Extended-Release Naltrexone for Opioid Relapse Prevention Following Release From Jail: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Extended-Release Naltrexone for Opioid Relapse Prevention Following Release From Jail (NCT01180647), a randomized phase 3 study. The primary outcome is Post-Release Opioid Relapse.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group Phase 3 trial listed as completed in the registry. The registry reports enrollment of 48 and lists the study start as 2010-05 and primary completion as 2013-07. The study is described as a pilot. Its randomized arms were extended-release naltrexone (XR-NTX) and Motivational Enhancement Counseling Only. Masking is listed as none, so the trial was open-label.

The XR-NTX arm was assigned a 380mg intramuscular depot injection in the week before jail release. A second injection was offered after release, 4 weeks after the first. Participants in the control arm received no medication treatment and were offered brief, two-session Motivational Enhancement Counseling before release. These descriptions establish the assigned approaches; they do not show whether each participant received every offered component.

The primary endpoint entries list 16 participants in the XR-NTX arm and 17 in the counseling-only arm. The registry notes that one randomized XR-NTX participant was excluded from final primary-outcome analysis because he was never released to the community. The original trial’s detailed analysis population, handling of other departures from follow-up, and allocation procedures beyond randomization are not reported in the registry record.

The stated purpose was to compare post-release opioid relapse. Secondary outcomes listed include participation in community drug treatment, any opioid use, injection drug use, accidental overdose, and adverse events. The registry does not provide detailed results for all these listed outcomes in the record summarized by the posted results.

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: Of the 48 consented participants enrolled into study between January 2010-May 2013, 34 were randomized into one of two trial arms, with n=17 to Extended-Release Naltrexone arm and n=17 to the Motivational Enhancement Counseling Only arm (treatment-as-usual).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: One XR-NTX participant randomized was excluded from final data analysis due to the fact he was never released from jail to community, so primary outcome (post-release opioid relapse) could not be measured.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Baseline analysis determined based on: (1) successful randomization into one of two treatment arms (ETAU;XR-NTX) and (2) actual release from jail back to the community. One participant who successfully randomized to XR-NTX was never released from jail custody and was instead sent to prison and therefore excluded from final analysis.

6. Primary Endpoint

The registry lists the primary outcome as Post-Release Opioid Relapse, measured over Four weeks post-release.

The primary endpoint is the number of participants with post-release opioid relapse at week 4. The registry defines relapse using self-reported opioid misuse, measured with Time Line Follow Back, and urine toxicology. An event is defined as self-reported opioid misuse on at least 10 of 28 days after release, or two or three positive results among the three urine samples scheduled during weeks 2, 3, and 4. A single positive urine result or a missing urine result counts as 7 opioid misuse days under this definition.

This combined endpoint uses self-report and biological testing to capture different forms of evidence about opioid use. The rule for missing or single-positive urine results is part of the endpoint definition and affects how those observations are classified. It should not be confused with a general missing-data procedure for the whole trial.

The registry’s brief study summary describes sustained relapse using self-reported use on more than half of the days during the first 30 days after release. The detailed primary outcome instead specifies a 28-day window and includes urine toxicology. Because these definitions differ, the detailed endpoint description is the appropriate reference when interpreting the posted primary counts. The reason for choosing this specific endpoint, beyond its role as the primary measure of relapse, is not reported in the registry record.

7. Results Posted in the Registry

• Motivational Enhancement Counseling Only: 88.2% (15/17) versus 37.5% (6/16) on control; risk difference 50.7 percentage points (95% CI 22.5 to 79.0), risk ratio 2.35 (1.22–4.53); unadjusted two-proportion z-test p = 0.002.

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.

Participation in Community Drug Treatment Post-release

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Motivational Enhancement Counseling Only: 11.8% (2/17) versus 18.8% (3/16) on control; risk difference -7.0 percentage points (95% CI -31.5 to 17.5), risk ratio 0.63 (0.12–3.28); unadjusted two-proportion z-test p = 0.576.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Motivational Enhancement Counseling Only and the control. The interval gives the range of effects that remain compatible with the data.

