Treatment With Lorcaserin for Cocaine Use: The TLC Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treatment With Lorcaserin for Cocaine Use: The TLC Study (NCT03192995), a randomized phase 2 study. The primary outcome is Adverse Clinical Events in the Lorcaserin and Placebo Arms (Descriptive).

2. Clinical Question

3. Trial Design

The TLC Study (NCT03192995) is registered as a phase 2 randomized, parallel-arm trial in cocaine use disorder. It compares lorcaserin with placebo, with substance use counseling and behavioral assessments included in both arm descriptions. The experimental arm also received lorcaserin extended release; the control arm received placebo. The brief summary describes treatment twice a day for 12 weeks, while the primary endpoint timeframe is 12 weeks.

The registry classifies the design as randomized and triple-masked. Its brief summary describes a double-blind trial. These labels are not identical, and the record does not explain which people were masked or how masking was maintained. Allocation procedures beyond the randomized designation are not reported in the registry record. The parallel design means the arm descriptions concern separate assigned groups rather than a stated crossover comparison.

The recorded enrollment is 22. The brief summary says the study would enroll 45 individuals, so that planned figure should not be mistaken for the enrollment recorded in the registry. The study status is terminated. The start date is 2018-01-01 and primary completion is listed as 2020-02-28. The reason for termination and the timing or circumstances of participant withdrawal are not reported in the registry record.

Besides adverse-event monitoring, listed study procedures include ACASI, cocaine-metabolite testing, ecological momentary assessment, the Balloon Analogue Risk Task, and qualitative exit interviews. The registry lists five outcome measures and five analyses, but the available record does not describe each measure or analysis in enough detail to reconstruct a complete statistical plan. No sample-size justification, interim-analysis plan, or detailed allocation procedure is 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: On 2/13/2020, the Food and Drug Administration (FDA) issued a safety alert after concluding the assessment of the long-term safety of lorcaserin in CAMELLIA clinical trial among 6,000 participants who took lorcaserin for over 4.3 years and were overweight or obese, with cardiovascular disease. The analysis showed an increased risk of cancer. In response to the safety alert, active participants in our study were instructed to stop study medication use and informed of the FDA safety alert.

Overall Study

Analysis population for the primary outcome, as defined in the registry: The Food and Drug Administration (FDA) issued an early termination of this study after concluding the assessment in the long-term safety of lorcaserin in another clinical trial among obese, cardiovascular patients who had been taking lorcaserin for an average of 4.3 years. At the time of early termination, we had enrolled a total of 22 participants and this is why the overall number varies for this analysis.

5. Baseline Characteristics

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

Population: Treatment and control assignments

6. Primary Endpoint

The registry lists the primary outcome as Adverse Clinical Events in the Lorcaserin and Placebo Arms (Descriptive), measured over 12 weeks.

The primary endpoint is the count of adverse clinical events in the lorcaserin and placebo arms over 12 weeks. The registry description says investigators intended to compute adverse events overall and by type to explore tolerability. It also explicitly notes that a participant could have more than one adverse event. Thus, the endpoint concerns events, not simply whether each participant experienced any event.

Counting events can preserve information about repeated occurrences that a yes-or-no measure would not retain. In general, such counts may be useful for describing the burden and types of events recorded during follow-up. However, counts need careful interpretation: participants can contribute different numbers of events, and a group’s total event count is not interchangeable with the number of participants affected. The record’s adverse-event summary separately labels people at risk and affected, but it does not provide a single arm-level comparative result for the primary count endpoint.

The endpoint is described as descriptive, and the registry does not report a primary contrast, confidence interval, or significance test for it. The record also does not state how event severity, recurrent events, or time at risk were handled in a statistical model. Those details are important when moving from descriptive counts to a claim about differences between treatment groups, so no such claim can be reconstructed from the endpoint description alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, parallel-arm comparison of lorcaserin and placebo. Randomization is intended, in general, to support a fair comparison by allocating participants without choosing treatment according to their prognosis. It does not guarantee that groups will be balanced on every characteristic, particularly in a small study. The allocation sequence, concealment procedure, and any checks of baseline balance are not reported in the registry record.

What does a count endpoint capture?

The primary outcome is a count of adverse events, rather than a continuous measurement or a simple indicator of whether an event occurred. A count can retain repeated events for the same participant, which matters because the registry explicitly says that a participant could have more than one adverse event. A count of events and a count of affected participants answer different descriptive questions. The posted adverse-event summary labels affected people, while the primary endpoint description calls for counting events. The record does not provide a complete set of arm-level primary event counts that would allow those measures to be reconciled.

In general, count data are nonnegative and may be unevenly distributed: many participants may have few events while some have more. A simple comparison of group averages can be misleading if the variability is much greater than a chosen model expects. This is called over-dispersion. When it is present, a model that accounts for extra variability may give more realistic uncertainty than a model that assumes the count variation is tightly constrained by its mean. This is general statistical context; the registry record does not say that over-dispersion was assessed or identify a count model.

