute graft-versus-host disease. It reports 0 analyses. No hierarchy among the secondary outcomes, adjustment method, or analysis plan is reported in the registry record. Thus, no family of statistical tests or multiplicity-adjusted result can be reconstructed from the posted information.
The number of patients contributing to the primary endpoint varies by follow-up: 24 patients at Day 21, 15 pts at Day 42, 29 pts at Day 60, 25 pts at Day 100, 18 pts at 6 Months, and 16 pts at 1 Year. These are the counts included for the specified measurements; reasons for the varying counts are not reported. The registry does not describe whether missing measurements resulted from missed assessments, withdrawal, death, or another reason. It also does not report imputation, sensitivity analyses, or an analysis population definition.
In general, missing outcome measurements can affect both the precision and interpretation of longitudinal summaries, especially when availability is related to participant outcomes. The registry counts alone do not establish the mechanism of missingness or its impact. The record does not report whether all enrolled participants were included in each secondary outcome analysis or how deaths and other unavailable outcomes were handled.
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 |
|---|---|---|---|
| Transplant Patients | 0 | 41 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Transplant Patients | 0 of 41 |
The serious adverse event information lists a Transplant Patients group with 41 at risk and 0 affected for serious adverse events. It also lists 41 at risk and 0 affected for other adverse events. No serious adverse event terms are listed. The deaths field is null, so it does not give a death count.
These are registry-record counts. They should be read as the posted numbers of patients recorded as affected in those categories, not as a detailed description of all events experienced during the study. The record does not give event timing, event duration, severity distributions beyond the category label, or patient-level detail. The absence of listed serious terms does not establish that no events occurred or that all safety information was captured. The secondary outcome list includes Grade III-IV acute graft-versus-host disease, but a result for that outcome is not reported in the registry record. Similarly, results for survival on study and failed engraftment are not reported.
In general, safety counts depend on how events are defined, collected, and attributed. The posted figures do not describe those procedures. They should not be used to infer a comparative safety profile because the study has no separate comparator group.
12. What the Result Does, and Does Not, Mean
The registry record identifies a Phase 2, single-group study of hematopoietic stem cell transplantation with chemotherapy conditioning for patients with the listed metabolic disorders. It specifies donor-cell chimerism as the primary outcome, measured at multiple follow-up times, and describes RFLP as the method for determining donor-derived engraftment. It also identifies several secondary outcomes and provides the numbers of patients included in the primary measurement at each listed time.
Those design details clarify what the study set out to measure, but they do not provide the numerical primary results. The mean chimerism values and standard deviations are not reported in the registry record. Nor are confidence intervals, tests, or analysis results given. The record therefore cannot establish the magnitude or precision of the observed donor-cell percentages, or how those measurements changed over time.
The single-group design also limits comparative interpretation. There is no concurrent control group described, so the posted record cannot estimate the difference between this regimen and another treatment. Outcomes observed after treatment cannot, by themselves, identify what would have occurred under an alternative regimen. The registry also does not report results for the listed secondary outcomes, including survival on study, failed engraftment, and Grade III-IV acute graft-versus-host disease.
The serious and other adverse-event counts are listed as 0 affected among 41 at risk in each category, while deaths are null. These fields do not provide enough detail to characterize all safety outcomes or to compare safety with another approach. The appropriate interpretation is narrow: the registry describes the trial design, planned outcome measures, follow-up counts, and posted adverse-event counts, while the primary outcome results and statistical analyses are not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable for pairing a clinically interpretable continuous endpoint with repeated follow-up in a single-group design. Donor-cell chimerism is summarized as a mean percentage, with standard deviation, at several specified times. That makes clear what quantity the registry intended to describe, while also raising questions about how repeated measurements and changing assessment counts were handled.
The follow-up counts vary across scheduled measurements, from 24 patients included at Day 21 to 16 pts at 1 Year, with other counts listed for the intervening assessments. Such variation matters because a time-specific mean describes the participants measured at that time. Without information about why counts differ or how missing measurements were handled, a sequence of time-specific summaries cannot be assumed to represent a fixed, unchanged group.
The design also illustrates the distinction between describing outcomes and estimating comparative effects. A single treatment group can provide descriptive information about the enrolled participants, but there is no concurrent control group in the registry record. No causal or comparative conclusion follows from the design alone. Statistical interpretation depends not only on the endpoint and measurement schedule, but also on what data are reported and how the analysis accounts for the study structure.
Finally, the gap between a specified outcome and a posted result is important. The registry names the primary measure and secondary outcomes, but does not report their numerical results or analyses. This means readers can understand the planned outcome framework while remaining unable to assess the magnitude, precision, or inferential strength of the findings. It is a useful reminder that study registration details and outcome results answer different statistical questions.
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 primary limitation for interpreting the outcome is that its observed values are not reported in the registry record. The chimerism endpoint is defined and the time points are specified, but the means and standard deviations are absent. Confidence intervals, p-values, and other primary analyses are not reported either. As a result, the endpoint’s magnitude and precision cannot be evaluated from this record.
The number of patients included varies across follow-up measurements. The registry does not explain the changing counts or report how missing measurements were handled. It also does not identify an analysis population or provide sensitivity analyses. These omissions prevent assessment of whether the time-specific measurements describe comparable participant groups.
The study is single-group, with no comparator arm and no allocation to multiple groups. The record therefore does not support a controlled treatment-effect estimate. Masking is listed as none. The registry does not report the statistical analysis plan, a sample-size justification for the trial, or interim analyses. It also lists 0 analyses and does not report results for the named secondary outcomes.
The posted adverse-event information is limited to counts of 0 affected among 41 at risk in each of the serious and other categories. No serious terms are listed, and deaths are null. Detailed event descriptions and results for the secondary safety outcome of Grade III-IV acute graft-versus-host disease are not reported in the registry record. These limitations leave the safety profile and clinical outcomes insufficiently characterized by the posted information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Stem Cell Transplantation for Hurler — NCT00176917.
- Registry record last updated 2017-12-28; status last verified 2017-12.
- Results first posted 2009-09-04.
- 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
NCT00176917 is a completed Phase 2, single-group study titled “Stem Cell Transplantation for Hurler.” The official title also names Maroteaux Lamy syndrome, MPS VI, and Alpha Mannosidase Deficiency (Mannosidosis). Enrollment was 41. The registry lists a study start of 1999-05 and primary completion of 2008-05.
All patients in the Treatment Arm received chemotherapy and transplantation. The primary outcome was mean donor-cell percentage, or chimerism, at 21 days, 42 days, 60 days, 100 days, 6 months, and 1 year, determined by RFLP. The record gives time-specific patient counts but does not report the observed endpoint values or analyses. Secondary outcomes concern survival on study, failed engraftment, and Grade III-IV acute graft-versus-host disease; their results are not reported in the registry record.