Effect of Lumbar Bracing on Spinal Function: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Lumbar Bracing on Spinal Function (NCT02251106), a non-randomized na study. The primary outcome is Oswestry Disability Index.

2. Clinical Question

3. Trial Design

The registry describes a completed, non-randomized, parallel-group study with a before-and-after design. The sponsor was the University of Alberta. The record gives a start of 2012-05 and a primary completion of 2014-01. It lists the study phase as not applicable. The recorded enrollment is 54.

Three groups were described. Asymptomatic participants in one group did not wear a brace; asymptomatic participants in another group wore one; and participants with acute low back pain wore one. The two braced groups were instructed to wear the lumbar corset continually for 2 weeks, with exceptions for bedroom and bathroom activities. Spine-function measures were assessed before and after the 2-week period. The unbraced asymptomatic group was also measured before and after a 2-week period.

Because allocation was non-randomized, differences between groups may reflect differences that existed before the study period, including symptom status, rather than the brace or the passage of time. A before-and-after comparison within a group addresses change over time but does not, by itself, establish why that change occurred. No masking was used. The registry record does not report how participants were recruited, how allocation to the groups was determined, or whether any additional eligibility criteria were applied.

The primary outcome was ODI. Secondary outcomes listed in the registry were the Modified Sorensen Test, Bulk Spinal Stiffness, and Rehabilitation Ultrasound Imaging. Although these outcomes are named, their numerical results and analysis methods 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

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 Oswestry Disability Index, measured over 2 weeks.

The primary endpoint was the Oswestry Disability Index, a self-reported measure of perceived disability related to back function. The questionnaire contains 10 questions, each scored from 0-5. The item scores are summed and divided by the number of questions answered, then converted to a percentage of disability. Scores range from 0-100%; lower scores mean less reported disability. If a section is missed or not applicable, the score is calculated using the total possible score with that section removed.

Self-reported function captures how participants perceive the effect of their condition on daily life. It complements the study’s objective or performance-based measures, which include a timed lumbar extension test and measures of spinal stiffness and muscle function. A questionnaire score is not a direct measurement of spinal mechanics, and it may reflect more than physical capacity alone.

The registry gives the endpoint timeframe as 2 weeks and describes the measure as a mean with standard deviation. It does not report the ODI values before or after the study period, the change in each group, or a between-group estimate. Therefore, the direction, magnitude, and precision of the primary endpoint results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a non-randomized, parallel-group before-and-after study. It does not report an inferential statistical plan for the primary outcome. In particular, the method used to compare measurements over time or across groups is not reported in the registry record. The endpoint is described as a mean with standard deviation, but that description alone does not specify the model, test, adjustment variables, or form of the primary comparison.

What does a before-and-after design estimate?

General statistical explanation: a before-and-after analysis compares measurements from participants at different times. A within-participant comparison can account for stable characteristics of each participant, but it cannot automatically distinguish an intervention effect from other changes over time. For example, natural symptom change, changes in activity, expectations, or measurement variation can coincide with the study period. Whether those influences were measured or addressed is not reported in the registry record.

The three groups provide different contexts, but they are not interchangeable. One group was asymptomatic and unbraced, one was asymptomatic and braced, and one had low back pain and was braced. Since allocation was non-randomized, measured or unmeasured differences at baseline may affect comparisons. The registry record does not report baseline ODI values or the method used to account for baseline differences. It also does not report whether the main comparison was a change within each group, a comparison of changes between groups, or another contrast.

Why does randomization matter?

General statistical explanation: random assignment tends to balance both known and unknown participant characteristics across comparison groups, on average. It does not guarantee identical groups, but it supports a causal comparison when the study is otherwise conducted and analyzed appropriately. In a non-randomized study, differences between groups can be related to how participants entered or were assigned to them. The registry explicitly notes that the arms are not a like-for-like control comparison. The process used to place participants in groups is not reported in the registry record.

What would a mean and standard deviation communicate?

General statistical explanation: a mean summarizes the average value in a group, while a standard deviation describes variation among individual values around that average. Neither one alone gives the uncertainty in a treatment contrast. A confidence interval for a group difference or change would help convey the precision of that estimate. No means, standard deviations, group contrasts, or confidence intervals for ODI are reported in the registry record.

