Effectiveness of an Evidence-based Stepped Care System for Alcohol and Other Drug Use Problems Among Congolese Refugees in Zambia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effectiveness of an Evidence-based Stepped Care System for Alcohol and Other Drug Use Problems Among Congolese Refugees in Zambia (NCT05471921), a randomized na study. The primary outcome is Change in Alcohol Use Disorders Identification Test (AUDIT) Score.

2. Clinical Question

3. Trial Design

This is a randomized controlled trial with a parallel-group design. The registry lists single masking, but does not report which people involved in the trial were masked or how masking was implemented. Allocation was randomized. The planned enrollment was 400, and the registry status is completed. The recorded start date is 2023-04-26 and the primary completion date is 2025-02-24.

The setting is Mantapala, an integrated settlement in northern Zambia. The study concerns alcohol and other drug use problems among Congolese refugees and people from the host community. The intervention is a behavioral SBIRT stepped-care system, while the comparator is behavioral treatment as usual. The intervention description refers to brief intervention (CETA-BI) and full Common Elements Treatment Approach (CETA), but does not give the complete decision rules, treatment sequence, or delivery details. Those details are not reported in the registry record.

The primary outcome is change in Alcohol Use Disorders Identification Test score. The listed assessment timeframe is baseline, 6-months, and 12-months. Secondary outcomes include depression, anxiety, trauma symptoms, substance-involvement risk, any substance use in the past 3 months, and sleep. The registry identifies seven outcome measures in total. It does not report the number analyzed, participant flow, group-specific outcome data, or an inferential analysis for the primary or secondary outcomes.

Random allocation can support a comparison of assigned groups when outcomes and analysis are reported, but the design description alone does not establish what happened after assignment. Receipt of the intended intervention, adherence, crossover, and follow-up completion are not reported in the registry record. The registry also does not describe the detailed statistical plan, the handling of repeated measurements, or the population used in any analysis. These omissions prevent assessment of how closely the posted record reflects the trial as conducted.

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 Alcohol Use Disorders Identification Test (AUDIT) Score, measured over Baseline, 6-months, 12-months.

The primary endpoint is change in Alcohol Use Disorders Identification Test score. AUDIT is a 10-item measure of hazardous alcohol use, with a possible total score range of 0-40. Higher scores are associated with more hazardous use. A score on this scale provides a way to measure alcohol-related risk using a common outcome across participants and assessment occasions.

The registry lists the mean and a 95% confidence interval as the outcome summary, with assessments at baseline, 6-months, and 12-months. Repeated assessment allows the study question to concern change over time rather than a single measurement alone. A comparison between randomized groups would need to specify how those measurements are combined or contrasted, and how the baseline score is treated. Those analysis details are not reported in the registry record.

A confidence interval describes the uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, but precision is not the same as importance or proof of a causal explanation. In this case, the registry does not post an AUDIT mean, an estimated change, a between-group contrast, or a confidence interval. Therefore, the stated endpoint and scale can be described, but the size and precision of any trial result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes randomized allocation in a parallel-group trial. In general, randomization assigns participants to study groups using a chance process, helping make groups comparable on average at the point of assignment. A parallel design follows the assigned groups over the same general study period rather than assigning each participant to multiple interventions in sequence. These design features define the intended comparison, but do not by themselves reveal the results or prove that all participants followed their assignment.

What does the primary outcome summary represent?

The primary outcome is a continuous score, and the registry identifies the mean as its summary measure. A mean is an average of participants' scores in the analyzed group or population. The registry describes AUDIT as a 10-item hazardous alcohol use measure with a possible score range of 0-40, where higher scores are associated with more hazardous use. The listed timeframe includes baseline, 6-months, and 12-months. The registry does not say whether the primary comparison uses change from baseline, a follow-up score adjusted for baseline, or another approach. It also does not report a fitted statistical model.

How should a confidence interval be read?

The listed dispersion measure is a 95% confidence interval. In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the method used to calculate it. It is not a guarantee that the true value lies within a particular interval, nor does it show whether a difference matters clinically. Its interpretation depends on the quantity estimated and the analysis that produced it. No primary-outcome confidence interval is reported in the registry record, so the precision of the treatment comparison cannot be assessed.

What does masking add?

The registry labels the trial as single masked. Masking can reduce the influence of expectations on some aspects of trial conduct or outcome assessment, depending on who is masked and how. The identity of the masked people, the masking procedures, and whether masking was maintained are not reported in the registry record. Because the interventions are behavioral, the registry label alone is not enough to establish which participants, providers, or assessors could have been unaware of assignment.

