Buprenorphine Group Medical Visits in Primary Care: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Buprenorphine Group Medical Visits in Primary Care (NCT02526212), a randomized phase 3 study. The primary outcome is Number of Participants With Opioid Abstinence at 8 Weeks.

2. Clinical Question

This is a question about the comparative outcome under two ways of delivering buprenorphine-related care, not a comparison of buprenorphine with no treatment. Both groups are described as receiving buprenorphine. The proposed rationale for group visits was that group accountability, exposure to beneficial habits, and behavioral interventions alongside medical management might improve treatment outcomes. That rationale is an investigator hypothesis; it is not itself evidence of an outcome difference.

The registered primary outcome is a count of participants meeting a combined self-report and urine-test definition at a specified follow-up. It is not a measure of abstinence over the entire study, and it is not described as a continuous measure of opioid use. The registry also lists outcomes concerning retention in treatment, sharing injection equipment, acceptability, and visit attendance, but these are not the primary question addressed by the result.

3. Trial Design

The registry describes a Phase 3, randomized, parallel-group trial with no masking. The stated enrollment is 18. One group was assigned to G-BMT with buprenorphine, and the other to treatment as usual with buprenorphine. The primary endpoint is assessed at 8 weeks. The record lists Montefiore Medical Center as the sponsor and marks the study completed.

The G-BMT description refers to group visits with a multidisciplinary care team, including a generalist physician and behavioral specialist. The treatment-as-usual description refers to primary care physicians trained to follow a buprenorphine treatment-intensification protocol, including more frequent visits and referrals. The registry’s intervention descriptions are not a full account of every procedure, and the full protocol is not reported in the registry record.

Random allocation is intended to make assigned groups comparable on average, including on factors that may affect outcomes. It does not ensure that small groups will be balanced on every characteristic. With a stated enrollment of 18, the outcome counts should be read in the context of a small trial. The registry gives 10 participants for the G-BMT arm and 8 for the treatment-as-usual arm in the primary outcome record. These arm counts describe the participants represented in that outcome record; they do not establish whether every participant completed every other assessment.

No masking was used, according to the registry. This means the study is not described as blinded, but the record does not specify which people involved in care, data collection, or outcome assessment knew assignment. It also does not report a detailed allocation-concealment procedure. Those details are not reported in the registry record and should not be inferred from the general design label.

The registry gives a start date of 2017-01-01 and a primary completion date of 2019-05. It lists four secondary outcomes in addition to the primary outcome: retention in buprenorphine treatment at 3 months and 6 months, sharing injection equipment at 8 weeks, acceptability, and feasibility measured as the percentage of visits attended. The record does not provide results for those secondary outcomes in the registry record used for this analysis. Nor does it report the trial’s sample-size justification, detailed statistical analysis plan, or interim-analysis arrangements.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intention to treat analysis - missing urine drug toxicology tests are considered to be positive for illicit opioids

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 Opioid Abstinence at 8 Weeks, measured over 8 weeks.

The primary endpoint is the number of participants with opioid abstinence at 8 weeks. The registry defines abstinence using two sources: self-reported opioid use in the prior 30 days and a urine toxicology test at the 8-week visit. A participant qualifies only if they report no opioid use and the test is negative for opiates, methadone, and oxycodone. The primary analysis is described as intention to treat, with missing urine toxicology tests considered positive for illicit opioids.

This combined definition uses self-report and biological testing rather than relying on either source alone. In general, combining measures can make an endpoint more operationally specific, but each component also affects who meets the endpoint definition. In this trial, a report of no use without a qualifying negative test would not meet the stated definition; neither would a negative test paired with reported use. The missing-test rule is conservative with respect to classifying abstinence: a missing test does not count as evidence of abstinence under the registry’s stated rule.

The endpoint is a count, not a duration of abstinence or a measure of the amount of opioid use. It captures status at the specified follow-up using a look-back period for self-report and a test at the visit. It is used to address the study’s primary question about opioid abstinence after assignment to the two care approaches. The registry does not report the underlying self-report and toxicology results separately, so the contribution of each component to the final counts is not available.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Why use Fisher Exact?

The primary outcome is binary at the participant level: a participant either meets the stated abstinence definition or does not. The result is reported as counts in two randomized groups, and the registry identifies Fisher Exact as the comparison method. General: Fisher’s exact test evaluates the association between group assignment and a binary outcome using the observed counts, with an exact calculation rather than a large-sample approximation. It is often suitable when counts are sparse. Its use does not depend on estimating a normal distribution for the endpoint.