Why can over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variation is greater than a statistical model expects. If a model assumes less variability than the data contain, its standard errors may be too small and its intervals too narrow. This is especially relevant for outcomes modeled as counts or proportions. ODI is described as a continuous score summarized by a mean and standard deviation, and the registry record does not report a model or an over-dispersion assessment. No claim about over-dispersion in this study can therefore be made.

What can the registry say about sample size planning?

The record lists enrollment of 54, but it does not report a sample-size justification or the assumptions used to choose the enrollment target. General statistical explanation: planning calculations depend on the target effect, outcome variability, chosen error rates, allocation, and analysis method. A planning illustration based on an observed effect is not evidence of the study’s original planning, and it is not observed power. The study’s own sample-size rationale is not reported in the registry record.

The registry record also does not report interim analyses, adjustment for baseline covariates, the handling of repeated measurements, or sensitivity analyses. Without those details and the outcome estimates, the statistical evidence for the primary question cannot be independently evaluated from the posted record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("-LBP/-Brace", "-LBP/+Brace", "+LBP/+Brace", "-LBP/-Brace @ 2 Weeks", "-LBP/+Brace @ 2 Weeks", "+LBP/+Brace @ 2 Weeks")
n   <- c(19, 18, 17, 19, 18, 17)
m   <- c(0.42, 0.83, 10.41, 0.42, 0.52, 6.1)
sp  <- c(0.9, 1.76, 5.87, 1.02, 1.31, 5.62)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  -LBP/-Brace  19  0.420  0.900  -0.014  0.854
CARM  -LBP/+Brace  18  0.830  1.760  -0.045  1.705
CARM  +LBP/+Brace  17  10.410  5.870  7.392  13.428
CARM  -LBP/-Brace @ 2 Weeks  19  0.420  1.020  -0.072  0.912
CARM  -LBP/+Brace @ 2 Weeks  18  0.520  1.310  -0.131  1.171
CARM  +LBP/+Brace @ 2 Weeks  17  6.100  5.620  3.210  8.990

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary ODI outcome and three secondary outcomes: the Modified Sorensen Test, Bulk Spinal Stiffness, and Rehabilitation Ultrasound Imaging. Testing several outcomes, time points, or group contrasts can increase the chance of finding at least one apparently notable result by chance. General statistical explanation: multiplicity procedures can control that risk, or a prespecified hierarchy can distinguish confirmatory questions from exploratory ones. Whether this study used any such approach is not reported in the registry record.

The record does not describe how many statistical comparisons were planned, whether outcomes were tested in a fixed order, or whether the primary endpoint was analyzed in a single prespecified contrast. It reports no analysis results, and the number of analyses is recorded as zero. That entry does not provide an analysis plan or explain whether analyses were not conducted, not submitted, or not entered in the registry.

Missing-data procedures are also not reported. The record does not state how missing questionnaire items were handled beyond describing the ODI scoring rule when one section is missed or not applicable. It does not report the number of missing ODI assessments, whether participants withdrew, how incomplete follow-up was handled, or whether any imputation or sensitivity analysis was used.

The analysis populations are not described. In particular, the registry record does not say how many enrolled participants contributed baseline and follow-up ODI values, whether all participants were analyzed in their assigned groups, or how exclusions were handled. The enrollment figure and adverse-event denominators should not be assumed to be the endpoint analysis sample sizes. Without outcome-specific denominators and missing-data information, the completeness and representativeness of the primary endpoint results cannot be assessed.

12. 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 adverse-event record lists zero serious adverse events and zero other adverse events in each of the three groups. It gives 19 participants at risk in the asymptomatic unbraced group, 18 in the asymptomatic braced group, and 17 in the group with low back pain that wore a brace. The record also lists zero deaths in every group.

These entries describe what was reported in the registry record; they do not establish that no adverse events occurred outside the recorded categories or observation period. The registry does not report event definitions, how events were collected, the duration of safety follow-up, or whether participants had complete follow-up for adverse events. It also does not provide a statistical comparison of safety between groups.

General statistical explanation: zero recorded events does not prove that the true event risk is zero. The information is limited by the number of participants observed and the completeness and duration of monitoring. These safety figures should therefore be read as registry-reported counts, not as definitive evidence about comparative safety.

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

The study addresses an important measurement question: it planned to assess self-reported and objective aspects of spinal function before and after a 2-week period that included lumbar brace use for two groups. The registry identifies the ODI as the primary outcome and lists additional measures of endurance, stiffness, and muscle function. It also distinguishes asymptomatic participants from participants with acute low back pain.

