Pharmacogenomics and Pharmacometabolomics of Acamprosate Treatment Outcome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pharmacogenomics and Pharmacometabolomics of Acamprosate Treatment Outcome (NCT03818191), a randomized phase 4 study. The primary outcome is Number of Participants With Continuous Sobriety According to Alcohol Timeline Follow Back.

2. Clinical Question

3. Trial Design

This was a completed phase 4, randomized, double-blind, parallel-group trial sponsored by Mayo Clinic. The registry lists an enrollment of 288 and identifies acamprosate and placebo as the interventions. The listed study start was 2019-07-15, and primary completion was 2023-11-04. The record marks the study as completed.

Random allocation and double masking are the design features stated in the registry. In general, random allocation is intended to make treatment groups comparable with respect to factors that could affect outcomes, while masking is intended to reduce the influence of treatment knowledge on participants’ reports and assessments. These design features do not by themselves establish that all relevant sources of bias were avoided. The sequence-generation method, allocation concealment, and practical details of masking are not reported in the registry record.

The posted primary analysis uses 101 participants in the acamprosate group and 55 in the placebo group. The registry describes the analyzed sample as including participants who completed 3 months, as well as those who dropped out but were known to have relapsed before that point. This outcome-specific analysis sample is not the same information as the overall enrollment figure. The record does not explain the relationship between enrollment, randomized participants, and the endpoint analysis in sufficient detail to reconstruct participant flow.

The project’s stated aim was to discover genomic and metabolomic markers associated with response to acamprosate. The registry also lists outcomes concerning time to first alcohol use, time to first heavy relapse, and cumulative abstinence duration. Details of treatment duration beyond the primary endpoint’s 3-month timeframe, follow-up procedures, and the original design assumptions are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Participants were evaluated by PRISM to confirm alcohol use disorder diagnosis and no secondary diagnosis of active other substance use disorder was present. Additional testing was done for renal impairment and advanced liver disease. Participants were required to be willing to stop chronic/daily use of prescribed benzodiazepines, opioids, stimulants, cannabis related medication such as CBD or medical marijuana during participation. Review of medications including anti-depressants was done.

Overall Study

Analysis population for the primary outcome, as defined in the registry: The analyzed sample included participants that completed 3 months of the study, as well as, those that dropped out but were known to have relapsed before 3 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 With Continuous Sobriety According to Alcohol Timeline Follow Back, measured over Will be defined as continuous sobriety (yes/no) during 3 months of treatment.

The primary endpoint is the number of participants classified as having continuous sobriety during 3 months of treatment. It is a binary outcome: each participant is categorized as meeting or not meeting the continuous-sobriety definition. The assessment used the Alcohol Timeline Follow Back, a method in which people use a calendar to provide retrospective estimates of daily drinking over a specified period. The registry describes the measure as evaluated with clinical and nonclinical populations.

A continuous-sobriety endpoint focuses on whether drinking occurred at any point during the specified treatment period, rather than on the amount or frequency of drinking across all days. It therefore answers a distinct question from measures that summarize abstinent days or time until relapse. In general, a binary endpoint can be presented as the proportion meeting the definition in each group and compared using an absolute difference in those proportions. The posted result gives group counts and an unadjusted risk difference.

The registry’s analyzed sample includes participants who completed 3 months and participants who dropped out but were known to have relapsed before 3 months. It does not describe how other missing or incomplete drinking information was handled. The endpoint’s value depends on the operational definition of continuous sobriety and the completeness and accuracy of retrospective drinking reports. Further details about verification, assessment timing, and handling of participants without known relapse who did not complete follow-up are not reported in the registry record.

7. Results Posted in the Registry

• Acamprosate: 65.3% (66/101) versus 70.9% (39/55) on control; risk difference -5.6 percentage points (95% CI -20.7 to 9.6), risk ratio 0.92 (0.74–1.15); unadjusted two-proportion z-test p = 0.479.

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.

Cumulative Abstinence Duration - Timeline Follow Back

• 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:
  • Acamprosate: mean 96.57 versus 96.01 on control; difference 0.56 (95% CI -3.38 to 4.50), standardized effect d = 0.06; z-test p = 0.781.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Acamprosate and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary outcomes concerning time until first alcohol use, time until first heavy relapse, and cumulative abstinence duration. A numerical group comparison is posted for cumulative abstinence duration. The time-to-event outcomes are named, but their estimates and results are not reported in the registry record. Accordingly, the secondary evidence cannot be treated as a complete set of comparable outcome findings.

