I-STAND R21: Reducing Sedentary Time in Older Adults: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for I-STAND R21: Reducing Sedentary Time in Older Adults (NCT02692560), a randomized na study. The primary outcome is Change in Hours of Sitting Time.

2. Clinical Question

The trial was designed to compare a sitting-time reduction program with an active control condition that offered general health content. The primary measure was continuous, so the central question is about average change rather than the proportion of participants who crossed a threshold. The registry record gives a between-group estimate and a confidence interval, allowing the direction and precision of that average contrast to be considered together. Details about the exact measurement instrument and the statistical model used for the original study analysis are not reported in the registry record.

3. Trial Design

The registry record describes NCT02692560, titled I-STAND R21: Reducing Sedentary Time in Older Adults, with the official title Take Active Breaks From Sitting (TABS): Reducing Sedentary Time in Older Adults. Kaiser Permanente is listed as the sponsor. The study is marked completed, with start in 2016-02 and primary completion in 2017-02. Phase is listed as NA.

The design is randomized, single-masked, and parallel. Random allocation means assignment to the study groups was intended to occur by chance, while a parallel design compares groups assigned to different conditions over the same study period. The identity of the person or people masked is not reported in the registry record, so the masking label cannot be interpreted more specifically. The record lists enrollment as 60.

Participants assigned to I-STAND were offered 2 in-person health coaching sessions and 4 biweekly phone-based sessions, along with a wristband that vibrated after 20 minutes of inactivity. The program encouraged standing if possible. Participants assigned to Healthy Living received 1 in-person health coaching session, 5 biweekly check-in letters, and a workbook with general healthy living topics. The registry description says those topics were not expected to affect sitting time.

The primary outcome was change in hours of sitting time, measured in minutes, at 12 weeks. Its description specifies average sitting time over the last 7 days at baseline and 12 weeks later. Secondary outcomes listed in the record include sit-to-stand transitions, periods of sitting for 30 or more minutes, physical function, systolic blood pressure, fasting glucose, total cholesterol, and depressive symptoms. The detailed posted results include numerical summaries for some, but not all, of these secondary outcomes. The record does not report the trial's original sample-size justification, planned analysis populations, or full protocol details.

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: 6 Healthy Living participants withdrew before completing the 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 Change in Hours of Sitting Time, measured over 12 weeks.

The primary endpoint is change in sitting time, expressed in minutes. The registry describes the underlying measure as average hours of sitting over the last 7 days, collected at baseline and again at 12 weeks. The outcome is therefore intended to capture whether participants’ average sitting time changed during the intervention period, rather than simply describing sitting time at one assessment.

A continuous endpoint preserves information about the size and direction of changes across participants. A mean change can communicate the group’s average shift, while the standard deviation describes how dispersed individual changes are around that average. Neither statistic shows the full distribution of participant responses. The registry gives group means and standard deviations, but it does not report individual-level observations or the measurement instrument used to assess sitting.

This endpoint is relevant to the study question because the stated aim was to learn whether an intervention to reduce sitting time changes sitting time compared with a control group. The posted values are negative for I-STAND and positive for Healthy Living. In the context of a change measure where less sitting is the target, a negative change represents a decrease and a positive change an increase. The registry’s wording does not provide further detail about how daily averages were constructed or how missing assessments were handled, so those measurement and processing details are not reported in the registry record.

7. Results Posted in the Registry

• Healthy Living: mean 6.50 versus -70.10 on control; difference 76.60 (95% CI 30.08 to 123.12), standardized effect d = 0.86; z-test p = 0.001.

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.

Sit-to-stand Transitions

• 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:
  • Healthy Living: mean 2.20 versus -0.10 on control; difference 2.30 (95% CI -3.68 to 8.28), standardized effect d = 0.21; z-test p = 0.451.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Healthy Living and the control. The interval gives the range of effects that remain compatible with the data.

Periods of Sitting for 30+ Minutes

• 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:
  • Healthy Living: mean 0.10 versus -2.50 on control; difference 2.60 (95% CI 0.92 to 4.28), standardized effect d = 0.81; z-test p = 0.002.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Healthy Living than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Physical Function

• 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:
  • Healthy Living: mean 0.20 versus -0.50 on control; difference 0.70 (95% CI -0.23 to 1.63), standardized effect d = 0.39; z-test p = 0.140.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Healthy Living and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists seven secondary outcomes, spanning sitting patterns, physical function, blood pressure, fasting glucose, total cholesterol, and depressive symptoms. Numerical summaries and unadjusted comparisons are posted for sit-to-stand transitions, periods of sitting for 30 or more minutes, and physical function. Numerical results for the other listed secondary outcomes are not reported in the registry record. The secondary results cover related but distinct questions: some describe sitting behavior directly, while others concern function or broader health measures.

