Fish Oil to Reduce Tobacco Use iN Expectant Mothers Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fish Oil to Reduce Tobacco Use iN Expectant Mothers Study (NCT03077724), a randomized phase 2 study. The primary outcome is Change in Cigarettes Per Day From Baseline to 4-weeks.

2. Clinical Question

3. Trial Design

This was a Phase 2, randomized, parallel-group study with quadruple masking. Its registered title identifies it as a fish-oil study for tobacco use among expectant mothers. The record lists an enrollment of 28 and a status of completed. The study started on 2017-03-02, and primary completion was recorded on 2018-01-23. These dates describe the registry record; they do not establish how long each participant received supplements.

The intervention was 4.2 grams per day of n-3 long chain polyunsaturated fatty acids, while the comparator was olive oil supplements. The registry record does not specify the method used to generate the random sequence, how allocation was concealed, or who was included in the quadruple masking. It also does not report the intended allocation ratio or the planned treatment duration.

The stated purpose was to collect pilot information for preparation of a future trial. The planned feasibility aims included developing and refining recruitment, assessing side effects, tolerability, and adherence, and gathering preliminary effect-size information. The record does not report the results of those feasibility aims as a complete set. It lists a primary endpoint of change in cigarettes smoked per day from baseline to 4 weeks, along with secondary outcomes of change in Fagerström scores from baseline to 4 weeks and point-prevalence abstinence. Results for those secondary outcomes 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants with both baseline and 4-week complete data on cigarettes smoked per day

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 Change in Cigarettes Per Day From Baseline to 4-weeks, measured over 4 weeks.

The primary endpoint is change in the number of cigarettes smoked per day between baseline and 4 weeks. It focuses on smoking quantity over a short follow-up interval, rather than directly measuring a sustained cessation outcome. The registry specifies that the primary outcome population consists of participants with complete cigarette-per-day data at both time points.

The reported summary measure is the median. In general, a median describes the middle of the observed values and can be useful when a distribution is skewed or influenced by unusually large or small observations. It does not describe every participant’s experience, and it does not by itself estimate the difference between randomized groups. The registry identifies the interquartile range as the dispersion measure, but the posted spread entry is empty; it also includes lower and upper values whose precise statistical meaning is not stated.

For the Fish Oil arm, the reported median change is -0.94; for the Placebo arm, it is 0.0. The record describes the endpoint as change from baseline but does not specify the subtraction convention used to encode that change. Consequently, the signed values can be reported as posted, but a direction such as reduction should not be assigned without that coding detail. Smoking cessation and nicotine craving were part of the study’s stated hypothesis, but the primary endpoint itself is cigarette count change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is summarized with a median for each arm. In general, the median is the value at the center of an ordered set of observations. It is less affected by extreme observations than the arithmetic mean, which can make it useful when data are skewed. A median is still only a summary: it does not show the full distribution or how individual participants changed.

What does the reported spread tell us?

The registry identifies the interquartile range as the intended measure of dispersion. In general, an interquartile range describes the central half of a distribution and gives information about how spread out observations are around the median. The posted spread entry is empty, however. Lower and upper values appear alongside the medians, but the record does not name their statistical meaning. They should not be interpreted as an interval estimate, a range of individual outcomes, or any other specific quantity unless that meaning is documented.

How should the arm summaries be compared?

The Fish Oil arm median is -0.94 and the Placebo arm median is 0.0. Comparing these two values informally is not the same as estimating a treatment effect. A between-arm estimate would quantify a contrast using a defined statistical method; an uncertainty interval would communicate how imprecisely that contrast is estimated. Neither a between-arm estimate nor its uncertainty is reported in the registry record. The signs of the medians also depend on how change was coded, and the record does not specify that convention.

Randomization is intended, in general, to make comparison groups similar on average with respect to measured and unmeasured factors. It does not guarantee balance in every small study, and the registry record does not report baseline characteristics by arm. The outcome counts apply to the complete-data population named for the endpoint: 6 for Fish Oil and 12 for Placebo. Without a reported analysis method, it is not possible to determine whether other data or adjustments were used in an analysis beyond the posted summaries.

Why does over-dispersion matter?

