Buprenorphine and Methadone for Opioid Dependent Chronic Pain Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Buprenorphine and Methadone for Opioid Dependent Chronic Pain Patients (NCT00879996), a randomized phase 4 study. The primary outcome is Number of Participants Retained in Treatment.

2. Clinical Question

3. Trial Design

The registry describes a Phase 4, randomized, unmasked, parallel-group trial sponsored by the State University of New York at Buffalo. Enrollment was 54. The study status is completed; the recorded start is 2009-04 and primary completion is 2011-10. The record does not report further operational dates or the details of how random assignment was generated or concealed.

The two arms compared methadone with buprenorphine/naloxone over 6 months. Methadone was listed at 10-60 mg per day in 2-4 divided doses. Buprenorphine/naloxone was listed at 4-16 mg per day in 2-4 divided doses, using tablets of buprenorphine/naloxone:4/1 mg. The registry does not report how doses were selected or adjusted for individual participants.

Because masking is recorded as none, the trial was unmasked. The record does not describe whether outcome assessors or analysts were masked. In an unmasked study, knowledge of assigned treatment can potentially affect behavior, reporting, or assessment; whether that occurred in this trial cannot be determined from the registry record.

The principal outcome was retention in treatment at 6 months. Other posted outcomes cover pain rating, functioning rating, and self-reported illicit opioid use at 6 months. The registry lists four outcome measures and four analyses overall. It does not report the study's original sample-size justification, randomization procedure, detailed protocol, or statistical plan. Those omissions limit what can be concluded about the rationale for the enrolled sample and the prespecification of analyses.

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: All participants that were randomized were analyzed regarding their retention in treatment at 6 months.

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 Retained in Treatment, measured over 6 months.

The primary endpoint is the number of participants retained in treatment at 6 months. The registry describes it as the number who completed treatment after 6 months, and states that all randomized participants were analyzed for retention. The posted counts are 13 participants in the methadone arm and 13 in the buprenorphine/naloxone arm. The arm totals at randomization were 28 and 26, respectively.

Retention is a measure of whether participants stayed in the assigned treatment through the stated follow-up point. It can summarize acceptability, feasibility, and the ability to remain engaged in a trial regimen, but it does not by itself explain why participants did or did not complete treatment. The registry record does not report reasons for leaving treatment or details on how completion was verified.

Retention is not equivalent to improvement in chronic pain, functioning, or opioid use. Those topics appear as secondary outcomes, with their own reported measures. A result on retention should therefore be interpreted as evidence about continued participation in treatment, rather than as a direct measure of symptom change or broader clinical benefit.

7. Results Posted in the Registry

• Buprenorphine/Naloxone: 50.0% (13/26) versus 46.4% (13/28) on control; risk difference 3.6 percentage points (95% CI -23.1 to 30.2), risk ratio 1.08 (0.62–1.87); unadjusted two-proportion z-test p = 0.793.

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.

Numerical Rating Score for Pain

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Buprenorphine/Naloxone: mean 5.60 versus 5.40 on control; difference 0.20 (95% CI -1.28 to 1.68), standardized effect d = 0.10; z-test p = 0.792.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Buprenorphine/Naloxone and the control. The interval gives the range of effects that remain compatible with the data.

Numerical Rating Score for Functioning

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Buprenorphine/Naloxone: mean 5.30 versus 5.00 on control; difference 0.30 (95% CI -1.13 to 1.73), standardized effect d = 0.16; z-test p = 0.680.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Buprenorphine/Naloxone and the control. The interval gives the range of effects that remain compatible with the data.

Self-reported Illicit Opioid Use

• 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:
  • Buprenorphine/Naloxone: 38.5% (5/13) versus 0.0% (0/13) on control; risk difference 38.5 percentage points (95% CI 12.0 to 64.9); unadjusted two-proportion z-test p = 0.013.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Buprenorphine/Naloxone than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Across the secondary outcomes, the pattern is mixed rather than uniformly favoring one arm. Pain and functioning are represented by mean scores, while self-reported illicit opioid use is a participant count. The registry and simple comparisons do not present a consistent signal across these different types of outcomes. This makes it especially important not to substitute a secondary result for the primary question about retention.

