Implementing FBT for Adolescent AN for Providers in Private Practice: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Implementing FBT for Adolescent AN for Providers in Private Practice (NCT04428580), a randomized na study. The primary outcome is Feasibility of Recruitment.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group study with no masking. The comparison was between online FBT training and webinar FBT training for providers in private practice. The study title identifies the work as a feasibility study. Its stated focus was implementation and uptake of FBT, rather than a clinical comparison of patient treatments. The record lists the study phase as not applicable.

Registry enrollment is 151. For the primary endpoint, the posted arm summaries list 61 participants in Online Training and 62 in Webinar Training. Those summaries describe participants contributing to that endpoint and should not be treated as a complete account of enrollment or participant flow. The record does not report why the endpoint denominators differ from the enrollment figure, or provide a detailed account of screening, exclusions, withdrawals, or missing baseline data.

The study status is completed. Its recorded start date is 2020-11-20, and its primary completion date is 2024-08-02. The listed sponsor is Stanford University. The registry describes Online FBT Training and Webinar FBT Training as the interventions. It does not report the randomization sequence method, allocation concealment, stratification factors, or whether the allocation ratio was specified in advance. Masking is listed as none; the record does not explain which study roles were aware of assignment.

The primary endpoint was recruitment feasibility, expressed as a count of participants providing a full baseline data set, with a stated rate of 50%. The secondary endpoint concerned an association between fidelity and outcome at baseline and follow-up after supervision. Although the study is randomized, interpretation should follow the actual endpoint definitions and posted results: the primary endpoint addresses recruitment and baseline data, while the secondary endpoint is an exploratory association. The registry record does not report a detailed protocol or a prespecified statistical analysis plan.

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: 1143 participants started the online screening process and 426 completed screening. 393 who completed the screen had sufficient information included in screening in order to assess eligibility. 151 participants signed informed consent, 123 were randomized.

Overall Study

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.

6. Primary Endpoint

The registry lists the primary outcome as Feasibility of Recruitment, measured over 1 day (day of baseline assessment).

The primary endpoint is titled Feasibility of Recruitment. It measures the number of recruited subjects who provide a full baseline data set, with the endpoint description referring to a rate of 50%. Its timeframe is one day, on the day of baseline assessment. This endpoint addresses whether recruitment and baseline data collection can be carried out in the intended provider population. It is therefore an implementation-feasibility measure, not a clinical outcome for adolescents with AN.

The posted arm summaries list 61 participants for Online Training and 62 for Webinar Training. The posted comparison reports a risk difference of 0.0, with a confidence interval from 0.0 to 0.0. The listed arm-level values are 1.0 in each group. These summaries describe the endpoint as recorded, but the registry does not explain how the stated 50% rate relates to the values shown, nor does it give a fuller operational definition of what qualified as a full baseline data set. That relationship is not reported in the registry record.

In general, a feasibility endpoint is useful because it can show whether recruitment and measurement procedures appear workable before a larger implementation effort. A count alone does not establish that the training was completed as intended, that therapists adopted FBT in practice, or that patients benefited. Those questions require other measures and suitable analyses. The posted primary endpoint should therefore be read narrowly as a recruitment and baseline-data measure.

7. Results Posted in the Registry

• Webinar Training: 100.0% (62/62) versus 100.0% (61/61) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0), risk ratio 1.00 (1.00–1.00); unadjusted two-proportion z-test p = n/a.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Exploring Association Between Fidelity and Outcome

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Webinar Training: 14.5% (9/62) versus 11.5% (7/61) on control; risk difference 3.0 percentage points (95% CI -8.8 to 14.9), risk ratio 1.26 (0.50–3.18); unadjusted two-proportion z-test p = 0.616.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Webinar Training and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists one secondary outcome: Exploring Association Between Fidelity and Outcome. It is described as measured at baseline and follow-up after supervision. The posted comparison is an unadjusted risk-difference analysis, and no reported analyses are listed in the record. The secondary outcome is distinct from the primary recruitment-feasibility measure: it addresses fidelity and outcome rather than the provision of a full baseline data set.

Across the posted comparisons, the primary result is a risk difference of 0.0, while the secondary estimate is 0.030 with an interval from -0.088 to 0.149. They address different questions and should not be combined into a single claim about training success. The primary result does not establish a relationship between fidelity and outcome, and the secondary result does not clarify the operational meaning of the primary endpoint's stated 50% rate.

