Predictors of Lorcaserin-Induced Weight Loss: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Predictors of Lorcaserin-Induced Weight Loss (NCT03353220), a randomized phase 4 study. The primary outcome is Mean Differences in Food Intake During a Laboratory Test Meal After Lorcaserin for One Week Compared to Placebo.

2. Clinical Question

The study is registered as a Phase 4, randomized, double-masked, crossover trial titled “Predictors of Lorcaserin-Induced Weight Loss.” Its brief description frames the research around both identifying possible predictors of response and understanding mechanisms that might limit drug efficacy. The posted primary outcome is a short-term laboratory measure; it is not itself a direct measure of long-term weight change.

The outcome population note says results were organized by placebo or lorcaserin exposure rather than by the two sequence arms. It also notes that a participant was exposed to either placebo or lorcaserin at a given point. That distinction matters for interpreting a crossover study: the sequence arms describe the order of treatments, while the posted primary summaries compare exposure periods. How the analysis accounted for the relationship between measurements from the same participant is not reported in the registry record.

3. Trial Design

The registry record describes a randomized, double-masked, crossover study with two phases. In the first phase, the two sequences received lorcaserin and placebo in opposite orders. Arm A received lorcaserin at 10 mg twice a day for 7 days, followed by a 3 week washout, and then placebo twice a day for 7 days. Arm B received placebo twice a day for 7 days, followed by the same washout period and then lorcaserin at 10 mg twice a day for 7 days.

The brief study description says the initial crossover phase was planned for 5 weeks and was to be followed by 24 weeks of lorcaserin treatment. The listed primary-measure timeframe is the first test meal and follow-up test meal, approximately up to 5 weeks. The registry record does not report results from the planned later treatment phase, nor does it report whether that phase was completed. The study status is terminated; the reason for termination is not reported in the registry record.

Enrollment is listed as 32. The primary exposure-period summaries report 30 observations for placebo and 30 for lorcaserin. These are exposure-specific figures and should not be added to infer a number of distinct participants. Reasons for the difference between enrollment and the posted outcome counts, and the handling of missing observations, are not reported in the registry record.

Columbia University is listed as the sponsor. The study start date is 2018-01-03, and the primary completion date is 2020-02-14. More detailed information about random-sequence generation, concealment, masking procedures, adherence, protocol deviations, and the analysis population is not reported in the registry record. Those details would help assess how the planned crossover design was implemented and how closely the posted analysis followed it.

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: Out of the 32 enrolled subjects: 30 subjects completed Phase 1 (Arms A and B) and 30 subjects continued into Phase 2. However, the study was stopped prematurely during Phase 2 as lorcaserin was withdrawn from the market. Data was collected and analyzed for the 30 subjects that completed phase 1 out of 32 subjects; the 2 subjects who did not complete phase 1 were excluded from analysis. 19 subjects completed phase 2.

First Intervention (7 Days) - Phase 1

Washout (3 Weeks) - Phase 1

Second Intervention (7 Days) - Phase 1

Third Intervention (6 Months) - Phase 2

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The data information were collected and analyzed separately for the time period of placebo or drug exposure - i.e., comparing participants receiving placebo only OR Lorcaserin only (instead of comparing Arm A and Arm B). At one point, the same participant was exposed to either placebo OR Lorcaserin. Therefore, there are 30 analyzed for placebo only and 30 analyzed for drug only.

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 Mean Differences in Food Intake During a Laboratory Test Meal After Lorcaserin for One Week Compared to Placebo, measured over First test meal and follow-up test meal (approximately up to 5 weeks).

The primary endpoint is the mean difference in food intake during a laboratory test meal after one week of lorcaserin compared with one week of placebo. Intake is expressed in kcal, with the endpoint described as the average calories consumed during the test meal. The registry gives the timeframe as the first test meal and follow-up test meal, approximately up to 5 weeks.

