Pain, Psychiatric Disorders, and Disability Among Veterans With and Without Polytrauma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pain, Psychiatric Disorders, and Disability Among Veterans With and Without Polytrauma (NCT00645970), a registered phase not stated study. The primary outcome is Numeric Rating Scales of Pain Over Past Week (11 Point Likert Scale).

2. Clinical Question

The study’s stated focus is broader than pain intensity alone: its description concerns pain and emotional problems, associated impairments, risk factors, barriers to care, and community reintegration among returning OEF and OIF service members with and without polytrauma. However, the single primary outcome listed in the registry record is a Numeric Pain Rating Scale measure. That endpoint captures reported pain intensity, not psychiatric diagnoses, disability, care access, or reintegration.

The listed groups should be read as group labels, not as randomized treatment assignments. The record does not state how participants entered either group, how the groups were formed, or whether they were intended to represent comparable populations. As a result, a difference in pain ratings, if one were reported, would describe a group contrast and would not by itself establish that group membership caused the difference.

3. Trial Design

The study is registered as completed and lists the US Department of Veterans Affairs as sponsor. Its recorded start is 2008-07 and its primary completion is 2011-09. Enrollment is listed as 359. The registry record does not report a detailed study-design label or an allocation procedure.

Two groups appear in the record: Polytrauma System of Care (PSC) and Registry. The record explicitly cautions that the comparison is not randomized, that allocation is not stated, and that the arms are not a like-for-like control comparison. There is no described assigned treatment, placebo, or randomization process. Thus, the group labels should not be interpreted as trial arms in the usual randomized-treatment sense.

The primary outcome is measured at baseline, 6 months, and 1 year. These time points allow repeated measurement of reported pain intensity, but the record does not describe the follow-up procedures, the timing windows, or how repeated observations were analyzed. It also does not report whether all participants were assessed at each time point.

The brief description frames the work as systematic data collection intended to inform future VA healthcare strategies and treatment development. It refers to examining pain and emotional problems, their course and associated impairments, risk factors, barriers to care, and community reintegration. Those aims provide context, but the registry record lists only one primary outcome measure and does not identify analyses for those broader topics.

No protocol details about eligibility criteria, recruitment, sample-size justification, interim analyses, or a prespecified statistical plan are reported in the registry record. The record lists no statistical analyses. Consequently, the design information supports a description of the population, groups, and planned outcome time points, but not a reconstruction of how the study was conducted or how its results were analyzed.

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

Analysis population for the primary outcome, as defined in the registry: Numeric Pain Rating Scale data are missing for 21 participants (PSC n=1; Registry n=20)

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 Numeric Rating Scales of Pain Over Past Week (11 Point Likert Scale), measured over Baseline, 6 months, 1 year.

The primary endpoint is the Numeric Rating Scale of pain over the past week, recorded in units on a scale. It asks participants to rate their “usual” or average pain intensity over the last week. The response range runs from “no pain” at 0 to “worst pain imaginable” at 10. The record states that a score >3 indicates moderate-to-severe pain.

This is a continuous self-report measure: each rating expresses a level of reported intensity rather than a count of events. The registry lists the mean as the summary measure and the standard deviation as its measure of dispersion. A mean describes the central level of ratings in a group, while the standard deviation describes how spread out the individual ratings are around that mean. Neither summary, by itself, shows the full distribution of responses.

Repeated ratings at baseline, 6 months, and 1 year can describe pain intensity at different points in follow-up. They can also support analyses of change over time if the analysis plan and the relevant numerical results are available. Those numerical results and the method used to compare time points are not reported in the registry record.

Pain intensity is relevant to the study’s focus on chronic pain and functional concerns, but this endpoint does not directly measure psychiatric disorders, disability, barriers to care, or community reintegration. The threshold described in the record gives a way to interpret individual scores; it does not supply group results or establish how many participants crossed that threshold.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean describe?

For a continuous outcome such as a pain rating, the mean is the arithmetic average of the recorded values in a group or at a time point. It gives a compact description of the group’s central rating. It does not indicate that every participant had a rating near that average, and it can be influenced by the distribution of individual observations. The registry specifies the mean as the summary measure for this outcome, but does not report the means themselves.

The standard deviation describes the spread of individual ratings around the mean. A larger standard deviation indicates more variation among recorded values; a smaller one indicates that values are more closely grouped. It is not the same as the uncertainty in the estimated mean. Confidence intervals for means or group differences would address estimation uncertainty, but such intervals are not reported in the registry record.

How should repeated measurements be understood?

The outcome is scheduled at baseline, 6 months, and 1 year. Because the same participant may contribute ratings at more than one time point, those observations are generally correlated. Treating repeated observations as independent can misstate uncertainty. General statistical approaches for repeated measurements model the relationship among observations from the same participant, or compare change from an earlier measurement while accounting for that relationship. The registry record does not report which approach, if any, was used.

