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 Melatonin Intervention For Neurocognitive Deficits in the St. Jude Lifetime Cohort (NCT01700959), a randomized phase 3 study. The primary outcome is Neurocognitive Function as Measured by Performance on Standardized Tests of Attention, Memory, and Executive Function..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01700959 |
| Phase | Phase 3 |
| Condition | Cancer Malignancies |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 911 |
| Arms in the primary outcome | n/a |
| Lead sponsor | St. Jude Children's Research Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Adult survivors of childhood cancer who had impaired neurocognitive functioning and/or difficulty falling asleep were eligible for this trial. The primary outcome description specifies Cohorts 1 and 2. The registry record does not give further eligibility details or explain the labels used for the subgroups in the adverse-event record.
Intervention
Participants assigned to melatonin received 3 mgs of time-release melatonin, with instructions to take it 1-2 hours prior to bedtime. The primary question concerned whether treatment affected neurocognitive functioning over the study period.
Comparator
Participants assigned to placebo received a placebo described as identical to the time-release melatonin, also taken 1-2 hours prior to bedtime. The trial is registered as randomized, double-blind, and placebo controlled.
Primary question
The primary outcome compared change in performance on standardized tests of attention, memory, and executive function from baseline to 6 months after the start of therapy between the melatonin and placebo groups. Scores were expressed as standardized z-scores, with higher scores representing better performance. Although the registry record describes the question and outcome measure, it does not report the result of this comparison.
3. Trial Design
The registry describes a randomized, double-blind, placebo-controlled trial with a parallel-group design. It is listed as phase 3 and completed. The registry lists enrollment as 911; that figure is the registered enrollment and should not be taken as the number included in the primary analysis. The record gives the study start as 2013-02-06 and primary completion as 2017-04-19.
Participants were adult survivors of childhood cancer with impaired neurocognitive functioning and/or difficulty falling asleep. The intervention was time-release melatonin, and the comparator was an identical-appearing placebo. Both groups were instructed to take their assigned treatment 1-2 hours prior to bedtime. The registry describes a six-month assessment for the primary outcome and specifies that its analysis concerned Cohorts 1 and 2.
Random assignment and masking are important design features: randomization is intended to reduce systematic differences between groups, while blinding can limit the influence of treatment expectations on participants and assessments. Those features do not, by themselves, establish that groups were comparable in every respect or that missing outcome data were handled without bias. The registry record does not report the randomization procedure, allocation concealment method, or further operational details of masking.
St. Jude Children's Research Hospital is listed as sponsor. The registry record gives no detailed protocol rationale or sample-size justification. It also does not report the results of the primary comparison, so the design description should not be confused with evidence about the direction or precision of an outcome difference.
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.
Before assignment: The remaining 580 participants were categorized into three mutually exclusive groups: (1) neurocognitive impairment (NI) without delayed sleep onset latency (DSOL), (2) NI with DSOL, and (3) No NI with DSOL. Participants were then randomized to take melatonin or placebo.
Overall Study
| Stage | Melatonin: NI Without DSOL | Placebo: NI Without DSOL | Melatonin: NI With DSOL | Placebo: NI With DSOL | Melatonin: No NI With DSOL | Placebo: No NI With DSOL |
|---|---|---|---|---|---|---|
| STARTED | 89 | 88 | 105 | 105 | 96 | 97 |
| COMPLETED | 62 | 64 | 65 | 70 | 69 | 72 |
| NOT COMPLETED | 27 | 24 | 40 | 35 | 27 | 25 |
Reasons for not completing this period:
| Reason | Melatonin: NI Without DSOL | Placebo: NI Without DSOL | Melatonin: NI With DSOL | Placebo: NI With DSOL | Melatonin: No NI With DSOL | Placebo: No NI With DSOL |
|---|---|---|---|---|---|---|
| Adverse Event | 0 | 1 | 1 | 2 | 0 | 2 |
| Withdrawal by Subject | 15 | 9 | 12 | 11 | 8 | 12 |
| Ineligible | 2 | 1 | 2 | 0 | 0 | 1 |
| Noncompliant | 9 | 9 | 17 | 18 | 15 | 9 |
| Side effects | 1 | 4 | 8 | 4 | 4 | 1 |
Analysis population for the primary outcome, as defined in the registry: Analysis based on intent to treat. Include participants who were randomized and completed the 6-month assessment.
