Improving Balance and Mobility: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving Balance and Mobility (NCT02374463), a randomized na study. The primary outcome is Balance and Lateral Mobility Assessed by the Four Square Step Test.

2. Clinical Question

The clinical question is comparative: it concerns the difference in change between the randomized intervention groups, not whether either group changed from baseline in isolation. The registry describes fall prevention as part of the study’s motivation, but the primary endpoint is the Four Square Step Test rather than a count of falls. The number of participants reporting falls is listed as a secondary outcome. These outcomes capture related but distinct aspects of balance and mobility, so a result on the timed test should not be treated as a direct estimate of fall prevention.

3. Trial Design

The registry identifies NCT02374463 as a completed, randomized, single-masked, parallel-group study of MMBI and Tai Chi. Enrollment was 41. The phase is listed as NA. The sponsor is the VA Office of Research and Development. The recorded start date is 2015-06-01 and the primary completion date is 2018-12-31.

A parallel-group design assigns participants to an intervention group and compares outcomes across groups. Randomization is intended, in general, to support a fair comparison by reducing systematic differences between groups at the start of a study. The registry record does not report the allocation sequence method, allocation concealment procedures, or the identity of the person or people masked. “Single” is the recorded masking designation; further details about what was masked are not reported in the registry record.

The primary outcome is change in Four Square Step Test score, defined as the 6 month post-intervention value minus the baseline value. The record describes assessment at baseline and 6 month. The primary results include 12.0 participants in the MMBI group and 9.0 in the Tai Chi group. The secondary falls outcome has group counts of 15.0 and 12.0, respectively. These outcome-specific counts differ; reasons for the differences are not reported in the registry record.

The registry lists four secondary outcomes, including functional gait analysis, changes in right knee and right hip strength, and the number of subjects who reported falls. Results are available for the falls outcome in the posted results, but results for the other listed outcomes are not reported in the registry record. The planned sample-size justification, intervention schedule, follow-up procedures beyond the stated outcome timeframes, and analysis populations 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: the change in four square step test score is calculated as the 6 month (post) - the baseline value (pre)

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 Balance and Lateral Mobility Assessed by the Four Square Step Test, measured over The FSST was assessed at 6 month (post) and at baseline (pre).

The primary endpoint is balance and lateral mobility assessed using the Four Square Step Test (FSST). The test measures, in seconds, the time taken to step forward, sideways, and backward. Its timed stepping task is intended to capture dynamic balance and coordination. The registry states that higher scores are associated with a worse outcome and that higher scores are associated with increased risk of falling. It also notes that some use a score of 15 seconds or higher as a high-risk threshold. That threshold is background information in the endpoint description; it is not the primary result of this trial.

The endpoint is expressed as change from baseline: the 6 month score minus the baseline score. Under that definition, a negative change indicates a shorter completion time at follow-up. Because the registry states that higher times are worse, a more negative change is in the favorable direction on this test. This direction describes the test score only; it does not establish a change in falls or other clinical outcomes.

The registry describes a minimum value of 5 seconds in young healthy populations and a maximum value of 60 seconds. If a participant is deemed unable to complete the test, the value is not reported. The record does not report how many participants were unable to complete the test, how such values were handled in the analysis, or whether the limits affected the reported results. The primary result is a mean change with standard deviation, allowing the group averages to be read alongside the spread of individual changes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary comparison is reported as a two-sided t-test. In general, a t-test compares group means while accounting for the variability of the measured outcome and the amount of data in each group. A two-sided test considers departures in either direction, rather than testing only for a result favoring one intervention. The FSST change is a continuous measure in seconds, so comparing mean changes is a natural way to describe the primary outcome. The registry does not report the test statistic, degrees of freedom, variance assumption, or detailed analysis specification.

What does the p-value tell the reader?

In general, a p-value describes how compatible the observed data are with a specified null hypothesis, under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it is not a measure of the size of an effect. The primary reported p-value, p < 0.05, indicates that the registry’s two-sided t-test met its stated significance threshold. Because the record does not give the exact p-value, a between-group estimate, or a confidence interval for this comparison, readers cannot use the p-value alone to judge the magnitude or precision of the primary effect.

