Inflammatory Responses to Acute and Chronic Opioid Exposure in Humans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Inflammatory Responses to Acute and Chronic Opioid Exposure in Humans (NCT01749826), a randomized na study. The primary outcome is Changes in Cytokine Release.

2. Clinical Question

The study aimed to examine whether inflammation is affected by acute and chronic opioid exposure. Its primary question focused on cytokine release, a biological measure relevant to inflammatory responses. The planned assessment called for blood samples on Day 1 and Day 30, with changes compared across those time points and between the exposure groups.

The arm labels distinguish chronic from acute exposure, but the registry descriptions of the two regimens are identical. The record does not explain how the exposure conditions were meant to differ, or what participants in either group would receive beyond the stated dosing description. It therefore does not establish a more specific contrast than the contrast named by the arm labels.

The registry also lists laser Doppler images, Peltier device-heat pain, and mechanical pain stimuli as secondary outcomes. Those outcomes do not supply evidence about the primary cytokine question. The record states that the study ended because of a lack of resources before any study-measure data were collected, so the clinical question remains unanswered by trial results.

3. Trial Design

The registry describes a randomized, triple-masked, parallel study. Random allocation is intended to reduce systematic differences between groups at the point of assignment. A parallel design assigns participants to a group rather than having each participant receive both study conditions. The record does not describe the randomization procedure or identify which parties were masked.

The two arms are titled Chronic Opioid Exposure and Acute Opioid Exposure. Both arm descriptions specify 15mg sustained-release morphine sulfate, a maximum dose of 120mg, and titration to a maximum of 8 pills a day for one month. The record does not clarify how the acute and chronic exposure conditions were to differ in practice. That ambiguity limits how precisely the intended comparison can be characterized from the registry alone.

Enrollment is reported as 20. The study start is listed as 2010-01, and primary completion as 2013-07. The status is TERMINATED. The primary outcome entry explains that the study was terminated because of a lack of resources before collection of any study-measure data. Thus, the design describes an intended comparison, not a completed efficacy or biological-response assessment.

The phase is listed as NA. Stanford University is named as sponsor, and inflammation is listed as the condition. The registry gives no further account of the allocation sequence, masking procedures, adherence monitoring, or participant flow. Information about these design details is 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: Data can not be summarized or included in this table as no data on this measure was collected. 5 CCs of blood were not drawn from any participants at any point in time during the study as the study was terminated due to a lack of resources prior to collection of any study measure data.

5. Baseline Characteristics

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

Population: We were unable to perform analysis as we were unable to detect any cytokines in our samples.

6. Primary Endpoint

The registry lists the primary outcome as Changes in Cytokine Release, measured over Changes in cytokine release are compared between blood samples drawn on Day 1 and Day 30.

The primary endpoint is titled Changes in Cytokine Release. The stated timeframe compares cytokine release between blood samples intended to be drawn on Day 1 and Day 30. The description specifies a 5 CC blood draw on each of those days. Cytokines are signaling molecules associated with immune and inflammatory activity; as a general concept, measuring their release can help characterize biological responses relevant to inflammation.

A comparison across the planned collection times could have assessed whether cytokine measurements changed over the study period. A comparison between groups could have addressed whether the planned exposure conditions were associated with different patterns of change. These are explanations of the endpoint’s intended role, not findings from this study.

The registry explicitly states that data for this measure cannot be summarized because no data were collected. It further states that blood was not drawn from any participants at any point during the study, which ended because of a lack of resources before collection of any study-measure data. Consequently, there is no observed cytokine value, change score, group contrast, or estimate of uncertainty to interpret. The endpoint was specified, but it was not measured in the trial.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General explanation: Randomization assigns participants to study groups by chance. Its purpose is to reduce the influence of systematic differences between groups on a comparison. Masking is intended to limit the effects of knowing group assignment on participant behavior, care, measurement, or assessment. The registry labels this study randomized and triple-masked, but does not specify the randomization procedure or which people were masked. These design labels alone do not show that the planned comparison was implemented or that data were collected.

General explanation: A parallel design compares groups that proceed in separate arms. The registry names a chronic-exposure arm and an acute-exposure arm. For a parallel comparison to be interpretable, the group conditions and the outcome measurements need to be defined clearly. Here, the arm descriptions state the same morphine regimen, while the titles imply different exposure patterns. The record does not explain that difference. This is a reporting limitation, not evidence about what participants actually received.