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.
Population: Analysis based on intent to treat. Include participants who were randomized and completed the 6-month assessment.
Only the first 6 of 7 groups are shown.
| Characteristic | Unit | Melatonin: NI Without DSOL | Placebo: NI Without DSOL | Melatonin: NI With DSOL | Placebo: NI With DSOL | Melatonin: No NI With DSOL | Placebo: No NI With DSOL |
|---|---|---|---|---|---|---|---|
| Participants analysed | 58 | 58 | 62 | 68 | 66 | 68 | |
| Age, Continuous | years | 32.8 (SD 9.1) | 36.4 (SD 8.1) | 32.8 (SD 7.8) | 32.4 (SD 9.3) | 35.8 (SD 9.0) | 36.5 (SD 8.2) |
| Sex: Female, Male: Female | Participants | 26 | 24 | 37 | 39 | 35 | 46 |
| Sex: Female, Male: Male | Participants | 32 | 34 | 25 | 29 | 31 | 22 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 2 | 4 | 1 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 55 | 52 | 59 | 61 | 59 | 61 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 3 | 6 | 1 | 3 | 6 | 7 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 | 0 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 6 | 5 | 8 | 9 | 1 | 7 |
| Race (NIH/OMB): White | Participants | 52 | 53 | 53 | 59 | 62 | 59 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 1 | 0 | 3 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Neurocognitive Function as Measured by Performance on Standardized Tests of Attention, Memory, and Executive Function., measured over Baseline and 6 months after start of therapy.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Z-score |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is neurocognitive function measured through performance on standardized tests of attention, memory, and executive function. The registry describes the measure as a standardized z-score, with a mean of 0 and standard deviation of 1; a higher z-score represents a better outcome. The analysis was described as comparing the change from baseline to 6 months after the start of therapy between the melatonin and placebo groups.
Assessing change over time relates each participant’s later performance to their baseline performance, while the comparison between randomized groups is intended to estimate whether average change differed by assigned treatment. A standardized score can put test performance on a common scale, which is useful when measures cover different cognitive domains. The registry record does not describe how results from the tests or domains were combined, whether each domain was analyzed separately, or which specific score was designated as the single primary contrast.
The record states that the primary analysis was based on intent to treat and included participants who were randomized and completed the 6-month assessment. It does not report the group results, an estimated between-group difference, a confidence interval, or a p-value for this endpoint. The endpoint’s definition therefore explains what the trial intended to assess, but the registry record does not establish the observed size or precision of any difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically relevant statistical question: whether change in standardized neurocognitive test performance from baseline to 6 months differed between participants assigned to melatonin and those assigned to placebo. The stated outcome covers attention, memory, and executive function, and higher z-scores represent better performance. These details define the direction of the measure, but they do not reveal how the groups’ results compared.
No primary-outcome results are reported in the registry record. In particular, it does not give a group mean change, a between-group estimate, a confidence interval, or a p-value. Without those quantities, the magnitude, direction, and precision of the primary comparison cannot be evaluated from this record. The absence of a posted result is not evidence that the groups had identical outcomes, and it is not evidence that either group had a better outcome.
A confidence interval, in general, describes a range of values compatible with the data and the analysis assumptions. Its width helps communicate precision; it is not a guarantee that the true effect lies within that range. A p-value, in general, measures how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the model assumptions. Neither measure replaces the effect estimate or answers the clinical question on its own. No such primary-outcome statistics are reported in the registry record.
The trial is registered as randomized and double-blind, features that can support a fair comparison when implemented as intended. However, the record does not describe the randomization procedure, adherence, balance in baseline characteristics, or the handling of missing outcome measurements. It states that the primary analysis included randomized participants who completed the 6-month assessment. That restriction makes the completeness and handling of follow-up relevant to interpreting any analysis, but further details are not reported in the registry record.
Other outcomes include sleep onset latency measured by actigraphy and self-report, as well as neurocognitive function and sleep onset latency. The brief summary also describes an objective of investigating whether improvement in sleep onset latency was associated with neurocognitive improvement. The registry record does not post results for these questions in the information. They should not be treated as substitutes for a reported primary comparison.