For the binary falls outcome, a risk difference expresses the difference between the proportions reporting falls in the two groups. The unadjusted recalculation is 0.05, and its confidence interval spans values below and above zero. In general, a confidence interval describes the range of effect values compatible with the data under the method used to construct it. When an interval for a risk difference includes zero, it includes no difference as one possibility. Here, the interval is also broad, conveying substantial uncertainty about the direction and size of the group difference. The unadjusted recalculated p-value is 0.756.

Why can sparse event counts make a comparison uncertain?

General explanation: when an outcome occurs in relatively few participants, a small change in the event count can have a substantial influence on the estimated group comparison. Estimates and confidence intervals may therefore be imprecise. The falls counts are 3.0 in each group, while the denominators are 15.0 and 12.0. The recalculated interval reflects uncertainty around the difference; it should not be read as proof that the groups are equivalent. Equivalence requires a prespecified margin and an analysis designed to evaluate it, neither of which is reported in the registry record.

The registry lists Chi-squared tests for the falls outcome, with p = 0.84 and p = 0.4. In general, a Chi-squared test compares categorical outcome counts across groups. Its interpretation depends on the data and the analysis specification. The record does not report the test statistic or other details explaining the two listed results. The unadjusted recalculated p-value is a separate calculation from the posted event counts; it is not a replacement for the sponsor’s analysis.

What is the role of recalculation?

A recalculated result is a simple, unadjusted calculation from posted summary statistics. It can help readers understand the information in the reported counts, but it may not reproduce an analysis that uses individual-level data, covariate adjustment, a different analysis population, or other methods. The registry record does not describe such details for the falls analyses. The discrepancy indicator is false, so no discrepancy between a recalculated result and the sponsor’s reported result is identified in the record. Where an identified discrepancy exists, the sponsor’s own analysis takes precedence; that caveat does not change the limits on interpretation of the available information.

Sample-size illustrations are planning aids rather than trial results. In general, such calculations estimate the participants per arm needed to detect a chosen effect under specified assumptions. The stated assumptions for this illustration are a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect defined as a fraction of the observed effect. These calculations are not the trial’s own design justification, and the registry does not report that justification. They are not observed power and should not be interpreted as evidence that the completed trial was or was not adequately powered.

Over-dispersion is a general concern when count data vary more than a chosen statistical model expects; it can make standard errors too small if the model does not account for that extra variation. The registry does not report an over-dispersion model for the falls outcome, and the simple posted counts do not establish whether over-dispersion is relevant. Likewise, the record does not report adjusted analyses, interim analyses, or a detailed statistical analysis plan. No inference about those procedures can be made from the reported p-values alone.

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("MMBI", "Tai Chi")
n   <- c(12, 9)
m   <- c(-1.8, -0.6)
sp  <- c(0.9, 0.3)
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  MMBI  12  -1.800  0.900  -2.372  -1.228
CARM  Tai Chi  9  -0.600  0.300  -0.831  -0.369

11. Analyses Reported by the Sponsor

For the primary FSST comparison, the registry reports the sponsor’s analysis as a two-sided t-test with p < 0.05. The posted group means and standard deviations describe change within each group, but the registry does not give a numerical between-group estimate or confidence interval for the primary comparison. The available information therefore does not permit a direct numerical comparison between the sponsor’s primary estimate and an unadjusted recalculation of that estimate.

For the falls outcome, the registry lists two Chi-squared p-values, p = 0.84 and p = 0.4. The record does not report which analysis details distinguish them. The unadjusted recalculation from the posted counts gives a risk difference of 0.05 and p = 0.756. These are not identical reported p-values, but the discrepancy indicator is false; the record does not identify a discrepancy. The recalculation is a simple summary-based analysis and should not be treated as a substitute for an analysis using the sponsor’s full data and methods. When the registry identifies a discrepancy, the sponsor’s own analysis takes precedence.

