Comparing Treatments for HIV-Infected Opioid and Alcohol Users in an Integrated Care Effectiveness Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparing Treatments for HIV-Infected Opioid and Alcohol Users in an Integrated Care Effectiveness Study (NCT01908062), a randomized phase 3 study. The primary outcome is Number of Participants With Successful Initiation of Treatment Within 4 Weeks of Randomization.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group, phase 3 study sponsored by Oregon Health and Science University. The registry lists enrollment of 51 participants, with 26 in the treatment-as-usual group and 25 in the extended-release naltrexone group for the primary outcome. Masking was listed as none. The study status is completed. The recorded start was 2014-06, and primary completion was 2015-03.

The intervention was XR-NTX by monthly injection, at a dose of 380 mg. The registry describes one injection per month for four months and a duration of 30 days. Treatment as usual was the comparator. Its description distinguishes usual care for opioid use disorders in HIV clinics from the typical referral pathway for alcohol use disorders. The record does not report how care was tailored for participants with both conditions, or which specific usual-care services each participant received.

The primary outcome was assessed within 4 weeks of randomization and counted successful initiation of the assigned treatment. The registry also lists secondary outcomes concerning HIV viral suppression, opioid and alcohol use, HIV care engagement, liver enzymes, urine tests for opioids and alcohol, and overdose. These outcomes cover different aspects of substance use, HIV care, and safety; they do not all address the same question as the primary endpoint.

The registry identifies the study as a pilot and describes its purpose as assessing whether XR-NTX would be feasible and acceptable for HIV-infected people with opioid or alcohol use disorders in an HIV clinic setting. It does not report the trial’s original sample-size justification, its original design assumptions, or a detailed account of randomization procedures. The observed enrollment and the planning illustrations should therefore be distinguished from any claim about the planned precision or operating characteristics of the original study.

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 Number of Participants With Successful Initiation of Treatment Within 4 Weeks of Randomization, measured over 4 weeks.

The primary endpoint is the number of participants who successfully initiated their assigned treatment within 4 weeks of randomization. For the XR-NTX group, successful initiation meant induction onto XR-NTX; for the treatment-as-usual group, it meant initiation of treatment as usual. The endpoint is recorded as a participant count, with the number meeting the criterion compared with the number assessed in each group.

This outcome fits the stated pilot purpose because it directly measures whether treatment initiation occurred within a defined early period. In a feasibility study, an initiation measure can describe whether participants reached the intended starting point for their assigned care. It is not a measure of how long treatment was continued, how acceptable participants found it, or whether substance use or HIV-related outcomes changed over a longer period.

The registry reports successful initiation for 25 of 26 participants assigned to treatment as usual and 17 of 25 assigned to XR-NTX. Those are observed counts, not a complete account of the participants’ subsequent care. The record’s endpoint description does not provide additional criteria for judging successful initiation, such as verification procedures or how missed assessments were handled. Those operational details are not reported in the registry record.

7. Results Posted in the Registry

• Extended Release Naltrexone: 68.0% (17/25) versus 96.2% (25/26) on control; risk difference -28.2 percentage points (95% CI -47.9 to -8.4), risk ratio 0.71 (0.53–0.94); unadjusted two-proportion z-test p = 0.008.

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.

HIV Viral Suppression at 16 Weeks

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Extended Release Naltrexone: 81.0% (17/21) versus 87.0% (20/23) on control; risk difference -6.0 percentage points (95% CI -27.7 to 15.7), risk ratio 0.93 (0.72–1.21); unadjusted two-proportion z-test p = 0.587.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Extended Release Naltrexone and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the study’s focus beyond treatment initiation to include HIV viral suppression, substance-use measures, HIV care engagement, laboratory findings, urine testing, and overdose. This breadth can help frame what the pilot was designed to monitor, but it also means that the outcomes address different questions and use different kinds of measurements. The secondary results should not be treated as a single combined assessment of whether the intervention succeeded.

The posted viral-suppression comparison is a secondary result at 16 weeks, whereas the primary endpoint concerns initiation within 4 weeks. They are related in the broad sense that both concern the care of HIV-infected participants, but they measure distinct stages and outcomes. A difference in early treatment initiation does not establish what happened to viral suppression, and a viral-suppression comparison does not explain the initiation result. The study does not report a formal analysis connecting these endpoints.

