Attachment Based Family Therapy for Suicidal Adolescents: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Attachment Based Family Therapy for Suicidal Adolescents (NCT01537419), a randomized na study. The primary outcome is Change in the Intensity of Suicidal Ideation Between Intake and End of Treatment.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group trial with single masking, conducted by Drexel University. The registry lists the phase as NA and enrollment as 129. The study start is recorded as 2012-03, primary completion as 2016-12, and status as completed. The registry describes a comparison of 16 weeks of Attachment-Based Family Therapy (ABFT) with 16 weeks of Family-Enhanced Non-directive Supportive Therapy (FE-NST).

Randomization means that participants are assigned to study groups by chance, which is intended to support a fair comparison of outcomes between groups. A parallel design means that each participant is assigned to one treatment group rather than moving between treatments. The record identifies the study as single masked, but does not report who was masked or how masking was implemented. Allocation concealment and details of the randomization procedure are not reported in the registry record.

The comparator was described as a control for non-specific effects of psychotherapy with suicidal youth. Its description says that it aims toward symptom relief or reduction without an expectation of change in basic personality structure. The ABFT description emphasizes a process-oriented, emotion-focused approach, while also noting behavior-focused and psychoeducational interventions. These are descriptions of the treatment models, not evidence that any particular treatment mechanism caused the observed results.

The registry lists three outcome measures, including the primary outcome and a secondary measure of family conflict. One secondary outcome is posted. The original sample-size justification, planned statistical analysis, analysis populations, and any interim analyses are not reported in the registry record. The posted results include arm summaries and an unadjusted comparison, but no separately reported analysis records.

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

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 Change in the Intensity of Suicidal Ideation Between Intake and End of Treatment, measured over 16 weeks (end of treatment).

The primary endpoint is change in the intensity of suicidal ideation between intake and the end of treatment at 16 weeks. It was measured with the Suicidal Ideation Questionnaire-JR, a 15-item self-report assessment. Its items reflect a continuum of suicidal ideation, from thoughts of death and wanting to be dead through suicidal plans, preparations, and attempts.

The scale ranges from 0 to 90. The registry describes a score of 0 as representing no suicidal ideation and a score of 31 or greater as indicating severe suicidal ideation. Those descriptions explain how to interpret the instrument’s score range; they are not participant results in this trial.

A change endpoint asks how a measure differs between two specified times. It can describe whether the group’s average score moved over the treatment period, while a between-group comparison asks whether the average change differed between the treatment arms. The registry reports mean changes and standard deviations for each arm, but it does not report the change-score sign convention or details of how the endpoint was calculated. Therefore, the negative values can be reported as posted, but their direction should not be translated into a precise score-change convention without that information. The registry does not report participant-level score distributions or the proportion of participants crossing a particular scale threshold.

7. Results Posted in the Registry

• Attachment-Based Family Therapy: mean -31.55 versus -27.42 on control; difference -4.13 (95% CI -5.09 to -3.17), standardized effect d = -1.65; z-test p = <0.001.

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.

Change in the Evidence of Family Conflict Between Parent and Youth After Intervention Between Intake and End of Treatment

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Attachment-Based Family Therapy: mean -1.25 versus -1.06 on control; difference -0.20 (95% CI -1.27 to 0.88), standardized effect d = -0.07; z-test p = 0.720.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Attachment-Based Family Therapy and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists three outcome measures and posts one secondary outcome: change in evidence of family conflict between parent and youth from intake to the end of treatment. This measure concerns family relationships, whereas the primary outcome concerns suicidal ideation. They address related but distinct aspects of the intervention’s proposed context, and results on one measure need not mirror results on another.

The overall pattern is that the posted primary comparison shows a difference in mean change, while the posted secondary comparison does not provide clear evidence of a between-group difference. This contrast is not inherently contradictory: outcomes can differ in sensitivity, variability, and relationship to treatment. The secondary result does not establish that family conflict was unchanged for every participant, nor does it negate the primary comparison.

Secondary findings generally carry less weight when they are unadjusted and when the analysis plan for multiple outcomes is unavailable. If many outcomes are tested, some results can appear noteworthy by chance. The registry does not report whether the trial specified a hierarchy, adjusted for multiplicity, or designated the posted secondary measure as confirmatory. The secondary comparison should therefore be read as supporting context rather than as an independent confirmation of the primary result.

The registry reports no analysis records and does not post the other outcome-measure details. The number of secondary outcomes available for interpretation is consequently limited. Without a complete outcome and analysis record, the pattern across all planned secondary measures cannot be assessed. The secondary evidence also cannot identify a mechanism for any primary difference; the registry does not report analyses linking changes in family conflict to changes in suicidal ideation.

