Reinforcement of Abstinence and Continuing Care in Substance Abuse Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Reinforcement of Abstinence and Continuing Care in Substance Abuse Treatment (NCT00288886), a randomized phase 2 study. The primary outcome is Abstinence Rate (During the Preceding 90 Days) at 12 Months Follow-up Point as Assessed by the Form-90.

2. Clinical Question

This is the clinical question stated in the registry record, not a conclusion about the comparative outcome. Although the record describes the study as randomized and identifies the primary endpoint, it does not report the abstinence counts or rates by group, an effect estimate, a confidence interval, or a test of the primary comparison. Consequently, the record does not establish whether the groups differed on this endpoint or how precisely any difference was estimated.

The record also lists secondary questions about abstinence at earlier follow-up points, time until first use, aftercare and self-help support-group attendance, days of substance use, and hospitalization. The brief summary discusses further hypotheses, but no corresponding analysis results are listed. The registry record does not report whether those hypotheses were supported.

3. Trial Design

The record describes a Phase 2, randomized, single-masked, parallel-group study sponsored by the US Department of Veterans Affairs. Enrollment is listed as 183. The study began in 2007-03, reached primary completion in 2009-06, and is marked completed. Participants were recruited while seeking residential treatment at the Salem and Jackson VAMCs.

The two arms were CPR and standard treatment. The CPR arm received contracting, prompting, and reinforcement for continuing-care attendance and abstinence. The control arm received routine care without those CPR components. The record identifies the allocation as randomized and the masking as single, but does not specify who was masked. Further details of the randomization procedure, allocation concealment, treatment delivery, adherence to the intervention, or the duration of treatment are not reported in the registry record.

Outcome assessment was planned at 3-, 6-, and 12-month follow-up, with comparison to baseline noted in the brief summary. The primary endpoint was abstinence during the preceding 90 days at 12 months. Several additional outcomes are listed, including earlier abstinence assessments and measures of substance use, attendance, and hospitalization. The registry record does not give a detailed schedule for every secondary measure or specify the statistical approach used to compare groups.

The trial’s recruitment setting and veteran population are important context when interpreting how broadly the findings might apply. The brief summary itself notes that generalizability to other sites had not been established for an earlier version of CPR. It describes the current study as a multisite randomized trial, but the registry record does not report results by site or provide evidence about effects in populations outside the recruited treatment setting. No conclusions about transportability can be drawn from the listed information alone.

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 Abstinence Rate (During the Preceding 90 Days) at 12 Months Follow-up Point as Assessed by the Form-90, measured over Assessed at 12 months.

The primary endpoint is the number of participants abstinent during the 90 days before the 12-month follow-up assessment, measured using the Form-90 interview. The registry describes the Form-90 as a structured, calendar-based follow-back interview covering substance use and related behaviors over the preceding 90 days. It collects information including days abstinent, days using alcohol, days using drugs, standard drinks, and self-help meeting attendance.

The endpoint is binary at the participant level: a participant is classified as abstinent or not abstinent at that follow-up point. The record says that a participant who denied use in the interview but had a positive substance-use screen was considered not abstinent. It also describes the use of briefer telephone versions when participants did not return for in-person interviews, and collateral interviews as a reliability check on self-report.

In general, a binary abstinence endpoint offers a direct way to compare the proportion of participants meeting a specified outcome definition in each group. Its interpretation depends on the time window, assessment procedure, and classification rules. Here, the 90-day window and the positive-screen rule are specified, but the registry record does not report the numbers classified as abstinent in either group. It therefore does not provide a comparative estimate or show the precision of that estimate.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the study as randomized, single-masked, and parallel-group. In general, random allocation is intended to make treatment groups comparable at the start of a trial with respect to both measured and unmeasured characteristics, apart from chance variation. That protection depends on the conduct and preservation of the allocation process. The registry record does not describe the sequence-generation method, allocation concealment, or procedures used to maintain masking, so those features cannot be assessed from the listed information.

What does the endpoint represent?

The primary measure is a participant count: participants meeting the stated abstinence definition during the 90 days before the 12-month assessment. In general, a binary endpoint reduces each participant’s assessment to one of two categories. A group comparison can then be expressed using counts, proportions, or a contrast between proportions. The registry provides the endpoint definition but no primary outcome counts, group proportions, or contrast. No recalculated comparison can be made from the record.

The Form-90 is described as a structured interview using calendar-based recall. The record states that a positive substance-use screen overrides a self-report of no use for the abstinence classification. It also notes telephone versions for participants not returning for in-person interviews and collateral interviews as a reliability check. In general, consistent outcome assessment and clear classification rules help make endpoint interpretation more transparent. They do not, on their own, establish that all assessments were completed or that missing information was handled in a particular way. Those details are not reported in the registry record.

