Pain Research: Innovative Strategies With Marijuana: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pain Research: Innovative Strategies With Marijuana (NCT03522324), a registered phase not stated study. The primary outcome is Pain Interference: Roland Morris Disability Questionnaire (RMDQ).

2. Clinical Question

3. Trial Design

The record describes an observational study of people with chronic pain who choose to use edible cannabis. Its official title focuses on edible cannabis and constituent cannabinoids in relation to pain, inflammation, and cognition. The sponsor is the University of Colorado, Boulder. The study is marked COMPLETED, with enrollment reported as 268. Its start date is 2018-06-01 and its primary completion date is 2023-04-10.

During a two-week period, participants use an edible product of their choice. Blood levels of THC and CBD are measured before, during, and after the exposure period. The record describes assessments of pain, inflammation, sleep, physical activity, anxiety/depression, and cognitive dysfunction. After the self-administration period, participants are followed for six months for self-report data on cannabis use, pain levels, sleep quality, and mental health symptoms.

The primary outcome is pain interference measured by the RMDQ. Its stated timeframe compares baseline, before the two weeks of edible use, with pre-administration, after two weeks of use and before acute administration. The registry lists THC, CBD, and THC+CBD groups for safety reporting, but does not state how participants were allocated to those groups. The record explicitly cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The protocol for product choice, group classification, or any adjustment for differences between groups is not reported in the registry record.

The registry also lists secondary outcomes involving pain intensity, health and wellbeing, sleep quality, motor function, depression and stress, acute cognitive impairment, and patient global impression of change. The status of COMPLETED describes the study record, but does not itself establish that outcome results were posted. Numerical primary-outcome results and statistical analyses are not reported in the registry record.

4. Participant Flow and Accounting

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

Before assignment: Note: 268 participants were consented for the study. Among those, 253 submitted photos of their experimental product and were thus assigned to product groups. It is not possible to "group" the 15 participants lost to attrition at that point in the study flow.

Overall Study

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 Pain Interference: Roland Morris Disability Questionnaire (RMDQ), measured over Change over two time points over 2 weeks: Baseline (before 2 weeks of edible use), Pre-Administration (after 2 weeks of use and before acute administration) using the total RMDQ score (0-24)..

The primary endpoint is the total score on the Roland Morris Disability Questionnaire. The instrument assesses self-rated physical disability caused by low back pain. The registry states that scores range from 0 to 24, with higher scores indicating more pain interference. The outcome is described as a mean, with standard deviation as the measure of dispersion.

The stated comparison is a change across two assessments: baseline before two weeks of edible use, and pre-administration after two weeks of use but before acute administration. Using the same questionnaire across assessments allows the study to describe whether participants’ reported disability scores differ over that period. It captures the functional impact of low-back-pain symptoms as reported by participants, rather than a direct measurement of cannabinoid concentration or an objective measure of physical function.

In general, a change score describes the difference between a participant’s measurement at one assessment and another. A group mean change can describe the average pattern, while a standard deviation describes how spread out individual scores are around that mean. Neither quantity alone establishes why scores changed. In this study, self-selected product use and the observational design mean that any change would need to be interpreted as an observed pattern over time, not automatically as an effect caused by edible cannabis.

The registry record does not report the mean RMDQ scores, the change estimate, its uncertainty, or a statistical test. It also does not report how missing assessments were handled or whether the primary analysis used individual change scores or another approach.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary measure represent?

The RMDQ is a continuous score, and the primary outcome is specified as a mean with standard deviation. A mean gives the average score in a group or at an assessment. A standard deviation describes the spread of observations around that average. These quantities answer different questions: the mean locates the center of the scores, while the standard deviation indicates how variable the scores are. The registry record does not report either quantity for the primary outcome.

The outcome description gives a possible score range of 0 to 24 and states that higher scores indicate more pain interference. A change over time can be represented by comparing scores at the two scheduled assessments. In general, a mean change indicates the average direction and size of that change in the analyzed participants. It does not show that every participant changed in the same direction, and it does not by itself identify the reason for change. The registry record does not state the exact change-score calculation or present a result.

What would a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate. For a mean change, it would indicate a range of values compatible with the data and the statistical procedure used. A narrower interval indicates greater precision under that procedure; a wider interval indicates less precision. An interval’s interpretation depends on the model and assumptions used to calculate it. No confidence interval for the RMDQ result is reported in the registry record, so its precision cannot be assessed from the registry entry.

A p-value, when reported, addresses how compatible the data are with a specified statistical model or null hypothesis. It is not a measure of clinical importance, and it does not establish causation. A p-value also does not replace the estimate and its uncertainty. The registry record reports no primary-outcome p-value or analysis. It lists zero analyses, so there is no posted analysis result to interpret in this record.