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

• Change in the Evidence of Family Conflict Between Parent and Youth After Intervention Between Intake and End of Treatment

9. Statistical Interpretation

10. Statistical Methods Explained

For a continuous outcome, the mean is the arithmetic average of the measured values in a group. In this trial, the posted primary outcome is expressed as mean change in suicidal ideation score. The standard deviation describes how spread out individual values are around the group mean. It is not the same quantity as the standard error: the standard error describes the uncertainty in an estimated mean, and depends on both variability and the number of observations included.

What does the between-group estimate represent?

The posted mean difference compares the average change in the ABFT arm with the average change in the FE-NST arm. The estimate is -4.13 units. Its sign depends on the order of the comparison and the registry’s change-score convention; the record identifies ABFT as the comparison arm against FE-NST, but does not state how change itself was signed. The estimate summarizes the difference between group averages. It is not a statement that each participant experienced that amount of change.

The comparison also reports a pooled standard deviation of 2.51 and a standardized effect estimate of -1.646. A standardized effect expresses a mean difference in relation to outcome variability, making it less dependent on the original scale’s units. It is a summary of this particular comparison, not a universal measure of clinical importance. The registry does not provide a threshold for a clinically meaningful difference on this measure, so the standardized estimate alone cannot establish clinical importance.

How should the p-value be understood?

The unadjusted p-value is < 0.001. In general, a p-value describes how incompatible the observed data are with a specified null hypothesis, under the statistical model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure the probability that chance alone caused the result. The registry does not report the test procedure or the full statistical analysis plan. The posted p-value should therefore be read as an unadjusted result, not as proof of a particular causal explanation.

Unadjusted means that the result is not reported as corrected for testing multiple outcomes or comparisons. When several hypotheses are examined, the chance of at least one apparently unusual result can increase. Whether that issue was addressed in the trial’s original analysis is not reported in the registry record. The primary outcome is identified, but the registry does not report a multiplicity strategy.

What does the confidence interval add?

A confidence interval expresses uncertainty around an estimate. In general, a 95% confidence interval is produced by a procedure that, under repeated use of its assumptions, would cover the underlying value in 95% of such intervals. It does not mean there is a 95% probability that this particular interval contains the true value. The primary comparison’s interval runs from -5.086 to -3.174 units. Its interpretation depends on the endpoint definition, comparison direction, and statistical method.

The interval excludes zero, the value corresponding to no between-group difference in mean change. That is consistent with the posted unadjusted p-value. The registry does not report whether the interval is adjusted for other factors or how missing observations were handled. No additional adjustment should be inferred from the posted summaries.

Why do variability and distribution matter?

Standard deviations indicate that there is variation in the change scores within each arm. A mean and standard deviation are useful summaries, but they do not reveal the shape of the outcome distribution, outliers, or whether a small subset of participants had particularly large changes. General statistical practice requires considering whether the analysis method is suitable for the data and design. The registry record does not report diagnostic checks or distributional details.

For a continuous outcome, the normal approximation is one possible basis for inference and planning. General statistical methods can be sensitive to departures from their assumptions, especially when summaries conceal skewness or unusual observations. No claim about the distribution of the observed scores can be made from the reported means and standard deviations alone.

What is and is not reported about the analysis?

The registry includes an unadjusted comparison summary but reports no analysis records. The original analysis model, covariate adjustments, missing-data method, analysis population, and any interim analyses are not reported in the registry record. The posted arm summaries can describe the registered results, but they do not supply those missing methodological details. Because the discrepancy indicator is false, no conflict between the comparison summary and a sponsor analysis is flagged in the record; no separate sponsor analysis result is reported.

11. Confidence Intervals and Precision

The primary comparison is estimated as -4.13 units, with a 95% confidence interval from -5.086 to -3.174. This interval describes the uncertainty around the estimated difference under the method’s assumptions. Because it does not include zero, the posted interval is compatible with a nonzero difference in mean change. It does not establish that the same difference would occur in every setting or for every participant.

Precision is distinct from magnitude. The point estimate is the single best estimate reported by the comparison, while the interval represents a range of estimates that remain compatible with the data and method. A narrow interval generally indicates greater precision than a wide interval, but the registry does not provide an externally defined threshold for a clinically important difference on this scale. Statistical precision should not be equated with clinical importance.

The interval reflects the reported analysis, not uncertainty arising from every possible limitation. In general, confidence intervals do not account for unreported design choices, bias, outcome measurement error, or selective reporting unless the analysis explicitly addresses them. The registry does not report the full statistical plan, missing-data handling, or analysis populations, so the interval cannot resolve those uncertainties.

