Cannabinoids for Pain Control During Medical Abortion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cannabinoids for Pain Control During Medical Abortion (NCT03604341), a randomized phase 4 study. The primary outcome is Maximum Self-reported Pain Score on a Numeric Rating Scale.

2. Clinical Question

The outcome is a participant-reported maximum pain score on an 11-point numeric rating scale, from 0 for no pain to 10 for the worst possible pain. The primary endpoint is summarized by the median and inter-quartile range in each randomized arm. The registry record reports a median of 7 for both arms. The inter-quartile range is 6 to 8 in the dronabinol arm and 5 to 8 in the placebo arm.

These arm-level summaries describe the observed scores; they do not by themselves answer whether the groups differ statistically or whether any difference would be clinically important. No between-arm statistical analysis, confidence interval, or significance test is reported in the registry record. The clinical question is therefore clear, but the posted results do not include an inferential estimate addressing it.

3. Trial Design

This is a phase 4, randomized, double-masked, parallel-group trial. The registry record gives enrollment as 72. Participants with gestational age up to 10 weeks 0 days were randomized to dronabinol 5mg Cap or placebo. The study objective describes the comparison as dronabinol in addition to ibuprofen versus ibuprofen and placebo.

In a randomized design, allocation is intended to make the groups comparable on average with respect to factors that could influence the outcome. Randomization does not ensure that every characteristic is identical between groups, particularly in a trial of this size; the posted record does not report baseline characteristics for evaluating that balance. Double masking means that the registry classifies the study as masked at two levels, but the identity of the masked groups and the specific masking procedures are not reported in the registry record.

The parallel-group structure assigns participants to one intervention group for the trial rather than comparing each participant with themself under both interventions. The posted primary outcome is maximum self-reported pain within 24 hours after misoprostol administration. Outcome summaries are reported for 33 participants in each arm. The registry record does not explain how these outcome counts relate to total enrollment, nor does it describe exclusions or missing outcome data.

The study status is completed. Its listed start date is 2018-11-01, and its primary completion date is 2019-05-07. Oregon Health and Science University is listed as sponsor. There is one posted outcome measure and no posted analyses. The record does not report the randomization procedure, allocation concealment method, protocol deviations, or the full statistical analysis plan. Those details should not be inferred from the randomized and double-masked design labels.

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: 2 participants failed to meet the inclusion criteria after enrollment and were not assigned to a treatment group.

Overall Study

Reasons for not completing this period:

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 Maximum Self-reported Pain Score on a Numeric Rating Scale, measured over 24 hours after misoprostol administration.

The primary endpoint is the maximum self-reported pain score on a numeric rating scale, measured within 24 hours after misoprostol administration. The scale runs from 0, meaning no pain, to 10, meaning the worst possible pain. The registry describes women texting responses to surveys during that period and reports the outcome as a median with an inter-quartile range.

Maximum pain captures the highest reported pain during the stated observation period, rather than pain at a single scheduled moment or an average across repeated measurements. As a general measurement rationale, a participant-reported rating can capture an experience that is not directly observable by a clinician. A standardized scale also gives participants a common response format. The endpoint is specifically about the reported peak within the defined period; it does not describe pain outside that period or other aspects of the abortion experience.

The registry reports a median score of 7 in each arm. The inter-quartile range is 6 to 8 for dronabinol and 5 to 8 for placebo. These summaries describe the distributions’ central values and spread, but do not show every individual score. The registry does not report a threshold for a clinically important difference, additional pain outcomes, or an inferential analysis of this endpoint. The outcome therefore supports a descriptive account of the reported scores, not a conclusion about statistical or clinical importance.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is reported as a median and an inter-quartile range rather than a mean and standard deviation. As a general statistical explanation, the median is the middle of an ordered set of observations. It is less influenced by unusually high or low values than the mean, which can make it useful when a distribution is skewed or has outlying observations. The inter-quartile range describes the spread of the central portion of the observations. It gives information about dispersion, but does not indicate the full range or reveal every feature of the distribution.

For this trial, the reported median maximum pain score is 7 in both arms. The inter-quartile range is 6 to 8 in the dronabinol arm and 5 to 8 in the placebo arm. These are descriptive summaries, not a direct estimate of the between-group difference. In particular, an apparent similarity between medians cannot establish that the distributions are identical. The spread summaries overlap, but overlap alone is not a formal test of a treatment contrast and cannot substitute for an uncertainty interval.

The endpoint uses an 11-point numeric rating scale, with defined endpoints of 0 for no pain and 10 for the worst possible pain. As a general measurement consideration, numeric ratings make subjective experiences recordable in a consistent format, but the resulting score is still a participant report. Its interpretation depends on the scale, the question asked, the time window, and how responses are collected. Here, the record defines the measure as the maximum score reported within 24 hours after misoprostol administration. It does not report validation details, a clinically important difference, or whether any additional scoring rules were used.