A baseline value can provide context for later ratings, but a change over time is not automatically a treatment effect. Interpreting change depends on the comparison being made, the participants observed at each time, and the handling of missing observations. The analysis population, the number assessed at each time point, and the treatment of incomplete records are not reported in the registry record.

Why does the group comparison need caution?

Random assignment is one way to make groups comparable on average at the outset. This record does not describe randomized allocation and explicitly says the groups are not a like-for-like control comparison. Therefore, group differences could arise from pre-existing differences or other factors, as well as from experiences related to group membership. Adjustment for measured characteristics can sometimes help address observed differences, but cannot guarantee removal of unmeasured confounding. Whether any adjustment was performed is not reported in the registry record.

Descriptive comparisons can still characterize the recorded groups. They should be framed as associations or differences between the groups, rather than as evidence that one group caused a change in pain. This distinction matters even when a statistical test indicates a difference: statistical significance alone does not establish comparability, causality, or clinical importance.

What can a significance test tell the reader?

A significance test evaluates how compatible the observed data are with a specified statistical model and a null hypothesis. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or importance of a difference. A small p-value can accompany a modest effect, and a larger p-value can occur when estimates are imprecise. The registry record lists no analyses or p-values, so no test-based conclusion can be drawn.

Confidence intervals add information about precision by displaying a range of estimates compatible with the data and assumptions. A narrow interval indicates greater precision than a wide interval, but precision does not eliminate bias from a nonrandom comparison or problematic missing data. No interval estimates are reported in the registry record.

What do the planning assumptions mean?

The sample-size description concerns planning illustrations based on an observed effect, not the original design justification. It specifies a two-sided significance level of 0.05, equal allocation between the groups, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those calculations are hypothetical planning aids. They are not observed power, do not show what the study was designed to detect, and do not establish that the groups were equally allocated in the actual study. The registry record does not report the original sample-size justification.

General sample-size calculations estimate how many participants per arm might be needed under chosen assumptions. Their result depends on the assumed effect, variability, significance level, power target, allocation, and statistical model. A planning illustration based on a fraction of an observed effect is conditional on those assumptions; it should not be treated as a guarantee that a future study will achieve a particular result. The record does not report an interim-analysis plan or a prespecified statistical analysis plan.

How should over-dispersion be considered?

Over-dispersion arises when observed variability exceeds what a statistical model assumes. In general, failing to account for extra variation can make standard errors too small and confidence intervals too narrow, producing overly confident inferences. The listed primary endpoint is continuous and is summarized with a mean and standard deviation; the registry record does not report a model or evidence about over-dispersion. This general concern therefore cannot be used to infer that it affected this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome measure, with ratings scheduled at baseline, 6 months, and 1 year. Multiple group, time-point, or change comparisons can raise a multiplicity issue: the more hypotheses tested, the greater the chance of at least one apparently unusual result by chance if all tests are interpreted independently. General approaches include prespecifying a primary contrast, using a correction for multiple testing, or treating secondary comparisons as exploratory. The registry record does not report a multiplicity plan, a hierarchy of contrasts, or any statistical analyses.

The record states that Numeric Pain Rating Scale data are missing for 21 participants, identified as PSC n=1 and Registry n=20. It does not state whether these missing values apply to one assessment or multiple assessments, why they are missing, or whether participants with missing outcomes differed from those with recorded outcomes. The number with available data at each follow-up is not reported in the registry record.

Missingness can affect both the number of observations used and the interpretation of an estimate. Complete-case analysis uses only participants with the required observed data; other methods may use partial records under specified assumptions. No method for handling missing data is reported in the registry record, so it is not possible to determine which approach was used or whether assumptions about missingness were examined.

The analysis population is also not described. The registry lists enrollment of 359, but does not state how many participants contributed to each outcome analysis or whether the analysis included all enrolled participants, only those with observed ratings, or another defined group. The registry record lists zero analyses and does not provide an analysis plan. These omissions limit assessment of how results would relate to the enrolled groups and whether missingness or multiple comparisons could affect interpretation.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

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 serious adverse event counts of 0 for the PSC group, with 141 at risk, and 0 for the Registry group, with 218 at risk. It also lists other adverse event counts of 0 for PSC, with 141 at risk, and 0 for Registry, with 218 at risk. These are the counts recorded in the registry; they do not describe the method or duration of adverse-event surveillance.

Zero recorded events should be read as a reported count, not as proof that an event was impossible or that all potential events were captured. The registry record does not describe event definitions, ascertainment procedures, reporting completeness, or comparisons of safety between groups. It also does not list serious adverse event terms.

Deaths are recorded as null for both groups. A null entry is not a numeric zero and should not be interpreted as a reported count of no deaths. The record does not provide an explanation for those null entries. These safety fields are separate from the primary pain-intensity outcome and do not supply evidence about pain ratings or changes over time.

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

The record establishes that the study focused on veterans with and without polytrauma and listed a self-reported pain-intensity measure at baseline, 6 months, and 1 year. It defines the response scale and identifies the mean and standard deviation as the intended summary statistics. It also records group labels, enrollment, a missing-data count, and adverse-event counts.

