Safety and Efficacy of the TransDiscal System Versus Medical Management in Treating Chronic Discogenic Low Back Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of the TransDiscal System Versus Medical Management in Treating Chronic Discogenic Low Back Pain (NCT01263054), a randomized na study. The primary outcome is Change in Average Daily Pain Visual Analog Scale (VAS) Score Between Screening and Follow up..

2. Clinical Question

The central statistical comparison is between the groups’ average changes from screening or baseline to follow-up, rather than a comparison of their follow-up scores alone. A negative change indicates a lower pain score at follow-up than at baseline. The posted group means are negative in both arms, with a larger-magnitude reduction in the TransDiscal System arm. The estimated between-group contrast and its confidence interval describe the size and precision of that difference in the posted results.

The registry record identifies the primary time point as 6 months after treatment or randomization. It also lists additional patient-reported outcomes, including physical functioning, health status, depression, perceived change, disability, and a pain-response measure. Those outcomes broaden the clinical questions, but they do not replace the prespecified primary comparison. The record does not report a more detailed eligibility description, so further assumptions about which patients the result represents are not warranted.

3. Trial Design

This was a prospective, randomized, multicenter, parallel-group clinical trial comparing disc biacuplasty with medical management for discogenic lumbar back pain. The registry identifies the intervention as the TransDiscal System and describes its arm as receiving the device in addition to standard medical management. The comparison arm received standard medical management. The study is listed as completed, with an enrollment of 67. The recorded start was 2010-12, and primary completion was 2014-12.

The study was open-label, with no masking recorded. That means the registry does not describe blinding of participants or investigators to assigned group. Open-label knowledge can matter when outcomes are reported by participants, as pain and other quality-of-life measures are: expectations and awareness may influence how people report symptoms. That is a general consideration, not evidence that such influence occurred in this trial.

The registry lists the phase as NA. The randomization method, allocation concealment procedures, stratification factors, and detailed conduct of treatment assignment are not reported in the registry record. The protocol’s intended sample size and its justification are also not reported in the registry record. The posted enrollment should therefore be read as the study’s recorded enrollment, not as evidence that a particular target was reached or that the study had a specified level of power.

The primary endpoint is a continuous measure: mean change in average daily pain score from baseline to the 6-month follow-up. The registry gives group means and standard deviations. The outcome description records follow-up data missing for five participants in the TransDiscal System arm and six in the Medical Management arm. How missing observations were handled in the primary analysis, and whether an intention-to-treat or another analysis population was used, are not reported in the registry record.

Safety outcomes are also posted, with groups described as at risk and numbers of participants affected by serious and other adverse events. The registry record does not give detailed event definitions, attribution methods, or a fuller account of safety-monitoring procedures. The study’s statistical analysis plan, including any prespecified adjustment or interim procedures, 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.

Before assignment: In this study, 67 subjects were randomized, with 63/67 being treated. Three of the non-treated subjects had exclusion criteria violations, while the fourth subject was not treated for an undisclosed reason. The disposition of subjects in the Participant Flow summary is with respect to the primary outcome.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Five subjects in the TransDiscal System study arm, and six subjects in the Medical Management study arm did not provide follow-up 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.

6. Primary Endpoint

The registry lists the primary outcome as Change in Average Daily Pain Visual Analog Scale (VAS) Score Between Screening and Follow up., measured over Baseline and 6 months.

The primary endpoint is change in average daily pain Visual Analog Scale score between screening or baseline and the 6-month follow-up. The score ranges from 0 to 10: 0 corresponds to no pain, and 10 to the worst pain imaginable. A change score compares each participant’s follow-up pain score with that participant’s starting score. Group means then describe the average change among participants included in the posted summaries.

Change scores are used to express whether pain scores moved over follow-up and to compare the average movement between assigned groups. A negative mean change represents a decrease on this scale; the posted means are negative in both groups. The between-group estimate expresses the contrast in those average changes. The registry’s posted contrast is 1.84 for Medical Management relative to the TransDiscal System group, reflecting the difference in direction and magnitude of the two changes as reported.