The record lists adverse-event groups and serious-event terms, but these are safety descriptions rather than evidence about the primary neurocognitive endpoint. In the absence of posted outcome estimates, the supported interpretation is limited to the trial’s registered question, design, and stated analysis population. A conclusion about the size or statistical precision of the primary result cannot be drawn from this registry record.
9. Statistical Methods Explained
The statistical description gives the intended endpoint and a broad outline of the comparison, but many details needed to reproduce or fully assess the analysis are not reported in the registry record. The concepts below explain how the stated methods generally work; they do not assert that any unreported procedure was used in this trial.
What does a change comparison estimate?
For a continuous measure such as a z-score, a group mean describes the average score in that group. A change score represents how a participant’s measurement differs between baseline and follow-up. Comparing average changes between randomized groups asks whether the groups’ mean trajectories differed over the stated period. The registry describes this type of comparison but does not report the group means, mean changes, or estimated between-group contrast.
Using baseline and follow-up measurements can account for participants’ starting scores in a direct way, but the analysis details matter. Some analyses compare change scores; others use a model that adjusts follow-up values for baseline or accounts for repeated measurements. These approaches can have different assumptions and precision. The registry record does not specify a model, covariates, or the exact calculation used beyond describing a comparison of change from baseline to 6 months.
What does a standardized score convey?
A z-score expresses a measurement relative to a standardized scale. In this record, the stated scale has a mean of 0 and standard deviation of 1, and higher scores indicate better performance. Standardization can help make measures with differing scales easier to compare. It does not, by itself, say whether a change is important to participants or how a score difference maps to everyday functioning. The registry record does not report a threshold for interpreting a meaningful difference.
How should uncertainty be read?
In general, an effect estimate gives the direction and size of a contrast, while a confidence interval conveys its statistical uncertainty under the analysis assumptions. A narrow interval indicates more precision than a wide interval, though precision is not the same as clinical importance. A p-value addresses compatibility with a particular null hypothesis under a statistical model; it does not measure the probability that a treatment effect is real. The registry record does not report an effect estimate, interval, or p-value for the primary endpoint, so these aspects of its result cannot be assessed.
What do the planning illustrations mean?
The planning illustrations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They are based on fractions of an observed effect, as described in the registry record. In general, such calculations estimate the participant count that would be needed under specified assumptions to detect a chosen effect with a chosen power. They are planning illustrations, not observed power and not the trial’s original design justification. The registry record does not report the trial’s own sample-size justification, and no planning figure should be read as an outcome or as proof that the trial was adequately powered for its primary question.
Sample-size calculations depend on assumptions about the target effect, outcome variability, allocation, analysis, and follow-up. If those assumptions differ from what occurs in a trial, the resulting planning number may not describe the study’s actual ability to estimate an effect. A calculation based on an observed effect is also retrospective: it does not establish what effect the study was designed to detect. The record does not report the assumptions used in the original design calculation.
What does randomization contribute?
In general, random assignment aims to balance known and unknown prognostic factors across treatment groups on average. It supports interpretation of a between-group contrast as an effect of assignment when the trial is conducted and analyzed appropriately. Double blinding can reduce some biases related to expectations or knowledge of assignment. The registry lists randomization and double masking, but does not report enough procedural detail to assess how allocation was generated, concealed, or maintained.
Analysis population and missingness also matter. The registry describes an intent-to-treat analysis including randomized participants who completed the 6-month assessment. The phrase intent to treat often refers to analyzing participants in their assigned groups, but the stated completion requirement means the record does not clarify how randomized participants without a completed assessment were incorporated. General methods for incomplete data include assumptions-based models, imputation, and sensitivity analyses; the record does not report which, if any, were used.
Finally, the endpoint includes several cognitive domains, and the registry also describes sleep-related outcomes. When multiple outcomes or contrasts are examined, the chance of at least one apparently unusual result can increase unless the analysis plan addresses multiplicity. The record does not report a multiplicity strategy or a detailed statistical analysis plan. This uncertainty limits what can be inferred about how the different outcomes were prioritized and interpreted.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome refers to standardized tests of attention, memory, and executive function. The record does not explain whether these domains were combined into one outcome, analyzed separately, or treated through a prespecified hierarchy. It also describes secondary outcomes involving sleep onset latency measured by actigraphy and self-report, neurocognitive function, and the association between sleep-onset improvement and neurocognitive improvement. Examining multiple domains, measures, or comparisons can raise multiplicity concerns: in general, the more hypotheses tested, the greater the chance of obtaining at least one apparently notable result by chance. The registry record does not report a multiplicity adjustment, hierarchy, or complete analysis plan.