This measure was selected to address a proposed predictive question: whether short-term differences in calories consumed during a test meal might predict longer-term lorcaserin-induced weight loss. A laboratory meal provides a standardized context for measuring food intake, but the posted endpoint is still a short-term behavioral measure. It does not directly measure long-term weight change, and the primary comparison alone cannot establish whether meal-intake differences predict later weight loss.

The posted exposure-period means are 919.8 kcal for placebo and 891.9 kcal for lorcaserin. The recalculated mean difference, defined as lorcaserin minus placebo, is -27.9 kcal. Its confidence interval extends from -343.8 to 288.0 kcal, indicating substantial uncertainty around the estimated difference. The confidence level for that interval is not reported in the registry record.

The population note says the data were analyzed by exposure period rather than by sequence arm. The registry record does not report whether the primary analysis used paired participant-level measurements, how the two meal measurements were combined or modeled, or how the predictor question was evaluated against later weight outcomes.

7. Results Posted in the Registry

• Lorcaserin: mean 891.90 versus 919.80 on control; difference -27.90 (95% CI -343.76 to 287.96), standardized effect d = -0.04; z-test p = 0.863.

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.

CSF Concentrations of ß-endorphin

• 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 errors.
• Result:
  • Lorcaserin: mean 55.80 versus 49.07 on control; difference 6.73 (95% CI -1.35 to 14.81), standardized effect d = 0.42; z-test p = 0.103.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lorcaserin and the control. The interval gives the range of effects that remain compatible with the data.

Mean Differences in AgRP Concentrations (pg/ml) in CSF After Lorcaserin for One Week Compared to Placebo

• 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 errors.
• Result:
  • Lorcaserin: mean 24.20 versus 25.90 on control; difference -1.70 (95% CI -10.16 to 6.76), standardized effect d = -0.10; z-test p = 0.694.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lorcaserin and the control. The interval gives the range of effects that remain compatible with the data.

Mean Differences in AgRP Concentrations (Fmol/ml) in Blood After Lorcaserin for One Week Compared to Placebo

• 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 errors.
• Result:
  • Lorcaserin: mean 79.20 versus 78.70 on control; difference 0.50 (95% CI -21.12 to 22.12), standardized effect d = 0.01; z-test p = 0.964.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lorcaserin and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the study’s focus from meal intake to biological measures, including CSF and blood concentrations and insulin. The registry lists five secondary outcomes, while numerical exposure-period results are posted for three continuous measures. The registry record does not report numerical results for every listed secondary outcome, so the available secondary data do not provide a complete account of all registered measures.

Across the posted secondary comparisons, the pattern is mixed rather than uniformly aligned in direction or apparent strength. Some recalculated intervals include zero, and the posted estimates vary in magnitude. This does not establish a coherent biological profile, nor does it establish that any secondary measure explains or predicts the primary meal-intake result. The primary endpoint and secondary biomarkers address different questions and should be interpreted on their own scales and with their own uncertainty.

Secondary results generally carry less weight than a prespecified primary comparison when many outcomes are examined. Each additional test creates more opportunities for a seemingly notable result to occur by chance. The registry record does not report a multiplicity adjustment, a hierarchy for interpreting secondary outcomes, or a complete analysis plan. The secondary p-values should therefore be treated as exploratory unless the protocol or analysis plan, not reported in the registry record, establishes otherwise.

Some secondary entries include sponsor-reported analyses, while others do not. The number and detail of reported analyses are not consistent across the posted measures. This limits direct comparison of inferential evidence across outcomes. In addition, the blood AgRP outcome title names Fmol/ml whereas its posted unit is pg/ml; that inconsistency warrants clarification before quantitative interpretation. The broad secondary pattern can add context, but it cannot resolve the uncertainty in the primary result or demonstrate a predictor of longer-term weight change.