Pain is a patient-reported outcome, so the score captures participants’ reported experience rather than an objective measurement of spinal structure. That makes it directly relevant to a trial asking about pain, while also making it potentially sensitive to expectations, recall, and the circumstances of reporting. Because the study was open-label, those considerations are relevant when interpreting the result; they do not establish that reporting was biased.

The registry identifies the outcome as a mean with standard deviation and gives a baseline and 6-month timeframe. It does not report a minimal clinically important difference or a threshold for interpreting the mean change as important to patients. Statistical evidence of a difference between group means should therefore be distinguished from a judgment about clinical importance.

7. Results Posted in the Registry

• Medical Management: mean -0.56 versus -2.40 on control; difference 1.84 (95% CI 0.57 to 3.11), standardized effect d = 0.82; z-test p = 0.004.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Mean Change in Score of Short Form 36-Physical Functioning (SF36-PF) From Screening to 6 Month Follow up Visit

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Medical Management: mean 1.70 versus 18.00 on control; difference -16.30 (95% CI -27.30 to -5.30), standardized effect d = -0.83; z-test p = 0.004.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Medical Management than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Mean Change in Score of EuroQuol 5d Visual Analog Scale (EQ-5d VAS) Between Screening and 6 Month Follow up Visit

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Medical Management: mean 6.00 versus 15.00 on control; difference -9.00 (95% CI -29.47 to 11.47), standardized effect d = -0.25; z-test p = 0.389.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Medical Management and the control. The interval gives the range of effects that remain compatible with the data.

Mean Change in Score of Beck's Depression Inventory (BDI) Between Screening and 6 Month Follow up Visit

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Medical Management: mean -0.23 versus 0.39 on control; difference -0.62 (95% CI -4.17 to 2.93), standardized effect d = -0.10; z-test p = 0.732.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Medical Management and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover several dimensions related to pain and its consequences: physical functioning, health status, depression, perceived change, disability, and a pain-response threshold. This breadth can help describe whether the primary pain comparison aligns with changes in other patient-reported domains. The available numerical summaries do not show a uniform pattern across all these domains. Some estimates are more distinct from zero, while others are less precise and compatible with a range that includes no difference.

That overall pattern should be read alongside, not as a substitute for, the primary pain result. Secondary measures can provide context about whether an observed pain-score difference appears alongside broader changes, but differing scales and constructs mean they need not move together. A change in one domain does not automatically validate a change in another. The registry record does not report a single combined outcome or an analysis designed to establish a coherent overall benefit across these measures.

Not all six listed secondary outcomes have numerical summaries in the posted results. The registry record does not report numerical results for every listed secondary endpoint. The available secondary analyses are described through group summaries and unadjusted comparisons, rather than a reported prespecified modeling strategy.

Multiplicity is an important reason for assigning secondary findings less weight. When several outcomes are examined, the chance of encountering an apparently notable result increases, even if no true differences exist across the outcomes. No adjustment for multiple comparisons, testing hierarchy, or confirmatory role for these secondary endpoints is reported in the registry record. Consequently, isolated unadjusted results are better regarded as supportive or exploratory signals than as independent confirmation of the primary result.

The registry record also does not report a minimal clinically important difference for these scales. Thus, statistical separation from zero cannot on its own establish that a change is meaningful to participants. The secondary outcomes can broaden interpretation, but uncertainty about multiplicity, missing observations, and clinical thresholds limits the strength of conclusions drawn from them.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Percentage of Study Group Subjects With Greater Than 2 Points Decrease or 30% Drop in Average Daily Pain Related Visual Analog Scale (VAS) Score.
• Mean Change in Score of Short Form 36-Physical Functioning (SF36-PF) From Screening to 6 Month Follow up Visit
• Mean Change in Score of EuroQuol 5d Visual Analog Scale (EQ-5d VAS) Between Screening and 6 Month Follow up Visit
• Mean Change in Score of Beck's Depression Inventory (BDI) Between Screening and 6 Month Follow up Visit
• Mean Change in Score of Patient Global Impression of Change (PGIC) Between Screening and 6 Month Follow up Visit
• Mean Change in Score of Oswestry Disability Index (ODI) Between Screening and 6 Month Follow up Visit

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, and the registry reports a mean and standard deviation for each group. A mean is the arithmetic average of the observed change scores. The standard deviation describes how spread out those scores are around the mean. A mean difference compares the group averages; it does not compare every participant with a matched participant in the other group.