The posted cumulative-abstinence comparison has a mean difference of 0.56, with a 95% confidence interval from -3.381 to 4.501 and an unadjusted p-value of 0.781. Its uncertainty includes no difference and contrasts in either direction. This broad pattern is compatible with the primary result, whose risk-difference interval also includes zero. Agreement in this limited sense does not mean the endpoints measure the same outcome: continuous sobriety is a yes-or-no classification, whereas cumulative abstinence summarizes the percentage of days abstinent.

In general, secondary outcomes can help describe different aspects of the clinical course and can provide context for a primary endpoint. They should not automatically be treated as independent confirmation. If several outcomes are tested, the chance of at least one apparently notable finding can increase unless the testing strategy accounts for multiplicity. The registry does not report a testing hierarchy, multiplicity adjustment, or which secondary outcomes were intended to support confirmatory conclusions.

Unadjusted secondary results therefore carry less weight as stand-alone evidence, particularly when analysis plans and missing-data handling are not available. The posted cumulative-abstinence comparison is best read as a descriptive supporting result with substantial uncertainty, rather than as a decisive confirmation or contradiction of the primary comparison. The unreported time-to-event results cannot be used to infer whether their patterns agree with the primary endpoint.

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

• Day Until First Alcohol Use (Relapse) - Alcohol Timeline Follow Back
• Days Until First Relapse (Heavy Relapse) - Timeline Follow Back
• Cumulative Abstinence Duration - Timeline Follow Back

9. Statistical Interpretation

10. Statistical Methods Explained

What does the primary comparison estimate?

The primary outcome is a count of participants who met a yes-or-no definition of continuous sobriety. For each group, the count is considered relative to the analyzed group size, producing an observed proportion. The posted risk difference compares the acamprosate proportion with the placebo proportion. A risk difference is expressed on the absolute proportion scale, so a value of zero represents equal observed proportions. The reported estimate is -0.056. Its direction is consistent with the posted proportions of 0.653 for acamprosate and 0.709 for placebo.

In general, a risk difference is often useful because it describes the absolute contrast between groups rather than a relative contrast. Its interpretation remains tied to the outcome definition and analyzed participants. The posted result is unadjusted: it does not account for covariates in a model. The registry record does not report a primary statistical model, covariate adjustment, or a prespecified analysis plan.

How should a confidence interval be understood?

In general, a confidence interval describes the range of estimates reasonably compatible with the data under the method’s assumptions. It reflects uncertainty in the estimated contrast, not the range of outcomes for individual participants and not a probability statement about a fixed treatment effect. The primary risk-difference interval runs from -0.207 to 0.096. Since it spans zero, it includes no observed difference as well as contrasts in either direction. The interval is broad enough that the result does not tightly determine the size or direction of the underlying difference.

The reported p-value of 0.479 is unadjusted. In general, a p-value measures how unusual data at least as inconsistent with a null hypothesis would be if that hypothesis and the analysis assumptions held. It is not the probability that a treatment effect is absent, and it does not measure clinical importance. The registry record does not report whether any multiplicity adjustment was planned or applied.

What is the continuous secondary outcome?

Cumulative abstinence duration is reported as the percentage of days over the 3-month follow-up during which participants were abstinent. Its specified scale ranges from 0, described as drinking continuously, to 100, described as complete abstinence. The posted means are 96.57 for acamprosate and 96.01 for placebo. The mean difference is 0.56, with a 95% confidence interval from -3.381 to 4.501 and an unadjusted p-value of 0.781.

In general, a mean difference summarizes the difference between group averages on the outcome’s measurement scale. The standard deviation describes variation among participant values around the mean; it is not the uncertainty in the mean itself. The posted standard deviations are 6.85 for acamprosate and 13.9 for placebo. The confidence interval for the mean difference includes zero and spans both positive and negative differences. The registry does not report a model or adjustment for the bounded nature of the percentage scale.

Why do analysis populations matter?