The mean changes are based on 52 participants in FE-NST and 54 in ABFT. The registry enrollment is 129, but it does not explain the relationship between enrollment and the participants included in each posted summary. It is not possible to determine from the record whether differences arise from missing measurements, exclusions, or another aspect of the analysis. The interval should therefore be interpreted as precision for the posted comparison, not as a complete account of uncertainty about the trial’s conduct or broader applicability.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size display is a planning illustration based on the observed effect, not the trial’s original design justification. The trial’s own sample-size assumptions are not reported in the registry record. For this continuous-outcome comparison, the figures are participants per arm, not total events. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to a stated fraction of the observed effect.

The 80% power column gives the planned number of participants per arm for a design that would have an 80% chance of detecting the specified effect under those assumptions, if that effect were the true one and the statistical model applied. The 90% power column uses the same idea with a higher target chance of detection. These are prospective planning concepts, not probabilities that the completed trial’s result is correct. The displayed values are planning illustrations, not observed power.

Rows planning for 100%, 75%, and 50% of the observed effect show how the planned sample size changes as the target effect becomes smaller. Smaller effects are harder to distinguish from random variation, so they require more participants per arm to reach the same target power under the stated assumptions. The displayed requirements for the primary outcome are 6 and 8 participants per arm for 100% of the observed effect; 11 and 14 for 75%; and 24 and 32 for 50%, for the 80% and 90% targets respectively.

These estimates should not be read as a reconstruction of the trial’s enrollment plan. They use the observed effect as an input, and the observed effect can differ from the effect that would be expected in a future study. The registry does not report the trial’s original target effect, chosen power, or justification for enrollment.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -4.130; pooled standard deviation σ = 2.510.
2. n = 2 × (1.96 + 0.842)² × 2.510² / -4.130² = 5.8, rounded up to 6 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -4.13                      # observed difference in means
sigma <- 2.50982760670621                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1537419)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 6 (80% power), 8 (90% power)
 75% of observed effect: n per arm = 11 (80% power), 14 (90% power)
 50% of observed effect: n per arm = 24 (80% power), 32 (90% power)
power.t.test: 6.9 
Simulated power at n = 6 per arm: 0.730 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary outcome and lists three outcome measures, but the original plan for handling multiple outcomes or comparisons is not reported in the registry record. Multiplicity matters because examining several outcomes can increase the chance of finding at least one apparently unusual result even when no true differences exist. Statistical approaches can control or describe this risk, but no such approach should be assumed when it is not documented.

The posted primary p-value is unadjusted. The secondary comparison is also presented without a reported multiplicity adjustment. The primary outcome’s designation gives it a clearer interpretive priority than secondary outcomes, but it does not reveal whether the trial’s full analysis plan included a testing hierarchy or other safeguards. The record does not report interim analyses or stopping rules.

Missing-data handling is also not reported. The primary arm summaries include 52 participants in FE-NST and 54 in ABFT, while enrollment is 129. The registry does not explain how the participants contributing to the summaries were selected, whether all randomized participants were included, or why the reported analysis counts differ from enrollment. The secondary outcome summaries use different arm counts, but the record does not explain the difference. No assumptions about attrition, exclusions, or the reason for missing observations should be inferred from these counts.

The analysis population is not reported in the registry record. It is therefore unclear whether the posted results follow an intention-to-treat approach, a per-protocol approach, or another definition. The registry also does not report imputation, sensitivity analyses, or methods for handling incomplete outcome data. These omissions limit the ability to judge whether the estimates could be affected by missingness or by choices about which participants were analyzed. They do not by themselves show that bias occurred; they identify information needed to evaluate the robustness of the posted results.

15. 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.

Most frequent non-serious adverse event terms

The serious adverse event summaries report zero affected participants in each arm: the at-risk counts are 63 for FE-NST and 66 for ABFT. Deaths are also reported as zero in each arm. The registry lists no serious adverse event terms among its top serious-event terms.

For other adverse events, the record reports 27 affected participants in each arm. The at-risk counts for these summaries are 63 in FE-NST and 66 in ABFT. These are descriptive registry counts; they do not establish that the types or severity of events were the same between arms, and the record does not provide event-level details in the posted summary.

Adverse event summaries should be interpreted in light of the population counted, observation period, and event definitions. The registry does not provide further detail about those aspects or a comparative safety analysis. A count of zero recorded serious events does not demonstrate that no event could occur, and the counts alone do not establish a safety advantage for either therapy.

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

The posted result describes a difference between the mean changes in suicidal ideation scores for two randomized therapy groups at the end of 16 weeks. It does not show that every participant changed by the group mean, or that every participant in one arm had a better outcome than every participant in the other. Individual outcomes can vary around the average, and the registry does not provide participant-level distributions.