The stated primary analysis population consists of randomized participants who completed the 6-month assessment. This is the population description in the record; it does not explain the treatment of randomized participants with missing assessments. The record does not report the number or reasons for missing primary-outcome measurements, whether participants were analyzed according to assignment, or how missing data were handled. It also does not describe sensitivity analyses that might test how conclusions depend on assumptions about missingness.
These gaps matter because incomplete follow-up can affect both the number of observations and the comparability created by randomization. In general, methods for missing data rely on assumptions, and different assumptions can lead to different estimates. The registry record does not provide enough information to assess those assumptions.
The registry record also does not report interim analyses, stopping rules, or a detailed statistical analysis plan. These items should not be presumed either present or absent in trial conduct; they are simply not reported in the registry record. The record lists no posted analysis comparisons for the primary outcome, so multiplicity and missing-data methods cannot be checked against reported primary results.
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 |
|---|---|---|---|
| Melatonin: NI Without DSOL | 2 | 58 | 3.4% |
| Placebo: NI Without DSOL | 2 | 58 | 3.4% |
| Melatonin: NI With DSOL | 9 | 62 | 14.5% |
| Placebo: NI With DSOL | 6 | 68 | 8.8% |
| Melatonin: No NI With DSOL | 2 | 66 | 3.0% |
| Placebo: No NI With DSOL | 10 | 68 | 14.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Melatonin: NI Without DSOL | 0 of 58 |
| Placebo: NI Without DSOL | 0 of 58 |
| Melatonin: NI With DSOL | 0 of 62 |
| Placebo: NI With DSOL | 0 of 68 |
| Melatonin: No NI With DSOL | 0 of 66 |
| Placebo: No NI With DSOL | 0 of 68 |
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 |
|---|---|
| Melatonin: NI Without DSOL | 37 of 58 |
| Placebo: NI Without DSOL | 37 of 58 |
| Melatonin: NI With DSOL | 52 of 62 |
| Placebo: NI With DSOL | 60 of 68 |
| Melatonin: No NI With DSOL | 57 of 66 |
| Placebo: No NI With DSOL | 58 of 68 |
Most frequent serious adverse event terms
| Event term | Organ system | Melatonin: NI Without DSOL | Placebo: NI Without DSOL | Melatonin: NI With DSOL | Placebo: NI With DSOL | Melatonin: No NI With DSOL | Placebo: No NI With DSOL |
|---|---|---|---|---|---|---|---|
| Headache | Nervous system disorders | 0 of 58 | 1 of 58 | 2 of 62 | 2 of 68 | 0 of 66 | 2 of 68 |
| Insomnia | Psychiatric disorders | 0 of 58 | 0 of 58 | 1 of 62 | 2 of 68 | 1 of 66 | 3 of 68 |
| Nausea | Gastrointestinal disorders | 0 of 58 | 0 of 58 | 1 of 62 | 2 of 68 | 0 of 66 | 0 of 68 |
| Vomiting | Gastrointestinal disorders | 0 of 58 | 0 of 58 | 1 of 62 | 1 of 68 | 0 of 66 | 1 of 68 |
| Fatigue | General disorders | 0 of 58 | 1 of 58 | 2 of 62 | 0 of 68 | 0 of 66 | 0 of 68 |
| Unintended pregnancy | Pregnancy, puerperium and perinatal conditions | 0 of 58 | 0 of 58 | 0 of 62 | 1 of 68 | 0 of 66 | 1 of 68 |
| Chest pain | Cardiac disorders | 0 of 58 | 0 of 58 | 0 of 62 | 1 of 68 | 0 of 66 | 0 of 68 |
| Blurred vision | Eye disorders | 0 of 58 | 0 of 58 | 0 of 62 | 1 of 68 | 0 of 66 | 0 of 68 |
| Esophageal perforation | Gastrointestinal disorders | 1 of 58 | 0 of 58 | 0 of 62 | 0 of 68 | 0 of 66 | 0 of 68 |
| Diarrhea | Gastrointestinal disorders | 0 of 58 | 0 of 58 | 0 of 62 | 1 of 68 | 0 of 66 | 0 of 68 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Melatonin: NI Without DSOL | Placebo: NI Without DSOL | Melatonin: NI With DSOL | Placebo: NI With DSOL | Melatonin: No NI With DSOL | Placebo: No NI With DSOL |
|---|---|---|---|---|---|---|---|
| Headache | Nervous system disorders | 15 of 58 | 18 of 58 | 23 of 62 | 27 of 68 | 26 of 66 | 27 of 68 |