The primary outcome population is described as participants who completed 3 months plus those who dropped out but were known to have relapsed before 3 months. This rule includes some participants who did not complete the full follow-up, based on their known relapse status. It does not tell the reader how participants with incomplete follow-up and no known relapse were classified or excluded. The registry does not report an intention-to-treat analysis definition, a per-protocol definition, or sensitivity analyses for missing outcomes.

The primary endpoint group sizes are 101 and 55, while the registry’s enrollment figure is 288. The record does not supply enough participant-flow detail to establish how enrollment maps to randomization, treatment receipt, and each endpoint analysis. Safety outcome denominators also differ from the primary endpoint group sizes. Those figures should be read as outcome-specific reported denominators, not assumed to be interchangeable.

What cannot be inferred from the posted analyses?

There are no reported analyses listed for the cumulative-abstinence outcome. The registry gives its group summaries and an unadjusted comparison, but it does not report a model specification, a testing hierarchy, subgroup analyses, or confirmatory biomarker findings. The time-to-first-use and time-to-heavy-relapse outcomes are listed, but their results and analysis methods are not reported in the registry record.

In general, statistical interpretation depends on matching the analysis to the design, outcome, and analysis population. Randomization supports a treatment-group comparison when allocation and follow-up are implemented appropriately, but missing outcomes, deviations from assigned treatment, and selective reporting can affect the evidence. The registry record does not contain enough detail to evaluate all of these issues. The estimates should therefore be understood as the posted, unadjusted summaries rather than as a complete account of every planned or conducted analysis.

11. Confidence Intervals and Precision

The primary estimate is a risk difference of -0.056, with a 95% confidence interval from -0.207 to 0.096. The interval includes zero and extends to both negative and positive differences. This means the posted data do not pin down the direction of the underlying contrast with precision. The interval also permits differences appreciably larger in magnitude than the point estimate, so the point estimate alone should not be treated as a precise description of the effect.

In general, a confidence interval combines the estimated contrast with its sampling uncertainty. A narrower interval indicates greater precision under the method’s assumptions; it does not guarantee that the estimate is unbiased or that the assumptions are appropriate. A wider interval leaves more uncertainty about the range of contrasts compatible with the data. The registry record does not report a prespecified threshold for a clinically important difference, so the interval cannot be classified against such a threshold from the posted information.

The cumulative-abstinence mean difference is 0.56, with a 95% confidence interval from -3.381 to 4.501. This interval also includes zero and allows differences in either direction. The measure is reported in percentage of days, so the estimate and interval are on that scale. The interval’s interpretation remains subject to the outcome’s analysis population and the registry’s unreported details about missing observations.

Neither interval establishes equivalence. Equivalence requires a prespecified margin and an analysis designed to assess whether the full uncertainty interval lies within that margin; such a margin and analysis are not reported in the registry record. The intervals also do not establish that all possible clinically relevant effects are excluded. They show that the posted estimates retain substantial uncertainty in direction and magnitude.

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 figures are illustrative, not the original trial design assumptions. They were calculated using a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The trial’s own original sample-size assumptions and justification are not reported in the registry record.

For the binary primary outcome and the continuous cumulative-abstinence outcome, the listed figures are participants per arm. They are not totals across both groups. The 80% power column represents a planning target that, under the stated assumptions and for the chosen effect size, would give an 80% chance of detecting an effect at the specified significance level if that effect were the true one. The 90% power column uses a higher target probability of detection under the same planning framework.

The rows describe planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. A smaller effect is harder to distinguish from random variation, so the planning calculation requires more participants per arm as the assumed effect becomes smaller. For example, the primary-outcome illustration lists 1,101 participants per arm for 80% power at 100% of the observed effect, and 4,299 participants per arm for 80% power at 50% of the observed effect. These are design illustrations based on an observed estimate, not evidence that the trial had a particular probability of detecting an effect.

This is not observed power. The figures do not show the probability that the completed trial detected an effect, and they do not revise the uncertainty in the posted results. Their usefulness is limited by the instability that can arise when planning from an observed effect estimate, especially when that estimate is imprecise. The calculations also depend on the stated assumptions and do not incorporate design or analysis features that are not reported in the registry record.