What the record does not establish is the result of that assessment. Numerical ODI findings, secondary-outcome results, uncertainty estimates, and statistical comparisons are not reported in the registry record. It is therefore not possible to state whether ODI changed, how large any change was, or whether the groups differed in their changes. The absence of reported results is not evidence that there was no change or no difference.

Even if outcome estimates were available, the non-randomized design would require cautious interpretation. A before-and-after change can reflect multiple influences over time, and differences between the three groups may be related to symptom status or other group characteristics. The registry does not report an analysis that adjusts for such differences or a randomized comparison that would support a direct causal interpretation.

The posted record can be used to understand the study’s question, group structure, intervention instructions, registered outcomes, and reported adverse-event counts. It cannot, on its own, answer whether brace use caused a change in function or establish the magnitude and precision of any effect. Those conclusions would require outcome results and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial is statistically notable for combining self-reported function with objective measures in a before-and-after design. The registry describes ODI alongside a timed lumbar extension test and measures of spinal stiffness and muscle function. Such outcomes capture different aspects of function; agreement or disagreement among them could be informative, but their results are not reported in the registry record.

The three-group structure also makes the estimand important. A change over time among participants with low back pain who wore a brace is not the same question as a comparison between braced and unbraced participants. The asymptomatic unbraced group provides a reference for change among people without back pain, while the asymptomatic braced group may inform a different contrast. Because the allocation was non-randomized and the groups differ in symptom status, the intended primary contrast and its interpretation matter. The specific analysis contrast is not reported.

The record illustrates why registration details and outcome results serve different purposes. It gives a clear description of the primary measure and the 2-week timeframe, but it does not provide the means, changes, uncertainty intervals, or tests needed to interpret the endpoint statistically. Likewise, the listed enrollment does not replace an endpoint-specific analysis population, and zero recorded adverse events do not quantify uncertainty about safety.

For biostatistical interpretation, the key lesson is to separate the study question, the design, the estimand, and the reported evidence. A study may measure a relevant outcome without the registry record supplying enough results to estimate the effect or its precision. Here, the design and outcome definitions are documented, whereas the primary outcome analysis is not reported in the registry record.

15. 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 important limitation of the registry record is that it does not report the primary endpoint results. There are no ODI values, estimated changes, between-group contrasts, confidence intervals, or p-values. The same absence of numerical results applies to the listed secondary outcomes. Consequently, neither the direction nor the size or precision of the measured changes can be assessed.

The non-randomized allocation limits causal interpretation. The groups differ by symptom status and brace use, and the registry record does not explain how participants entered each group or report an adjustment strategy for baseline differences. No masking was used. The record does not report participant recruitment details, eligibility criteria, adherence to brace instructions, or co-interventions, so their roles cannot be evaluated.

Other analysis details are not reported: the primary statistical method, prespecified group contrast, endpoint-specific sample sizes, baseline outcome values, handling of missing data, analysis populations, multiplicity strategy, interim analyses, and sample-size justification. These omissions restrict assessment of risk of bias, precision, and robustness.

Safety reporting is also limited to event counts and denominators. Event definitions, ascertainment, follow-up completeness, and the safety analysis method are not reported in the registry record. These limitations describe gaps in the posted record and should not be interpreted as proof that the study did not collect or analyze additional information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effect of Lumbar Bracing on Spinal Function — NCT02251106.
• Registry record last updated 2023-03-08; status last verified 2022-03.
• Results first posted 2023-03-08.
• 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.

19. Record Summary

The registry describes a completed, non-randomized, parallel-group before-and-after study sponsored by the University of Alberta, with enrollment of 54. It lists a start of 2012-05 and primary completion of 2014-01. Participants were asymptomatic without a brace, asymptomatic with a brace, or participants with low back pain who wore a lumbar corset for 2 weeks. The primary outcome was ODI, with additional measures of spinal endurance, stiffness, and muscle function.

The registry record reports zero serious adverse events, zero other adverse events, and zero deaths in each group. It does not report primary or secondary outcome results, statistical comparisons, uncertainty estimates, the analysis population, missing-data procedures, or a sample-size justification. The record therefore describes the study design and registered measures but does not permit interpretation of the size or precision of the primary outcome findings.