In general, secondary endpoints can help explore mechanisms, implementation processes, or patterns that are not captured by a primary endpoint. They are often less definitive when they are exploratory, when the analysis plan is not reported, or when there are multiple opportunities to examine outcomes. Unadjusted results do not account for multiplicity. When multiple endpoints or analyses are considered, the chance of seeing an apparently notable result by chance can increase; the registry does not report a multiplicity strategy for this study.

The secondary comparison should therefore be treated as exploratory rather than confirmatory. Its unadjusted p-value and interval offer a description of the posted estimate and its uncertainty, but they cannot establish causation or a clinically important effect. The relationship between fidelity and outcome, the direction of any causal pathway, and the effect of supervision are not reported in sufficient detail to support stronger conclusions. The registry record also does not report how fidelity or outcome was measured, so the measurement properties and interpretation of that endpoint cannot be assessed from the available description.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Exploring Association Between Fidelity and Outcome

9. Statistical Interpretation

10. Statistical Methods Explained

The primary comparison is presented as a risk difference. In general, a risk difference subtracts the event proportion in one group from the event proportion in another. Its sign depends on the comparison order. The posted secondary estimate is 0.030 for Webinar Training relative to Online Training. The registry lists the underlying counts as 9 of 62 and 7 of 61, respectively. The posted estimate and confidence interval are the values to use; no new calculations are needed to interpret them.

What does the risk difference convey?

In general, a risk difference expresses an absolute contrast in event proportions, rather than a relative contrast. A value near zero indicates that the estimated proportions are close, while the uncertainty interval is needed to judge how much larger or smaller the underlying contrast might plausibly be. For the primary endpoint, the posted risk difference is 0.0 and the interval runs from 0.0 to 0.0. The registry also lists both arm-level values as 1.0. This is the reported comparison, but the record does not explain how the stated 50% feasibility rate maps to those values.

For the secondary endpoint, the posted interval runs from -0.088 to 0.149 around an estimate of 0.030. In general, an interval that spans zero does not rule out no difference, and it also leaves room for differences in either direction. The result does not show that the training formats are equivalent. Establishing equivalence would require a prespecified equivalence margin and an analysis designed for that purpose; neither is reported in the registry record.

How should the p-value be read?

The secondary comparison has an unadjusted p-value of 0.616. In general, a p-value describes how unusual data at least as incompatible with a specified null model would be if that model and the analysis assumptions held. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The registry lists no reported analyses, so the unadjusted value should be read as the posted comparison summary, not as a complete account of the study's statistical analysis.

The primary comparison does not list an unadjusted p-value. The numbers 1.0 in its arm summaries are arm-level values, not a reported p-value. Keeping those quantities distinct prevents a mistaken interpretation of the primary result.

What does randomization contribute?

In general, random assignment can reduce systematic differences between groups at baseline, on average, when implemented appropriately. It does not guarantee that groups will be identical, remove measurement error, or resolve missing-data problems. The registry identifies the study as randomized, but the method used to generate and conceal assignments is not reported in the registry record. The record also lists masking as none. These details matter when judging how allocation and knowledge of assignment might affect recruitment, measurement, or implementation.

What do the planning illustrations mean?

The sample-size assumptions describe a planning illustration based on the observed secondary effect, not the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the arms, and a normal approximation. For planning for 100% of the observed effect, the illustration gives 1,919 participants per arm for 80% power and 2,568 participants per arm for 90% power. For planning for 75% of the observed effect, it gives 3,327 participants per arm for 80% power and 4,453 participants per arm for 90% power. For planning for 50% of the observed effect, it gives 7,292 participants per arm for 80% power and 9,761 participants per arm for 90% power.

These are prospective planning values under stated assumptions. They are not observed power, do not describe the actual study design, and do not establish that the observed effect is reliable. In general, planning from an observed effect can be sensitive to random variation in the initial estimate. Smaller effects require larger planned samples when other assumptions are held fixed. The registry does not report the trial's own sample-size justification or a target enrollment rationale.

Why can over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a model assumes. It can make standard errors too small and confidence intervals too narrow if ignored. The posted endpoints are counts and the record does not report an over-dispersion parameter or a model addressing it. Whether over-dispersion is relevant depends on the outcome structure and analysis model; the registry does not report enough detail to assess that issue for this study.

Other key analytical details, including handling of missing data, covariate adjustment, analysis populations, and any interim analyses, are not reported in the registry record. The comparisons should be read in that context, with the posted estimates treated as summaries rather than a substitute for a full analysis plan.