Any Opioid Use Post-release

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Motivational Enhancement Counseling Only: 82.4% (14/17) versus 18.8% (3/16) on control; risk difference 63.6 percentage points (95% CI 37.3 to 89.9), risk ratio 4.39 (1.55–12.47); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Motivational Enhancement Counseling Only than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes provide context around the primary relapse result, but they do not all address the same question. Community drug-treatment participation concerns engagement with care after release, while any opioid use is a broader post-release use outcome. Injection drug use, accidental overdose, and adverse events are also listed as secondary outcomes, but detailed results for these outcomes are not reported in the registry record.

The reported pattern for any opioid use points in the same direction as the primary relapse comparison: fewer participants in the XR-NTX arm were recorded with the outcome than in the counseling-only arm. Community treatment participation does not show a similarly clear between-arm contrast in the posted estimate. These differences in pattern underscore that the endpoints are related but not interchangeable. Relapse under the primary definition, any opioid use, and participation in treatment capture distinct aspects of post-release experience.

General: secondary outcomes can help characterize a trial, but their interpretation depends on how many outcomes were assessed, whether they were prespecified, and whether analyses account for multiple comparisons. The registry lists several secondary outcomes and reports unadjusted comparisons for the detailed results available. It does not report a multiplicity procedure, and it does not provide reported analyses for the full listed set. Results across many outcomes can generate chance findings even when each comparison is considered separately.

For that reason, secondary findings carry less weight than the designated primary result as evidence for the trial’s main question. They may be informative and can suggest questions for further evaluation, but the registry record does not support treating them as confirmatory or as independent demonstrations of the primary pattern. The absence of detailed results for some listed outcomes also means the overall secondary-outcome picture is incomplete.

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

• Participation in Community Drug Treatment Post-release
• Any Opioid Use Post-release
• Injection Drug Use Post-release
• Accidental Drug Overdose
• Adverse Events and Serious Adverse Events

9. Statistical Interpretation

10. Statistical Methods Explained

Binary outcomes record whether each participant did or did not experience an event during the defined observation period. For the primary endpoint, the event is post-release opioid relapse under the registry’s combined self-report and urine-toxicology definition. The arm counts are therefore counts of participants classified as having the event, not counts of relapse episodes. General: binary outcomes are often compared by estimating the event proportion in each group and then expressing the contrast as a risk difference, risk ratio, or odds ratio.

What does the risk difference express?

The risk difference is the difference between the two group event proportions, with the direction determined by which arm is subtracted from the other. For the primary comparison, the posted estimate is 0.507, comparing counseling-only with XR-NTX. It is an absolute contrast on the risk scale, rather than a relative change. The confidence interval runs from 0.225 to 0.790. General: an interval for a risk difference that includes zero is compatible with no difference on that scale under the interval’s assumptions; an interval entirely on one side of zero is compatible with a difference in that direction. The interval does not remove uncertainty about the true effect.

How should the p-value be read?

The primary unadjusted p-value is 0.002. General: a p-value describes how unusual data at least as inconsistent with a null hypothesis would be under the assumptions of a statistical test if that null hypothesis were true. It is not the probability that the null hypothesis is true, nor does it measure the size or importance of an effect. The registry does not report a multiplicity adjustment for the primary and secondary comparisons, so the p-value should be understood as unadjusted.

What do the relative measures add?

The posted comparison also gives a risk ratio of 2.353 with a confidence interval from 1.221 to 4.534, and an odds ratio of 12.5 with a confidence interval from 2.089 to 74.81. The risk ratio compares the event proportions; the odds ratio compares event odds. They are relative measures, whereas the risk difference is absolute. General: odds and risks are not interchangeable, and an odds ratio can appear more extreme than a risk ratio when events are common. The wide odds-ratio interval indicates substantial uncertainty in that relative estimate. These measures describe the same data from different scales; they are not separate replications of the finding.

The primary endpoint is based on a binary classification at week 4, not on time until relapse. No time-to-event analysis is reported. The primary count is paired with a 95% confidence interval in the registry, while the comparison gives an interval for the risk difference. These intervals answer different questions: an arm-level interval concerns the count or group result as encoded in the registry, whereas the comparison interval concerns the contrast between arms. The most direct measure of the randomized-group difference is the comparison estimate and its interval.