Randomization is a design method for reducing systematic differences in prognostic factors between intervention groups. It supports a fair comparison in expectation, but the registry record does not give the allocation sequence or enough baseline information to assess the achieved balance. The double-masked designation indicates that the trial was registered as masked, but the record does not specify who was masked, how masking was maintained, or whether masking was assessed. These omissions limit the ability to evaluate the practical conduct of the design from the registry record alone.

A between-group analysis would ordinarily quantify the contrast in the outcome and its uncertainty using a method appropriate to the endpoint and design. The registry record does not report such an analysis for the primary outcome. It also does not report a confidence interval or p-value. A confidence interval is a general way to communicate uncertainty around an estimate, while a hypothesis test evaluates data against a specified statistical model. Without a reported estimate and analysis, neither the magnitude nor the precision of the group contrast is available. The arm medians and inter-quartile ranges should not be treated as though they were an adjusted or unadjusted treatment-effect estimate.

Planning calculations are distinct from analyses of observed trial results. The record describes a planning illustration based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such an illustration is a hypothetical design exercise, not observed power and not an outcome of the trial. The record does not state that these assumptions formed the original design justification, and the original sample-size justification is not reported in the registry record. No particular planning result should be interpreted as proof that the trial was adequately or inadequately powered.

Over-dispersion is a general concern when the observed variability in data is greater than a statistical model assumes. If a model understates variability, its uncertainty estimates can be too narrow and its tests can be misleading. The registry record does not identify a model for the primary endpoint, report an over-dispersion assessment, or provide enough analysis detail to evaluate such an issue. Because the outcome is presented with a median and inter-quartile range and no analysis, it would be inappropriate to claim that a specific distributional model was used or that its assumptions were checked.

The record lists one outcome measure and no analyses. It does not report covariate adjustment, subgroup analyses, interim analyses, a missing-data method, or a statistical analysis plan. These items cannot be reconstructed from the arm summaries. General statistical methods can explain what such procedures are intended to do, but they cannot establish that a procedure was prespecified or applied in this trial. The available interpretation is therefore limited to the reported descriptive summaries and event counts.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no posted analyses. It does not list secondary outcomes. These details do not establish whether investigators considered additional outcomes or analyses in a protocol, nor do they establish how many comparisons may have been planned. The multiplicity approach, if any, is not reported in the registry record. Multiplicity is a general concern when many hypotheses are tested: the chance of at least one apparently unusual result can rise as the number of tests increases. No adjustment or testing strategy should be attributed to this trial without a report.

The primary outcome summaries include 33 participants in each arm, while total enrollment is listed as 72. The registry does not explain how the outcome population was defined or account for participants who are not represented in those summaries. It does not report missing responses, exclusions, withdrawal reasons, or an imputation method. Consequently, it is not possible to determine whether the posted summaries reflect all randomized participants, only those with recorded responses, or another analysis population.

The analysis population is not reported in the registry record. In general, an intention-to-treat analysis retains participants in their randomized groups, while other analysis populations may use different eligibility or data-completeness rules. The registry does not identify which approach, if any, was used. The primary outcome denominators should not be used to infer the analysis population or the reasons for absent observations.

The adverse-event record lists 35 participants at risk in each arm, distinct from the outcome denominators. The record does not explain this difference. These counts should be read as posted for the safety data rather than reconciled with the pain summaries by assumption.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events among 35 participants at risk in the dronabinol arm and zero among 35 at risk in the placebo arm. It reports zero deaths in each arm. The record lists other adverse events affecting 2 participants in the dronabinol arm and 0 in the placebo arm. No serious adverse-event terms are listed.

These are counts in the registry record, not a complete account of the nature, timing, duration, severity, or relatedness of events. The record does not identify the other adverse events or state whether investigators judged them related to an intervention. It also does not explain why the safety denominators differ from the primary outcome denominators. The counts therefore describe what was posted for safety, without resolving those questions.

As a general statistical point, zero reported serious events does not prove that an event is impossible or that no event occurred outside the record’s collection and reporting. Small numbers of recorded events also provide limited information about how frequently uncommon events might occur. No rates or comparative safety estimates are calculated. The event counts alone should not be treated as evidence that one intervention is safer or more hazardous than the other.

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

The registry record describes a randomized, double-masked comparison of dronabinol plus ibuprofen with placebo plus ibuprofen for maximum self-reported pain during medical abortion. The primary outcome summaries show a median score of 7 in both arms. The inter-quartile ranges are 6 to 8 for dronabinol and 5 to 8 for placebo. These results describe the reported scores among the participants included in the posted summaries.

They do not establish that the interventions are equivalent. Equivalence requires a defined margin and an appropriate analysis; neither is reported in the registry record. The summaries also do not establish a statistically significant difference, because no statistical test, p-value, or confidence interval is posted. A shared median is not a finding that every participant experienced the same pain, and the reported spread does not reveal the full distribution.