How should a group comparison be read?

In general, a comparative analysis estimates how the outcome differs between assigned groups. The direction and size of the estimate matter, and uncertainty matters as well. A confidence interval conveys a range of estimates compatible with the observed data and the model’s assumptions. A narrow interval would indicate greater precision than a wide interval, but either interval must be interpreted alongside the endpoint and analysis plan. No interval or effect estimate for this trial’s primary comparison is reported.

For binary outcomes, methods may compare event proportions directly or use a model that relates participant characteristics and group assignment to the probability of the outcome. In general, adjustment for baseline factors can affect the estimate and its precision, especially if adjustment was prespecified and appropriately conducted. The registry record does not state whether the primary comparison was adjusted, identify covariates, or describe a statistical model. It would be inappropriate to infer an analysis method from the outcome definition alone.

What does the sample-size information mean?

The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; it says the effect to detect is a stated fraction of the observed effect. No numerical planning values or effect estimate are listed in the registry record. These illustrations are planning calculations, not observed power and not evidence that the trial detected an effect. The record does not report the trial’s own sample-size justification, assumptions used in its original design, or whether the completed enrollment met a prespecified target.

In general, a sample-size calculation estimates how many participants would be needed under chosen assumptions about the effect, variability, significance level, and desired power. Such a calculation is only as informative as those assumptions. It does not establish the probability that a result is true, and an observed study result should be interpreted through its estimate and uncertainty rather than a retrospective power calculation. Here, the missing endpoint results mean that the planning illustration cannot be connected to a reported primary comparison.

What can be concluded from the listed analysis fields?

The registry record lists no analyses. It does not give the primary analysis population, the handling of withdrawals or missing outcomes, the model specification, or a multiplicity procedure. In general, an intention-to-treat analysis compares participants according to randomized assignment, while other analysis populations may apply different inclusion rules. Because the record does not identify the population used, no such analysis label should be attributed to this trial.

Multiplicity arises when many outcomes, time points, or subgroup comparisons are examined. In general, conducting multiple tests can increase the chance of at least one apparently notable result, so a statistical plan may specify which outcome is primary and how additional tests are interpreted or adjusted. This record identifies a primary endpoint and lists several other outcomes, but does not report a multiplicity strategy or analysis results. It is not possible to assess how the investigators managed multiple comparisons.

These methodological concepts describe how clinical-trial results are generally interpreted. They do not establish which methods were used in this study. The registry record does not provide enough analysis detail to reconstruct or independently verify a primary endpoint comparison.

10. Multiplicity, Missing Data and Analysis Populations

The record names a primary endpoint and several secondary outcomes, including abstinence at earlier follow-up points, time until first use, aftercare attendance, self-help support-group attendance, days of substance abuse, and hospitalization. The brief summary also describes secondary hypotheses involving psychiatric comorbidity, duration in aftercare and support groups, substance use, hospitalization, and costs. The registry record does not report a multiplicity adjustment or a plan for prioritizing or interpreting these additional comparisons.

In general, when investigators examine multiple outcomes, time points, or subgroups, the interpretation of isolated statistical findings can be affected by the number of comparisons. A prespecified hierarchy or adjustment may help define which comparisons are confirmatory and how others should be viewed. The record does not describe such procedures, so no claim about their use is warranted.

The registry record also does not report how missing endpoint assessments were handled, how many participants completed each follow-up, or whether any imputation or sensitivity analysis was performed. The description of telephone interviews and collateral interviews concerns assessment procedures; it does not establish how missing data were addressed in the analysis. The analysis population is not reported in the registry record, and no analyses are listed.

These omissions limit the ability to judge possible bias, precision, and the robustness of any comparison. Without outcome counts and an analysis description, the primary and secondary results cannot be independently evaluated from this registry record.

11. Safety Results

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

Other (non-serious) adverse events

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

The registry lists 91 participants at risk in the Standard Treatment (STX) group and 92 in the Contracts, Prompts and Reinforcement (CPR) group. It records 0 participants affected by serious adverse events in each group and 0 affected by other adverse events in each group. No serious adverse-event terms are listed. Death counts are null for both groups, so deaths are not reported as a numeric count in the registry record.

These fields should be interpreted narrowly. They describe the entries recorded for these adverse-event categories; they do not provide event narratives, definitions, severity gradations beyond the serious/non-serious grouping, exposure time, or an assessment of relatedness to the intervention. A zero in the affected-participant field is not the same as proof that no event of any kind occurred, and the null death entries should not be read as zero deaths.

In general, safety comparisons require attention to how events were collected, the period of observation, and the number of participants with available follow-up. The registry record does not report those details or a statistical comparison of safety between groups. The listed figures therefore support only a limited description of the recorded adverse-event fields, not a broad conclusion about comparative safety.