General explanation: A repeated measurement design can compare a participant’s outcome at different times, while a between-group comparison can assess whether changes differ by assigned group. The primary outcome description indicates an intended comparison of cytokine release from blood samples on Day 1 and Day 30. The registry does not report whether the analysis was meant to compare final values, changes from baseline, or another summary. More importantly, the samples were not collected, so no such analysis can be performed from observed trial measurements.

General explanation: An effect estimate describes the magnitude and direction of a comparison. Its interpretation depends on the outcome definition, the groups being compared, and the analysis population. A confidence interval conveys uncertainty around an estimate under the method’s assumptions. A p-value, when reported, assesses compatibility between observed data and a specified null hypothesis under a statistical model. None of these results is reported for the primary outcome, because the outcome data were not collected. No statistical analysis plan or model is reported in the registry record.

General explanation: Repeated measurements can be correlated because observations from the same participant are related. An analysis that treats them as independent may misrepresent uncertainty. Researchers can account for such dependence using methods appropriate to the data structure, but the choice depends on the estimand and analysis plan. The registry does not report a planned model for the Day 1 and Day 30 measurements. Since neither set of measurements exists, no assumptions about their correlation can be checked and no repeated-measures analysis can be evaluated.

General explanation: Over-dispersion occurs when observed variation exceeds what a chosen statistical model expects. If outcomes are more variable than assumed, standard errors and uncertainty estimates can be misleading unless the model accounts for that variation. This is a general concern for some data types; it is not a reported feature of this study. With no cytokine observations, the degree of variability and whether over-dispersion matters cannot be assessed.

The registry includes a sample-size assumption describing an illustration based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such calculations are planning illustrations, not observed power. The record contains no observed primary effect because no cytokine data were collected; no sample-size result or effect estimate is reported in the registry record for interpretation. The trial’s own sample-size justification is not reported in the registry record. The illustration assumptions should not be mistaken for the study’s actual design rationale or a guarantee that a particular effect could have been detected.

For general interpretation, sample-size planning depends on the outcome, the effect considered important, outcome variability, the allocation scheme, and the chosen error rates and analysis method. A calculation using an observed effect is especially difficult to interpret when the trial has no observed outcome data. Any planning illustration in this context cannot establish that the trial was adequately powered or that a null result was obtained. There is no null result: there is no primary outcome result at all.

The registry lists four outcome measures and zero analyses. It does not report an interim-analysis plan, multiplicity adjustment, missing-data method, or analysis population. These omissions mean the intended statistical handling of multiple outcomes and repeated time points cannot be reconstructed. They also prevent assessment of whether a prespecified model was followed. No statistical methods beyond the design labels and sample-size assumptions are reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and three secondary outcomes: laser Doppler images, Peltier device-heat pain, and mechanical pain stimuli. The record does not report a multiplicity plan, such as a hierarchy among outcomes or an adjustment to account for multiple statistical tests. Without results or an analysis plan, it is not possible to assess how multiple comparisons would have been handled.

The primary outcome description refers to measurements on Day 1 and Day 30. The record does not say how multiple time points or any categories within outcomes would be analyzed. It also does not report an interim-analysis plan. The absence of those details should not be interpreted as evidence that such procedures were or were not planned beyond what the registry states.

The primary outcome entry says no blood samples were drawn and no study-measure data were collected before termination due to a lack of resources. This is not ordinary partial missingness in an otherwise measured endpoint: the registry reports that the planned primary measurement was not obtained from any participant. It gives no missing-data method, imputation procedure, or sensitivity analysis. There is consequently no basis for evaluating how missing outcome observations might affect a treatment estimate.

The record reports enrollment of 20 but does not define an analysis population or explain participant disposition by arm. It does not report whether all enrolled participants were randomized, received an intervention, or were included in any analysis. The number of analyses is recorded as zero. For these reasons, neither an intention-to-treat population nor a per-protocol population can be identified from the registry record.

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

This study record is informative about the intended research question and why the planned primary assessment is unavailable. The study aimed to examine inflammatory responses to acute and chronic opioid exposure, with cytokine release compared between intended blood collections on Day 1 and Day 30. The registry says the study was terminated because of a lack of resources before any study-measure data were collected.

That means the posted record does not show whether cytokine release changed, whether the named groups differed, or how precise any such difference might have been. There is no reported effect estimate, confidence interval, or statistical test for the primary outcome. The absence of a result is not evidence of no effect; it means that the planned endpoint was not measured.