For the primary endpoint, the registry’s contrast is oriented as Medical Management relative to the TransDiscal System group. The reported means are -2.4 and -0.56, respectively, and the estimated mean difference is 1.84. The positive contrast does not mean that pain increased in the Medical Management group: its posted mean change is negative. Instead, the sign reflects the order used for the between-group subtraction. When reading any contrast, the group order matters. The registry lists the comparator as Medical Management and the reference group as TransDiscal System for this comparison.

A confidence interval gives a range of estimates compatible with the observed data under the statistical model and its assumptions. It reflects sampling uncertainty, not all sources of uncertainty. For the primary mean difference, the interval runs from 0.573 to 3.107. Since the interval lies on the positive side of zero, it is consistent with a positive contrast under the stated group ordering. The interval does not account automatically for missing-data bias, measurement effects, selection issues, or choices made in the analysis plan.

The unadjusted p-value for the primary comparison is 0.004. In general, a p-value measures how unusual data at least as incompatible with a null model would be if that model and the test assumptions held. It does not measure the size or clinical value of a difference, and it is not the probability that the null hypothesis is true. The p-value is labeled unadjusted because the registry record does not report a multiplicity adjustment for this result.

The posted comparisons are simple unadjusted calculations from group summaries, rather than reported adjusted analyses. They use the group means, standard deviations, and analysis counts. Such calculations can help readers understand the scale and uncertainty of a comparison, but they cannot reproduce covariate adjustment, repeated-measures modeling, imputation, or other procedures that might have been part of a sponsor analysis. No reported analyses are listed for the secondary outcomes, and the statistical plan is not reported in the registry record.

Standard deviations and standard errors serve different purposes. A standard deviation describes variation among participant scores. A standard error describes uncertainty in an estimated mean and depends on both the variation and the amount of information available. The posted arm summaries include standard deviations; the comparison calculations also characterize uncertainty in the group means. Neither measure indicates the range within which every participant’s result falls.

As a general statistical point, the usual mean-comparison methods rely on assumptions about the sampling process and the distribution of the outcome, especially for small groups. The registry does not report diagnostic checks or a detailed model specification. A continuous change score can be influenced by unusually large changes, and its distribution may not be symmetric. Without participant-level data or a reported model, the degree to which such features matter in this trial cannot be assessed from the registry record.

Randomization aims to make assigned groups comparable on average, including on measured and unmeasured factors, but it does not guarantee identical group composition in a particular trial. It also does not resolve differences arising after assignment, such as missing follow-up or changes in care. The posted result compares the available group summaries; the record does not state whether the analysis preserved all randomized assignments or how deviations from assigned treatment were handled.

Over-dispersion is a general concern for some outcomes when observed variability exceeds what a simple model expects. That issue is particularly important for counts, rates, and event outcomes; it is not the stated model for this continuous primary endpoint. Here, the primary outcome is summarized with means and standard deviations. The registry does not report a model-based assessment of dispersion or a sensitivity analysis.

Multiplicity refers to the increased chance of at least one apparently notable result when many outcomes or tests are examined. This trial lists a primary outcome and several secondary outcomes. Without a reported hierarchy, prespecified testing sequence, or adjustment method, secondary p-values should not be treated as confirmatory evidence. For the primary result, the registry’s record does not explain whether other planned comparisons were considered in setting its inferential status.

Finally, statistical significance and clinical importance are separate questions. The confidence interval and p-value address compatibility with a no-difference model under assumptions. Clinical interpretation would also require an accepted threshold for a meaningful change, context about participant priorities, and confidence that the result is robust to missing data and analysis choices. A minimal clinically important difference is not reported in the registry record.

