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 The Effect of Natalizumab (Tysabri) on Sexual Dysfunction in Multiple Sclerosis (NCT01455220), a na na study. The primary outcome is Sexual Dysfunction (as Measured by the Multiple Sclerosis Intimacy and Sexuality Questionnaire (MSISQ-19) ).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01455220 |
| Phase | NA |
| Condition | Multiple Sclerosis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 45 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of South Florida |
| Results posted | Yes |
2. Clinical Question
The clinical question is whether sexual dysfunction scores and quality-of-life measures change during treatment with natalizumab in people with multiple sclerosis. The registry describes an assessment of MSISQ-19 scores at baseline and 6 months, with change from baseline identified as the primary outcome. It also lists measures of sexual function and health-related quality of life.
Population
People with multiple sclerosis were the intended study population. The registry lists enrollment of 45, but does not report further eligibility details, participant characteristics, or the number with primary-outcome data at each assessment.
Intervention
The intervention was Tysabri, also identified as natalizumab. The study purpose describes examining symptoms and quality-of-life measures in patients prescribed the drug. The registry does not report treatment duration beyond the outcome timeframe or details of how treatment was managed.
Comparator
No separate control group is described. The study is recorded as single-group, with allocation listed as NA and masking listed as none. Baseline is the reference assessment for the stated change outcome; it is not a concurrent control group.
Primary question
How does the mean MSISQ-19 score change from baseline to 6 months? The questionnaire score ranges from 19 to 95, and higher scores indicate greater sexual dysfunction. The registry record does not report the observed score change or its uncertainty.
That framing is narrower than a comparison of natalizumab with another treatment or with no treatment. A baseline-to-follow-up change can describe what happened over time among assessed participants, but by itself it cannot separate a treatment effect from other influences on change. The posted record gives no numerical primary-outcome results with which to judge the direction, size, or precision of any observed change.
3. Trial Design
The registry identifies NCT01455220 as a completed study sponsored by the University of South Florida. The listed study title concerns the effect of natalizumab, also called Tysabri, on sexual dysfunction in multiple sclerosis. Enrollment is recorded as 45. The study start is listed as 2011-01 and primary completion as 2014-10.
The design is recorded as single-group. Allocation is listed as NA and masking as none; phase is listed as NA. These entries do not describe a randomized comparison or a blinded assessment. The registry’s own design classification therefore matters when interpreting any change: there is no separate concurrent comparison group in the record against which to distinguish treatment-associated change from change over time.
The intervention is listed as Tysabri (natalizumab), with drug as its type. The study purpose says it seeks to determine whether sexual dysfunction symptoms and quality-of-life measures may improve in patients prescribed Tysabri. The record does not report a dosing schedule, treatment duration, adherence measure, co-intervention policy, or details of how participants entered the study.
The primary outcome is sexual dysfunction measured with the Multiple Sclerosis Intimacy and Sexuality Questionnaire, MSISQ-19, at baseline and 6 months. The registry describes change at the end of the study relative to baseline. Secondary outcomes include sexual function and quality of life measured with MSQOL-54, and health-related quality of life measured with FAMS. It lists four outcome measures in total, but no outcome analyses.
Details that would clarify the conduct of the study—including eligibility criteria, recruitment procedures, follow-up completion, protocol deviations, and the statistical analysis plan—are not reported in the registry record. The status is recorded as completed, but that status alone does not establish how many participants contributed data to each measure or whether every planned assessment was completed.
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 | All Patients |
|---|---|
| STARTED | 45 |
| COMPLETED | 15 |
| NOT COMPLETED | 30 |
Reasons for not completing this period:
| Reason | All Patients |
|---|---|
| screen fail | 30 |
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 | Tysabri |
|---|---|---|
| Participants analysed | 15 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 15 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 4 |
6. Primary Endpoint
The registry lists the primary outcome as Sexual Dysfunction (as Measured by the Multiple Sclerosis Intimacy and Sexuality Questionnaire (MSISQ-19) ), measured over Baseline, 6 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is sexual dysfunction measured with the MSISQ-19. The registry describes comparing questionnaire responses at baseline and 6 months and assessing change from baseline. The outcome is specified as a mean on a continuous scale, with units described as units on a scale and standard deviation as the dispersion measure. No mean, standard deviation, change estimate, or other numerical outcome result is reported.
The total score ranges from 19 to 95, with higher scores indicating greater sexual dysfunction. The questionnaire total is described as the sum of primary, secondary, and tertiary subscale scores. The stated ranges are 5 to 25 for the primary subscale, 9 to 45 for the secondary subscale, and 5 to 25 for the tertiary subscale. This makes the direction of the score interpretable: a higher total represents greater reported dysfunction, while a lower total represents less.