The outcome is limited to participants’ maximum pain reports within 24 hours after misoprostol administration. It does not directly describe pain at other times, other symptoms, the overall abortion experience, or outcomes that are not listed in the registry record. The record does not provide a threshold for a clinically important score change, so clinical importance cannot be judged from the arm summaries alone.

The adverse-event counts are also limited: the record reports no serious adverse events or deaths in either arm, and other adverse events affecting 2 participants in the dronabinol arm and 0 in the placebo arm. The event descriptions and relatedness assessments are not reported. These counts do not determine comparative safety.

The completed status and the posted descriptive results are useful for understanding what the registry records. However, the absence of analyses, an explained analysis population, and a missing-data account prevents a fuller statistical assessment. Conclusions should not extend beyond the outcomes and counts recorded.

13. Why This Trial Matters Statistically

This trial raises a clear comparative question: whether adding dronabinol to ibuprofen changes maximum self-reported pain compared with placebo plus ibuprofen during medical abortion. Its randomized, double-masked, parallel-group design is relevant to that question because those design features are intended to support a controlled comparison and reduce some sources of bias. Design labels alone, however, do not replace information about implementation or analysis.

Statistically, the record illustrates the distinction between descriptive results and an inferential comparison. Medians and inter-quartile ranges communicate central tendency and spread, and the equal reported medians make the summaries easy to compare. But without a contrast estimate and its uncertainty, readers cannot assess how precisely the groups differ or how compatible the data are with different possible effects. The two arm summaries are not themselves a formal test.

The record also makes denominator interpretation important. Enrollment is listed as 72, the outcome summaries include 33 participants in each arm, and the safety groups list 35 participants at risk per arm. These figures refer to different reported contexts, and the record does not explain their relationship. Transparent reporting of analysis populations, missing observations, and event denominators is necessary for readers to understand which participants contribute to each result.

Finally, statistical significance and clinical importance are separate questions. Even when a statistical analysis is available, readers need an estimate, uncertainty, and a meaningful clinical context to judge what a result represents. The registry record does not report a clinically important threshold or an inferential analysis. Its value is therefore in documenting the design and the available outcome summaries, while also showing why concise arm-level statistics are not a substitute for full results reporting.

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 primary outcome is self-reported maximum pain within a specified period. The registry describes the scale and timing, but does not report response rates, validation details, or whether all participants were prompted and able to respond in the same way. These details matter when interpreting a patient-reported measure, especially when the endpoint depends on recall and reporting during a defined window.

The pain summaries include 33 participants per arm, whereas enrollment is 72. The registry does not describe the outcome analysis population or explain the difference. It gives no account of missing responses, withdrawals, exclusions, or sensitivity analyses. As a result, the potential influence of incomplete outcome data cannot be assessed from the posted record.

No statistical analysis is posted for the primary comparison. There is no reported contrast estimate, confidence interval, p-value, adjustment strategy, or analysis plan. The record also does not report baseline characteristics, the randomization method, allocation concealment, or details of how masking was implemented. These limitations prevent assessment of important design and analysis features beyond the registered labels.

The safety record reports event counts but does not identify the other adverse events or give relatedness, timing, severity, or further descriptive detail. Its safety denominators differ from the primary outcome denominators, and the record does not explain why. The available safety figures therefore have limited interpretive detail.

Finally, the registry does not report a clinically important difference for the pain scale or a sample-size justification for the trial’s original design. Any planning illustration based on an observed effect is not a substitute for that justification and should not be read as observed power. Together, these gaps mean that the posted record supports a description of the registered study and its reported summaries, but not a complete evaluation of efficacy, precision, missing-data bias, or safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cannabinoids for Pain Control During Medical Abortion — NCT03604341.
• Registry record last updated 2020-04-07; status last verified 2020-03.
• Results first posted 2020-04-07.
• 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

NCT03604341, titled “Cannabinoids for Pain Control During Medical Abortion,” is a completed phase 4 randomized, double-masked, parallel-group trial sponsored by Oregon Health and Science University. The registry lists enrollment of 72 and compares dronabinol 5mg Cap with placebo for women with gestational age up to 10 weeks 0 days.

The primary outcome is maximum self-reported pain on an 11-point numeric rating scale within 24 hours after misoprostol administration. The reported median is 7 in each arm; the inter-quartile ranges are 6 to 8 for dronabinol and 5 to 8 for placebo, with 33 participants reported per arm. No analyses are posted.

The safety record lists zero serious adverse events and zero deaths in both arms; other adverse events affected 2 participants in the dronabinol arm and 0 in the placebo arm. The registry record does not provide an inferential pain comparison, explain the outcome denominators, or detail the other adverse events.