In general, count outcomes can vary more than a simple statistical model expects. This is called over-dispersion. If present, it can make standard errors from an overly restrictive model too small and confidence intervals too narrow. Assessing and addressing over-dispersion requires information about the distribution and the analysis model. The registry record does not report a model for the primary endpoint, diagnostics for over-dispersion, or an adjusted analysis. This general concern should not be mistaken for evidence that over-dispersion occurred in this study.

What does the absence of a comparison analysis imply?

The registry record lists no analyses and indicates that values were missing or not estimable for a two-arm comparison in a median-time endpoint. The primary outcome described elsewhere is a median change in cigarette count, not a time-to-event endpoint; the record does not reconcile that terminology. No hazard ratio is posted for the primary endpoint. A time-to-event interpretation therefore cannot be inferred from the available primary result.

When a result is not accompanied by inferential statistics, the medians can still describe the observed complete-data groups, but they cannot establish how precise a contrast is or whether it is distinguishable from chance variation. In general, a confidence interval presents a range of values compatible with the data and an analysis method, subject to its assumptions. No such interval is reported for the primary comparison. Any planning calculations based on an observed effect are illustrations for future study design, not evidence of the probability that this study detected an effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures: the primary cigarette-per-day change and two secondary outcomes, change in Fagerström scores from baseline to 4 weeks and point-prevalence abstinence. The record does not report results for the secondary outcomes. It also does not report a prespecified approach to handling multiple outcomes, such as a hierarchy or adjustment for multiple testing. Without that information, the role of multiplicity in the study’s intended analysis is not reported in the registry record.

The primary endpoint population is defined as participants with complete data at baseline and 4 weeks. The posted arm counts for that population are 6 for Fish Oil and 12 for Placebo. These counts make clear that the primary summary is not described as an analysis of all enrolled participants. The registry record does not report the reasons data were unavailable, the number with missing outcome values at each time point, or a method for handling missingness. It also does not state whether the analysis followed an intention-to-treat principle or another analysis-population definition.

In general, analyzing only complete cases can be misleading if the availability of outcome data is related to participants’ outcomes or treatment assignment. That is a methodological consideration, not evidence that such a relationship occurred in this study. The record does not describe sensitivity analyses or methods for imputation. It also does not report an analysis plan that would clarify whether the complete-data definition was prespecified.

The record lists no statistical analyses for a two-arm comparison. It does not report adjustment variables, interim analyses, or a sample-size justification. Those details are not reported in the registry record, so their presence or absence in the investigators’ work cannot be determined from the registered information.

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

Serious events with the highest arm-level rate: hospitalization (7.1%).

The safety record lists 14 participants at risk for serious adverse events in each arm. One serious adverse event is recorded for the Fish Oil arm and none for the Placebo arm. The record lists 14 participants at risk for other adverse events in each arm and reports zero affected in both groups. No deaths are recorded in either arm.

Hospitalization is identified as the top serious adverse event term, with 7.1% reported. The registry record does not provide additional details about the event, its timing, severity, relationship to study treatment, or the participant’s clinical course. A serious adverse event is a safety classification and does not, by itself, establish that an intervention caused the event. The posted counts describe what was recorded; they do not establish comparative safety, particularly without a reported statistical comparison and with limited outcome counts.

The safety counts and primary-outcome counts should not be assumed to describe identical analysis populations. The record lists 14 at risk in each arm for the serious-event measure, while the primary endpoint population consists of participants with complete baseline and 4-week cigarette data. The registry does not explain the relationship between these populations or provide further safety follow-up details.

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

The record documents a randomized, quadruple-masked feasibility study comparing fish oil with olive oil placebo among pregnant women who smoked. The primary endpoint was change in cigarettes smoked per day from baseline to 4 weeks. The posted medians are -0.94 for Fish Oil and 0.0 for Placebo. These values characterize the observed complete-data groups, but they are not a reported estimate of the between-arm effect.

The study’s stated purpose was to collect pilot information relevant to a future trial, including recruitment, tolerability, adherence, side effects, and preliminary effect-size data. That purpose shapes how the outcome should be read: the record offers descriptive information from a feasibility study, not a complete confirmatory analysis. It lists secondary outcomes for Fagerström score change and point-prevalence abstinence, but their results are not reported in the registry record.