How should the observational comparison be understood?

In general, randomization creates treatment groups by chance and can reduce systematic differences in prognostic characteristics. Here, the record describes participants choosing edible cannabis and explicitly states that the listed arms are not a randomized, like-for-like control comparison. The grouping basis and allocation process are not reported in the registry record. As a result, a difference between groups could be associated with the cannabinoid category while also reflecting differences in participants, products, or patterns of use. Statistical adjustment can address measured differences under appropriate assumptions, but it cannot guarantee removal of unmeasured confounding. Whether any adjustment was planned or performed is not reported in the registry record.

The record describes measuring blood THC and CBD levels before, during, and after the two-week period. In general, relating a measured blood level to an outcome is an association analysis. Such an analysis can describe co-variation, but it does not alone show that the blood level caused the outcome. The timing and relationship of the measurements, the model used, and any adjustment variables are not reported in the registry record.

Why can variability matter?

Participants may have different RMDQ scores and different changes over time. In general, greater variability makes an average change less precise when other features of the data are held constant. A standard deviation describes observed variation, while a standard error or confidence interval describes uncertainty in an estimate; these are not interchangeable. The registry identifies standard deviation as the dispersion measure but does not post the observed values or an uncertainty estimate.

Over-dispersion is a general issue for some statistical models when observed variation exceeds what the model assumes. It can lead to uncertainty estimates that are too small if ignored. The primary endpoint is specified as a continuous mean score, and no model details or indication of over-dispersion are reported. There is therefore no basis in this record to state that over-dispersion was assessed or affected the analysis.

What can planning calculations say?

In general, a sample-size calculation estimates how much information a future study might need under stated assumptions about the effect to detect, significance level, allocation, and statistical model. Such calculations are planning illustrations, not observed evidence and not a measure of the study’s achieved power. The registry record describes planning assumptions based on fractions of an observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. It does not report numerical planning estimates in the information available for this analysis. These assumptions should not be mistaken for evidence about the actual design or observed results. The trial’s own sample-size justification is not reported in the registry record.

More broadly, the statistical analysis plan, methods for handling repeated measures, assumptions about distributions, model covariates, and treatment of missing observations are not reported in the registry record. Without those details and the outcome estimates, the analysis cannot be independently assessed for its modeling choices or precision.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple outcome areas, including pain intensity, health and wellbeing, sleep quality, motor function, depression and stress, acute cognitive impairment, and patient global impression of change. The record also describes measurements of inflammation, physical activity, anxiety/depression, and cognitive dysfunction. Testing many outcomes can raise a general multiplicity concern: when many statistical hypotheses are examined, the chance of at least one apparently unusual result can increase. Methods such as prespecifying a primary outcome or adjusting for multiple comparisons can address particular multiplicity questions, but their appropriateness depends on the analysis plan.

The RMDQ is identified as the primary outcome, but any multiplicity strategy, hierarchy of secondary outcomes, or adjustment for multiple testing is not reported in the registry record. The number of listed outcomes does not establish how many were analyzed or whether tests were conducted. The registry lists zero analyses, and numerical outcome results are not reported.

Missing data can affect both estimates and their precision. In general, an analysis may use only participants with measurements at both assessments, or use a statistical method that incorporates incomplete observations under specified assumptions. These approaches can produce different results, and each relies on assumptions about why data are missing. The registry record does not state the extent of missing primary-outcome data, the reasons for missingness, or the method used to handle it.

The analysis population is also not reported in the registry record. It is not stated whether the primary result was intended to include all enrolled participants, only those with complete assessments, or another defined group. The record does not describe exclusions, protocol deviations, or analysis-set definitions. As a result, the population represented by any primary estimate cannot be determined from the registry 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.

The registry lists three groups for adverse-event reporting: THC Group, CBD Group, and THC+CBD Group. For serious adverse events, the reported affected counts are 0 in each group. For other adverse events, the reported affected counts are also 0 in each group. Deaths are reported as 0 in each group. The registry lists 36 at risk in the THC Group, 95 at risk in the CBD Group, and 117 at risk in the THC+CBD Group for both the serious and other adverse-event entries.

These figures describe what is entered in the registry record. They are not comparative risk estimates, and the groups are not randomized like-for-like controls. No rates or confidence intervals are reported, and none should be inferred from the counts. The registry record does not report the method or completeness of adverse-event collection, the observation period for these entries, or further details about event definitions. Zero recorded affected counts should therefore be read as registry entries, not as evidence that the intervention has no risk or that no events could have occurred.