It does not report numerical pain ratings, group means, standard deviations, estimates of change, confidence intervals, p-values, or statistical analyses. Consequently, it cannot show whether pain ratings were higher in one group, changed over time, or differed by an amount that is precise or meaningful. The threshold of >3 is a scale interpretation in the outcome description, not a reported finding about participants’ scores.

Even if a group difference were available from another analysis, the record’s warning that this was not a randomized, like-for-like comparison would limit causal interpretation. A contrast between PSC and Registry participants could reflect group characteristics and other factors. The registry record does not report whether adjustments were made or what factors were considered.

The broad study description addresses pain, emotional problems, impairments, risk factors, barriers to care, and community reintegration. The registered primary endpoint measures pain intensity only. It cannot, on its own, establish findings about the broader topics. The absence of reported analyses also means that no conclusion about those topics can be attributed to the registry record.

The appropriate reading is therefore descriptive and limited: the record documents a planned pain measure and the study’s context, but not the numerical results needed to evaluate the observed pain ratings. It does not establish that a treatment or service worked or failed, and it does not identify a causal effect.

13. Why This Trial Matters Statistically

This study is statistically notable because it brings a repeated self-report measure of pain into a broader context involving veterans with and without polytrauma. The outcome is defined clearly enough to identify what participants were asked to rate, the scale anchors, and the time points. That information helps distinguish pain intensity from other concepts in the study’s broader description, such as psychiatric disorders, disability, or reintegration.

The record also makes an important design limitation explicit: the groups are not a randomized, like-for-like control comparison, and allocation is not stated. That caveat shapes what a group contrast could mean. Statistical methods can quantify uncertainty around an estimate, but cannot by themselves make nonrandom groups comparable or establish causation.

Repeated outcomes raise questions about within-person correlation, incomplete follow-up, and the definition of change over time. The record does not report how these issues were handled, nor does it supply the pain estimates needed to examine them. The missing-data count and its group breakdown are useful context, but the reasons and pattern of missingness remain unknown.

The record’s limited results reporting is itself relevant to statistical interpretation. Without estimates, uncertainty intervals, and analysis details, readers cannot assess effect size, precision, or robustness. The study description can inform what was intended to be examined, while the available registry results do not support conclusions about the magnitude or direction of pain ratings. Keeping those distinctions clear prevents the study’s broad aims from being mistaken for reported evidence.

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 registry record does not report the numerical results for the primary pain outcome. Means, standard deviations, group contrasts, changes over time, confidence intervals, and test results are absent. This prevents assessment of the outcome’s magnitude, precision, or direction from the registry record.

The groups are explicitly not described as a randomized, like-for-like comparison, and allocation is not stated. The record does not explain how participants entered the PSC or Registry group, or report whether the groups differed in baseline characteristics. Any unadjusted group contrast would therefore need cautious interpretation, and the presence or nature of adjusted analyses is not reported in the registry record.

Although ratings are scheduled at baseline, 6 months, and 1 year, the record does not report the number assessed at each time point, the follow-up procedures, or the analysis of repeated observations. It records missing Numeric Pain Rating Scale data for 21 participants, including PSC n=1 and Registry n=20, but does not describe reasons for missingness or how missing outcomes were handled.

The primary endpoint is a self-report measure of pain over the past week. The registry record does not report additional details about administration, the timing windows for assessments, or whether the scale was completed consistently across follow-up. The record’s broader aims include emotional problems and other forms of impairment, but those topics are not represented by the sole listed primary outcome.

Finally, the registry record lists no analyses and does not report a statistical analysis plan, multiplicity approach, interim analyses, or sample-size justification for the study’s own design. These gaps limit evaluation of how the reported data, if available elsewhere, were selected, analyzed, and interpreted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pain, Psychiatric Disorders, and Disability Among Veterans With and Without Polytrauma — NCT00645970.
• Registry record last updated 2015-05-15; status last verified 2015-05.
• Results first posted 2014-12-30.
• 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.

18. Record Summary

This completed study, sponsored by the US Department of Veterans Affairs, concerns pain, psychiatric disorders, and disability among veterans with and without polytrauma. The registry lists enrollment of 359 and groups labeled Polytrauma System of Care (PSC) and Registry. Allocation is not stated, and the record cautions that the comparison is not randomized or like-for-like.

The primary outcome is a self-reported Numeric Pain Rating Scale rating of usual pain over the past week, measured at baseline, 6 months, and 1 year. The record defines the scale from 0 to 10 and states that a score >3 indicates moderate-to-severe pain. It reports missing scale data for 21 participants, with PSC n=1 and Registry n=20.

Numerical outcome results and statistical analyses are not reported in the registry record. Adverse-event entries list zero serious and other events in both groups; death entries are null. The available record supports description of the outcome and study context, but not a conclusion about pain differences or change over time.