11. Confidence Intervals and Precision

The primary estimate is a mean difference of 1.84, comparing Medical Management with the TransDiscal System group. Its confidence interval extends from 0.573 to 3.107. The interval gives a range of plausible values for the group contrast under the calculation’s assumptions. Because the whole interval is above zero, the posted unadjusted comparison is consistent with a greater average decrease in the TransDiscal System group, given the stated contrast order.

The interval is informative about precision: its lower and upper limits are separated, so the data do not identify one exact value for the underlying contrast. The estimate is more precise than a result whose interval spans a much wider range, but its limits still allow meaningful uncertainty about the size of the difference. The interval should not be read as containing a specified proportion of individual participants’ responses. It concerns uncertainty in the estimated mean contrast.

The group standard deviations for pain-score change were 2.8 for the TransDiscal System group and 1.6 for Medical Management. These describe observed variability, not the precision of the group contrast by themselves. Precision also depends on the number of observations contributing to the summaries: 24 in the TransDiscal System group and 28 in the Medical Management group. The record notes five and six participants, respectively, without follow-up data.

Confidence intervals address sampling uncertainty under the analysis assumptions. They do not account for possible bias from missing outcomes, open-label reporting, measurement limitations, or unreported analysis choices. The registry record does not provide sensitivity analyses to show how the estimate might change under alternative missing-data assumptions. Nor does it report a clinical-importance threshold that would indicate whether the interval’s range is clinically consequential.

For the secondary outcomes, the posted intervals vary in width and sometimes include zero. That variation reflects differences in outcome variability and available observations; it is not, by itself, evidence that one measure is more important than another. Unadjusted secondary intervals also need caution because multiple outcomes were assessed and no adjustment strategy is reported in the registry record.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm for 80% power and participants per arm for 90% power. They are not total enrollment figures or event counts. The calculation assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The target effect is set as a stated fraction of the observed effect: the planning illustrations consider 100%, 75%, and 50% of that effect.

The 80% power column indicates the number of participants per arm that the illustration estimates would be needed for an 80% chance of detecting the specified effect under those assumptions, if that effect were the true effect and the model assumptions held. The 90% power column represents a higher chance of detection under the same conditions and therefore generally requires more participants per arm. These are design-planning quantities, not guarantees about what a future study would find.

The rows that use a smaller fraction of the observed effect require more participants. This is expected: smaller differences are harder to distinguish from random variation, so more information is needed to detect them at the chosen significance and power levels. The figures are anchored to the observed effect in this trial, which may not equal the effect in a future population or study.

The registry record does not report the original sample-size justification or the assumptions used to design this trial. These planning calculations use stated assumptions for illustration and are separate from the trial’s original design. This is not observed power; it does not measure the probability that the completed trial detected an effect after seeing the results.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 1.840; pooled standard deviation σ = 2.234.
2. n = 2 × (1.96 + 0.842)² × 2.234² / 1.840² = 23.1, rounded up to 24 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 1.84                      # observed difference in means
sigma <- 2.23356217733019                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1263054)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 24 (80% power), 31 (90% power)
 75% of observed effect: n per arm = 42 (80% power), 56 (90% power)
 50% of observed effect: n per arm = 93 (80% power), 124 (90% power)
power.t.test: 24.1 
Simulated power at n = 24 per arm: 0.793 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary pain outcome and multiple secondary outcomes. Testing several outcomes creates a multiplicity issue: even when each test is considered separately, the chance of obtaining at least one apparently notable result across a collection of tests can rise. Statistical approaches can address this through adjustment, a prespecified hierarchy, or a distinction between confirmatory and exploratory analyses. The registry record does not report which approach, if any, was planned for this trial.

The primary comparison is posted with an unadjusted p-value. The record does not describe whether the primary test was protected by a testing hierarchy or whether other planned tests were considered in interpreting it. For the secondary endpoints, no reported analyses are listed as sponsor analyses, and the numerical comparisons available are unadjusted recalculations. They should therefore not be treated as a family of confirmatory tests with controlled error rates.