Across the detailed secondary results, the estimates do not all have the same degree of statistical clarity. The interval for periods of sitting for 30 or more minutes is on one side of zero, whereas the intervals for sit-to-stand transitions and physical function include zero. This is a general pattern, not a basis for treating each outcome as an independent confirmation of the primary finding. The secondary outcomes can add context about related measures, but they do not replace the primary endpoint or explain the mechanism of the primary difference.

The secondary comparisons are unadjusted. When many outcomes are examined, the chance of seeing at least one apparently notable result can increase, even if none of the underlying effects is real. A multiplicity plan or adjustment is not reported in the registry record, so the individual secondary p-values should be regarded as exploratory rather than as a family of confirmatory tests. The registry also reports no formal analyses in its reported-analyses listing. This limits the ability to determine whether the posted outcome summaries correspond to prespecified analyses.

The primary result and secondary pattern should therefore be read together but not conflated. The primary measure directly addresses change in average sitting time. Secondary measures can offer supporting or contrasting descriptive evidence, yet they differ in construct, scale, and precision. In the absence of a reported multiplicity strategy and complete numerical results across all listed outcomes, the secondary findings carry less evidential weight than a prespecified, fully reported primary analysis.

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

• Sit-to-stand Transitions
• Periods of Sitting for 30+ Minutes
• Physical Function
• Blood Pressure (Systolic Blood Pressure)
• Fasting Glucose (mg/dL)
• Total Cholesterol (mg/dL)
• Depressive Symptoms

9. Statistical Interpretation

10. Statistical Methods Explained

The primary measure is continuous: each participant’s sitting-time change can take a range of values, rather than belonging only to a category. The registry reports the mean and standard deviation in each group. The mean is the arithmetic average of the observed changes; the standard deviation describes how spread out those changes are around the group mean. A mean is useful for describing the average group shift, but it does not indicate whether most participants had similar changes or whether the average was influenced by a smaller number of larger changes.

What does the mean difference represent?

The posted primary comparison is a mean difference between Healthy Living and I-STAND. The group means are -70.1 minutes for I-STAND and 6.5 minutes for Healthy Living, and the reported contrast is 76.6 minutes. The contrast’s direction follows comparator minus I-STAND: a positive estimate means the Healthy Living mean is higher, or less negative, than the I-STAND mean. Because negative change represents reduced sitting in this measure, that direction corresponds to a larger average reduction in I-STAND. The comparison is unadjusted and is calculated from the posted summary statistics.

What does the confidence interval add?

A confidence interval gives a range of values that are compatible with the observed data under the calculation’s assumptions and method. It conveys uncertainty about the estimated difference, rather than the spread of individual participant outcomes. The primary interval is 30.08 to 123.1 minutes. Its endpoints apply to the group mean contrast, not to the range of changes expected for individual participants. An interval’s width is affected by variability and the amount of information in the data. The registry does not identify an original sponsor analysis that can be compared with this recalculation.

How should the p-value be read?

The unadjusted p-value for the primary comparison is 0.001. In general, a p-value measures how inconsistent the observed statistic, or a more extreme one, would be with a specified null model if that model and the analysis assumptions held. It is not a measure of effect size, practical relevance, or the probability that a finding is due to chance. The result should be considered alongside the mean difference, its interval, the study design, and limitations in the posted analysis details. The registry does not report a multiplicity adjustment for the primary result.

What role do the standard deviations play?

The primary standard deviations are 104.0 minutes in I-STAND and 69.0 minutes in Healthy Living. They describe variation among observed changes within each group. The pooled standard deviation used in the recalculated comparison is 89.56 minutes. Pooling combines the group variability for a standardized comparison and is an assumption-based summary; it does not mean the groups had identical variability. The reported standardized effect size is 0.855. Such a standardized measure expresses the mean contrast relative to a standard deviation, but it is less directly interpretable in minutes and depends on the chosen standardization.