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 = 0.709; treatment proportion p₁ = 0.653; average p̄ = 0.681.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6590 = 1.2916.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6578 = 0.5536.
4. n = (1.2916 + 0.5536)² / (-0.0556)² = 1,100.4, rounded up to 1,101 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 <- 0.709090909090909                          # control proportion
p1 <- 0.653465346534653                          # 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(3818191)
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 = 1,101 (80% power), 1,473 (90% power)
 75% of observed effect: n per arm = 1,935 (80% power), 2,589 (90% power)
 50% of observed effect: n per arm = 4,299 (80% power), 5,755 (90% power)
power.prop.test: 1100.4 
Simulated power at n = 1,101 per arm: 0.799 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a statistical analysis plan describing the primary testing procedure, any hierarchy among outcomes, or adjustments for multiple comparisons. This matters because the record lists a primary endpoint and several secondary outcomes, and the broader project also aimed to identify genomic and metabolomic markers. In general, testing many outcomes or candidate markers can increase the chance of finding an apparently notable association by chance. Prespecified prioritization and suitable multiplicity procedures help clarify which findings are confirmatory and which are exploratory. The registry does not state whether such procedures were used.

The primary analysis population is described as participants who completed 3 months and participants who dropped out but were known to have relapsed before 3 months. This provides some information about how known relapse among dropouts entered the analysis, but it does not explain the treatment of other incomplete records. The registry does not report the number or reasons for missing outcome assessments, whether any imputation was used, or sensitivity analyses under alternative missing-data assumptions. It also does not report how incomplete daily drinking histories were handled.

In general, missingness can affect a comparison when the likelihood of having an observed outcome is related to treatment assignment or the unobserved outcome. Simply analyzing participants with available data can yield a biased contrast under some patterns of missingness. Including dropouts known to have relapsed addresses that specific known outcome status but does not resolve uncertainty for participants whose status was not known.

The record does not define an intention-to-treat population or describe exclusions after randomization. It also does not report adherence, treatment discontinuation, protocol deviations, or a per-protocol analysis. Participant flow from enrollment to outcome analysis is not fully reported. These omissions limit assessment of whether the posted estimates preserve the comparison created by randomization and how robust they are to alternative assumptions about incomplete follow-up.

15. 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.

Most frequent non-serious adverse event terms

The registry reports serious adverse events in 0 of 184 participants at risk in the acamprosate group and 0 of 104 participants at risk in the placebo group. It reports deaths as 0 in each group. No serious adverse-event terms are listed. These figures indicate that the posted record contains no reported serious adverse events or deaths in the stated safety groups.

Other adverse events are reported for 55 of 184 at risk in the acamprosate group and 35 of 104 at risk in the placebo group. The registry does not provide event-specific descriptions in these results, so the counts should not be interpreted as identifying particular symptoms or causes. The intervention description mentions diarrhea and other frequently occurring side effects, but the posted adverse-event counts do not establish which events were recorded for individual participants.

Safety denominators differ from the primary endpoint analysis group sizes. The registry does not explain the relationship between the safety populations and the endpoint populations, nor does it provide detailed event collection, coding, severity, or attribution methods. These safety figures describe what is reported in the registry record; they do not establish that no unreported events occurred.

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

The posted primary comparison describes continuous sobriety during 3 months of treatment. The observed proportion was 0.653 for acamprosate and 0.709 for placebo, with a risk difference of -0.056 and a 95% confidence interval from -0.207 to 0.096. The interval includes zero and values in either direction. The data therefore do not precisely determine the direction or size of the difference in this analyzed sample.

This finding should not be read as proof that the treatments are equivalent, or as proof that one is better. The registry does not report an equivalence margin or a noninferiority analysis. The unadjusted p-value of 0.479 is not the probability that there is no effect, and it does not quantify the probability that either treatment would produce a particular outcome for an individual.

The endpoint is based on retrospective daily drinking estimates and a binary continuous-sobriety classification. It does not summarize all dimensions of alcohol use, and it is not interchangeable with the percentage of days abstinent or time to relapse. The cumulative-abstinence estimate likewise has uncertainty: its mean difference is 0.56, with a 95% confidence interval from -3.381 to 4.501. The other listed secondary outcomes do not have posted results in the registry record.