Follow-up time also matters for event counts. If participants contribute different durations of observation, a raw total can reflect both event frequency and time observed. In general, an analysis may account for exposure time, but the registry record does not say whether follow-up time varied, whether an exposure-time adjustment was used, or how incomplete observation was handled. The stated timeframe is 12 weeks; that alone does not establish that every participant contributed a complete 12 weeks of observation.

How should uncertainty be understood?

In general, a confidence interval describes a range of effect values compatible with the data under the analysis assumptions. Its width conveys precision: a wider interval indicates less precise estimation than a narrower interval. A p-value, when used, describes how unusual data at least as incompatible with a specified null model would be if that model were true; it is not the probability that a treatment works or that the null hypothesis is true. These are general explanations. The registry record reports no confidence interval or p-value for a primary comparison, so neither precision nor statistical evidence for an arm difference can be assessed from such measures.

A descriptive count can still be informative about what was recorded, but without an estimate of uncertainty it cannot show how stable the apparent difference might be in another sample. In general, sparse counts and small groups can produce substantial uncertainty. No inferential method, adjustment, or uncertainty calculation for the primary endpoint is identified in the registry record. The design is randomized, but randomization by itself does not supply a treatment-effect estimate or establish its precision.

What do the planning assumptions mean?

The registry’s sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. In general, a significance level is a design threshold used to define how often a test would reject a null hypothesis under that hypothesis and the test assumptions. Equal allocation is a planning condition that assigns the same intended number of participants to each arm. A normal approximation uses a normal distribution to approximate the sampling behavior of an estimate or test statistic.

The illustrations are not observed power and are not evidence that the completed study had a particular probability of detecting an effect. Sample-size illustrations depend on the effect chosen for planning and on assumptions about variability and analysis. The registry says that the effect to detect is a stated fraction of the observed effect, but the primary outcome is not reduced to one comparison. No numerical planning results or single observed primary effect are reported in the registry record, so no planning requirement can be interpreted as a result from this trial. For time-to-event outcomes, the stated convention is a total number of events; for other outcomes it is participants per arm. The primary outcome is a count, not a stated time-to-event endpoint.

More broadly, the registry lists five outcome measures and five analyses, but does not report enough detail to identify the full analysis strategy. The endpoint population, model specification, handling of repeated events, and approach to uncertainty are not reported in the registry record. Without those details, a reader cannot reproduce an adjusted or model-based analysis from the adverse-event summary alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures and five analyses. The primary measure concerns adverse-event counts, but the remaining outcomes, their order of importance, and the relationship between the listed analyses and outcomes are not described in enough detail to reconstruct a testing hierarchy. Whether the investigators adjusted for multiple comparisons is not reported in the registry record.

Multiplicity matters when several outcomes, event types, time points, or subgroup comparisons are examined. In general, repeated testing can increase the chance of seeing an apparently notable result even when there is no underlying effect. A prespecified hierarchy or adjustment can help interpret that risk, but neither can be inferred from the number of listed measures and analyses alone. The endpoint description mentions overall counts and counts by type, which could involve multiple descriptive summaries; the record does not state whether any formal tests were performed across those categories.

Missing-data procedures are not reported in the registry record. It does not specify how missing outcome assessments, missed visits, incomplete follow-up, or withdrawal were handled. Nor does it state whether adverse events were collected for all participants through the full 12-week timeframe. The terminated status makes completeness relevant, but the reason for termination and its effect on follow-up are not reported.

The analysis population is also not reported in the registry record. The record does not specify whether analyses used all randomized participants, only those who began treatment, participants with available outcome data, or another defined group. No intention-to-treat or per-protocol designation is given. These omissions limit interpretation of the arm-level safety summaries and prevent assessment of whether exclusions or missing observations could have affected the comparison.

11. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: plasma alanine aminotransferase level and plasma aspartate aminotransferase levels (16.7%), abscess of hip (6.2%).

The serious-event figures are presented as at-risk and affected counts. The experimental group is recorded as 16 at risk and 1 affected; the control group is recorded as 6 at risk and 1 affected. The corresponding death entries are 0 for each group. For other adverse events, the record lists 16 at risk and 16 affected in the experimental group, and 6 at risk and 6 affected in the control group.

These counts should be read as the registry labels them. In particular, “affected” does not mean that the total number of events was the same as the number of affected people. The primary endpoint description allows more than one event per participant, and the safety summary does not give the total event count for each group. The record does not report event timing, duration, relatedness, or a detailed severity breakdown beyond the serious-event classification.

The listed serious-event terms are “Plasma Alanine aminotransferase level and plasma aspartate aminotransferase levels” at 16.7% and “Abscess of Hip” at 6.2%. The record does not report the denominator or whether these percentages refer to participants, events, or another basis. It also does not assign these terms to an arm in the listed information. They therefore should not be used to infer arm-specific incidence or comparative risk.

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

The record establishes that a randomized phase 2 trial was registered to compare lorcaserin with placebo in actively using men who have sex with men with cocaine use disorder. Its primary endpoint was intended to describe adverse-event counts over 12 weeks, overall and by type. The record also gives descriptive affected counts for serious and other adverse events and records 0 deaths in each group.