11. Confidence Intervals and Precision

The primary comparison has a risk difference of 0.0 and a confidence interval from 0.0 to 0.0. The secondary comparison has an estimated risk difference of 0.030 and a confidence interval from -0.088 to 0.149. In general, a confidence interval conveys uncertainty about an estimated quantity under the statistical model used. It is not a range that guarantees the true effect lies within it, and its interpretation depends on the method and assumptions behind the calculation. The registry record does not report the confidence-interval method.

The primary interval is reported with identical endpoints. That is a feature of the posted summary; the record does not describe the calculation in enough detail to explain why the interval has that form. The secondary interval includes zero and extends to values on both sides of zero. Thus, the estimate is not precise enough to establish the direction of an association. Its endpoints also indicate that the data are compatible with a range of absolute contrasts, not just the point estimate.

Precision is distinct from statistical significance and from practical importance. A small point estimate can have substantial uncertainty, and an interval that includes zero does not prove that effects are absent. Conversely, a narrow interval does not show that an endpoint is important in practice. The registry does not report a threshold for a practically meaningful difference in fidelity or outcome, so the clinical or implementation importance of the secondary estimate cannot be judged from the posted comparison alone.

The sample-size planning illustration uses the observed secondary effect and stated assumptions. Its values are planning illustrations, not evidence about the precision or power actually achieved in this completed study. The record does not report a prespecified target for detecting a clinically or operationally meaningful effect. The posted results should therefore be read with attention to the breadth and limits of their uncertainty, without treating a non-significant unadjusted result as proof of equivalence.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary recruitment-feasibility endpoint and one secondary endpoint exploring an association between fidelity and outcome. It does not report a statistical analysis plan that defines a hierarchy of tests, a multiplicity adjustment, or a strategy for distinguishing confirmatory from exploratory analyses. The secondary comparison is explicitly unadjusted in the posted summary. In general, when multiple outcomes or analyses are examined, unadjusted p-values do not control the overall chance of false-positive findings across that set. The single posted secondary endpoint does not establish whether other analyses were planned or conducted.

Missing-data methods are not reported in the registry record. The primary endpoint itself refers to participants who provide a full baseline data set, but the record does not describe how incomplete baseline data were handled, how completeness was defined, or whether missingness differed by assignment. It also does not give participant-flow details for the endpoint denominators. The enrollment figure and the endpoint-specific group denominators are both reported, but the reasons for the difference are not reported in the registry record.

Analysis populations are not reported. The record does not say whether results are based on everyone randomized, everyone who began training, participants who completed training, or another defined group. It also does not report whether assignment was analyzed as randomized. Such information is important because excluding participants after randomization can affect comparability between arms.

The registry record does not report interim analyses, a sample-size justification for the actual study, covariate adjustment, or a plan for sensitivity analyses. These omissions limit assessment of how the posted comparisons relate to the original study plan. They do not imply that any particular method was or was not used; the relevant methods are simply not reported in the registry record.

13. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event summaries list zero serious adverse events, zero other adverse events, and zero deaths for Online Training and for Webinar Training. The reported numbers at risk are 61 for Online Training and 62 for Webinar Training for both serious and other adverse events. The registry lists no serious-event terms.

These figures describe what was recorded in the registry summaries. In general, a zero count means no events of that category were reported in the stated group and record; it does not establish that an event could never occur or that every possible harm was measured. The record does not provide additional detail about how adverse events were solicited, defined, monitored, or attributed, or about the duration and completeness of safety follow-up. It is therefore not possible to use these figures alone to compare safety profiles or make broader safety conclusions about the training formats.

The listed safety counts should also be interpreted within the study's focus on training providers, not as a comprehensive safety assessment of FBT for adolescents. No medical advice or treatment-effect conclusion follows from these adverse-event summaries.

14. What the Result Does, and Does Not, Mean

The primary result describes recruitment feasibility as recorded in the registry: the arm-level values are both 1.0, and the posted risk difference is 0.0 with a confidence interval from 0.0 to 0.0. The registry endpoint description refers to a rate of 50%, but the record does not explain how that target relates to the values displayed. The result can be reported as the posted summary; it cannot by itself resolve that ambiguity or establish feasibility across other settings.

The secondary result is an exploratory comparison of fidelity and outcome. Its estimate is 0.030, its interval includes zero, and its unadjusted p-value is 0.616. These results do not establish that the training formats differ, nor do they establish equivalence. The registry does not report a prespecified equivalence margin or a detailed analysis plan. The secondary finding should not be treated as evidence that either format changes patient outcomes.