The record identifies the comparison as a simple, unadjusted recalculation from posted summaries. This approach uses the means, standard deviations, and sample sizes to estimate the contrast and its uncertainty. It does not substitute for a fully reported analysis of the trial. Details such as the original model, any baseline adjustment, treatment of repeated measurements, assumptions about missing data, and analysis population are not reported in the registry record. Consequently, the recalculated statistics should not be attributed to a particular unreported modeling strategy.

Randomization is intended to make the groups comparable on average at assignment, including characteristics that were not measured. It does not guarantee identical groups, and it cannot correct problems arising after assignment, such as differential missingness or departures from the assigned intervention. The registry’s single-masked designation does not identify who was masked. Adherence, fidelity, and whether outcome assessment was masked are not reported. These design and reporting details matter when deciding how far a numerical contrast can support a causal interpretation.

Statistical uncertainty and study limitations are related but different. The confidence interval represents uncertainty under the calculation’s assumptions; it does not account for every possible bias, measurement error, or limitation in generalizing the result. Likewise, an unadjusted p-value does not compensate for missing analysis details or for multiple outcomes. A careful reading therefore combines the estimated difference and interval with the record’s information about design, outcome availability, and analysis reporting.

11. Confidence Intervals and Precision

The primary estimated mean difference is 76.6 minutes, with a confidence interval from 30.08 to 123.1 minutes. The estimate is not a single exact value known without uncertainty. The interval expresses the range of values supported by the unadjusted recalculation under its statistical assumptions. It is an interval for the difference between group means, not a prediction interval for individual participants and not a range containing a specified share of individual changes.

Both endpoints are above zero for the Healthy Living-minus-I-STAND contrast. This indicates that, under the calculation used, the data are compatible with a positive average contrast across the interval’s range. The interval also shows that the estimated magnitude is not pinned down to one precise value: its endpoints allow a range of possible differences. The lower and upper limits should be considered together with the point estimate rather than treating the point estimate as definitive.

Precision depends in part on the amount of outcome information and on how variable the observations are. The posted primary standard deviations, 104.0 minutes for I-STAND and 69.0 minutes for Healthy Living, indicate that participant changes varied around the group means. The endpoint summaries include 29 I-STAND participants and 25 Healthy Living participants. The registry also reports 6 Healthy Living withdrawals before completion, but it does not explain how missing outcome values were treated. The interval does not account for uncertainty about missing-data assumptions or unreported aspects of the analysis.

The registry does not specify a confidence level for this recalculated interval, so no confidence percentage should be inferred from the record. Precision is also not the same as practical importance: the interval describes statistical uncertainty in the mean contrast, while whether values in its range matter to participants or researchers requires context not reported in the registry record. The unadjusted p-value is 0.001, but it does not replace the interval’s information about the range and scale of plausible mean differences.

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 this continuous-outcome comparison, not total events. The illustration assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It uses the observed effect as its reference and shows planning for 100%, 75%, and 50% of that observed effect. These assumptions describe the posted planning illustration, not the trial’s original design; the original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the estimated participants per arm for a future study to have an 80% chance of detecting the specified effect under the illustration’s assumptions, if that effect is the true one and the model assumptions hold. The 90% column expresses the corresponding planning target for a higher chance of detecting that effect. They are design targets, not guarantees, and they do not indicate the probability that the trial’s conclusion is correct.

For the primary outcome, the planning entries are 22 and 29 participants per arm when planning for 100% of the observed effect; 39 and 52 when planning for 75%; and 86 and 115 when planning for 50%, with the 80% target listed first in each pair and the 90% target second. The pattern illustrates that smaller effects require more participants to detect under otherwise unchanged assumptions. The displayed planning figures are not observed power; observed power is not an appropriate way to summarize the uncertainty in the completed trial’s result.

The curve should be read as a visual representation of how the planning requirement changes with the effect size chosen for design. It is not a forecast of recruitment, evidence that the observed effect will recur, or a substitute for a design-specific calculation using justified assumptions. Because the observed effect can be uncertain and may not represent the effect a future study should target, the illustration is best treated as a sensitivity aid. It does not reveal how the original trial’s enrollment target was selected.