In general, differences between a recalculation and a sponsor analysis can arise from analytic choices or information not present in a summary record. Here, the available record does not give enough detail to explain the two Chi-squared results or to recreate the sponsor’s analysis. The appropriate reading is therefore to retain the reported analyses as the sponsor’s results and use the recalculated falls estimate only as a transparent, unadjusted description of the posted counts.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and four secondary outcomes, with six outcome measures and seven analyses recorded. The primary outcome is change in FSST score. The available secondary outcome results include the number of participants reporting falls; numerical results for the other listed secondary outcomes are not reported in the registry record. The record does not describe a multiplicity strategy, such as a hierarchy of outcomes or an adjustment to account for testing multiple outcomes.

General explanation: when researchers test multiple outcomes, the chance of at least one apparently unusual result can increase if each test is interpreted without regard to the others. A prespecified testing strategy can help clarify which comparisons are confirmatory and how other findings should be interpreted. Without a reported strategy, the primary outcome remains the clearest stated focus, while secondary findings should be treated as supportive or exploratory rather than as independent confirmation. The record does not report whether the seven analyses were planned in advance or how their results were prioritized.

Missing-data handling is also not reported in the registry record. The primary outcome counts are 12.0 for MMBI and 9.0 for Tai Chi, while the falls outcome counts are 15.0 and 12.0. The reasons for these outcome-specific counts and the status of other enrolled participants are not reported. The FSST description says that a value is not reported when a participant is deemed unable to complete the test, but the number of such cases and their treatment in the analysis are not reported. The record does not describe imputation, complete-case analysis, or sensitivity analyses.

The analysis population is not reported in the registry record. It is therefore not possible to determine whether the primary analysis followed an intention-to-treat principle, included only participants with observed follow-up measurements, or used another definition. The record also does not report whether baseline values or other participant characteristics were used as covariates. These gaps matter because analysis populations and missing-data methods can affect which participants contribute to an estimate and how the estimate is interpreted. They do not establish that the analysis was inappropriate; they limit what can be concluded from the registry record.

13. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hospitalization (8.3%).

The registry reports serious adverse event figures for 15 participants at risk in the MMBI group and 12 at risk in the Tai Chi group. One participant in each group is listed as affected by a serious adverse event. The record lists other adverse events affecting 3 participants in each group. Deaths are listed as 0 in both groups. The registry identifies hospitalization as the leading serious-event term at 8.3%.

These counts describe events recorded in the registry; they do not establish whether an event was caused by an intervention. The record does not provide event-level descriptions, timing, severity beyond the serious-versus-other categories, or a group-specific breakdown for the hospitalization term. The denominator and counting details for the 8.3% figure are not reported in the registry record. Because the numbers at risk are limited, the counts alone provide only a narrow description of safety experience and cannot rule out uncommon events or precise differences between groups.

The adverse-event counts should be considered separately from the FSST and falls outcomes. They do not determine the size or precision of the primary balance result, and the registry record does not report a formal statistical comparison of adverse events. These figures are descriptive registry information rather than a complete evaluation of safety.

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

The primary posted results show mean decreases in FSST time in both intervention groups over the baseline-to-6 month change period. The MMBI mean change is more negative than the Tai Chi mean change, and the registry reports a two-sided t-test with p < 0.05. Given the endpoint’s stated direction, these means describe shorter average test times. The result is evidence of a difference in the primary comparison under the reported test, but the registry does not provide the numerical between-group estimate or its confidence interval.

The result does not by itself quantify how large or important the between-group difference is. A p-value is not an effect size, and the absence of a confidence interval leaves the precision of the primary comparison unclear. The result also does not show how many individuals improved, remained stable, or worsened. Group means and standard deviations summarize the outcome but do not reveal the full distribution of participant-level changes.

The primary measure is a timed stepping test, not a direct count of falls. The separate secondary falls outcome has equal event counts in the posted groups and an unadjusted recalculation with a broad confidence interval that extends across no difference. This does not demonstrate that fall outcomes are the same between groups; it indicates that the available comparison is uncertain. The other listed secondary results are not reported in the registry record, so they cannot be used to establish whether the primary pattern is reflected in other measures of gait or strength.

The findings also do not establish which intervention is preferable for an individual, nor do they establish effects beyond the study population and assessment period described in the record. The enrollment was 41, and the primary outcome counts were 12.0 and 9.0. The registry does not report enough information about participant characteristics, missing outcomes, adherence, or analysis populations to assess how these factors may shape generalizability. The appropriate conclusion is confined to the posted results: a reported difference in mean FSST change, alongside limited and imprecise information about falls and unreported results for several other secondary outcomes.