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

• CSF Concentrations of ß-endorphin
• Mean Differences in AgRP Concentrations (pg/ml) in CSF After Lorcaserin for One Week Compared to Placebo
• Mean Differences in AgRP Concentrations (Fmol/ml) in Blood After Lorcaserin for One Week Compared to Placebo
• Mean Differences in Cortisol Concentrations (ng/ml) in CSF After Lorcaserin for One Week Compared to Placebo
• Insulin Level

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a mean of meal calories. For a continuous measure, the group mean describes the center of the observed values, while a standard error describes the precision of the estimated mean under the analysis assumptions. The posted primary standard errors are 118.7 kcal for placebo and 109.0 kcal for lorcaserin. A standard error is not the same as the spread of individual participant measurements; it reflects uncertainty in an estimated mean.

What does the mean difference represent?

The reported comparison is lorcaserin minus placebo. Its estimate is -27.9 kcal, so the point estimate places mean meal intake lower during lorcaserin exposure than during placebo exposure. This direction describes the estimate, not a conclusion that the exposure caused a change. The accompanying interval ranges from -343.8 to 288.0 kcal, so the estimate is uncertain. The interval’s confidence level is not reported in the registry record.

A confidence interval describes a range of values compatible with the data and the method used to calculate it. In general, a narrow interval indicates greater precision than a wide interval, all else being comparable. An interval containing zero does not show that the true difference is zero; it indicates that zero is among the values not excluded by that interval. The assumptions and confidence level matter when interpreting an interval, and the registry does not state the confidence level for the posted comparison.

Why does the crossover structure matter?

General statistical explanation: crossover designs can use within-participant comparisons, because the same participant may receive each exposure at different times. Measurements from the same person are often related. An analysis that accounts for this relationship can differ from an analysis that treats exposure groups as independent. The registry says the primary data were organized by placebo or drug exposure rather than by Arm A or Arm B, and that a participant was exposed to either treatment at a given point. It does not report whether the primary test used paired observations, how sequence or period effects were handled, or whether carryover was assessed.

The posted recalculation is based on the summary statistics and is described as an unadjusted recalculation. It cannot recover the within-participant covariance from the separate means and standard errors. Therefore, it is useful as a transparent summary-statistic comparison, but it may not reproduce the analysis that would be obtained from participant-level crossover data. The registry lists a sponsor-reported two-sided t-test, but does not report enough detail to establish whether that test was paired or how it related to the crossover design.

How should the p-values be read?

The recalculated primary p-value is 0.863, while the registry lists a sponsor-reported p-value of 0.65 for a two-sided t-test. A two-sided test considers departures in either direction from the null value. In general, a p-value is a measure of how unusual data at least as incompatible with the null model would be if that model and the analysis assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the size or importance of a difference.

The registry does not report the detailed sponsor model or the reason its p-value differs from the summary-statistic recalculation. The recalculation should therefore be understood as a separate, unadjusted calculation rather than a substitute for participant-level analysis. The registry record does not report a prespecified statistical analysis plan, the intended handling of multiple outcomes, or any adjustment for the crossover design.

What do the standardized effect and planning values mean?

A standardized effect expresses a mean difference relative to a measure of variability, allowing effects measured on different scales to be compared descriptively. Such a measure does not remove uncertainty or make a small study more informative. The planning illustrations use fractions of the observed effect as target effects. They are hypothetical design calculations, not estimates of how many participants the original trial was intended to enroll.

General statistical explanation: over-dispersion means that observed variability is greater than a model assumes. When that occurs, uncertainty can be understated if the model does not accommodate the extra variability. The registry does not report an over-dispersion analysis for this continuous primary endpoint; this concept is relevant more generally and should not be read as a finding about these data.

The endpoint title and posted unit both describe meal intake in kcal, so they are aligned. For one secondary outcome, the title refers to AgRP concentrations in blood in Fmol/ml while the posted unit is pg/ml. That unit inconsistency is in the registry record and should be resolved before interpreting that measure quantitatively.