Secondary findings carry less confirmatory weight when they are unadjusted and considered alongside several other outcomes. Considering many outcomes can increase the possibility of apparently notable results arising by chance. The registry does not report a multiplicity procedure, a hierarchy for interpreting secondary outcomes, or a detailed analysis plan. As a result, secondary comparisons are most appropriately read as descriptive evidence that can inform further study, rather than as a set of definitive tests.

The registry lists nine posted secondary outcomes, while the specific secondary comparison with a full estimate and confidence interval is for HIV viral suppression at 16 weeks. The record does not report analyses for every listed secondary outcome in the same level of detail. No inference about an unreported secondary result should be drawn from its inclusion in the outcome list. More broadly, the secondary outcomes can contextualize the pilot’s scope, but they do not independently confirm or overturn the primary initiation comparison.

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

• HIV Viral Suppression at 16 Weeks
• Mean Days of Opioid Use in Past 30 Days
• HIV Care Engagement
• Participant Safety: Change in Liver Enzymes Between Baseline and Week 16
• Number of Participants With Urine Drug Screen (UDS) Positive for Opioids
• Mean Days of Alcohol Use in Past 30 Days
• Number of Participants With Urine Ethyl Glucuronide (EtG) Positive for Alcohol
• Participant Safety: Any Fatal or Non-fatal Overdose Between Baseline and Week 16

9. Statistical Interpretation

10. Statistical Methods Explained

Statistical methods answer related but distinct questions: how the outcome is defined, how the groups are compared, how uncertainty is expressed, and how results should be interpreted alongside the study design. The registry posts a primary risk-difference comparison and a separate secondary risk-difference comparison for HIV viral suppression. It does not report a detailed statistical analysis plan, named testing procedure, or analysis-population definition.

What does a risk difference describe?

A risk difference compares the proportions of participants who meet a binary outcome in two groups. For this study, the binary primary outcome is successful initiation within 4 weeks. The reported comparison is XR-NTX relative to treatment as usual. A negative estimate means the observed proportion with the outcome was lower in the XR-NTX group. A positive estimate would mean it was higher. A value of zero would correspond to equal observed proportions.

The primary estimate is -0.281. The registry also reports the group counts and the proportions used in the comparison: 25 of 26 participants in the treatment-as-usual group and 17 of 25 in the XR-NTX group. The risk difference expresses the contrast on an absolute scale, rather than as a ratio. This scale is useful for understanding the size and direction of the observed difference in event proportions. It does not explain the cause of the difference, nor does it account for factors beyond the posted comparison.

How should the p-value be read?

The primary unadjusted p-value is 0.008. A p-value measures how unusual the observed data, or data more extreme, would be under a specified null hypothesis and test procedure. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. Because the registry does not report which test was used or its assumptions, interpretation should not assign an unreported test method to this result. The term unadjusted also matters: the reported value is not described as corrected for considering multiple outcomes or comparisons.

For HIV viral suppression at 16 weeks, the unadjusted p-value is 0.587. This result does not demonstrate that the groups are equivalent. A non-small p-value can arise when the data are compatible with a range of effects, including effects in either direction. The confidence interval for that comparison includes zero, and its breadth is relevant to how much remains uncertain.

What does a confidence interval add?

A confidence interval gives a range of estimates compatible with the observed data under the interval’s statistical method. It is not a range containing a known, fixed percentage of individual participant outcomes, and it does not guarantee that the true effect lies within its endpoints. For the primary comparison, the interval runs from -0.479 to -0.084. Both endpoints are negative, indicating that the interval excludes zero. For the viral-suppression comparison, the interval runs from -0.277 to 0.157 and includes zero. The intervals should be read together with the point estimates, the limited study size, and the outcomes’ different timeframes.

Why are unadjusted secondary findings more tentative?

The record lists multiple secondary outcomes, covering several domains. When many outcomes are assessed, the chance of finding an apparently notable result by chance can increase if each is considered without accounting for the full set of comparisons. The registry does not report a multiplicity adjustment or a prespecified hierarchy among secondary outcomes. Therefore, unadjusted secondary comparisons are best treated as descriptive or exploratory rather than as independent confirmation of the primary result.