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 = 76.600; pooled standard deviation σ = 89.562.
2. n = 2 × (1.96 + 0.842)² × 89.562² / 76.600² = 21.5, rounded up to 22 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 <- 76.6                      # observed difference in means
sigma <- 89.5621829534353                     # 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(2692560)
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 = 22 (80% power), 29 (90% power)
 75% of observed effect: n per arm = 39 (80% power), 52 (90% power)
 50% of observed effect: n per arm = 86 (80% power), 115 (90% power)
power.t.test: 22.5 
Simulated power at n = 22 per arm: 0.790 (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 a primary outcome and seven secondary outcomes, but it does not report a plan for controlling multiplicity. Multiplicity arises when several outcomes or comparisons are examined: even when each test is considered on its own, the chance of at least one apparently notable result across a set of tests can be greater than for a single test. Without a stated testing hierarchy, adjustment, or distinction between confirmatory and exploratory outcomes, the secondary p-values should not be treated as if each were the sole planned test. The record does not report whether such procedures were specified elsewhere in the study protocol.

The registry lists 8 outcome measures and reports 0 analyses in the reported-analyses field. Numerical summaries and recalculated comparisons are nevertheless available for the primary outcome and some secondary outcomes. The record does not provide enough detail to establish which analyses were planned in advance, whether there were additional analyses, or whether the posted summaries represent all analyses conducted. A statistical analysis plan is not reported in the registry record.

Missing-data handling is also unclear. The primary outcome description notes that 6 Healthy Living participants withdrew before completing the study. The reported primary outcome summaries include 29 I-STAND participants and 25 Healthy Living participants. The registry does not report reasons for withdrawal, when the withdrawals occurred relative to outcome assessment, whether any withdrawn participants contributed partial data, or how missing values were handled. It does not say whether imputation, a complete-case approach, or another method was used. No such method should be inferred.

The analysis population is not reported in the registry record. In particular, the record does not identify whether the primary comparison included all randomized participants, only participants with observed endpoint data, or another defined population. The number randomized to each group and the reasons for any differences between enrollment, assignment, and outcome availability are not fully described in the posted results. These omissions matter because the interpretation of a randomized comparison depends partly on how participants are retained in the analysis after randomization.

These reporting gaps do not change the arithmetic of the posted means or comparison, but they limit assessment of bias and robustness. The confidence interval and p-value describe uncertainty under the recalculation’s assumptions; they do not resolve uncertainty from unreported analysis choices, missingness, or multiple testing. Readers should separate the numerical result from claims about prespecification, completeness, or confirmatory status, which cannot be established from the registry record.

15. 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 non-serious adverse event terms

The adverse-event record reports no serious adverse events in either group and no deaths in either group. For other, non-serious adverse events, the record lists 4 affected participants among 29 at risk in I-STAND and 0 affected among 31 at risk in Healthy Living. These are descriptive counts as posted; they should not be treated as a definitive comparison of safety between groups.

The denominators differ from the primary outcome summaries: the adverse-event record lists 29 at risk for I-STAND and 31 for Healthy Living, while the primary outcome summaries include 29 and 25 participants, respectively. The registry does not explain the difference in the Healthy Living counts, provide event-level details, or describe how events were collected and classified. It also does not report the timing, duration, or severity of the non-serious events beyond their category.

A zero count in a posted record means no events were reported for that category in that group; it does not establish that no event could occur or that the interventions have no safety concerns. The figures should be interpreted as the registry’s reported event counts within the listed at-risk groups, with the limitations of the available reporting in mind.

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

The posted primary result describes a difference in average change in sitting time between the randomized groups over 12 weeks. I-STAND had a mean change of -70.1 minutes, while Healthy Living had a mean change of 6.5 minutes. The Healthy Living-minus-I-STAND estimate is 76.6 minutes, with a confidence interval from 30.08 to 123.1 minutes. In the direction of this measure, the group means indicate a larger average decrease in sitting time in I-STAND than in Healthy Living.

This result does not mean that all I-STAND participants reduced sitting time, that all Healthy Living participants increased it, or that the estimated difference applies to every older adult. A mean difference describes group averages, and the standard deviations show that individual changes were variable. The record does not report the distribution of individual responses, adherence to the programs, or the extent to which the result depended on particular participants.

The posted comparison is unadjusted, and important details about missing data, analysis populations, measurement procedures, and the original statistical plan are not reported in the registry record. The Healthy Living group had 6 participants who withdrew before study completion, but the record does not explain how that affected the analysis. These uncertainties mean the estimate should not be interpreted as a fully documented, adjusted causal effect or as proof of a particular mechanism.

The comparison also concerns the 12-week assessment only. The registry record does not report a longer-term primary outcome result, so persistence beyond that time point cannot be inferred. Nor does the primary endpoint alone establish effects on physical function, blood pressure, glucose, cholesterol, depressive symptoms, or other health outcomes. Some secondary outcomes have numerical summaries, while others do not, and the secondary testing strategy is not reported.