A continuous score can preserve gradations in responses rather than reducing them to a binary outcome. A mean change can describe the average direction and size of change in the analyzed group, while a standard deviation describes the spread of individual scores around the mean. Those summaries answer different questions: a group average does not show whether every participant changed similarly.
The MSISQ-19 was selected to address the study’s central question about sexual dysfunction. The registry also names quality-of-life outcomes, but does not provide their results. It does not report additional measurement details, interpretation thresholds, or a minimally important change for the MSISQ-19.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record does not report numerical results for the primary endpoint. Although it describes a comparison of MSISQ-19 responses at baseline and 6 months, there is no posted mean at either assessment, mean change, standard deviation, confidence interval, or test result. Consequently, the direction and magnitude of the observed change, and the precision of any estimate, cannot be assessed from the record.
The absence of reported analyses is important. The registry lists four outcome measures and zero analyses. The record therefore does not establish whether an analysis was performed but not entered, whether the planned outcome was not analyzed, or whether results are available elsewhere. The statistical results needed to evaluate the primary question are not reported in the registry record.
The design also limits what a change score could establish. In a single-group study, participants serve as their own baseline reference, but there is no concurrent control group. If a mean score changed over time, that observation would describe the participants with available measurements; it would not, on its own, identify how much of the change was due to natalizumab. Changes could also reflect other influences over the follow-up period, and the registry does not report a method for addressing them.
General statistical interpretation: an estimate describes the observed result, while a confidence interval expresses uncertainty around that estimate under the analysis assumptions. A test result addresses compatibility with a specified statistical null hypothesis, but it does not convey the size or practical importance of a change by itself. None of these numerical summaries is reported for the primary endpoint in this record. No conclusion about statistical significance or precision can therefore be drawn.
The scale’s direction is clear from the record: higher MSISQ-19 scores indicate greater dysfunction. That direction would help interpret a reported change, but it cannot substitute for an observed estimate. Nor does the record provide a threshold for deciding whether a numerical change would be important to participants.
The study’s status is completed, and enrollment is recorded as 45. Neither fact supplies the missing outcome data. Enrollment is not necessarily the number included in a particular analysis, and the registry does not report the number assessed at baseline or 6 months. The listed safety figures are also separate from the unreported primary efficacy summaries and should not be used to infer them.
Overall, the registry states the question, measurement instrument, and assessment timeframe, but not the primary result. It is possible to describe how the endpoint was intended to be read and why the single-group design constrains causal interpretation. It is not possible to quantify the observed change, assess its uncertainty, or judge the listed secondary measures from the posted results.
9. Statistical Methods Explained
The registry describes a continuous primary outcome summarized as a mean, with standard deviation identified as the measure of dispersion. It specifies a baseline and 6-month timeframe and describes change from baseline. However, the registry record does not report the actual endpoint values or the statistical analysis used to estimate change. The discussion below distinguishes the general meaning of these statistical concepts from what can be established for this study.
What does a mean change describe?
General explanation: a mean change is the average of participant-level differences between a follow-up measurement and a reference measurement, when the analysis is based on paired observations. It can convey the average direction and amount of change in the analyzed group. The registry identifies baseline as the reference and 6 months as the follow-up, but does not describe the calculation details, the handling of incomplete pairs, or the analysis population. It is therefore not possible to verify how the stated change was calculated.
A group mean does not imply that every participant experienced the same direction or degree of change. Individual responses can vary around the average. The standard deviation describes the spread of observed scores or changes, depending on what was summarized; the record names standard deviation but does not state a reported value or clarify the specific result to which it would apply.
How should the scale direction be read?
General explanation: interpretation depends on the score’s direction and construction. Here, the registry says the MSISQ-19 total ranges from 19 to 95 and that higher scores indicate greater sexual dysfunction. It also says the total is formed by summing primary, secondary, and tertiary subscale scores, with ranges of 5 to 25, 9 to 45, and 5 to 25, respectively. These descriptions explain the intended score direction, but do not provide observed scores or a threshold for meaningful change.
The use of a continuous score permits analysis of variation across the scale rather than only counting participants as improved or not improved. General explanation: a mean can be useful for describing an average, but distributional information and individual-level data may be relevant when responses differ substantially. No distributional summaries beyond the stated dispersion type are reported for this outcome.
What would uncertainty measures add?
General explanation: a confidence interval gives a range of estimates compatible with the observed data and analysis assumptions. Its width reflects statistical uncertainty, which is influenced by factors including data variability and the amount of usable information. It is not a guarantee that the true value lies within the interval, and it does not establish that a result is clinically important. The registry does not report a confidence interval for the primary outcome.
A p-value, when used, evaluates data compatibility with a specified null hypothesis under model assumptions. It does not measure the probability that the null hypothesis is true, and it does not describe effect size. No p-value or hypothesis-testing result for the primary endpoint is reported. The registry also does not report whether an estimate was adjusted for covariates or whether a particular statistical model was used.