11. Confidence Intervals and Precision

The primary mean difference is -27.9 kcal, and its interval runs from -343.8 to 288.0 kcal. The interval spans values on either side of zero and is wide, indicating that the point estimate is not tightly determined by the posted summaries. The observed means are 919.8 kcal for placebo and 891.9 kcal for lorcaserin, but those means alone do not convey the uncertainty in their comparison.

The confidence level attached to the interval is not reported in the registry record. The interval should therefore be described by its endpoints rather than labeled with a particular coverage percentage. In general, a confidence interval reflects both the observed data and the assumptions of the calculation; it is not a range guaranteed to contain the true effect.

The posted exposure-specific standard errors are 118.7 kcal and 109.0 kcal. They describe precision of the separate means, but do not reveal the correlation between the two exposure measurements for the same participants. In a crossover design, that correlation may affect the precision of the paired treatment contrast. The registry record does not provide the participant-level covariance or enough analysis detail to assess its contribution.

The broad interval means the primary result does not sharply distinguish among potentially meaningful differences in either direction. It does not show equivalence, and it does not rule out effects merely because the recalculated p-value is 0.863. More precise estimation would require a design and analysis that address the crossover measurements and yield a narrower interval; the registry does not report the assumptions used for the trial’s original design.

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 sample-size illustrations are participants per arm, not total events. The registry’s planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The target effect is set to the stated fraction of the observed effect. The original trial’s own design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm under those assumptions for a design with an 80% chance of detecting the target effect, if that effect and the assumptions are correct. The 90% power column gives the corresponding planning figure for a 90% chance. These are design probabilities under a hypothetical model, not guarantees for a future study.

The rows consider planning for 100%, 75%, and 50% of the observed effect. Smaller target effects require more participants to detect, all else being equal, which is why the illustrated participant counts rise as the assumed fraction falls. The primary endpoint’s observed effect is very small relative to the uncertainty in the posted comparison, so planning around the full observed effect yields especially large illustrations. Those figures depend heavily on treating the observed effect as a meaningful planning target.

These calculations are planning illustrations based on the observed effect, not observed power. They do not establish that the completed trial had a particular probability of finding a result, and they do not substitute for a design justification based on a prespecified clinically or scientifically relevant effect. Because the registry does not report its original assumptions, the illustrations should not be read as the intended enrollment target for this trial.

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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -27.900; pooled standard deviation σ = 624.148.
2. n = 2 × (1.96 + 0.842)² × 624.148² / -27.900² = 7,856.0, rounded up to 7,857 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
delta <- -27.9                      # observed difference in means
sigma <- 624.147698866222                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3353220)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 7,857 (80% power), 10,518 (90% power)
 75% of observed effect: n per arm = 13,967 (80% power), 18,697 (90% power)
 50% of observed effect: n per arm = 31,425 (80% power), 42,069 (90% power)
power.t.test: 7857 
Simulated power at n = 7,857 per arm: 0.798 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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 sponsor analysis for the primary comparison as a two-sided t-test with p = 0.65. The summary-statistic recalculation gives an unadjusted p-value of 0.863 and a mean difference of -27.9 kcal, with an interval from -343.8 to 288.0 kcal. The registry does not provide a sponsor-reported estimate or interval for this comparison in the posted analysis entry.

The sponsor’s p-value and the recalculated p-value are both descriptions of the primary comparison, but they need not match when the analysis methods or assumptions differ. The registry record does not report whether the sponsor’s t-test was paired, how it handled the crossover structure, or why its p-value differs from the recalculation. The recalculation uses posted summary statistics and is unadjusted; it cannot reproduce participant-level modeling choices that are not documented.

The reported sponsor result should be distinguished from the recalculated estimate rather than blended into a single analysis. Neither p-value gives the size or precision of the treatment contrast. The posted mean difference and interval are useful for describing the scale and uncertainty of the summary-statistic contrast, while the registry’s reported p-value records the sponsor’s stated test result. Detailed analysis documentation is not reported in the registry record.

15. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary outcome and multiple secondary outcomes, with several measures and analyses described. It does not report how the statistical analysis handled the possibility of multiple comparisons. A multiplicity plan might specify which result is confirmatory, how secondary outcomes are ordered, or whether significance thresholds are adjusted. Without that information, isolated secondary p-values should not be treated as if they arose from a single prespecified test.

Missing-data methods are not reported in the registry record. Enrollment is listed as 32, while the posted primary exposure summaries each report 30 observations. The record does not explain why those counts differ from enrollment, whether the same participants contributed to both exposure summaries, whether all randomized participants were analyzed, or how unavailable outcome measurements were handled. Those details should not be inferred from the displayed counts.

The analysis population is not reported in the registry record. It is not stated whether the results use all randomized participants, participants who completed both exposure periods, or another defined group. The record also does not describe protocol deviations, adherence criteria, imputation, or sensitivity analyses. These details matter because exclusions and missing observations can affect both the estimated contrast and its uncertainty.

The crossover design raises additional analysis questions. The registry notes that outcome data were compared by treatment exposure rather than by sequence arm, but it does not report whether within-participant pairing, treatment period, sequence, or possible carryover was included in the model. The washout period is described in the arm sequences, but the analysis of period or carryover effects is not reported in the registry record.

The reason for trial termination, the statistical analysis plan, interim analyses, and the original sample-size justification are also not reported in the registry record. Their absence limits assessment of whether the posted outcomes and analyses reflect prespecified decisions or later choices. This uncertainty is a reporting limitation; it is not evidence that any particular design or analysis decision was made.

16. 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 5% reporting threshold.

The registry reports zero serious adverse events during the lorcaserin time period among 30 participants at risk, and zero during the placebo time period among 30 participants at risk. It also reports zero other adverse events in each exposure period and zero deaths. No serious adverse-event terms are listed.

These figures describe the events recorded in the registry for the reported exposure periods. They do not establish that no adverse event was possible, and they do not by themselves provide a full comparison of safety. The registry record does not report event definitions, the method of event collection, exposure-adjusted rates, or details of adverse-event severity beyond the serious and other categories shown. It also does not report whether the same participants contributed to both exposure-period summaries.

The crossover periods were short, with each exposure described as 7 days and a 3 week washout between periods. The posted figures therefore concern these reported periods and should not be generalized to the planned 24-week phase, for which adverse-event results are not reported in the registry record. The zero counts are a description of the registry entry, not a conclusion about safety in other settings or over longer exposure.

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

The primary comparison estimates average food intake during a laboratory meal after short exposure to lorcaserin versus placebo. The posted means are close, and the recalculated difference is -27.9 kcal. However, its interval from -343.8 to 288.0 kcal is broad, so the posted summaries do not precisely determine the size or direction of the underlying contrast. The result is not evidence of equivalence, and it does not prove that the exposures have identical effects.

The study’s broader scientific aim was to explore predictors of lorcaserin-induced weight loss and mechanisms that might limit efficacy. The primary meal-intake endpoint could contribute to that aim if it were linked to later weight change, but the posted primary result is a comparison of meal intake by exposure. A predictive relationship, its strength, and its performance are not reported in the registry record. The posted result therefore cannot establish that short-term food intake predicts long-term weight loss.

The study description includes a planned later 24-week lorcaserin phase, but results from that phase are not reported in the registry record. The trial status is terminated, and the reason is not reported. The available record consequently does not answer whether the intended longer-term outcomes were collected or how they relate to the short-term crossover measures.

The evidence is also limited by incomplete reporting of the analysis. The registry does not specify the confidence level for the primary interval, whether the t-test accounted for paired crossover observations, how missing measurements were handled, or how multiplicity was addressed. The summary-statistic recalculation is informative about the posted means and their estimated contrast, but it cannot recover participant-level relationships or undocumented model choices.