The test addresses whether the observed allocation of outcome counts across groups is unusual under its null model. The registry reports p=0.44. The test result is not an effect-size estimate. To describe the magnitude and precision of a group contrast, readers would generally look for an effect measure and its confidence interval, but neither is reported for this outcome in the registry record. A p-value alone cannot show whether any underlying difference is small or large, or how uncertain that difference is.

For a binary endpoint, statistical methods may express a contrast using measures such as a difference in event probabilities or a relative measure. Those are general examples, not reported results for this trial. No such comparative estimate should be inferred from the p-value. Nor should a new estimate be calculated from the counts when the registry result is being described as the sponsor’s analysis.

What does the reported p-value tell readers?

General: A p-value is calculated under a null hypothesis and a statistical model. It summarizes how extreme the observed data, or data more extreme, would be under that model. It is not a measure of the probability that the intervention has no effect. It is also not a measure of how likely it is that chance alone produced the result in a broader, unconditional sense. Interpretation depends on the design, endpoint definition, analysis choices, and quality and amount of information in the data.

The registry’s p-value should therefore be read alongside the small observed counts and the absence of a confidence interval. A test can be computed exactly while the estimated effect remains imprecise. Exactness concerns the test’s probability calculation under its assumptions; it does not mean the underlying treatment effect is known exactly. The record does not report a threshold for declaring the primary comparison statistically significant, so the p-value should be presented as reported rather than used to infer an unreported decision rule.

How do the planning assumptions differ from observed power?

The registry’s sample-size assumptions describe planning illustrations 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 stated fraction of the observed effect. The registry entries used for this analysis do not include the resulting participant requirements or the particular fractions represented in the planning rows, so no such figures or specific scenarios can be restated.

General: A planning illustration asks how many participants might be needed under specified assumptions about the effect, error rate, allocation, and analysis. It is not the number of participants actually enrolled, and it is not proof that a completed trial had a particular probability of finding an effect. “Observed power” calculated after seeing the outcome is not a substitute for an effect estimate and confidence interval. Any sample-size values associated with these assumptions are planning illustrations, not observed power.

The registry record does not report the trial’s own sample-size justification. The planning assumptions therefore should not be interpreted as the documented design basis for this study. The actual stated enrollment is 18, with arm counts of 10 and 8 in the primary outcome record. Those are observed design and outcome-record details, not evidence that the study was sized to detect a particular effect.

What can be concluded from the analysis record?

The reported method is Fisher Exact, the comparison is identified as a superiority analysis, and the reported p-value is 0.44. The registry does not list a test statistic, effect estimate, confidence interval, or adjusted analysis for the primary outcome. It also does not report the full statistical analysis plan, including any prespecified covariate adjustment, interim analysis, or handling rules beyond the endpoint’s stated missing-test classification. Those details are not reported in the registry record.

The trial is randomized and parallel-group, which gives the comparison a design intended to assess outcomes by assigned group. The record identifies the primary analysis as intention to treat, but does not describe additional analysis populations or sensitivity analyses. General: intention-to-treat analyses aim to analyze participants according to randomized assignment, retaining the benefits of randomization. The precise implementation can vary, and the registry’s stated rule for missing urine tests is part of how this endpoint was operationalized.

Over-dispersion is a concern for some count-data models when variability exceeds what a model assumes. General: it can make standard errors too small and confidence intervals too narrow if ignored. That issue is not the central method question for this primary endpoint, because the endpoint is analyzed as a binary participant outcome and the registry reports Fisher Exact. No dispersion parameter is reported. The registry lists other outcomes, including counts and visit attendance, but the registry entries used do not provide their analysis methods or numerical results. Accordingly, no conclusions about their model assumptions or findings should be drawn from the primary-outcome test.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("G-BMT, Buprenorphine", "Treatment as Usual, Buprenorphine")
n      <- c(10, 8)
events <- c(0, 1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  G-BMT, Buprenorphine  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5
ARM  Treatment as Usual, Buprenorphine  8  1  12.5  0.3  52.7  2.2  47.1  2.8  48.2

11. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary comparison as Fisher Exact, with p=0.44. It gives the outcome counts as 0 participants meeting the abstinence definition in the G-BMT group and 1 in the treatment-as-usual group. No sponsor-reported effect estimate or confidence interval is listed.