The pain analysis deserves particular caution because the registry's reported ANOVA p-value differs sharply from the simple comparison based on the posted final means. The available record does not explain the difference. The functioning comparison does not provide a clear pattern of separation in the simple recalculation. The illicit-use comparison shows a contrast in the posted counts, but its interpretation is limited by the small outcome groups and the fact that it is one among multiple secondary measures.

Secondary outcomes can add context to the primary endpoint, but they do not automatically confirm or overturn it. Pain and function relate to patient-reported experience, while illicit-use reporting concerns a different behavior; retention measures continued treatment participation. These outcomes answer distinct questions, and their results need not move together.

The registry does not report a multiplicity strategy. When several outcomes are examined, the chance of at least one apparently notable result can increase, even when no adjustment is made. Accordingly, unadjusted secondary findings carry less weight than a prespecified primary analysis and are best viewed as exploratory. The record also does not report whether all intended secondary analyses were posted, so the full context for selecting or interpreting these results is unavailable.

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

• Numerical Rating Score for Pain
• Numerical Rating Score for Functioning
• Self-reported Illicit Opioid Use

9. Statistical Interpretation

10. Statistical Methods Explained

Two types of comparison appear in the results: analyses reported by the registry and simple unadjusted recalculations from the posted summary statistics. These answer related but not always identical questions. The registry's reported methods should be understood on their own terms, while the recalculations provide a transparent comparison based on the displayed counts or means. Neither should be mistaken for a fully adjusted analysis unless the record describes one.

What a risk difference means

For a binary outcome, a risk difference subtracts the outcome proportion in one arm from the outcome proportion in the other. In the primary comparison, the recalculation is expressed as buprenorphine/naloxone minus methadone. A value of zero would mean equal observed proportions; a positive value indicates a larger observed proportion in the first named arm. The estimate is 0.036. The confidence interval ranges from -0.231 to 0.302, so the data are compatible with differences in either direction as well as with little separation. This is a simple comparison of the posted counts, not a model adjusting for other factors.

What the log-rank result describes

The registry reports a log-rank method and a hazard ratio for retention. In general, a log-rank analysis compares the timing of events across groups while accounting for the ordering of event times. A hazard ratio compares event rates over follow-up under the assumptions of the analysis; it is not a difference in the proportions retained at one fixed time. The registry reports the hazard ratio as 0.913 with a 95% confidence interval from 0.416 to 2.007 and p = 0.77. The record does not provide further detail about event definitions, censoring, or the coding of the comparison, so those aspects cannot be examined independently.

What a mean difference means

For pain and functioning, the posted arm summaries are means with standard deviations. A mean difference compares the average score in one arm with the average in the other. The recalculated difference is a simple, unadjusted contrast of the posted final values. Its uncertainty depends on the variation in scores and the amount of information available. The registry reports ANOVA for both outcomes, but does not provide enough detail to establish whether the reported analysis included covariates, repeated measurements, or another structure. ANOVA is a general method for comparing means; its label alone does not disclose the full model.

Why uncertainty matters

A p-value describes how unusual results at least as incompatible with a specified null hypothesis would be under the assumptions of a test. It does not measure the probability that the null hypothesis is true, the size or importance of an effect, or the chance that a result will reproduce. A confidence interval gives a range of effect values compatible with the data and analysis assumptions at its stated confidence level. Wide intervals indicate limited precision. For this trial, the primary risk-difference interval extends across both negative and positive values, which is why the point estimate alone should not be read as a settled comparison.

Why analysis details affect interpretation

Randomization helps make groups comparable in expectation, but a modest trial can still have chance imbalances. An adjusted analysis can account for specified covariates or the structure of repeated measurements, but its interpretation depends on prespecified choices and model assumptions. The registry record does not report the detailed statistical plan, adjustment variables, or handling of repeated observations. These details should not be inferred from a method label.

For a binary outcome, small counts can make estimates unstable. In the self-reported illicit-use comparison, one arm has no observed participants with the outcome. Such data require care in interpreting measures such as odds ratios, because a zero cell can make ordinary ratio estimates difficult or undefined without a specific method. The registry reports a Fisher Exact analysis, while the displayed simple recalculation is a risk difference. These are different summaries and should not be collapsed into one number.