Missing follow-up is explicitly noted for the primary outcome: five participants in the TransDiscal System arm and six in Medical Management did not provide follow-up data. The group summaries use 24 and 28 observations, respectively. Other secondary outcomes have differing posted analysis counts, indicating that the number of available observations varies by measure. The registry record does not give reasons for missingness, whether participants with missing data differed from those observed, or whether missing values were imputed.

These details matter because an available-case mean describes participants whose outcomes were observed. If missingness is related to pain, treatment experience, or group assignment, that mean may not represent the experience of all randomized participants. This is a general statistical concern, not evidence that missingness was biased in this trial. The record does not report sensitivity analyses under alternative assumptions about missing outcomes.

The analysis population is also not described in detail. The registry record does not state whether the primary analysis followed intention-to-treat principles, how treatment discontinuation or crossover was handled, or which participants were included in each analysis beyond the posted counts. The original statistical analysis plan, any interim analyses, and the approach to multiplicity are not reported in the registry record. These omissions limit assessment of whether the reported results follow a prespecified strategy and how robust they are to alternative analytic choices.

15. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pancreatitis (3.4%), abdominal pain upper (3.4%), completed suicide (3.4%), iliac artery occlusion (3.4%), chest pain (2.9%).

The registry posts serious and other adverse-event summaries by group. For serious adverse events, the at-risk group sizes are 29 for the TransDiscal System arm and 34 for Medical Management; the numbers affected are 3 and 1, respectively. For other adverse events, the at-risk group sizes are 29 and 34, and the numbers affected are 24 and 23. These are counts of affected participants as recorded in the registry, not a complete description of event severity, timing, or recurrence.

The listed serious event terms include pancreatitis, abdominal pain upper, completed suicide, iliac artery occlusion, and chest pain, with the percentages reported in the record. The registry does not provide enough detail to determine whether the listed events were considered related to the intervention, how terms were selected for listing, or whether participants could contribute more than one event. Death counts are not reported in the registry record.

These summaries are descriptive. The group sizes at risk differ from the primary outcome analysis counts, and safety follow-up may use a different population or observation period. The record does not provide person-time, detailed exposure duration, or a comparative safety analysis. The event counts should therefore be read as posted observations, not as proof of causation or as a complete estimate of relative risk.

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

The posted primary result is a difference in average change in pain score at 6 months. The mean change was -2.4 in the TransDiscal System group and -0.56 in Medical Management, and the estimated contrast was 1.84 for Medical Management relative to the TransDiscal System group. The confidence interval from 0.573 to 3.107 and the unadjusted p-value of 0.004 indicate that the posted summaries are not consistent with an equal group mean change under the simple comparison assumptions.

This statistical result does not establish that the intervention caused the full observed difference, nor does it show that every participant experienced a decrease. The trial was randomized, which supports a causal comparison when assignment, follow-up, and analysis are appropriately maintained. However, the registry record does not report key details about randomization implementation, analysis populations, or missing-data handling. The open-label design and patient-reported outcome also mean that expectations and reporting context are relevant considerations, although the record does not show whether they affected the results.

The estimate is an average. Individual outcomes can vary, as reflected in the group standard deviations, and a mean does not describe the distribution of responses or identify which participants benefited most. No responder breakdown for the primary endpoint is posted in the primary result. The listed secondary outcomes offer additional perspectives, but their unadjusted nature and incomplete numerical reporting limit how strongly they can reinforce the primary finding.

Statistical evidence of a difference is not the same as evidence that the difference is large enough to matter to patients. The registry record does not report a minimal clinically important difference or a threshold for judging the observed pain change. Interpretation of clinical importance would require that context, along with consideration of adverse events, follow-up completeness, and the range of possible effects reflected in the confidence interval.

The result also does not establish how well it generalizes beyond the population and care setting represented in the trial. More detailed eligibility criteria and a fuller account of treatment delivery are not reported in the registry record. The appropriate conclusion is therefore limited: the posted data show a statistically distinguishable difference in average pain-score change at 6 months, while important questions about clinical importance, robustness, safety attribution, and applicability remain unresolved by the registry record.