No independent recalculated two-group comparison is presented in the registry information used for this analysis: the binary comparison is marked as having values missing or not estimable for recalculation. The reported result therefore remains the sponsor’s Fisher exact test, rather than a second estimate to compare against it. The record indicates no discrepancy between sponsor and recalculated results; that does not add an unreported estimate or confidence interval.

In general, a simple recalculation from summary counts can be useful as a check, but it may not reproduce an analysis that uses participant-level data, adjustment, or other details not available in a registry record. Here, the posted information does not include a recalculated comparative estimate. Interpretation should therefore stay with the reported counts and p-value and should not imply that an independent calculation confirms or contradicts the sponsor’s analysis.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and four secondary outcomes. The secondary outcomes concern retention in buprenorphine treatment at 3 months and 6 months, sharing injection equipment at 8 weeks, acceptability, and feasibility measured as the percentage of visits attended. The registry entries used for this analysis provide no numerical results for those secondary outcomes. The record also lists 5 outcome measures and 2 analyses, but does not explain how those analyses relate to each outcome or specify a multiplicity procedure.

General: when several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase if each is interpreted without accounting for the full set of tests. Prespecified primary outcomes and adjustment procedures can help clarify how multiple findings should be interpreted. The registry record does not report whether any adjustment for multiple comparisons was planned or performed, nor does it specify a hierarchy or testing sequence. It is therefore not possible to determine from this record how multiplicity was handled.

For the primary endpoint, the registry specifies an intention-to-treat analysis and states that missing urine toxicology tests are considered positive for illicit opioids. That rule determines how a missing test affects the abstinence classification. The record does not give the number of missing tests, explain reasons for missingness, or report sensitivity analyses under alternative assumptions. It also does not describe missing-data handling for the secondary outcomes in the registry record used.

General: missing-data rules can affect both the classification of individual outcomes and the interpretation of a group comparison. Treating a missing test as positive is a defined classification choice, not a recovery of the unobserved test result. Without counts of missing assessments or sensitivity analyses, readers cannot assess how robust the primary comparison is to other missing-data assumptions.

The intention-to-treat label indicates the stated analysis population for the primary outcome, but the record does not describe other populations, exclusions, or deviations from assignment. No interim-analysis plan, stopping rule, detailed protocol, or full statistical analysis plan is reported in the registry record. These omissions limit evaluation of prespecification and of whether all planned analyses are represented in the posted results.

13. 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.

The registry’s safety record lists 0 serious adverse events among 10 participants at risk in the G-BMT group and 0 among 8 participants at risk in the treatment-as-usual group. It lists 0 other adverse events in each group. Deaths are recorded separately: 0 in the G-BMT group and 1 in the treatment-as-usual group.

These are counts within the registry’s stated at-risk groups. The record does not identify the cause, timing, or relationship to treatment of the death, so none should be inferred. It also does not provide details about the event or explain whether it was counted within another safety category. No serious adverse event terms are listed in the record.

General: zero recorded serious events in a small group does not establish that the risk is absent. Safety counts describe events recorded during the study under the registry’s reporting framework; they do not by themselves establish comparative safety or causation. The one death should be reported as recorded, without attributing it to either intervention. The available counts do not provide enough detail to characterize the circumstances or compare safety risks precisely.

The serious adverse event figures should not be confused with the primary abstinence outcome. They address separate aspects of the trial record, and the primary endpoint’s p-value does not apply to safety outcomes. The registry does not provide additional event descriptions or a statistical safety comparison in the registry record used.

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

The result describes the primary outcome as recorded: no participants in the G-BMT group and 1 participant in the treatment-as-usual group met the registry’s opioid-abstinence definition at 8 weeks. The reported Fisher exact p-value is 0.44. These findings concern this endpoint, in this trial, under the stated rule for defining abstinence and handling missing urine tests.

The result does not establish that the two approaches have the same effect. A failure to show a clear statistical difference is not evidence of equivalence. The registry does not report an equivalence or non-inferiority design, a prespecified margin, or a confidence interval that could indicate the range of effects compatible with the data. The result also does not establish that either approach improves abstinence, because the record reports no comparative effect estimate and the observed counts are sparse.

The result does not describe the full course of opioid use. The primary measure combines self-report for the prior 30 days with a urine test at the 8-week visit; it is not a continuous measure of use throughout follow-up. Nor does it answer the separate questions about retention, sharing injection equipment, acceptability, or visit attendance. Although those secondary outcomes are listed, their numerical results are not reported in the information used.