Secondary outcomes also differ in measurement and available data. Some are participant counts, some concern mean days of use, and others concern laboratory measures, care engagement, or safety. The registry lists nine posted secondary outcomes, but the outcome descriptions and analyzed denominators are not identical across them. A result for one endpoint cannot be assumed to represent the others. The record does not report a common model or a strategy for synthesizing these distinct outcomes.

What is not documented?

The registry record does not report the original sample-size rationale, interim-analysis procedures, detailed handling of missing observations, or a full statistical analysis plan. It also does not define a named intention-to-treat or per-protocol population. These omissions restrict reproducibility and make it difficult to assess whether the posted comparisons followed prespecified methods. They should not be filled in by assuming customary procedures. The available numbers can be interpreted as the posted group summaries and comparisons, while questions about unreported analytic choices remain unresolved.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.281, with a confidence interval from -0.479 to -0.084. The interval is entirely below zero, so the posted interval estimate is consistent with a lower proportion meeting the initiation endpoint in the XR-NTX group than in the treatment-as-usual group. At the same time, the interval covers a range of negative values; the point estimate alone should not be treated as an exact measure of the underlying difference. Its breadth reflects uncertainty in the estimate, especially in a study with 51 participants overall.

A confidence interval is a measure of statistical uncertainty under the method used to construct it. In general, narrower intervals indicate greater precision and wider intervals indicate less precision. An interval does not show the spread of individual responses, and it does not assign a probability to each possible value of the true effect. The registry does not report the interval-construction method, so additional assumptions about that method are not warranted.

The viral-suppression comparison at 16 weeks has an estimated risk difference of -0.06, with a confidence interval from -0.277 to 0.157. This interval includes zero and spans negative and positive values. It therefore leaves uncertainty about the direction and size of the difference. It should not be read as establishing equal outcomes between the groups.

Precision depends on the amount of information available for a particular outcome, not just the overall enrollment. The reported denominators for the primary endpoint and the viral-suppression endpoint differ. The registry does not explain why the denominators differ or how missing observations were handled. Consequently, the confidence intervals should be interpreted as applying to the posted comparisons, without assuming that all randomized participants contributed data to every endpoint.

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 planning illustrations express required sample sizes as participants per arm, not as total enrollment. This applies to the primary endpoint and the reported viral-suppression comparison. The record’s general planning description specifies a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It evaluates effects defined as a stated fraction of the observed effect. The original trial’s own design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives an illustrative number of participants per arm for a design with 80% power under those planning assumptions and for the effect size stated in that row. The 90% power column gives the corresponding illustration for 90% power. Power is the probability, under the assumed effect and statistical model, of detecting an effect at least as extreme as the one specified using the stated significance level. It is a feature of a hypothetical design under assumptions, not a guarantee of what a future study will find.

For the primary outcome, the illustration based on 100% of the observed effect lists 28 participants per arm for 80% power and 37 participants per arm for 90% power. The illustrations based on 75% of the observed effect list 43 and 57 participants per arm, respectively; those based on 50% list 76 and 101. The viral-suppression illustrations are also per arm and use the same stated planning assumptions, but the numbers are much larger because the observed effect used for that illustration is smaller. In general, smaller effects require more participants to detect under otherwise unchanged assumptions.

These figures are planning illustrations, not observed power. The record’s general statement distinguishes time-to-event planning, which would be expressed as total events, from other outcomes, which are expressed as participants per arm. The displayed outcomes are not time-to-event 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 = 0.962; treatment proportion p₁ = 0.680; average p̄ = 0.821.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5424 = 1.0631.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5046 = 0.4246.
4. n = (1.0631 + 0.4246)² / (-0.2815)² = 27.9, rounded up to 28 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 <- 0.961538461538462                          # control proportion
p1 <- 0.68                          # 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(1908062)
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 = 28 (80% power), 37 (90% power)
 75% of observed effect: n per arm = 43 (80% power), 57 (90% power)
 50% of observed effect: n per arm = 76 (80% power), 101 (90% power)
power.prop.test: 27.9 
Simulated power at n = 28 per arm: 0.852 (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

Multiplicity arises when statistical tests are conducted across several outcomes, groups, time points, or comparisons. Even if each test is considered separately, examining a collection of results can increase the chance that one appears noteworthy by chance. Common approaches include prespecifying a primary outcome, adjusting significance thresholds, or organizing outcomes in a testing hierarchy. These are general statistical strategies; the registry record does not report which, if any, were planned or used for this study beyond identifying the primary endpoint.