The endpoint is a self-report measure of suicidal ideation. It is not, by itself, a count of suicide attempts, deaths, or other clinical events. The scale description includes thoughts, plans, preparations, and attempts, but the registry’s primary result is a change in the scale score. It should not be interpreted as a direct estimate of change in any one component unless that component is separately reported.

The result pertains to the comparison of ABFT with FE-NST, not to a comparison with no treatment or with all other forms of care. FE-NST was an active therapy control intended to account for non-specific effects of psychotherapy. The trial summary does not isolate the contribution of any individual treatment component or mechanism.

The registry reports a mean difference and confidence interval, but does not specify the change-score sign convention, full analysis plan, missing-data approach, or analysis population. Those limits matter when translating a statistical estimate into a practical interpretation. The record also does not report a threshold for a clinically meaningful difference in the Suicidal Ideation Questionnaire-JR score. Statistical evidence for a difference is not the same as evidence that the size of the difference is meaningful to participants.

The completed study record provides a time-specific comparison at the end of treatment. Longer-term outcomes, persistence of any change, and results beyond the 16-week timeframe are not reported in the registry record. The summaries therefore support interpretation of the posted comparison at its stated endpoint, not broader conclusions about later outcomes or other populations.

17. Why This Trial Matters Statistically

This trial illustrates why a clinical result needs more than a p-value. The mean difference gives the comparison’s estimated size on the outcome scale, while the confidence interval shows the uncertainty around that estimate. Reading both together is more informative than treating statistical significance as a complete account of the result.

It also highlights the importance of the comparator. FE-NST was designed to control for non-specific effects of psychotherapy, so the trial’s central question is the contrast between two active therapy conditions, not the effect of therapy compared with no treatment. That distinction defines what the randomized comparison can address.

The record also shows why endpoint interpretation depends on measurement details. The primary endpoint is a change score on a self-report instrument with a stated range and threshold descriptions, but the sign convention for change is not reported. A clear definition of how a change score is calculated is necessary to interpret its direction without qualification.

Finally, registry summaries are easier to evaluate when the analysis plan, analysis populations, missing-data methods, multiplicity strategy, and safety definitions are fully described. Those details are not reported. Their absence does not invalidate the posted estimates, but it limits assessment of how robustly the estimates answer the intended question. The trial is therefore a useful example of both what arm-level results can show and what remains uncertain without fuller statistical reporting.

18. 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 trial-specific details needed for a fuller interpretation are not reported in the registry record. Eligibility criteria, participant characteristics, recruitment sites, and details of the randomization procedure are not available in the registry entries. Although the study is identified as single masked, the person or group masked and the masking procedures are not specified.

The primary result is based on posted arm summaries and an unadjusted comparison. The registry does not provide the original statistical analysis plan, the exact comparison method, covariate adjustments, analysis population, missing-data method, or sensitivity analyses. It also does not explain the relationship between enrollment and the outcome-specific analysis counts. These gaps prevent a detailed assessment of possible effects from missing observations or analysis choices.

The registry lists three outcome measures but posts only one secondary outcome. The other outcome details and any analysis records are not reported. The approach to multiple testing is unknown, so the secondary evidence cannot be interpreted as a complete confirmatory set of results. The sign convention for the primary change score is also not stated.

The endpoint is measured at the end of treatment, and follow-up results beyond 16 weeks are not reported in the registry record. The registry summaries do not provide participant-level data, score distributions, or a clinically important difference threshold for the scale. These limitations constrain assessment of individual variation, longer-term outcomes, and the practical importance of the estimated difference. They do not establish that the posted results are biased; they define what cannot be evaluated from the available record.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Attachment Based Family Therapy for Suicidal Adolescents — NCT01537419.
• Registry record last updated 2018-02-06; status last verified 2018-01.
• Results first posted 2018-02-06.
• 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.

22. Record Summary

NCT01537419 is a completed randomized, single-masked, parallel-group study sponsored by Drexel University. The registry lists enrollment as 129, a study start of 2012-03, and primary completion in 2016-12. The study compared 16 weeks of Attachment-Based Family Therapy with Family-Enhanced Non-directive Supportive Therapy for suicidal adolescents.

The primary outcome was change in suicidal ideation intensity from intake to the end of treatment, measured with the Suicidal Ideation Questionnaire-JR. The posted mean changes were -27.42 for FE-NST and -31.55 for ABFT; the estimated mean difference was -4.13, with a 95% confidence interval from -5.086 to -3.174 and an unadjusted p-value of < 0.001.

The registry also posts one secondary family-conflict outcome and adverse event summaries. The original analysis plan, missing-data methods, analysis populations, and multiplicity strategy are not reported in the registry record.