The study compares G-BMT plus buprenorphine with treatment as usual plus buprenorphine. It does not compare buprenorphine with no buprenorphine. The registry’s description of group accountability and behavioral support provides a rationale for the intervention, not a demonstrated mechanism or a finding that those elements changed outcomes.

General: randomized trials can support causal comparisons when their design, conduct, outcome measurement, and analysis are adequately described. Randomization alone does not guarantee precise estimates, especially when the number of participants and outcome events is small. In this record, the available primary result is too limited to characterize a precise effect. A measured p-value should not be converted into a claim about benefit, lack of benefit, or clinical importance.

15. Why This Trial Matters Statistically

This trial raises a statistical question about how to evaluate a group-based care model when the outcome is a sparse binary event. The primary endpoint has a clear operational definition combining self-report and toxicology, and the registry specifies how missing tests are classified in the intention-to-treat analysis. Those details matter because the definition and missing-data rule determine which participants count as meeting the endpoint.

The reported use of Fisher Exact highlights that binary outcomes with small counts call for methods suited to sparse data. General: an exact method can avoid relying on some large-sample approximations, but it cannot compensate for limited information. Readers still need an effect estimate and an interval to understand the size and precision of a comparison. The registry reports neither for the primary endpoint, leaving the p-value and counts as the available numerical description.

The study also illustrates the difference between a trial’s observed enrollment and a sample-size planning illustration. The registry provides assumptions for planning illustrations but does not report the study’s own sample-size justification. Treating planning values as observed power, or assuming that they describe the design rationale, would overstate what the record establishes. A small observed dataset can yield an uncertain estimate even when a test is calculated exactly.

Finally, the record places the primary result among several listed outcomes but does not report a multiplicity strategy or numerical results for the secondary outcomes. This makes it important to distinguish the primary comparison from unanswered questions about retention, feasibility, acceptability, and other measures. The statistical lesson is not a verdict on either care approach: it is that interpretation depends on endpoint definition, analysis population, missing-data handling, multiplicity, and precision, as well as the nominal test result.

16. 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 the primary comparison is the limited amount of outcome information. The registry reports only 0 and 1 participants meeting the abstinence definition in groups with 10 and 8 participants, respectively. It gives a p-value but no comparative effect estimate or confidence interval. As a result, the magnitude and precision of the contrast cannot be characterized from the reported analysis.

The primary endpoint combines self-report and urine toxicology. The registry does not provide the component-level results or the number of missing urine tests. Although it specifies that missing tests count as positive for illicit opioids, readers cannot determine how many outcome classifications were affected by this rule or assess sensitivity to another missing-data approach.

The trial is described as randomized and unmasked. The record does not provide details about allocation concealment, who knew group assignment during outcome assessment, or whether any outcome assessor was masked. The arm descriptions also do not provide a complete intervention manual: the G-BMT description is incomplete, and the full protocol is not reported in the registry record.

The registry lists secondary outcomes but the numerical results and analysis details for those outcomes are not present in the registry record used. It does not report a multiplicity strategy, detailed statistical analysis plan, interim analyses, or the trial’s sample-size justification. Those omissions make it difficult to assess prespecification and the relationship between planned and reported analyses.

The safety record gives event counts but not details about the death or the context of the safety observations. The registry entries also do not provide participant characteristics, adherence information, or other details that could help assess the study groups and conduct. These are limitations of what can be established from the registry record; they should not be replaced with assumptions about unreported procedures or results.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Buprenorphine Group Medical Visits in Primary Care — NCT02526212.
• Registry record last updated 2026-06-22; status last verified 2026-05.
• Results first posted 2020-07-07.
• 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.

20. Record Summary

NCT02526212 is a completed, randomized, unmasked, parallel-group Phase 3 trial sponsored by Montefiore Medical Center. The stated enrollment is 18. It compares G-BMT with buprenorphine against treatment as usual with buprenorphine among participants with opioid-related disorders.

The primary outcome is the number of participants with opioid abstinence at 8 weeks, defined by self-report and a negative urine toxicology test for opiates, methadone, and oxycodone. Missing urine tests are considered positive for illicit opioids in the stated intention-to-treat analysis. The registry reports 0 of 10 participants meeting the definition in the G-BMT group and 1 of 8 in the treatment-as-usual group, with Fisher Exact p=0.44.

No primary effect estimate or confidence interval is reported. The registry lists four secondary outcomes, but their results are not reported in the registry record used for this analysis. Safety counts include no serious adverse events in either group and one death in the treatment-as-usual group; circumstances are not reported in the registry record.