Why does the single-group structure matter?
General explanation: a baseline-to-follow-up comparison can describe change within the observed group. Without a concurrent comparison group, it cannot by itself distinguish the effect of treatment from other changes that occur over time. A before-and-after difference may be affected by natural course, changes in care or circumstances, measurement variability, and who remains available for follow-up. These are general interpretive concerns, not findings established for this study.
The registry records a single-group model, allocation as NA, and masking as none. It does not report a randomized or blinded comparison. No adjustment method or causal analysis is reported, so the record does not provide a basis for a stronger treatment-effect interpretation.
What statistical plan is documented?
The registry reports four outcome measures and zero analyses. The sample-size assumptions in the record describe a planning illustration based on an observed effect, but no trial-specific design justification or actual analysis is reported. Such planning illustrations are not observed power and cannot replace an estimate from the trial’s outcome data. The registry does not report the effect used for planning, a sample-size justification, an interim analysis plan, or a formal statistical analysis plan.
General explanation: over-dispersion matters when the variability in data is greater than a model assumes; an inappropriate variance assumption can make uncertainty appear too small or too large. That issue cannot be evaluated without the observed data and model details. The primary endpoint is described as continuous, and no over-dispersion analysis is documented. The record also does not provide diagnostics or assumptions for any fitted model.
In short, the record gives enough information to explain the intended scale and general type of endpoint, but not enough to reproduce or evaluate an analysis. The numerical estimates, uncertainty measures, model specification, and analysis population are not reported in the registry record.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Baseline to 6 Months (MSISQ-19 Scores) | 15 | -0.697 | 0.290 | -0.858 to -0.536 |
R code and output
arm <- c("Baseline to 6 Months (MSISQ-19 Scores)")
n <- c(15)
m <- c(-0.697)
sp <- c(0.29)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Baseline to 6 Months (MSISQ-19 Scores) 15 -0.697 0.290 -0.858 -0.53611. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures: the primary MSISQ-19 sexual dysfunction measure and secondary measures of sexual function and quality of life using MSQOL-54, plus health-related quality of life using FAMS. It lists zero analyses. No test results, estimates, or analysis details are reported for these outcomes.
Multiplicity arises when several outcomes or statistical tests are considered. General explanation: the more opportunities there are to identify a result as notable, the more important it is to know which outcomes were designated primary, which analyses were planned, and whether any adjustment or interpretive strategy was used. This does not mean that an adjustment is always required in the same way; the appropriate approach depends on the study question and analysis plan. The registry does not report a multiplicity strategy or a statistical analysis plan, so it is not possible to determine how the listed outcomes were handled analytically.
Missing-data methods are also not reported in the registry record. It does not state how missing baseline or 6-month questionnaire responses were handled, whether participants with incomplete measurements were excluded, or whether any imputation method was used. These omissions matter because a mean change based on participants with both measurements may describe a different set of participants from the full enrolled group.
The analysis populations are not reported. Enrollment is listed as 45, but the number contributing data to the primary outcome or to each secondary outcome is not given. The registry also does not describe an intention-to-treat population, a per-protocol population, or another analysis set. No assumption about these populations or the effect of missing data can be made from the record.
Thus, the outcome list indicates what was measured, but not which results were analyzed or how incomplete observations and multiple outcomes were addressed. Those details are not reported in the registry record.
12. 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 |
|---|---|---|---|
| All Patients | 0 | 15 | 0.0% |
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 |
|---|---|
| All Patients | 0 of 15 |
The registry lists one safety group titled All Patients. In that group, 15 are recorded as at risk for serious adverse events and 0 as affected. For other adverse events, 15 are recorded as at risk and 0 as affected. These are the safety counts recorded for the listed group; they are not outcome estimates for sexual dysfunction or quality of life.
The safety at-risk counts should not be assumed to represent everyone enrolled. Enrollment is recorded as 45, while the safety group lists 15 at risk for each adverse-event category. The registry does not explain this difference, identify the safety analysis population, or provide further context about who was included. No additional denominator should be inferred.
The record lists no top serious adverse-event terms. Deaths are not reported in the registry record. Zero affected in the listed group means that the registry entry records no affected participants within that group and category; it does not establish that no events occurred outside the reported record or explain how events were collected and classified.
These figures do not establish causation. A registry safety count alone does not show whether an event was related to the intervention, and the record does not report attribution details. The counts should be read narrowly as the safety information entered for the specified group, not as a comparative safety analysis.
13. What the Result Does, and Does Not, Mean
The record establishes the study’s stated focus: sexual dysfunction and quality-of-life measures among people with multiple sclerosis prescribed natalizumab. It identifies MSISQ-19 change from baseline to 6 months as the primary outcome and explains how to interpret the score direction. It also lists MSQOL-54 and FAMS measures. These details clarify what investigators intended to assess, but they are not evidence of an observed change.