| Somnolence | Nervous system disorders | 19 of 58 | 15 of 58 | 23 of 62 | 21 of 68 | 25 of 66 | 29 of 68 |
| Fatigue | General disorders | 10 of 58 | 13 of 58 | 21 of 62 | 25 of 68 | 21 of 66 | 29 of 68 |
| Incomnia | Psychiatric disorders | 11 of 58 | 11 of 58 | 14 of 62 | 20 of 68 | 26 of 66 | 24 of 68 |
| Diarrhea | Gastrointestinal disorders | 7 of 58 | 7 of 58 | 10 of 62 | 11 of 68 | 14 of 66 | 17 of 68 |
| Dizziness | Nervous system disorders | 6 of 58 | 6 of 58 | 16 of 62 | 10 of 68 | 12 of 66 | 12 of 68 |
| Anxiety | Psychiatric disorders | 5 of 58 | 6 of 58 | 10 of 62 | 11 of 68 | 10 of 66 | 20 of 68 |
| Dry skin | Skin and subcutaneous tissue disorders | 8 of 58 | 8 of 58 | 12 of 62 | 10 of 68 | 8 of 66 | 11 of 68 |
| Dry mouth | General disorders | 6 of 58 | 6 of 58 | 9 of 62 | 10 of 68 | 9 of 66 | 11 of 68 |
| Pruritus | Skin and subcutaneous tissue disorders | 9 of 58 | 7 of 58 | 6 of 62 | 10 of 68 | 10 of 66 | 9 of 68 |
Serious events with the highest arm-level rate: insomnia (4.4%), fatigue (3.2%), headache (3.2%), nausea (2.9%), esophageal perforation (1.7%).
The safety record separates serious adverse events from other adverse events and lists participants at risk and affected within six labeled groups. The group labels distinguish melatonin and placebo alongside the categories NI and DSOL; the record does not define NI in the information. For the groups labeled NI Without DSOL, the serious-event counts are 2 of 58 in each arm, and the other-event counts are 37 of 58 in each arm. For NI With DSOL, serious events are listed as 9 of 62 for melatonin and 6 of 68 for placebo; other events are 52 of 62 and 60 of 68, respectively. For No NI With DSOL, serious events are 2 of 66 for melatonin and 10 of 68 for placebo; other events are 57 of 66 and 58 of 68, respectively. Deaths are listed as 0 in all six groups.
These figures are stratified counts, not a single overall comparison. The record does not explain the subgroup definitions further or provide an adjusted analysis of safety differences. The listed serious-event terms and percentages include Insomnia, 4.4%; Fatigue, 3.2%; Headache, 3.2%; Nausea, 2.9%; Esophageal perforation, 1.7%; and Thyroid cancer, 1.7%. The record does not give further context for interpreting these percentages here, such as event timing or a comparison by assigned group. Counts and listed terms describe what the registry reports; they do not by themselves establish whether an event was caused by treatment.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, double-blind, placebo-controlled trial was conducted to assess melatonin in adult survivors of childhood cancer. It identifies a primary neurocognitive question, describes the standardized outcome and follow-up, and lists secondary sleep-related questions. These details clarify what the investigators set out to evaluate.
The record does not report the primary outcome results. There is no posted group contrast, estimate of change, confidence interval, or p-value for neurocognitive performance. Accordingly, the registry information does not show the direction or magnitude of the primary comparison, nor how precisely it was estimated. The lack of a posted result should not be interpreted as evidence of no difference or as evidence of a benefit.
Likewise, the design label and registered enrollment do not establish that the trial had a particular level of statistical power or that all participants contributed to the primary analysis. The registry describes an analysis population requiring completion of the 6-month assessment, but does not report the number included or the handling of missing measurements. The planning illustrations are hypothetical calculations based on stated assumptions, not observed power and not a substitute for a reported estimate with its uncertainty.