Why does the endpoint’s classification rule matter?

The primary definition combines self-report with urine toxicology, and counts a single positive or missing urine result as 7 opioid misuse days. That rule is not a neutral detail: it affects how observations are classified as meeting the relapse threshold. General: when an endpoint is assembled from multiple measurement sources, the analysis depends on the prespecified rules for combining those sources. The registry provides the rule but does not report additional sensitivity analyses testing alternative classifications.

The control group received counseling and no medication, while the intervention arm was assigned XR-NTX with a second injection offered after release. Because masking is listed as none, participants and study staff may have known the assigned approach. General: lack of masking can influence self-reported outcomes or other aspects of measurement, although the registry record does not establish that such influence occurred. Urine testing adds a biological measure, but the primary endpoint still includes self-report in its definition.

The posted primary comparison is unadjusted. The registry does not report a model specification, covariate adjustment, interim analyses, or the original statistical analysis plan. It also lists no reported analyses in the analyses entry. Those details should not be inferred from the effect estimates or p-values. General: analysis choices such as adjustment, missing-data handling, and multiplicity procedures can affect inference, particularly when several outcomes are assessed. The available results support a description of the posted comparisons, not a reconstruction of an unreported analysis plan.

11. Confidence Intervals and Precision

The primary comparison has a 95% confidence interval from 0.225 to 0.790 around the risk difference of 0.507. The interval is entirely above zero, but it is broad. This means the data are compatible with a range of positive differences, and the exact magnitude remains uncertain. The interval should be read alongside the point estimate rather than as a guarantee that the true difference falls within these limits.

General: a confidence interval describes the uncertainty associated with an estimate under the method’s assumptions. A narrower interval indicates greater precision, while a wider one indicates less precision. Precision is not the same as validity: a narrow estimate can still be affected by bias, limitations in measurement, or limitations in how participants were selected. Conversely, a wide interval does not mean that the estimate is necessarily biased.

The relative estimates also vary in precision. The risk-ratio interval is 1.221 to 4.534, and the odds-ratio interval is 2.089 to 74.81. In particular, the odds-ratio interval spans a wide range of values, so its point estimate should not be treated as an exact measure of the relative contrast. The risk difference is often easier to interpret as an absolute comparison, while relative measures describe the contrast on other scales.

The secondary comparison for participation in community drug treatment has a risk-difference interval from -0.315 to 0.175, which includes zero. The interval for any opioid use runs from 0.373 to 0.899. These secondary intervals differ in what they allow for, and should be interpreted with the fact that they are unadjusted and that the record does not report analyses for all listed secondary outcomes.

General: confidence intervals reflect sampling uncertainty under their statistical assumptions; they do not account automatically for every possible source of uncertainty, such as measurement choices, missing observations, or selective reporting. The registry’s primary outcome population excludes one randomized participant who was never released to the community. The record does not provide enough detail to assess other potential contributions to uncertainty.

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 figures are planning illustrations based on the observed effect, not the trial’s original design calculation. The primary comparison’s planning figures are participants per arm, not total events. The stated 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 as the stated fraction of the observed effect. The registry’s original sample-size assumptions are not reported in the registry record.

The columns for 80% and 90% power indicate the planned number of participants per arm under those assumptions to have the corresponding probability of detecting the specified effect if that effect were true and the assumptions held. Power is a design concept: it describes a procedure’s ability to detect an effect of a chosen size under a statistical model. It is not a statement about the probability that the trial result is correct.

Rows describing a smaller fraction of the observed effect require more participants per arm than rows based on the full observed effect. This is the usual relationship in planning: smaller differences are harder to distinguish from sampling variability, so more information is needed. The curve should be read in that same planning context, rather than as a record of what the completed trial achieved.