The primary result is reported with an unadjusted p-value. The registry also lists multiple secondary outcomes and provides a comparison for viral suppression at 16 weeks. No multiplicity adjustment is reported. The primary comparison can therefore be distinguished from the secondary comparisons by its designated role, but the record does not establish whether the primary p-value was adjusted for any additional analyses. Unadjusted secondary results merit particular caution because they are considered among a wider set of outcomes.

Missing-data handling is also not reported in detail. The endpoint denominators recorded for the primary outcome are 26 and 25, while the viral-suppression denominators are 23 and 21. The record does not explain the difference in available denominators, identify reasons for unavailable observations, or describe an imputation or sensitivity-analysis approach. It is therefore not possible to determine from the registry whether missingness could have influenced the secondary comparison or whether the analysis made assumptions about unobserved outcomes.

The registry record does not identify a named analysis population, such as an intention-to-treat or per-protocol population, and does not describe how participants who did not initiate assigned treatment were handled in analyses beyond the primary endpoint’s definition. It does not report interim analyses or a complete statistical analysis plan. These omissions limit assessment of prespecification, reproducibility, and the potential effect of analytic decisions. They do not change the posted counts, but they constrain how confidently the results can be interpreted as the product of a particular planned analysis.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: suicidal ideation (4.0%), ankle fracture (3.8%).

The registry reports serious adverse events affecting 1 participant in the treatment-as-usual group and 1 participant in the XR-NTX group. The numbers at risk for these serious-event summaries were 26 and 25, respectively. These are participant counts, not event rates adjusted for duration of follow-up, and the record does not provide further details about timing, relatedness to treatment, or severity beyond the serious-event classification.

The other adverse-event summaries report 5 affected participants in treatment as usual and 9 in the XR-NTX group, with 26 and 25 participants at risk, respectively. The record lists suicidal ideation at 4.0% and ankle fracture at 3.8% among the top serious-event terms. It does not provide enough context in these summaries to attribute either term to a particular group or to establish a causal relationship with treatment. Deaths are not reported in the registry record.

These summaries describe the safety information posted for the study; they do not establish comparative safety. With the small groups and without fuller information on event definitions, follow-up, attribution, or analysis, counts should be read descriptively. The absence of a reported event count should not be interpreted as proof that no such event occurred.

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

The primary result describes an observed difference in successful initiation within 4 weeks. The treatment-as-usual group had 25 of 26 participants meeting the endpoint, compared with 17 of 25 in the XR-NTX group. The estimated risk difference was -0.281, and the confidence interval from -0.479 to -0.084 excluded zero. The unadjusted p-value was 0.008. These statistics indicate that, in this study, the posted initiation outcome was less frequent in the XR-NTX group than in the treatment-as-usual group.

That finding does not establish why the observed groups differed. Randomization is part of the design, but the registry does not report detailed procedures for sequence generation, concealment, or implementation. The data also do not establish what would happen in a larger sample, in another clinic setting, or among a differently defined population. The pilot’s enrollment of 51 participants limits the scope of what can be inferred, and the record does not provide the original sample-size rationale.

The primary outcome is about starting assigned treatment within a specified period. It does not directly measure ongoing treatment, acceptability over time, changes in substance use, or later HIV outcomes. The registry lists those topics among secondary outcomes, but listing an outcome does not itself provide evidence about its result. The posted viral-suppression comparison is separate from the primary endpoint and has an interval that includes zero; it should not be used to claim either equivalence or a confirmed difference.

Similarly, the safety counts are descriptive and do not establish whether adverse events were caused by treatment or whether one strategy is safer. The record does not report detailed safety analyses or the relationship of individual events to the intervention.