17. Why This Trial Matters Statistically

This trial illustrates why a group mean difference, its confidence interval, and the underlying outcome scale should be interpreted together. The primary estimate is not just a statement that one group had a lower score; it compares changes from baseline and preserves the group ordering used for the contrast. Reading the sign without checking that ordering can lead to a mistaken interpretation. Connecting the estimate to the 0-to-10 pain scale gives the statistical contrast its measurement context.

The result also shows how precision and statistical evidence answer different questions. The unadjusted p-value indicates incompatibility with a no-difference model under the comparison assumptions, while the confidence interval communicates a range of plausible contrast sizes. Neither determines whether the difference is important to patients. That requires a meaningful-change benchmark, which is not reported in the registry record.

Follow-up completeness is central to interpreting a randomized comparison. The registry notes missing primary outcome data in both arms, while the posted analysis counts are smaller than the recorded enrollment. Without a reported missing-data strategy or sensitivity analyses, readers cannot determine how strongly the estimated contrast depends on the observed participants. This is a practical reminder that randomization at assignment does not by itself guarantee an unbiased comparison after loss to follow-up.

The open-label design is also relevant because the endpoint is self-reported pain. This does not invalidate the result, but it makes the measurement process part of the interpretation. Finally, several secondary measures are listed, creating a multiplicity concern when unadjusted findings are considered. Taken together, the trial offers a useful example of how statistical evidence, measurement, missingness, and prespecification all shape the strength of a clinical-trial conclusion.

18. 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.

Several trial-specific limitations affect interpretation of the posted results. The study was open-label and the primary endpoint was a participant-reported pain score. Awareness of assigned group may influence reporting or expectations in general, although the registry record does not establish that this occurred. The record does not describe blinded assessment or procedures intended to reduce reporting effects.

Follow-up data were missing for five participants in the TransDiscal System arm and six in Medical Management. The primary outcome summaries include 24 and 28 participants, respectively. Reasons for missingness, handling of missing outcomes, and sensitivity analyses are not reported in the registry record. This leaves uncertainty about whether the observed-case comparison represents all assigned participants.

The record does not describe the randomization sequence, allocation concealment, detailed eligibility criteria, treatment adherence, co-interventions, or analysis population. These features can affect the risk of bias and the applicability of results. The registry also does not report the original sample-size rationale, the prespecified statistical plan, interim analyses, or a multiplicity strategy.

Numerical summaries are not available for every listed secondary outcome, and the available secondary comparisons are unadjusted. The registry record does not report a minimal clinically important difference for the pain scale or the secondary measures, limiting interpretation of clinical importance. Safety information is presented descriptively, without event attribution, timing, person-time, or a detailed comparative analysis; death counts are not reported in the registry record.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Safety and Efficacy of the TransDiscal System Versus Medical Management in Treating Chronic Discogenic Low Back Pain — NCT01263054.
• Registry record last updated 2018-07-10; status last verified 2015-03.
• Results first posted 2016-03-09.
• 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.

22. Record Summary

The registry describes a completed, prospective, randomized, multicenter, open-label, parallel-group trial of the TransDiscal System plus standard medical management versus standard medical management for discogenic lumbar back pain. Recorded enrollment was 67. The primary endpoint was change in average daily pain score from baseline to 6 months on a 0-to-10 scale.

The posted mean changes were -2.4 for the TransDiscal System group and -0.56 for Medical Management. The estimated mean difference was 1.84 for Medical Management relative to the TransDiscal System group, with a confidence interval from 0.573 to 3.107 and an unadjusted p-value of 0.004. Follow-up data were missing for five and six participants in the respective groups.

The registry also lists secondary patient-reported outcomes and descriptive adverse-event counts. Important details—including missing-data methods, the original sample-size justification, the analysis plan, and multiplicity procedures—are not reported in the registry record. The statistical result indicates a difference in average change, but the record does not establish its clinical importance or resolve all questions about robustness and applicability.