Over-dispersion is a general concern when observed variability exceeds what a simple probability model expects; it can make standard errors too small if ignored. The posted primary outcome is a count of participants with an event, rather than a rate across repeated counts, and the registry does not report an over-dispersion assessment. There is no basis in the record to assert that over-dispersion was present or that a particular correction was used.

The simple recalculations are not substitutes for access to individual participant data or a full statistical analysis plan. They use the arm summaries posted in the registry and do not account for unreported covariates, event timing, missing observations, or other model features. Where reported results differ from a simple recalculation, the available record may not contain enough detail to explain why.

11. Confidence Intervals and Precision

The primary risk-difference estimate is 0.036, with a 95% confidence interval from -0.231 to 0.302. A confidence interval describes the uncertainty around an estimate under the assumptions of the analysis. This interval includes zero, the value corresponding to no difference in the simple risk-difference measure. It also extends to values on either side, so the posted counts do not tightly determine the direction or size of the contrast.

The registry's time-to-event analysis gives a hazard ratio of 0.913 with a 95% confidence interval from 0.416 to 2.007. For a hazard ratio, 1 represents equal hazards under the comparison being made. The interval includes 1 and spans a broad range of possible values. The risk difference and hazard ratio refer to different estimands, so their intervals cannot be directly compared as if they were alternate scales for exactly the same analysis.

Precision is also limited by the scale of the study: 54 participants were enrolled, and the primary counts were 13 in each arm. The record does not report a precision target or the original sample-size justification. The size of the confidence intervals should therefore be considered alongside the observed counts, rather than treating the point estimate as definitive. Wide uncertainty does not show that a difference exists; it means that the posted data leave substantial uncertainty about its size and direction.

The secondary pain and functioning recalculations also have confidence intervals that span zero. The registry does not give confidence limits for its reported ANOVA estimates. For illicit opioid use, the recalculated risk-difference interval is 0.120 to 0.649, but that outcome has a small number of observations and is one of several secondary measures. Each interval is tied to its analysis and assumptions; none alone resolves concerns about missingness or multiple testing.

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 use the observed effects as starting points and show the number of participants per arm for 80% power and for 90% power. The listed rows consider planning for 100%, 75%, and 50% of the observed effect. These are hypothetical planning scenarios, not the trial's original design calculations. The figures for the primary and other non-time-to-event outcomes are participants per arm; time-to-event planning figures, when used, are total events. The posted calculations for this trial's outcomes are presented as participants per arm.

In plain terms, the 80% power column gives the planned per-arm sample size under which the calculation would have an 80% chance of detecting the specified effect if that effect were real and the assumptions held. The 90% power column represents a higher planned chance of detecting that effect under those same conditions. Power is not a guarantee for any particular study and depends on assumptions about the effect, variation, test, and design.

The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect. The registry does not report the assumptions used for the trial's original design, so these illustrations should not be treated as a reconstruction of the original planning.

Smaller target effects require more participants to distinguish them from random variation. That pattern is reflected by the increasing sample-size figures when planning for smaller fractions of the observed effect. The calculations are not observed power: they are prospective planning illustrations based on the posted effect estimates, not a measure of the trial's achieved ability to detect a result.

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 = 0.464; treatment proportion p₁ = 0.500; average p̄ = 0.482.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7067 = 1.3850.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.7062 = 0.5944.
4. n = (1.3850 + 0.5944)² / (0.0357)² = 3,071.7, rounded up to 3,072 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 <- 0.464285714285714                          # control proportion
p1 <- 0.5                          # 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(879996)
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 = 3,072 (80% power), 4,112 (90% power)
 75% of observed effect: n per arm = 5,458 (80% power), 7,306 (90% power)
 50% of observed effect: n per arm = 12,271 (80% power), 16,427 (90% power)
power.prop.test: 3071.7 
Simulated power at n = 3,072 per arm: 0.796 (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. Analyses Reported by the Sponsor

The registry reports a log-rank analysis for the primary retention outcome: hazard ratio 0.913, 95% confidence interval 0.416 to 2.007, and p = 0.77. The simple recalculation from the posted six-month counts instead gives a risk difference of 0.036, with a 95% confidence interval from -0.231 to 0.302 and p = 0.793. These are different methods and different effect measures. The hazard ratio concerns event timing; the recalculated risk difference contrasts the proportions retained at 6 months. Their estimates should not be read as duplicate outputs.