Why do repeated observations matter?

Assessing participants at baseline and at follow-up creates measurements over time. Statistical methods for repeated measurements can account for the fact that scores from the same participant are related rather than independent. Different methods can target different quantities, such as a group difference at a particular follow-up or a pattern of change across assessments. The registry does not report which repeated-measures method was used, how within-participant correlation was handled, or whether the primary comparison was tied to one follow-up or the overall trajectory.

What can planning calculations tell readers?

Planning calculations are not observed trial outcomes. The registry describes the associated sample-size illustrations as planning examples based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. Such calculations illustrate how a hypothetical planning target depends on assumptions about the effect and design. They are not the trial's own design justification and are not observed power. The registry does not report its sample-size justification, and the illustrations do not replace the missing analysis of the trial outcomes.

General statistical power is the chance that a specified analysis will detect an effect of a specified size under stated assumptions. It is not a measure of the probability that a result is true. A planning estimate can be useful before a study begins, but calculating power after observing data does not establish that a trial was adequately designed or that a null result indicates no effect. Since the registry does not post the primary estimate or its uncertainty, no interpretation of the trial's observed precision can be made from the record.

What does the record leave unspecified?

The statistical plan, analysis population, missing-data method, baseline adjustment, covariate adjustment, handling of protocol deviations, and treatment of multiple outcomes are not reported in the registry record. These details matter because they determine the analysis population and the meaning of an estimate. For example, an intention-to-treat analysis generally compares participants according to their randomized assignment, while other analysis populations may use different inclusion criteria. The registry does not identify which population was used, so no such approach can be attributed to this trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary AUDIT outcome and six secondary outcomes, with the primary measure assessed at baseline, 6-months, and 12-months. Testing or estimating several outcomes and time points raises multiplicity questions: the more comparisons considered, the greater the chance that some findings may appear notable by chance if each is interpreted independently. In general, a prespecified hierarchy or an adjustment for multiple comparisons can help structure interpretation. The statistical plan and any multiplicity strategy are not reported in the registry record.

Missing outcome data can affect both the size and reliability of a comparison, especially if the likelihood of a missing measurement differs by group or relates to participants' scores. In general, analysis methods make assumptions about missingness, and those assumptions should be stated and examined where possible. The registry does not report follow-up completion, the amount or pattern of missing data, imputation methods, or sensitivity analyses. It is therefore not possible to assess how missing observations were handled or whether they could influence the reported results.

The record does not identify the analysis population or explain how participants who did not receive their assigned care, withdrew, or deviated from the protocol were treated in an analysis. It also does not report a primary statistical model or analysis plan. These are not minor details: they define which participants contribute to estimates and how the group comparison is calculated.

The record reports planned enrollment and completed status, but no analyzed sample sizes or primary and secondary outcome analyses. The planning illustrations described for the trial are not observed power and do not fill that gap. Since the registry does not report results, multiplicity and missing-data handling cannot be evaluated against an actual set of estimates.

11. 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 serious adverse event terms

Serious events with the highest arm-level rate: hospitalization (2.0%), illness (1.0%), intimate partner violence (0.5%), suicidal ideation (0.5%).

The registry lists serious adverse event figures for both groups. For SBIRT, the serious-event risk denominator is 199 and the number affected is 8; for treatment as usual, the corresponding denominator is 201 and the number affected is 1. Other adverse events affected 0 participants in each group. The record lists 0 deaths for SBIRT and 3 for treatment as usual. These are descriptive counts; the registry does not provide an analysis that compares groups or establishes a cause for any event.

The listed serious-event terms and percentages are Hospitalization, 2.0%; Illness, 1.0%; Intimate partner violence, 0.5%; and Suicidal ideation, 0.5%. The registry does not clarify in this listing whether terms can overlap, how percentages were calculated, or how these terms are distributed between groups. They should not be read as additional group-specific estimates.

Adverse-event counts require context. They can depend on how events were defined, collected, and attributed, and counts alone do not establish whether an intervention caused an event. The registry record does not report event timing, severity details beyond the serious-event category, relatedness assessments, or a statistical safety comparison. Thus the figures describe what the registry lists, but do not independently establish a difference in safety between assigned groups.

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

The registry record establishes that a randomized parallel-group trial was conducted to evaluate an SBIRT stepped-care system against treatment as usual among Congolese refugees and host-community participants in Mantapala, Zambia. It identifies change in AUDIT score as the primary outcome and lists follow-up at baseline, 6-months, and 12-months. It also gives a planned enrollment of 400 and marks the study completed.