15. Why This Trial Matters Statistically

This trial is statistically informative because it illustrates how the choice of endpoint shapes the question answered. The primary outcome measures timed stepping performance, while the study’s motivation also concerns falls. These are related concerns, but they are not interchangeable outcomes. A primary test result can support a comparison on the measured performance scale without directly answering whether participants experienced fewer falls.

The registry also illustrates the importance of reporting an effect estimate and its uncertainty, not only a significance test. The primary p-value is reported as p < 0.05, but a numerical between-group estimate and confidence interval are not reported. Without them, readers cannot judge the range of primary effects compatible with the data from the registry record. The group means describe the direction of within-group change, while the test addresses the comparative question; those are different pieces of information.

The falls result provides another useful statistical lesson. Equal counts across groups do not automatically imply equal risk, because the group denominators differ. The unadjusted estimate and its broad confidence interval make the uncertainty visible, while the two registry-listed Chi-squared p-values cannot be reconciled from the available analysis details. Transparent reporting of denominators, effect estimates, uncertainty, and analysis methods helps readers understand what a result can support.

Finally, the record highlights why missingness and multiplicity details matter. Outcome-specific participant counts differ, the results for several secondary outcomes are not reported, and the registry does not describe its missing-data approach or multiplicity strategy. These omissions do not show that the trial was conducted incorrectly. They define the limits of what readers can evaluate and underscore the value of complete statistical reporting in small clinical studies.

16. 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 limitations are specific to the information reported for this trial. Enrollment was 41, while the primary FSST result includes 12.0 participants in MMBI and 9.0 in Tai Chi. The falls outcome uses 15.0 and 12.0 participants. The record does not explain why these outcome counts differ or how participants without a reported primary measurement were handled. This limits assessment of the relationship between enrollment, follow-up, and the analyzed groups.

The primary comparison is reported with a p-value but without a numerical between-group effect estimate or confidence interval. The reported group means and standard deviations do not supply that missing comparative precision. The record also does not report the t-test statistic or detailed modeling assumptions. For falls, two Chi-squared p-values appear without an explanation of the analytic distinction, and the summary-based recalculation is unadjusted. These reporting gaps make it difficult to compare the sponsor’s analysis with an independent reconstruction.

The registry lists several secondary outcomes, but numerical results are not reported for functional gait analysis or the strength outcomes. It also does not report a plan for multiplicity, missing-data methods, analysis populations, or whether analyses were adjusted for baseline measurements or other variables. The number of participants who could not complete the FSST, if any, is not reported, even though the endpoint description specifies that a value is not reported when a participant is deemed unable to complete the test.

Further details that would help interpret the study—including participant characteristics, intervention frequency and duration, adherence, the identity of the masked party, and the sample-size justification—are not reported in the registry record. These omissions limit evaluation of applicability, implementation, and precision. They do not permit conclusions about the quality of conduct or the reasons for the reported outcome counts; they restrict interpretation to the results and descriptions recorded.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Improving Balance and Mobility — NCT02374463.
• Registry record last updated 2020-03-27; status last verified 2020-03.
• Results first posted 2020-03-27.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

20. Record Summary

NCT02374463 is a completed randomized, single-masked, parallel-group study comparing MMBI with Tai Chi in older Veterans. Enrollment was 41. The primary outcome was change in Four Square Step Test time from baseline to 6 month, with lower scores associated with a better outcome.

The registry reports mean changes of -1.8 seconds for MMBI and -0.6 seconds for Tai Chi, with standard deviations of 0.9 and 0.3, respectively, and a two-sided t-test result of p < 0.05. It does not report a numerical primary between-group estimate or confidence interval. For the secondary falls outcome, 3.0 participants in each group reported falls; the unadjusted recalculation is imprecise, and the registry lists two Chi-squared p-values without explaining the distinction. Results for the other listed secondary outcomes are not reported in the registry record. The record does not describe its missing-data, multiplicity, or analysis-population methods.