For pain, the registry reports ANOVA with a mean difference of 0.2 and p <0.043. The simple recalculation from the posted final means gives a mean difference of 0.2, a 95% confidence interval from -1.285 to 1.685, and p = 0.792. The p-values point to different inferential conclusions, and the record does not give enough analytic detail to reconcile them. The functioning result is also reported using ANOVA, while a simple recalculation is based on the final means.

The registry's method labels and reported values should be distinguished from recalculations based only on posted summaries. Detailed model specifications and analysis populations are not reported in the registry record. The record does not explain the pain-result difference, so readers should preserve that uncertainty rather than assume the analyses used identical data or methods.

15. Multiplicity, Missing Data and Analysis Populations

The record lists a primary retention outcome and secondary outcomes for pain, functioning, and self-reported illicit opioid use. It does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or a prespecified rule for interpreting multiple tests. When multiple outcomes are tested, unadjusted p-values do not account for the increased opportunity for chance findings. This matters particularly when one secondary result appears more notable than the rest.

The primary retention description states that all randomized participants were analyzed for retention at 6 months. For the secondary pain and functioning summaries, the posted arm sizes are 13 in each arm; for illicit opioid use, the posted arm sizes are also 13 in each arm. These figures are smaller than the randomized arm totals of 28 and 26. The registry does not report the disposition of participants between randomization and those secondary outcome summaries, reasons for missing values, or whether missingness was handled using any particular method.

The registry does not describe the analysis population for the secondary outcomes, imputation procedures, sensitivity analyses for missing data, or whether participants were analyzed according to randomized assignment for every outcome. No assumptions about missingness or the reason for the different posted sample sizes can be verified from the record.

The record also does not report an interim-analysis plan, stopping rules, a detailed analysis plan, or the original sample-size justification. It is therefore not possible to determine from the registry whether the listed analyses and outcome choices followed a prespecified plan. These omissions do not establish that the analyses were inappropriate, but they limit assessment of selective reporting, multiplicity, and the robustness of the findings.

16. 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.

The serious adverse event counts are reported as zero among 28 participants at risk in the methadone arm and zero among 26 participants at risk in the buprenorphine/naloxone arm. The registry also reports zero other adverse events in each arm, using the same at-risk counts. No serious adverse event terms are listed.

These figures mean that no events in those categories were posted for the stated groups. They do not establish that the treatments have no safety risks. Safety counts are limited by the participants observed, the follow-up period, and how events were collected and classified. The registry record does not provide additional details on event definitions, ascertainment procedures, severity beyond the serious-event category, or the handling of missing safety information.

Deaths are not reported as numeric counts in the record. That absence should not be interpreted as a confirmed zero. The posted adverse-event summaries are descriptive and should be read separately from the efficacy outcomes; they do not, by themselves, support a broad comparison of safety between treatment arms.

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

The results describe a randomized comparison of methadone and buprenorphine/naloxone for opioid-dependent patients with chronic pain, with retention in treatment at 6 months as the primary outcome. The posted counts are equal in number retained, and both the simple risk-difference comparison and the registry's log-rank analysis have substantial uncertainty. The data do not establish a clear difference in retention, but they also do not show that the two treatments are equivalent.

Equivalence requires a prespecified margin defining how much difference is considered acceptably small, along with an analysis designed to evaluate that question. The registry does not report an equivalence or noninferiority design, margin, or corresponding analysis. A non-significant comparison is not sufficient evidence of equivalence.

The trial also reports secondary outcomes in pain, functioning, and illicit opioid use. Those outcomes are distinct from treatment retention, and the results do not form a uniform pattern. The pain finding is especially difficult to interpret because the registry's ANOVA result differs from the simple recalculation using the posted means, with no explanation in the record. The secondary findings should not be treated as definitive proof of a broad treatment effect.