In general, a statistically notable result for one endpoint is not a complete assessment of a treatment strategy. It is one estimate from one study, interpreted in light of its endpoint, design, precision, missing-data information, and multiplicity context. The registry record supports describing the observed difference in treatment initiation. It does not support broad conclusions about effectiveness, acceptability, or clinical benefit beyond the outcomes and comparisons that were posted.

17. Why This Trial Matters Statistically

This study is statistically interesting because its primary endpoint is closely aligned with a practical question in an HIV clinic setting: whether participants with opioid or alcohol use disorders initiated their assigned treatment within 4 weeks. It also compares two care approaches that the registry describes differently for opioid and alcohol use disorders. That context helps explain why initiation is meaningful as a feasibility outcome, while also reminding readers that the comparator was not a single uniform service described in detail for every participant.

The result illustrates why effect estimates and confidence intervals add information beyond a p-value. The risk difference gives the direction and absolute scale of the observed group contrast, and the interval conveys uncertainty around that estimate. A p-value alone would not communicate either the size of the contrast or the range of estimates compatible with the data.

The record also illustrates the distinction between a pilot’s observed results and later-study planning. Its sample-size illustrations use fractions of the observed effect under stated assumptions. They are not the original trial’s design justification and do not describe observed power. Planning around a smaller effect requires more participants under otherwise unchanged assumptions, but those illustrations depend on the effect and assumptions used.

Finally, this study highlights the importance of complete reporting. The registry identifies the primary endpoint, group counts, and comparisons, but does not report a full analysis plan, missing-data approach, multiplicity strategy, or named analysis population. Those details matter when readers assess reproducibility and the strength of conclusions, particularly when several secondary outcomes are listed. The primary finding is interpretable, but unreported methods leave important questions open.

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 limitations specific to this study affect interpretation. First, the study was a pilot with 51 participants. The primary comparison is therefore based on modest group sizes, and the confidence interval indicates meaningful uncertainty around the estimated difference. The result should not be treated as a precise prediction for other settings or populations.

Second, the primary outcome is limited to successful initiation within 4 weeks. It does not establish whether participants continued treatment or whether initiation led to later changes in substance use, HIV care, or health outcomes. Although the registry lists secondary outcomes in these domains, the record does not provide complete analysis details for all listed outcomes.

Third, the comparator description includes different usual-care pathways for opioid use disorders and alcohol use disorders. The registry does not describe which services individual participants received, whether care varied across clinics, or how participants with both conditions were managed. This leaves uncertainty about the precise contrast represented by treatment as usual.

Fourth, the primary comparison is posted without a detailed account of the statistical test, analysis population, or missing-data handling. The different denominators for the primary and viral-suppression outcomes are not explained. The record also does not report multiplicity procedures, interim analyses, or the trial’s original sample-size justification. These reporting gaps prevent a full audit of the analysis and reduce confidence in interpreting secondary comparisons as confirmatory.

Finally, the registry labels masking as none, and the primary endpoint involves treatment initiation, which may be influenced by care processes and participant decisions. The record does not describe outcome verification procedures or whether endpoint assessment was independent. These limitations do not negate the posted results, but they define the boundaries of what can be concluded from them.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Comparing Treatments for HIV-Infected Opioid and Alcohol Users in an Integrated Care Effectiveness Study — NCT01908062.
• Registry record last updated 2019-03-19; status last verified 2019-03.
• Results first posted 2019-02-26.
• 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

NCT01908062 is a completed randomized, parallel-group phase 3 pilot study sponsored by Oregon Health and Science University. It enrolled 51 HIV-infected people with opioid or alcohol use disorders and compared monthly extended-release naltrexone with treatment as usual. The registry lists no masking.

The primary endpoint counted successful initiation of assigned treatment within 4 weeks of randomization. The outcome was recorded for 25 of 26 participants in the treatment-as-usual group and 17 of 25 in the XR-NTX group. The posted risk difference for XR-NTX relative to usual care was -0.281, with a confidence interval from -0.479 to -0.084 and an unadjusted p-value of 0.008.

The registry also lists secondary outcomes across HIV care, substance use, and safety. Its viral-suppression comparison at 16 weeks had a confidence interval that included zero. Detailed analysis methods, missing-data procedures, and the original sample-size justification are not reported in the registry record.