The posted results do not include a numerical primary-outcome estimate, the scores at either assessment, an uncertainty interval, or a statistical test. The direction and magnitude of any change are therefore unknown from the registry record. No conclusion about the size, precision, or statistical significance of a primary result can be drawn. Results for the secondary outcomes are also not reported.
Even if a pre-to-post change were available, the single-group design would support a description of change over time rather than a direct comparison with an untreated or alternative-treatment group. General explanation: changes in a group can coincide with treatment without showing that treatment caused them. A concurrent comparison can help address alternative explanations, whereas a baseline measurement alone cannot provide that comparison.
The record does not report who contributed data at each time point, how missing responses were handled, or the analysis population. As a result, the listed enrollment cannot be treated as the number analyzed. The posted safety counts also have their own listed at-risk group and cannot fill gaps in the efficacy results.
The defensible reading is limited: the registry records a completed single-group study with a defined questionnaire-based primary endpoint and listed quality-of-life measures, but does not report the numerical outcome analyses needed to evaluate the study’s stated question. This is not evidence that the measures changed or did not change. It is an absence of reported results in the registry record.
14. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a clearly stated measurement plan and a reportable result. The registry identifies a continuous primary measure, its direction, its component subscales, and a baseline-to-6-month timeframe. Those details help readers understand what a future estimate would represent. Yet without the estimate and its uncertainty, the central statistical question remains unanswered by the posted record.
The single-group design also illustrates why study structure affects interpretation. A within-group change can be meaningful as a description of observed participants, but it does not provide the same evidence as a comparison against a concurrent group. The distinction is not about whether a questionnaire is useful; it is about what conclusions the design can support.
Completeness of reporting matters alongside design. The record lists four outcomes but zero analyses, and it does not report missing-data methods, analysis populations, or a statistical analysis plan. Without these details, readers cannot trace how the planned assessments became analyzed results, assess the role of incomplete follow-up, or understand how multiple outcomes were interpreted.
The safety entry adds a separate reporting lesson. It records zeros among the listed at-risk group, but that group does not match the enrollment figure and the registry does not explain the relationship. Keeping the safety denominator and efficacy enrollment distinct avoids treating unlike counts as interchangeable.
Overall, the study record shows why statistical interpretation depends on more than a named endpoint or a completed status. Estimates, uncertainty, analysis methods, and transparent denominators are needed to evaluate what the data show. Here, the available record permits a careful description of the design and measurement, but not a quantitative assessment of the primary result.
15. 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 important trial-specific limitation of the available record is that it does not report numerical results for the primary endpoint. The stated comparison of MSISQ-19 responses between baseline and 6 months is not accompanied by the scores, mean change, standard deviation, confidence interval, or test result. This prevents assessment of direction, magnitude, and precision.
The study is recorded as single-group, with allocation listed as NA and masking as none. There is no separate concurrent control group described in the record. Consequently, even a reported pre-to-post change would have limited ability to identify how much change was attributable to natalizumab rather than other influences over time.
The record does not report the number assessed at each time point, the analysis population, or methods for handling missing responses. Although enrollment is listed as 45, it cannot be assumed that this number contributed complete primary-outcome data. The registry also does not explain why the safety group lists 15 at risk for each category.
Further study details are not reported in the registry record, including eligibility criteria, participant characteristics, dosing and treatment-management details, adherence, outcome-analysis methods, and protocol deviations. The record lists secondary measures but does not report their results. It also does not report a statistical analysis plan, multiplicity approach, interim analyses, or a trial-specific sample-size justification.
These limitations concern both the study design information and the completeness of the registry results. They do not establish that the study was conducted improperly; they mean that the posted record does not contain enough information to evaluate the primary estimate or its robustness.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: The Effect of Natalizumab (Tysabri) on Sexual Dysfunction in Multiple Sclerosis — NCT01455220.
- Registry record last updated 2017-03-31; status last verified 2017-02.
- Results first posted 2017-03-31.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT01455220 is recorded as a completed, single-group study sponsored by the University of South Florida, with enrollment of 45. Its listed intervention is Tysabri (natalizumab), and its stated purpose concerns sexual dysfunction symptoms and quality of life in multiple sclerosis.
The primary outcome is MSISQ-19 sexual dysfunction score, described as change from baseline at 6 months. Higher scores indicate greater dysfunction. Secondary measures include MSQOL-54 and FAMS quality-of-life assessments. The registry lists four outcome measures and zero analyses.
No numerical primary or secondary outcome results are reported in the registry record. The safety entry records 0 affected in each listed adverse-event category among 15 at risk, while deaths are not reported in the registry record. Interpretation is limited by the single-group design and the absence of reported outcome analyses, missing-data methods, and analysis populations.