Statistical evidence, clinical importance, and generalizability are separate questions. The interval and p-value summarize the unadjusted comparison’s statistical uncertainty; they do not determine whether the size of the difference is meaningful to participants. The study record concerns adults aged 60 and older in the context of obesity and sedentary lifestyle, but recruitment details and participant characteristics beyond the registry summary are limited. The findings should therefore be described as the posted trial-group comparison, not as medical advice or a conclusion about effects in other settings.

17. Why This Trial Matters Statistically

This trial illustrates how a continuous primary endpoint can be interpreted through both a mean difference and its uncertainty. The mean change describes the average shift within each group, while the between-group contrast makes the randomized comparison explicit. Reading the contrast in its stated direction avoids reversing the interpretation when one group’s mean is negative and the other’s is positive.

It also demonstrates why a p-value should not stand alone. The primary p-value is 0.001, but the confidence interval adds information about the range of mean differences compatible with the unadjusted calculation. The interval does not describe individual outcomes, and neither the p-value nor the interval resolves questions about measurement, missing data, or the analysis population. Statistical interpretation requires keeping these distinct sources of information separate.

The secondary outcomes show another important issue: a trial can collect measures addressing related but different concepts. Sitting transitions and prolonged sitting bouts are not interchangeable with total sitting time, and functional or metabolic measures answer different questions again. When several outcomes are examined without a reported multiplicity strategy, secondary findings should be interpreted with restraint. An apparently clear result for one secondary measure does not automatically confirm the primary result or establish a broader health effect.

Finally, the sample-size illustration is useful as a planning concept, but it is not a retrospective measure of trial quality or success. It shows how design targets depend on the effect size chosen and the assumptions used. The original sample-size justification is not reported, so the posted illustration cannot explain the enrollment target. Together, these features make the record a useful example of why estimates, precision, design, and reporting completeness all matter in clinical biostatistics.

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.

The registry record gives limited detail about how sitting time was measured. It describes average sitting over the last 7 days at baseline and 12 weeks but does not name the assessment instrument, explain data processing, or report validation information. The record also does not specify whether the sitting-time measure depended on participant report, a device, or another method. Those details are not reported in the registry record and should not be assumed.

Implementation information is also limited. The intervention descriptions state what participants were offered, but adherence, coaching attendance, wristband use, responses to vibration, and fidelity to the intervention are not reported. The single-masked designation does not identify who was masked. These omissions prevent a detailed assessment of exposure to the assigned programs or the potential influence of awareness on measurement and behavior.

The primary outcome summaries show fewer Healthy Living participants than the adverse-event record’s at-risk count, and the record notes 6 withdrawals in Healthy Living. Reasons, timing, and the handling of missing outcome observations are not reported. Since missingness can affect an observed group mean if it is related to outcomes, the absence of a documented missing-data strategy is a specific limitation of the posted comparison.

The record provides limited participant characteristics beyond age range and the listed conditions, so the degree to which the study population represents other older adults cannot be assessed. It reports a 12-week primary assessment but does not provide longer-term primary results. The registry’s analysis listing does not describe a statistical plan, analysis population, or multiplicity approach. These omissions constrain evaluation of prespecification, robustness, and generalizability; they do not establish that any particular methodological problem occurred.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: I-STAND R21: Reducing Sedentary Time in Older Adults — NCT02692560.
• Registry record last updated 2018-06-29; status last verified 2018-05.
• Results first posted 2018-05-11.
• 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

NCT02692560 is a completed randomized, single-masked, parallel study sponsored by Kaiser Permanente. It compared the behavioral I-STAND program with the Healthy Living enhanced usual care control condition in older adults, with a stated focus on reducing sitting time. Enrollment is listed as 60, and the primary assessment occurred at 12 weeks.

The primary endpoint was change in average sitting time over the last 7 days. The posted group means were -70.1 minutes for I-STAND and 6.5 minutes for Healthy Living. The unadjusted Healthy Living-minus-I-STAND mean difference was 76.6 minutes, with a confidence interval from 30.08 to 123.1 minutes and an unadjusted p-value of 0.001.

The registry lists seven secondary outcomes, with numerical results posted for some but not all. It reports no serious adverse events or deaths in either group and lists 4 non-serious events in I-STAND and 0 in Healthy Living. Details about the original sample-size justification, missing-data handling, analysis population, multiplicity plan, and full statistical analysis plan are not reported in the registry record.