Those design and measurement details do not show the result of the primary comparison. The registry does not report group scores, mean changes, a between-group estimate, a confidence interval, or a statistical test. It is therefore not possible to say from the registry record whether the groups differed, in which direction any difference went, or how precisely an effect was estimated. The same limitation applies to the listed secondary outcomes.

Nor does a missing result demonstrate that there was no effect. Absence of an estimate in the registry record is different from an analysis finding no difference. Likewise, the planned enrollment and planning illustrations cannot be treated as evidence of the outcome or as observed power. A completed trial status is not a substitute for posted outcome analyses.

The adverse-event figures provide descriptive information, but do not establish that assignment caused an event or that the groups differed in risk. Interpretation would require details about event definitions, reporting, attribution, and analysis that are not reported in the registry record.

In general, a trial result is most informative when its estimate, uncertainty, analysis population, and methods are available together. The registry information supports understanding the question and the measures, while leaving the central effectiveness estimate and important analysis details unreported. Conclusions about treatment benefit, lack of benefit, or comparative safety would therefore go beyond the posted results.

13. Why This Trial Matters Statistically

This trial addresses an important statistical challenge: evaluating a behavioral care system in a population that includes both displaced people and members of the host community. A randomized parallel-group design offers a framework for comparing assigned care strategies, while repeated AUDIT assessments allow the research question to concern change over time. The registry identifies a continuous primary outcome and a set of secondary measures spanning mental health, substance involvement, and sleep.

Statistically, however, a well-defined question and design are only part of an evidence base. Interpretation also depends on outcome estimates, uncertainty, participant flow, analysis populations, missing-data handling, and the prespecified approach to multiple outcomes and time points. Those results and methods are not reported in the registry record. This makes the trial a useful example of the distinction between a registered study design and a publicly interpretable analysis.

The record also illustrates why sample-size planning and observed results must be kept separate. Planning examples based on an assumed or observed effect do not convey the precision of the trial's actual estimate, and they are not observed power. The study's enrollment target cannot answer whether the primary comparison was precise without analyzed sample sizes and outcome data.

Clear reporting matters because clinicians, researchers, and policy decision-makers need to distinguish the question a trial set out to answer from the findings it actually reports. For this record, the question, setting, intervention categories, outcome scales, and adverse-event counts are available, but the primary and secondary outcome analyses are not reported. That distinction is central to responsible statistical interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpreting this trial is that the registry record does not report primary or secondary outcome results. No group-level AUDIT scores, estimated changes, between-group contrasts, confidence intervals, or significance tests are available. This prevents assessment of effect direction, size, or precision, regardless of the completed status or planned enrollment.

The registry does not report the analysis plan, including the model for repeated measurements, baseline adjustment, covariates, analysis population, or handling of protocol deviations. It does not report follow-up completion or missing-data methods. These omissions limit evaluation of the validity and robustness of any result, even if outcome estimates were available elsewhere.

The intervention description is incomplete: it refers to CETA-BI and full CETA but does not state the criteria for stepping between them or provide full delivery details. The comparator is described as the current standard of treatment, without further detail. The registry also labels masking as single but does not identify who was masked. These gaps constrain assessment of intervention contrast and potential sources of bias.

The record lists several secondary outcomes and repeated assessment occasions, but does not report how multiplicity was handled. The adverse-event listing gives counts and selected terms, but does not provide event-level context or a group-comparison analysis. Finally, the registry information alone does not establish whether the listed population, intervention delivery, and follow-up represent all trial conduct. Further details are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effectiveness of an Evidence-based Stepped Care System for Alcohol and Other Drug Use Problems Among Congolese Refugees in Zambia — NCT05471921.
• Registry record last updated 2026-08-19; status last verified 2026-07.
• Results first posted 2025-11-06.
• 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.

18. Record Summary

The registry record concerns NCT05471921, a randomized, single-masked, parallel-group behavioral trial of SBIRT stepped care versus treatment as usual in Mantapala, Zambia. The study population includes Congolese refugees and host-community participants. Planned enrollment was 400. The record lists a start date of 2023-04-26, a primary completion date of 2025-02-24, and status as completed.

The primary outcome is change in AUDIT score, a 10-item measure with a possible range of 0-40, assessed at baseline, 6-months, and 12-months. The registry lists six secondary outcomes, but does not report outcome analyses. It also lists serious adverse event counts and selected serious-event terms. The statistical plan, analysis population, missing-data approach, and primary treatment-effect estimate are not reported in the registry record.