Those entries do not amount to a complete comparison of the primary endpoint. The registry does not provide a single arm contrast, an uncertainty interval, or a significance test for the event-count outcome. The affected counts are not interchangeable with total event counts, especially because participants could experience more than one event. The serious-event percentages also lack a reported denominator and arm attribution. As a result, the available figures do not establish the relative frequency of all adverse events between groups.

The record does not establish that lorcaserin is effective or ineffective for cocaine use disorder. The endpoint described is a tolerability-focused adverse-event count, and the available information does not provide an efficacy estimate. It also does not establish that either regimen is safe or unsafe. Descriptive event entries are useful as a record of what was reported, but cannot by themselves characterize all potential harms or their causal relationship to treatment.

Enrollment was recorded as 22, while the brief summary describes a plan for 45. The study status is terminated. These details signal that the record of the completed study differs from the stated enrollment plan, but the reason for termination and its consequences for analysis are not reported in the registry record. It would be inappropriate to infer that the termination was caused by safety, lack of efficacy, recruitment, or any other specific factor.

Accordingly, the most defensible interpretation is limited: the registry reports group-level safety descriptors, but does not report the analysis needed to quantify a treatment contrast for the primary endpoint. Further details about outcome definitions, follow-up, missing data, statistical methods, and participant disposition would be needed to support a fuller statistical interpretation.

13. Why This Trial Matters Statistically

This trial illustrates why endpoint definitions and result labels matter in clinical statistics. The primary outcome is a count of adverse events, and the registry explicitly allows repeated events for a participant. The safety summary, however, labels the number affected. Event totals and affected-person counts are different quantities. Keeping that distinction clear prevents a reader from treating a participant count as though it were the endpoint’s event count.

The record also illustrates how a trial’s stated plan and registered enrollment can differ. The brief summary describes planned enrollment of 45, while recorded enrollment is 22, and the study status is terminated. Those details are relevant context for the amount of information available, but they do not explain why enrollment differed or why the trial ended. Statistical interpretation should separate what the record documents from possible explanations that it does not document.

Another important issue is that descriptive safety entries are not the same as a comparative analysis. A randomized design can support a treatment comparison, but readers still need the actual contrast, its uncertainty, and a clear account of the analysis population and missing observations. Here, the primary outcome is not reduced to one comparison, and the record does not identify a statistical model or provide a confidence interval or p-value.

Finally, percentages attached to serious-event terms can be difficult to interpret without a stated denominator and arm attribution. Reporting a percentage without its basis does not make the comparison self-evident. This study therefore offers a practical example of the value of transparent endpoint definitions, denominators, analysis plans, and participant-follow-up reporting when interpreting trial safety data.

14. 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 important trial-specific details unresolved. It lists a planned enrollment of 45 in the brief summary and recorded enrollment of 22, and it marks the study terminated. The reason for termination, the disposition of participants, and the completeness of the 12-week follow-up are not reported in the registry record. These gaps prevent a reader from determining how the termination affected the available outcome data.

The record describes the primary endpoint as the number of adverse events overall and by type, but does not provide a single arm-level result for that event-count endpoint. The adverse summary instead reports at-risk and affected counts. Since participants could have more than one event, those summaries do not reveal the total number of events. The denominator and arm attribution for the listed serious-event percentages are also not reported in the registry record.

Other limitations concern the analysis. The registry does not specify an analysis population, missing-data handling, treatment of recurrent events, model, or method for calculating uncertainty. It lists five outcome measures and five analyses without describing their full hierarchy or whether multiplicity was addressed. The record also does not describe the randomization procedure or clarify the difference between its triple-masking classification and the brief summary’s double-blind wording.

The trial concerns a particular population—actively using men who have sex with men with cocaine use disorder—and the record does not provide participant characteristics that would permit a more detailed assessment of who enrolled. These limitations constrain interpretation of the registry results and do not support conclusions beyond the descriptive details recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Treatment With Lorcaserin for Cocaine Use: The TLC Study — NCT03192995.
• Registry record last updated 2023-08-14; status last verified 2023-08.
• Results first posted 2023-08-14.
• 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.

18. Record Summary

NCT03192995 is a phase 2 randomized, parallel-arm trial of lorcaserin versus placebo for cocaine use disorder. The target population was actively using men who have sex with men. The registry lists triple masking, while the brief summary describes a double-blind trial. Both arm descriptions include substance use counseling and behavioral assessments; the experimental arm includes lorcaserin extended release and the control arm placebo.

The brief summary describes treatment twice a day for 12 weeks. The primary endpoint is a descriptive count of adverse events overall and by type during 12 weeks, with the possibility of multiple events per participant. Recorded enrollment is 22; the brief summary states a planned enrollment of 45. The study is marked terminated. The registry reports descriptive serious and other adverse-event affected counts and 0 deaths in each group, but does not provide a single comparative primary-outcome estimate or detailed analysis methods. The reason for termination and the missing-data and analysis-population procedures are not reported in the registry record.