In general, a nonsmall p-value is not proof of no effect, and a point estimate is not a causal conclusion in isolation. The most defensible reading is that the posted primary summaries show a modest estimated difference with substantial uncertainty, while the registry record leaves important questions about analysis and the planned longer-term study unanswered. No treatment recommendation follows from these statistics.

18. Why This Trial Matters Statistically

This trial illustrates why a treatment comparison and a prediction question are not interchangeable. The primary outcome measures meal intake during a laboratory test meal, while the title and study rationale concern predictors of longer-term weight loss. A difference between exposure-period means would not, by itself, show that the measure predicts weight change. Prediction requires a reported relationship between the candidate predictor and a later outcome, which is not reported in the registry record.

The crossover structure also makes the analysis details especially important. When participants experience both treatments, the relation between each participant’s measurements can affect the treatment contrast and its precision. The registry describes the exposure comparisons and the treatment sequences, but does not report whether the primary test used paired data or modeled period and sequence. Summary statistics cannot settle that question.

The primary interval is broad, making uncertainty visible rather than hiding it behind a point estimate or p-value. Reading both the estimate and interval helps distinguish the estimated direction from the range of values compatible with the calculation. The planning illustrations further show how sample-size requirements depend on the target effect: planning for a smaller fraction of the observed effect entails larger participant counts under the stated assumptions.

Finally, the record demonstrates the limits of interpreting a terminated study from posted summaries. It reports the status and outcome figures, but not the reason for termination, the original sample-size rationale, the complete analysis plan, or the planned longer-term results. Recognizing those reporting gaps is part of statistical interpretation, not a substitute for the results that are absent.

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.

The main limitation specific to this trial is the incomplete description of how the crossover design was analyzed. The record reports exposure-period means and standard errors and lists a two-sided t-test, but does not establish whether the comparison accounted for repeated measurements within participants. It also does not report treatment period, sequence, or carryover modeling. The recalculation from summary statistics cannot address these design features.

The primary result is imprecise, with an interval from -343.8 to 288.0 kcal, and the interval’s confidence level is not stated. The available summary does not include participant-level observations or the within-participant covariance needed to assess how a paired analysis might affect precision. Reasons for the difference between enrollment of 32 and the 30 observations reported for each exposure are not reported in the registry record.

The registered research rationale includes longer-term weight loss, but the posted primary endpoint is short-term meal intake, and results for the planned 24-week phase are not reported. The record does not report an analysis connecting the meal measure to later weight outcomes. Thus, the predictor question cannot be evaluated from the primary comparison alone.

The record also does not report missing-data methods, the analysis population, the original sample-size justification, the statistical analysis plan, interim analyses, multiplicity handling, or the reason for termination. Secondary results are incomplete relative to the listed outcomes, and one secondary outcome title and unit disagree. These reporting gaps constrain interpretation without indicating what the unreported details would have shown.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Predictors of Lorcaserin-Induced Weight Loss — NCT03353220.
• Registry record last updated 2024-03-27; status last verified 2024-03.
• Results first posted 2021-09-23.
• 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

NCT03353220 is a Phase 4, randomized, double-masked crossover study sponsored by Columbia University. It enrolled 32 participants and is registered for overweight and obesity. The record lists a start date of 2018-01-03, a primary completion date of 2020-02-14, and a status of terminated.

The primary outcome compares mean laboratory test-meal food intake after one week of lorcaserin with intake after one week of placebo. Posted means are 891.9 kcal for lorcaserin and 919.8 kcal for placebo; the recalculated mean difference is -27.9 kcal, with an interval from -343.8 to 288.0 kcal. The registry lists a sponsor-reported two-sided t-test p-value of 0.65.

The study description planned a later 24-week lorcaserin phase, but results from that phase and the reason for termination are not reported in the registry record. The crossover analysis details, missing-data handling, multiplicity plan, and original sample-size justification are also not reported.