The study’s stated purpose included identifying genomic and metabolomic markers associated with response. The posted clinical outcome summaries do not establish whether such markers were identified or validated. No biomarker results, analyses, or clinical prediction performance are reported in the registry record.

Interpretation is also limited by incomplete reporting of participant flow, missing outcomes, treatment adherence, and the statistical analysis plan. The registry’s enrollment figure is 288, while the primary outcome summaries use outcome-specific group sizes. Without fuller accounting, these summaries cannot answer every question about retention or the impact of incomplete follow-up. They describe the reported comparisons, not a complete reconstruction of the trial.

17. Why This Trial Matters Statistically

This trial is statistically informative because it places a binary sobriety outcome and a measure of abstinent days within a randomized, double-blind comparison of acamprosate with placebo. The two outcomes address related but different aspects of drinking during follow-up. Reading them together can clarify whether the broad pattern depends on defining success as continuous sobriety or summarizing the proportion of abstinent days.

The posted primary result also illustrates why point estimates and uncertainty intervals must be considered together. A single estimated difference can look definitive if read alone, whereas its confidence interval shows that the data remain compatible with differences in either direction. The posted cumulative-abstinence comparison likewise has an interval that includes zero. Neither result supports a precise conclusion about the direction or magnitude of a group difference.

The trial’s stated biomarker-discovery aim raises a further statistical challenge: associations between genomic or metabolomic measures and response require careful control of multiplicity, clear definitions of response, and validation beyond the data used to discover candidate markers. Those methods and findings are not reported in the registry record. The clinical outcome summaries therefore should not be mistaken for evidence that predictive biomarkers were established.

Finally, the record shows why outcome-specific populations and transparent participant flow matter. The primary and safety summaries use different denominators, while the relationship of those groups to overall enrollment is not explained in detail. This limits assessment of missingness and the extent to which each result represents the randomized groups. These reporting gaps do not negate the posted estimates, but they constrain the strength and scope of conclusions that can be drawn from them.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record leaves several trial-specific details unresolved. It does not report the acamprosate dose or schedule, the treatment allocation procedure beyond stating that allocation was randomized, or the practical steps used to maintain masking. It also does not provide a participant-flow account linking the enrollment figure to randomized participants, treatment exposure, and outcome-specific analyses.

The primary outcome population includes completers and participants known to have relapsed before 3 months, but the record does not explain how other participants with incomplete follow-up were treated. Missing outcome counts, reasons for dropout, and sensitivity analyses are not reported. Since the endpoint relies on retrospective drinking estimates, the record’s lack of detail about incomplete calendars, verification, and assessment procedures also limits appraisal of measurement quality.

Only the cumulative-abstinence secondary outcome has a posted numerical comparison. Results for time until first alcohol use and time until first heavy relapse are not reported in the registry record. The registry also does not report analyses of the genomic or metabolomic markers central to the stated project aim. Statistical methods, covariate adjustment, subgroup analyses, multiplicity procedures, and the original sample-size rationale are not reported.

The registry reports no serious adverse events and no deaths in the stated safety groups, but event collection and attribution methods are not described in detail. Different denominators across outcomes further limit direct comparisons between safety and efficacy summaries. These are limitations of what can be established from the registry record, rather than claims about procedures or findings that may exist outside it.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Pharmacogenomics and Pharmacometabolomics of Acamprosate Treatment Outcome — NCT03818191.
• Registry record last updated 2024-12-17; status last verified 2024-11.
• Results first posted 2024-12-17.
• 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

NCT03818191 is a completed phase 4 randomized, double-blind, parallel trial sponsored by Mayo Clinic, with an enrollment of 288. It compared acamprosate with placebo and listed continuous sobriety during 3 months as the primary outcome, assessed using the Alcohol Timeline Follow Back.

The primary result was 66 of 101 participants continuously sober in the acamprosate group and 39 of 55 in the placebo group. The risk difference was -0.056, with a 95% confidence interval from -0.207 to 0.096 and an unadjusted p-value of 0.479. The posted cumulative-abstinence comparison also had an interval that included no difference.

The project aimed to identify genomic and metabolomic markers of response, but biomarker findings are not reported in the registry record. Results for the listed time-to-relapse outcomes, detailed missing-data methods, and the original statistical design assumptions are also not reported.