The posted primary summary does not show how precisely the arm contrast is estimated. No confidence interval, p-value, or statistical test for a two-arm comparison is reported. The lower and upper values accompanying the medians are not assigned a clear statistical interpretation. The study’s outcome counts also refer only to participants with complete measurements at both time points, and the record does not explain missing outcomes or the analysis population beyond that definition.

Accordingly, the posted data do not establish whether fish oil changed smoking behavior relative to placebo, nor do they establish that the arms were equivalent. The registry record also does not report the secondary outcome findings needed to assess the stated hypotheses about cessation and nicotine craving. Planning calculations based on observed effects can inform design scenarios for future work, but they are not observed power and do not substitute for an uncertainty estimate from the current study.

13. Why This Trial Matters Statistically

This study is statistically relevant because it illustrates the distinction between a feasibility study and a confirmatory comparison. Its stated aims included assessing recruitment, tolerability, adherence, and side effects, as well as collecting preliminary effect-size information. Those aims can guide the design and conduct of later research, but they do not replace complete outcome reporting or an estimate of comparative effect with uncertainty.

The primary endpoint is a count-based measure summarized by medians. That choice communicates the center of the observed data without requiring the mean to represent the typical participant. At the same time, the missing spread entry and undefined lower and upper values limit what can be learned about variability. The posted medians alone cannot show whether a contrast is precise or robust to the distribution of individual changes.

The endpoint population also matters. The primary summaries use participants with complete baseline and 4-week data, and the registry does not explain missing outcomes or report an analysis population beyond that definition. In general, transparent reporting of participant flow, missing-data handling, outcome distributions, and analysis methods helps readers understand how an estimate was constructed and what population it describes.

Finally, the record lists secondary outcomes without their results and does not report a multiplicity approach. These omissions limit interpretation of the broader study hypotheses. The study can still serve its intended pilot role, but the registered information does not provide a complete statistical account of the clinical outcomes or a basis for a definitive between-group conclusion.

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 main limitation of the posted primary result is that it consists of arm-specific medians without a reported between-arm estimate or uncertainty measure. The registry does not report a p-value, confidence interval, or analysis method for the comparison. Its lower and upper values are not clearly defined, and the spread entry is empty despite the registry identifying the interquartile range as the dispersion measure.

The outcome summaries are restricted to participants with complete cigarette-per-day data at baseline and 4 weeks. The record does not report missingness reasons, the outcome status of other participants, or methods used to handle missing data. It also does not report baseline characteristics by arm, so readers cannot assess the observed comparability of the outcome groups from the posted information.

Although the record lists Fagerström score change and point-prevalence abstinence as secondary outcomes, their results are not reported. It does not explain the analysis plan, multiplicity handling, sample-size justification, or whether interim analyses were conducted. Such details are not reported in the registry record.

The primary endpoint is a short-term change measure, and the record does not state how the change was coded. It therefore does not establish how to interpret the signs of the reported medians as increases or decreases. The safety information is also limited: the event listing does not provide details about timing, attribution, or clinical course. These limitations constrain what can be concluded from the registry record; they should not be treated as proof that unreported analyses or information do not exist elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Fish Oil to Reduce Tobacco Use iN Expectant Mothers Study — NCT03077724.
• Registry record last updated 2019-01-09; status last verified 2018-12.
• Results first posted 2019-01-09.
• 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.

18. Record Summary

The registry record describes a completed Phase 2 randomized, quadruple-masked, parallel-group feasibility study of fish oil versus olive oil placebo in pregnant women who smoked. The fish-oil intervention was 4.2 grams per day of n-3 long chain polyunsaturated fatty acids. The primary outcome was median change in cigarettes smoked per day from baseline to 4 weeks among participants with complete data at both time points.

The posted median changes are -0.94 for Fish Oil and 0.0 for Placebo, with outcome counts of 6 and 12, respectively. No statistical comparison or uncertainty estimate for the primary endpoint is reported. Results for the listed secondary outcomes are not reported in the registry record. The stated study purpose was to gather feasibility and preliminary information for future research; the posted outcome summaries do not by themselves establish a comparative treatment effect.