These figures are not observed power. They are planning illustrations calculated from the effect observed in this small trial. If the observed effect is unstable or larger than the effect that would recur in a future study, planning directly from it may produce optimistic sample-size estimates. The illustrations do not substitute for the unreported original design rationale, and they should not be mistaken for trial outcomes.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.375; treatment proportion p₁ = 0.882; average p̄ = 0.629.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6833 = 1.3392.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5815 = 0.4894.
4. n = (1.3392 + 0.4894)² / (0.5074)² = 13.0, rounded up to 13 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
p0 <- 0.375                          # control proportion
p1 <- 0.882352941176471                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1180647)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 13 (80% power), 17 (90% power)
 75% of observed effect: n per arm = 26 (80% power), 34 (90% power)
 50% of observed effect: n per arm = 60 (80% power), 80 (90% power)
power.prop.test: 13 
Simulated power at n = 13 per arm: 0.843 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 secondary outcomes, but the original statistical analysis plan is not reported in the registry record. The record does not report whether the outcome hierarchy was prespecified in detail, whether there were interim analyses, or whether any adjustment for multiple comparisons was planned or used. The posted comparison p-values are unadjusted. Consequently, the reported p-values should not be read as accounting for the set of primary and secondary questions considered.

General: testing multiple outcomes can increase the chance of at least one apparently unusual result under a collection of null hypotheses. A multiplicity procedure can address that issue, but it may also change how uncertainty is assessed. Without a reported plan, it is not possible to determine whether multiplicity was handled elsewhere or to reconstruct an adjusted inference. The registry lists 6 outcome measures and gives no reported analyses in its analyses entry; this does not establish what analyses may have been conducted outside the registry record.

The primary endpoint includes an explicit rule for missing urine results: a missing result is counted as 7 opioid misuse days, as is a single positive result. This is part of the endpoint’s classification definition. It does not describe how missing self-report information, missing secondary-outcome data, or other incomplete observations were handled. Those procedures are not reported in the registry record.

The registry specifically notes that one randomized XR-NTX participant was excluded from the final primary-outcome analysis because he was never released to the community. The record does not explain whether any other randomized participants were excluded from that analysis, whether the posted groups represent an intention-to-treat population, or how deviations from assigned treatment were handled. The number of outcome entries alone cannot resolve those questions.

These gaps matter because multiplicity and missing-data decisions affect how confidently results can be interpreted. The posted counts and unadjusted comparisons remain describable as reported, but a complete assessment of the trial’s inferential procedures is not possible from the registry record.

15. 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.

Most frequent non-serious adverse event terms

The registry reports serious adverse events among 16 participants at risk in the XR-NTX arm and among 17 participants at risk in the Motivational Enhancement Counseling Only arm. It reports 0 participants affected by serious adverse events in each arm. This is a count of affected participants, not a list of event episodes or a comparison adjusted for follow-up or exposure.

For other adverse events, the registry reports 5 affected participants in the XR-NTX arm and 1 in the counseling-only arm, with the same respective numbers at risk as listed for serious events. The record does not provide the specific terms for these other events in the information. Death counts are not reported in the registry record.

General: zero reported serious events in these groups does not establish that serious harms are impossible or that risks are equivalent. The figures describe what was recorded in this trial; the relatively limited group sizes and the lack of event-level detail constrain interpretation. The registry’s serious-event counts should be read separately from the primary relapse outcome and should not be treated as a complete safety assessment.

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

The posted results support a statistical description of the randomized comparison: the counseling-only arm had more observed participants meeting the primary relapse definition than the XR-NTX arm, and the estimated risk difference was 0.507 with a 95% confidence interval from 0.225 to 0.790. The unadjusted p-value was 0.002. These figures describe this trial’s data; they do not establish a universal effect or guarantee the same result in another population.

The trial is described as a pilot and was open-label. The primary endpoint combined self-report with urine toxicology and used a specific classification rule for positive or missing urine samples. One randomized participant in the XR-NTX arm was excluded from the final primary analysis because he was never released to the community. The registry does not report enough information to assess the full analysis plan, other missing-data procedures, or how the results might vary under alternative endpoint rules.

General: statistical evidence of a difference does not by itself show that a difference is large enough to matter in practice. The confidence interval conveys substantial uncertainty about the size of the primary contrast. The secondary results are unadjusted, and detailed results for all listed secondary outcomes are not reported in the registry record. They should not be used to make stronger claims than the primary comparison supports.