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

The record documents a randomized comparison of a continuing-care reinforcement intervention with routine care among veterans seeking residential substance-use treatment. It defines the primary outcome as abstinence during the 90 days before the 12-month assessment and describes the interview and screening rules used to classify abstinence. These details establish what the primary clinical question was.

The record does not report the group-specific primary outcome data or a statistical comparison. It therefore does not show whether the abstinence rate was higher in either group, how large a group difference may have been, or how precisely it could be estimated. The stated hypothesis in the brief summary is not an outcome result. The absence of an analysis in the record is not evidence of no difference, just as the intervention’s description is not evidence of benefit.

The same distinction applies to secondary measures. Outcomes and hypotheses are listed, but comparative findings are not. No conclusion about attendance, substance-use days, hospitalization, or other outcomes can be drawn from the registry entries. In general, a registered outcome identifies what investigators intended to measure; a result requires outcome data and an analysis.

The listed adverse-event fields show zero affected participants for serious and other adverse events in both groups, with deaths not reported numerically. That information is limited and does not establish the absence of all harms or a safety difference. The registry record also does not report missing-data handling, the analysis population, or a multiplicity plan, all of which would matter when appraising a complete set of trial results.

The appropriate statistical reading is therefore descriptive and bounded: the trial design and endpoint are documented, but comparative efficacy and its precision are not. No treatment recommendation follows from this registry record.

13. Why This Trial Matters Statistically

This trial raises a clinically relevant statistical question: whether a structured approach to contracting, prompting, and reinforcement is associated with a different abstinence outcome than routine care in a defined treatment population. The randomized, parallel-group design is intended to support a comparison between assigned groups, while the specified 90-day abstinence window gives the primary endpoint a clear time frame.

The record also illustrates why endpoint definitions and outcome reporting need to be read together. It describes how abstinence was assessed and how a positive screen affected classification, but does not provide the arm-level results. Without those data, a reader cannot estimate the group contrast, evaluate its precision, or judge whether any observed difference might be compatible with chance variation.

Multiple follow-up points and several secondary outcomes create additional interpretive questions. In general, a trial can yield many possible comparisons, making it important to distinguish the primary question from secondary or exploratory analyses. The registry record identifies the primary endpoint but does not report the analysis plan for multiple comparisons or the results for the other outcomes.

The case also highlights the difference between a study’s hypothesis and its findings. A registered hypothesis explains what investigators set out to examine; it does not establish the direction or magnitude of an outcome. Statistical interpretation depends on reported data, estimates, uncertainty, and transparent analysis methods. Since these are not listed for the primary endpoint, the trial’s comparative result cannot be assessed from this record.

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 principal limitation for interpreting this trial record is the absence of reported primary outcome counts and a comparative analysis. No effect estimate, confidence interval, or p-value is listed for abstinence at the 12-month follow-up. Although the endpoint is clearly described, its observed distribution across groups is not available in the registry record.

Analysis details are also limited. The record does not report the analysis population, how missing follow-up assessments were handled, whether baseline adjustment was used, or the statistical model. It does not describe the allocation procedure beyond identifying the study as randomized, and it does not specify who was masked. The listed single-masking designation alone does not identify which people were masked.

The record lists several secondary outcomes and additional hypotheses but does not provide their results or describe a multiplicity strategy. It also does not report outcome completion by follow-up time, intervention fidelity, or the level of participation in the continuing-care activities. Those omissions make it difficult to assess outcome completeness, implementation, and the robustness of any treatment contrast.

The study population and sites are described as veterans seeking residential treatment at the Salem and Jackson VAMCs. The registry record does not provide site-specific results or evidence about other populations or settings. Finally, adverse-event fields are sparse: counts of affected participants are listed, but deaths are null and details of event ascertainment are not reported. These limitations constrain conclusions to what the record explicitly documents.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Reinforcement of Abstinence and Continuing Care in Substance Abuse Treatment — NCT00288886.
• Registry record last updated 2015-04-24; status last verified 2014-07.
• Results first posted 2014-10-29.
• 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.

18. Record Summary

This completed Phase 2 trial was randomized, single-masked, and parallel-group, with enrollment of 183. It compared Contracts, Prompts and Reinforcement (CPR) with standard treatment among veterans seeking residential substance-use treatment at the Salem and Jackson VAMCs. The sponsor was the US Department of Veterans Affairs; the study began in 2007-03 and reached primary completion in 2009-06.

The primary endpoint was abstinence during the preceding 90 days at 12 months, assessed with the Form-90. The registry also lists secondary outcomes addressing earlier abstinence, time until first use, attendance, substance-use days, and hospitalization. No analyses are listed, and the primary group comparison and secondary outcome results are not reported in the registry record. Serious and other adverse events are each recorded as affecting 0 participants in both groups; deaths are null in both groups.