The record also does not establish a distinct dosing regimen for the two arm labels. Both descriptions use the same stated regimen. Without clarification of the intended exposure distinction, even a hypothetical group contrast would be difficult to interpret from the registry descriptions alone. The listed secondary outcomes likewise do not provide evidence of effects because the record states that no study-measure data were collected.

The zero adverse-event entries do not establish that exposure was free of adverse events. The registry does not provide a documented safety observation set, and the study ended before its measures were collected. A lack of reported event counts in this context is not a finding that no events occurred.

In general, a terminated study may still contribute information about feasibility, recruitment, measurement procedures, or reasons for stopping if those details are reported. This record gives lack of resources as the reason for termination, but does not describe recruitment performance or completed measurement procedures. Its contribution is therefore chiefly to document an intended study and the absence of collected outcome data, rather than to estimate biological or clinical effects.

12. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the distinction between a specified endpoint and an observed result. The registry describes a primary cytokine outcome with planned blood collection at two time points, yet it also states that no blood samples were collected. A detailed endpoint definition cannot substitute for measurements; without observations, there is no empirical estimate to analyze.

It also highlights how registry design labels and arm descriptions serve different purposes. Randomization, masking, and a parallel model describe intended features of the study structure. The arm labels name the intended exposure groups, but the identical dosing descriptions leave the contrast unclear. Statistical interpretation depends on knowing what conditions the groups represent, as well as on having outcome data.

The record is a reminder that enrollment information is not itself an outcome analysis. Enrollment is reported as 20, but the registry does not report a participant flow or analysis population, and it records zero analyses. These registry entries cannot be turned into a treatment-effect estimate, a test of the primary question, or an observed-power claim.

Finally, the record helps distinguish an empty result from a negative result. A negative result would require measured data and an analysis that failed to demonstrate a specified difference under its assumptions. Here, the primary measure was not collected. Statistical reporting should preserve that distinction, especially when interpreting event entries, sample-size illustrations, and planned secondary outcomes. The record documents an interrupted research effort, not evidence for or against a cytokine response.

13. 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 most direct limitation is that the registry reports no primary outcome data: no blood was drawn for cytokine measurement, and no study-measure data were collected before termination. The planned comparison between Day 1 and Day 30 therefore has no observed result. The reason for termination is recorded as a lack of resources.

The intervention descriptions also limit interpretation. The chronic and acute arm titles suggest different exposure conditions, but both descriptions specify the same sustained-release morphine regimen. The registry does not explain the intended distinction or report what participants actually received. It is not possible to determine from the record whether this reflects incomplete description or another feature of the protocol.

Although enrollment is listed as 20, participant characteristics, group-specific enrollment, participant flow, adherence, and exposure received are not reported in the registry record. The record does not identify an analysis population, and it records zero analyses. It also does not report a statistical analysis plan, missing-data strategy, multiplicity handling, interim analyses, or the study’s own sample-size justification.

The adverse-event entries contain zeros, but the record does not provide evidence of an observed safety population or an outcome-measure collection period. These entries cannot establish that no adverse events occurred. Secondary outcomes are named, but no results or analyses are reported for them.

Together, these limitations mean the record can describe the intended design and stopping circumstance, but cannot support estimates of efficacy, biological response, pain outcomes, precision, or safety. Further protocol or participant-level information is not reported in the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Inflammatory Responses to Acute and Chronic Opioid Exposure in Humans — NCT01749826.
• Registry record last updated 2019-01-30; status last verified 2019-01.
• Results first posted 2019-01-30.
• 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.

17. Record Summary

The registry record describes a randomized, triple-masked, parallel study sponsored by Stanford University, with inflammation listed as the condition. It reports enrollment of 20, a start of 2010-01, primary completion of 2013-07, and status TERMINATED. The phase is listed as NA.

The study aimed to examine inflammatory responses to acute and chronic opioid exposure. Its primary outcome was changes in cytokine release, intended to be compared between blood samples on Day 1 and Day 30. The two arm descriptions state the same morphine regimen, although their titles differ.

The registry says the study was terminated because of a lack of resources before any study-measure data were collected; no blood samples were drawn. It reports zero analyses. Consequently, no primary or secondary outcome effect estimates are available, and the record does not establish a clinical or biological effect.