The study addresses implementation of FBT training for providers in private practice. It does not provide a clinical comparison of FBT against another patient treatment, and the posted primary outcome is not a patient health endpoint. The registry's background describes FBT as a treatment for adolescent AN, but that background does not turn this training-feasibility study into a test of patient treatment efficacy.

In general, a randomized design can support comparisons between assigned groups, but interpretation still depends on implementation, measurement, missing data, and analysis choices. Those details are not fully reported in the registry record. The posted figures are informative about the registered outcomes as summarized, while leaving uncertainty about recruitment procedures, training completion, therapist adoption, measurement of fidelity, and the relation of fidelity to clinical outcomes.

The results do not show whether therapists used FBT in routine practice after training, whether adolescents received the treatment, or whether patients experienced changes in health. They also do not establish which training format is more practical, acceptable, or sustainable. Those questions require outcomes and analyses that the registry record does not report.

15. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the difference between a feasibility endpoint and an effectiveness endpoint. Recruitment and baseline data completion can help assess whether a study process is workable. They do not measure clinical benefit. A precise-looking primary comparison therefore answers only the question represented by that endpoint, and the stated 50% target remains difficult to connect to the displayed arm-level values because the registry does not explain the relationship.

The secondary comparison illustrates why effect estimates should be read alongside uncertainty. The point estimate is 0.030, while the confidence interval extends from -0.088 to 0.149. In general, the range of plausible values can matter more than whether a single threshold is crossed. An unadjusted p-value is not a measure of effect size, and a result that does not rule out zero does not prove there is no association.

The posted planning illustrations also highlight how strongly sample-size requirements depend on the assumed effect size. They are based on the observed effect and stated assumptions, not on the study's own design, and should not be read as observed power or as evidence that the original study was adequately sized for a particular target. The registry does not report an actual sample-size justification.

More broadly, dissemination studies need clear descriptions of what counts as training completion, fidelity, adoption, and outcome. The available record identifies the training formats and endpoint labels, but important details of measurement and analysis are not reported. That distinction matters for researchers assessing reproducibility and for readers deciding what conclusions the registered outcomes can support.

16. 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.

Several limitations are specific to the information reported for this study. The primary endpoint description refers to a 50% rate, while the posted arm summaries show values of 1.0 and a risk difference of 0.0. The registry does not explain how those summaries relate to the stated feasibility rate or define the full-baseline-data criterion in further detail. This limits interpretation of what the primary result represents in operational terms.

The posted endpoint denominators are 61 and 62, while the registry enrollment figure is 151. The record does not provide participant flow or explain why these figures differ. It also does not report the analysis population, exclusions, withdrawals, training completion, or handling of missing data. These omissions make it difficult to assess the role of incomplete follow-up or post-randomization selection in the reported outcomes.

The secondary outcome description is broad: it concerns an association between fidelity and outcome at baseline and follow-up after supervision, but the record does not report how fidelity or outcome was measured, the relevant time points in detail, or a model for the association. The registry lists no reported analyses. The unadjusted comparison therefore does not give a complete account of how the secondary question was addressed.

Other design and analysis details, including the randomization method, allocation concealment, sample-size justification, multiplicity strategy, interim analyses, and covariate adjustment, are not reported in the registry record. Masking is listed as none. The intervention descriptions provide some format details but do not report whether participants completed the training as intended or how implementation was assessed. These gaps constrain reproducibility and the strength of conclusions, without showing that any unreported method was necessarily absent from the study itself.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Implementing FBT for Adolescent AN for Providers in Private Practice — NCT04428580.
• Registry record last updated 2025-08-29; status last verified 2025-08.
• Results first posted 2025-08-29.
• 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.

20. Record Summary

NCT04428580 is a completed randomized, parallel-group feasibility study of online and webinar training in FBT for adolescent AN providers in private practice. Masking is listed as none, and the sponsor is Stanford University. Registry enrollment is 151; the recorded study start date is 2020-11-20, and the primary completion date is 2024-08-02.

The primary endpoint, Feasibility of Recruitment, concerns recruited subjects providing a full baseline data set and is measured on the day of baseline assessment. Its description specifies a rate of 50%. The posted primary summaries list values of 1.0 for each arm and a risk difference of 0.0, with a confidence interval from 0.0 to 0.0. One secondary outcome explores the association between fidelity and outcome at baseline and follow-up after supervision. Its posted unadjusted comparison has a risk difference of 0.030, a confidence interval from -0.088 to 0.149, and an unadjusted p-value of 0.616. The registry does not report a detailed analysis plan, analysis populations, or the relationship between the primary endpoint values and its stated 50% rate.