These findings do not establish that the assigned intervention caused every observed difference, nor do they establish the balance of benefits and harms beyond the reported trial data. They do not determine what would happen with different participants, delivery conditions, or follow-up. The registry record supports a cautious conclusion about the observed post-release comparisons, not medical advice or a recommendation for an individual.

17. Why This Trial Matters Statistically

This trial illustrates why the definition of a clinical endpoint matters as much as the label attached to it. “Post-release opioid relapse” is operationalized through both self-reported use and urine toxicology, with a specified rule for positive or missing urine results. A reader who overlooks that rule could misunderstand what the event count represents. The brief study summary and the detailed primary endpoint also describe different windows and definitions, making careful attention to the detailed outcome specification important.

The results also show the distinction between an absolute and a relative comparison. The risk difference gives the contrast on an absolute scale, while the risk ratio and odds ratio express it relatively. The estimates all arise from the same trial observations, and their intervals—especially the broad odds-ratio interval—show why no single point estimate should be treated as exact.

The trial is a useful example of how randomization and open-label conduct can coexist: assignment was randomized, but masking is listed as none. Randomization supports a between-arm comparison, while lack of masking and self-report in the endpoint remain relevant considerations. The registry’s explicit note about the participant who was never released also illustrates how the target outcome population can differ from the set of randomized participants.

Finally, the unadjusted secondary comparisons and incomplete reporting of analysis details demonstrate why a statistically notable primary result should be interpreted with its design and reporting context. Confidence intervals, endpoint definitions, missing-data rules, and multiplicity are not technical footnotes; they shape what conclusions the observed data can support.

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.

The study is described as a pilot, and the primary comparison includes 16 participants in the XR-NTX arm and 17 in the counseling-only arm. The confidence interval around the primary risk difference is broad, so the magnitude of the contrast remains uncertain. Estimates based on limited group sizes can also be sensitive to the outcome classification of a small number of participants.

The trial was open-label. The primary outcome incorporates self-reported opioid misuse as well as urine toxicology, and the record does not report procedures that would establish whether outcome assessment was blinded. The combined definition may be useful for capturing more than one source of evidence, but its classification rules determine which participants count as having relapsed. The registry does not report sensitivity analyses using alternative definitions.

The registry notes that one randomized participant in the XR-NTX arm was excluded from final primary-outcome analysis because he was not released to the community. It does not report the handling of other missing observations or enough information to establish the analysis population for every outcome. The endpoint’s rule assigning 7 opioid misuse days to a missing urine result addresses that particular measurement within the relapse definition; it does not resolve all potential missing-data questions.

The record does not report the original sample-size rationale, a full statistical analysis plan, interim analyses, or a multiplicity adjustment. It also does not include detailed results for every listed secondary outcome. The intervention description says a second injection was offered after release, but the registry information does not state how often it was received. These reporting limits prevent a complete assessment of treatment exposure and analysis decisions.

Finally, the study concerns people with opiate dependence returning from jail, so the observed comparison should not automatically be generalized to populations or settings not described in the registry. The record does not provide further participant characteristics that would allow a more detailed assessment of generalizability.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Extended-Release Naltrexone for Opioid Relapse Prevention Following Release From Jail — NCT01180647.
• Registry record last updated 2016-04-07; status last verified 2016-03.
• Results first posted 2016-04-07.
• 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

The registry describes NCT01180647, “Extended-Release Naltrexone for Opioid Relapse Prevention Following Release From Jail,” as a completed, randomized, open-label, parallel-group Phase 3 pilot trial sponsored by NYU Langone Health. Enrollment is listed as 48, with a start date of 2010-05 and primary completion of 2013-07.

The primary outcome was post-release opioid relapse at week 4, defined using self-report and urine toxicology. The posted primary counts were 6 of 16 participants in the XR-NTX arm and 15 of 17 in the counseling-only arm. The unadjusted risk difference was 0.507 (95% CI 0.225 to 0.790; p = 0.002), comparing counseling-only with XR-NTX.

The registry notes one XR-NTX participant excluded from final primary analysis because he was never released to the community. It lists secondary outcomes and adverse-event counts, but does not report a full statistical plan, multiplicity handling, or detailed results for all listed secondary outcomes.