The adverse-event record provides counts in several labeled groups and lists serious-event terms. Those summaries can describe the registry’s safety reporting, but subgroup counts alone do not establish causation or a reliable treatment difference. The record does not include a detailed statistical safety comparison in the information.
In short, the registry supports a description of the trial’s design, intended endpoint, and some safety reporting. It does not support a conclusion about whether melatonin changed neurocognitive outcomes, how large any change was, or how precise the estimate might be. Those questions require the outcome results and sufficient analysis details, which are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial raises statistical issues common in studies that evaluate complex outcomes over time. Neurocognitive functioning is represented by standardized tests of attention, memory, and executive function, rather than a single directly observed event. The choice of scale, the handling of multiple domains, and the definition of the primary contrast all affect how a result should be interpreted. The registry record identifies the intended domains and six-month comparison but does not report how domain-level measurements were combined or analyzed.
The randomized, double-blind, placebo-controlled design is relevant because it aims to support a fair comparison between assigned groups. But a design description is only one part of the evidence. The result also needs an effect estimate and a measure of uncertainty, plus enough detail about follow-up and analysis populations to judge the comparison. Those primary-outcome results and several analysis details are not reported in the registry record.
The record also illustrates the difference between an original design calculation and a retrospective planning illustration. Calculations based on an observed effect and fractions of that effect can help show how sample size depends on a chosen target under specified assumptions. They do not establish the study’s original rationale, nor do they represent observed power. The record does not report the original sample-size justification.
Finally, the cognitive and sleep-related questions create a multiplicity issue that requires transparent prioritization and analysis methods. Without a reported hierarchy or adjustment strategy, it is difficult to understand how evidence across several measures was intended to support claims. These considerations make complete reporting especially important: the research question and design can be described, but the primary statistical conclusion cannot be evaluated from the registry record alone.
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.
A major limitation is that the registry record does not report the primary neurocognitive results. It provides no group-level changes, between-group estimate, confidence interval, or p-value. The size, direction, and precision of the primary comparison therefore cannot be assessed.
The outcome description refers to attention, memory, and executive function, but does not clarify whether the domains were combined or analyzed separately, how scores were constructed across tests, or how multiple comparisons were handled. The record also does not provide a detailed statistical analysis plan. It is therefore not possible to determine from the registry description how the primary contrast was operationalized beyond the stated comparison of change from baseline to 6 months.
The record defines its primary analysis population as randomized participants who completed the 6-month assessment, but does not report how many participants met that definition, how many lacked follow-up, or how missing outcomes were addressed. It does not describe sensitivity analyses, adherence, or baseline group characteristics in the information. Those omissions constrain assessment of the analysis population and the consequences of incomplete follow-up.
Although the trial is described as randomized and double-blind, the registry record does not report the randomization procedure, allocation concealment, or details of how masking was maintained. It also does not report the original sample-size justification, interim analyses, or stopping rules. These details should not be inferred from the phase or design labels.
The adverse-event information is presented in labeled subgroups, and the registry record does not define every label or provide a fuller comparative analysis. The posted safety terms and counts should therefore be read as registry descriptions rather than causal estimates. Together, these limitations mean the record is useful for understanding the intended study question and design, but insufficient for evaluating its primary efficacy result or a complete comparative safety profile.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Melatonin Intervention For Neurocognitive Deficits in the St. Jude Lifetime Cohort — NCT01700959.
- Registry record last updated 2018-06-28; status last verified 2018-03.
- Results first posted 2018-06-28.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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.
18. Record Summary
NCT01700959 is a completed, phase 3, randomized, double-blind, parallel-group, placebo-controlled trial sponsored by St. Jude Children's Research Hospital. The registry lists enrollment as 911, a study start date of 2013-02-06, and primary completion on 2017-04-19. It studied time-release melatonin in adult survivors of childhood cancer with impaired neurocognitive functioning and/or difficulty falling asleep.
The primary outcome was neurocognitive performance on standardized tests of attention, memory, and executive function, comparing change from baseline to 6 months between melatonin and placebo. The record describes the score as a z-score, with higher values representing better performance, and states that the primary analysis included randomized participants who completed the 6-month assessment. It also lists sleep-related secondary outcomes and adverse-event summaries. Primary-outcome results and important details of the statistical analysis are not reported in the registry record.