Interpretation is further constrained by the modest enrollment, smaller posted secondary-outcome groups, lack of reported missing-data methods, and absence of a multiplicity plan. The record does not provide participant characteristics or detailed protocol information needed to assess applicability beyond the enrolled population. The posted results are therefore best understood as limited evidence from this trial's recorded outcomes, not as a complete account of comparative effectiveness or safety.

No conclusion about what an individual should take follows from these statistics. The findings describe group-level outcomes under the study's recorded conditions and do not replace clinical judgment or other evidence.

18. Why This Trial Matters Statistically

This trial illustrates why the endpoint and the effect measure need to be identified before interpreting a comparison. The primary outcome is retention at a fixed follow-up point, while the registry's reported analysis uses a log-rank method and hazard ratio, which addresses event timing. The simple risk difference addresses the proportion retained at 6 months. Both can be informative, but they answer different statistical questions.

It also shows why uncertainty should be read alongside point estimates. The primary risk-difference interval extends across zero, while the time-to-event interval extends across 1. These intervals leave room for effects in either direction. Equal observed counts alone do not demonstrate equivalence, and a point estimate should not be mistaken for a precise effect.

The difference between the registry's reported pain ANOVA result and the simple recalculation from the posted means is a useful reminder that summary statistics do not always reproduce a reported analysis. Models may use information or assumptions not visible in the arm summaries, but the registry does not report enough detail to determine the explanation in this case. Transparent reporting of the analysis model and analysis population would help readers assess such differences.

Finally, the secondary outcomes and adverse-event counts show the limits of drawing broad conclusions from a small set of posted results. Multiple outcomes raise multiplicity questions, smaller outcome groups raise missing-data questions, and zero observed events do not establish absence of risk. These are general statistical interpretation issues illustrated by the registry record, not claims about what happened beyond the posted information.

19. 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 trial-specific limitations constrain interpretation. Enrollment was 54, and the primary retained counts were 13 in each treatment arm. The resulting primary confidence intervals are broad, so the comparison is not very precise. The registry does not report the original sample-size justification, making it impossible to assess the trial's planned ability to answer the primary question.

Although the trial is described as randomized and parallel-group, the registry does not report how the sequence was generated, how assignments were concealed, or whether any outcome assessors were masked. Masking is recorded as none. Participant and clinician knowledge of assignment could influence retention or self-reported outcomes, though the record does not establish that such effects occurred.

Secondary outcome summaries include 13 participants per arm, fewer than the randomized arm totals. Reasons for the difference, missing-data handling, and the secondary analysis populations are not reported. The pain analysis also has an unresolved mismatch between the registry's ANOVA p-value and the simple recalculation from posted final means. The detailed model, data, and analysis plan needed to resolve this are not reported in the registry record.

The registry does not report a multiplicity plan, detailed baseline characteristics, reasons for treatment discontinuation, or full protocol information. As a result, assessment of outcome selection, comparability at baseline, and the practical meaning of retention is limited. The posted safety data give zero serious and zero other adverse events, but event definitions and ascertainment details are not reported; deaths are not given as numeric counts. These gaps preclude a broad safety conclusion.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Buprenorphine and Methadone for Opioid Dependent Chronic Pain Patients — NCT00879996.
• Registry record last updated 2012-08-07; status last verified 2012-08.
• Results first posted 2012-07-09.
• 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.

23. Record Summary

The registry describes a completed Phase 4 randomized, unmasked, parallel-group trial sponsored by the State University of New York at Buffalo, with enrollment of 54. The study compared methadone with buprenorphine/naloxone over 6 months in opioid-dependent patients with chronic pain. Its primary outcome was the number of participants retained in treatment at 6 months.

The primary counts were 13 in each arm. The simple risk-difference estimate is 0.036, with a 95% confidence interval from -0.231 to 0.302. The registry also reports a log-rank hazard ratio of 0.913, with a 95% confidence interval from 0.416 to 2.007. Both comparisons are uncertain, and they measure different aspects of the outcome.

Secondary outcomes cover pain, functioning, and self-reported illicit opioid use. Their interpretation is limited by smaller posted outcome groups, absent multiplicity and missing-data details, and the unexplained difference between the reported and recalculated pain analyses. Serious and other adverse event counts are zero in both arms; death counts are not reported numerically.