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

The record establishes that the study was designed to examine edible cannabis use, blood cannabinoid levels, and several pain-related and other outcomes in people with chronic pain. Its primary endpoint is a measure of self-rated physical disability due to low back pain, assessed before and after a two-week period of edible use. The record also describes six months of follow-up for self-report data on cannabis use, pain, sleep, and mental health symptoms.

It does not establish the size or direction of any primary-outcome change. The mean RMDQ scores, change estimate, uncertainty interval, and statistical test are not reported in the registry record. Results for the listed secondary outcomes and analyses of blood THC or CBD in relation to outcomes are also not reported. The record’s COMPLETED status should not be interpreted as a finding about the outcomes.

Even if outcome differences or associations were available, the observational design would matter. Participants chose an edible product, and the record does not describe randomized allocation. Differences between cannabinoid groups could reflect factors other than cannabinoid category or level. An observed change from baseline to follow-up would describe what happened during the study period, but would not alone show that edible cannabis caused that change.

The registry’s adverse-event entries report zero affected counts and zero deaths in the listed groups. Those entries do not establish absence of risk, particularly because details about event ascertainment and completeness are not reported. The information supports a description of the study’s question and recorded design, but not a conclusion about efficacy, lack of efficacy, or safety.

13. Why This Trial Matters Statistically

This study raises a statistical question that is common in observational clinical research: how to interpret changes and associations when participants choose their exposure rather than being randomly assigned. The registry describes self-selected edible cannabis use and measurements of blood THC and CBD. This design can document patterns in the participants studied, but causal interpretation requires caution because the groups may differ in ways related to both exposure and outcome.

The outcome timing also makes the estimand important. The primary question concerns RMDQ scores at baseline and after two weeks of use, before acute administration. That is a defined repeated-measure comparison, distinct from the later six-month self-report follow-up and from acute cognitive assessments. Clear separation of these timepoints matters because they represent different questions and should not be conflated.

The registry record identifies a continuous primary measure and its direction, which helps explain what a reported score would mean. However, it does not report estimates, uncertainty, or analysis methods. Without those elements, readers cannot judge the magnitude, precision, or robustness of the primary finding. The record also lists multiple outcome domains, making a transparent account of outcome prioritization and multiplicity methods relevant; those methods are not reported.

Finally, the safety entries illustrate why adverse-event counts require context. Counts are informative only alongside definitions, ascertainment procedures, follow-up, and the population analyzed. Those details are not reported in the registry record. The study’s statistical value therefore lies, in the information recorded, in its defined research question and measurement schedule; its outcome conclusions remain unavailable from this registry entry.

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 for interpretation is that the registry record does not report numerical results for the primary endpoint or the listed secondary outcomes. No primary estimate, measure of uncertainty, or statistical test is available. The record lists zero analyses, so the outcomes cannot be evaluated for magnitude, precision, or consistency from this entry.

The study is observational, and participants choose an edible product. Allocation to the THC, CBD, and THC+CBD groups is not stated. The record cautions that the groups are not a like-for-like control comparison. This limits causal interpretation of any potential group contrast and leaves the grouping process unclear.

The intervention is described as an edible product of the participant’s choice, but details about product standardization, dose, frequency, adherence, and variation in use are not reported in the registry record. Blood THC and CBD are measured, but the methods and results for relating blood levels to outcomes are not reported. The record also does not give details of the primary-outcome analysis, covariate adjustment, missing-data handling, analysis population, or multiplicity strategy.

The primary outcome is a self-reported measure of disability due to low back pain. The record does not provide additional information on assessment procedures or completeness at either timepoint. Safety counts are recorded as zero affected counts in each listed group, but event ascertainment and follow-up details are not reported. These limitations mean the registry entry supports understanding of the planned measurements and broad design, but not an assessment of outcome effects or the completeness of safety reporting.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pain Research: Innovative Strategies With Marijuana — NCT03522324.
• Registry record last updated 2025-08-27; status last verified 2025-08.
• Results first posted 2025-08-27.
• 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

NCT03522324 is an observational study titled Pain Research: Innovative Strategies With Marijuana. Its official title describes edible cannabis and constituent cannabinoids in relation to pain, inflammation, and cognition. The sponsor is the University of Colorado, Boulder. The registry reports enrollment of 268, a start date of 2018-06-01, a primary completion date of 2023-04-10, and status COMPLETED.

Participants choose an edible product for a two-week self-administration period. The primary outcome is the RMDQ total score, comparing baseline with the assessment after two weeks of use and before acute administration. The record also describes six-month follow-up and multiple secondary outcome areas. THC, CBD, and THC+CBD groups appear in safety reporting; allocation is not stated, and the record cautions that the groups are not like-for-like controls.

Numerical outcome results, statistical analyses, analysis populations, missing-data methods, and multiplicity procedures are not reported in the registry record.