Sedentary Behavior Interrupted Randomized Controlled Trial (P2): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Sedentary Behavior Interrupted Randomized Controlled Trial (P2) (NCT03473145), a randomized na study. The primary outcome is Insulin Regulation (mU/L).

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group trial with three conditions: Health Living Attention Control, Reduce Sitting, and Sit-to-Stand Transition. It lists masking as single, but does not identify who was masked or explain how masking was implemented. Further details about sequence generation, concealment of allocation, or the procedures used to assign participants are not reported in the registry record.

The attention-control condition focused on healthy-aging education. Participants in that group were scheduled for one in-person coaching session and six phone counseling sessions. The two behavior-change conditions each included five in-person coaching sessions and two phone counseling sessions. Reduce Sitting aimed to lower daily sitting time; Sit-to-Stand Transition aimed to increase brief transitions from sitting to standing. The registry also lists an activPAL inclinometer and tools to prompt standing or sit-to-stand transitions among the interventions, but does not describe their use in sufficient detail to specify which participants used each item or how use was monitored.

The brief summary describes a 3-month trial and says it was designed to assess the approaches in 405 overweight, postmenopausal women. The registry lists enrollment of 407 and gives the primary outcome timeframe as 3 months. It records the study as completed, with a start date of 2018-05-30 and a primary completion date of 2022-12-31. The record identifies University of California, San Diego as sponsor and lists the phase as NA.

These design details identify the broad randomized comparison, but do not establish the exact analysis population or the way participants were handled after randomization. Those details, along with the randomization method and the identity of the masked party, are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Insulin Regulation (mU/L), measured over 3 months.

The primary endpoint is insulin regulation, expressed as mean insulin in mU/L. The registry says insulin was measured from fasting blood draws at baseline and 3 months. A fasting blood measurement provides a laboratory measure of insulin under the study’s stated collection conditions. The endpoint is a continuous measure, so its summary focuses on a mean and a confidence interval rather than a count of participants who did or did not meet a threshold.

Insulin is the biomarker named by the registry as the primary outcome. The study’s broader context concerns biomarkers of healthy aging and physical functioning, but the registry does not explain the biological rationale for selecting insulin as the primary endpoint or specify a clinically meaningful difference. It also does not state whether the primary comparison is based on follow-up values, change from baseline, or another model-based estimate. Those analysis details are not reported in the registry record.

A mean describes the center of the measured values, while a confidence interval conveys uncertainty around an estimated mean or contrast. For a treatment comparison, interpretation depends on the exact estimand and on which groups are compared. Although the record names the primary measure and timeframe, it does not report the mean values, confidence intervals, or a between-group result. Therefore, the endpoint definition can be described, but the size and precision of any observed effect cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, parallel-group design. Randomization is a method for assigning participants to study groups by chance, with the aim of making the groups comparable at the start on average. In a parallel design, participants are assigned to a group and the groups are followed over the study period. These general features do not reveal how random assignment was generated or concealed in this trial. Those procedural details are not reported in the registry record.

The record says masking was single. Masking means that some party involved in a trial is kept unaware of treatment assignment, which can help limit certain biases. The identity of the masked party and the practical masking procedures are not reported in the registry record. The label alone does not establish whether participants, intervention staff, outcome assessors, or analysts were masked.

The primary measure is continuous: mean insulin in mU/L, with a 95% confidence interval named as the dispersion measure. A mean is the arithmetic center of observed measurements. A confidence interval is a range of values generated by a statistical procedure intended to express uncertainty about an estimate. It is not a range containing a stated proportion of individual participants’ insulin values, and it does not by itself establish clinical importance. The registry does not post the actual means or intervals, so their width and the precision of the estimated result cannot be assessed.

Baseline and 3-month fasting blood draws are identified in the endpoint description. In general, a repeated measurement design can be analyzed in different ways: investigators might compare follow-up values, compare changes from baseline, or use a model that accounts for measurements over time. These approaches answer related but not identical questions and can rely on different assumptions. The analysis approach used for insulin is not reported in the registry record. The record also does not specify an adjustment set, model form, handling of baseline values, or the exact contrast used to estimate a treatment effect.

There are three randomized groups. In general, a study with multiple groups may have several possible pairwise contrasts, and a statistical plan can identify which comparisons are primary and how the risk of false-positive findings across multiple tests will be addressed. The registry does not identify the intended primary contrast or report a multiplicity procedure. It also gives no outcome analysis estimates or tests. Consequently, no trial-specific inference about group differences can be reconstructed from the posted record.

General statistical interpretation also depends on the target population and analysis population. An intention-to-treat analysis generally aims to analyze participants according to randomized assignment, while other analysis populations can apply additional eligibility or adherence conditions. The registry record does not state which population was used for the primary outcome, whether participants were excluded from analysis, or how deviations from assigned interventions were handled. These omissions prevent a reader from determining the exact population to which a potential estimate would apply.

The sample-size assumptions described in the registry concern a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. Such illustrations are hypothetical planning calculations; they are not observed power and are not evidence that the study detected an effect. No planning results are included in the record. The trial’s own sample-size justification and design assumptions are not reported in the registry record, and the planning illustration should not be treated as the trial’s original calculation.

In general, over-dispersion matters when observed variability is greater than a model expects: standard errors may then be too small if the model does not account for the extra variability, leading to intervals that are too narrow and tests that are too optimistic. This is a general concept, not a reported feature of this trial. The registry does not report a model or diagnostics that would allow over-dispersion to be assessed for the insulin endpoint.

The record includes adverse-event counts, but does not specify the statistical methods used to summarize or compare them. Counts alone do not describe exposure time, event recurrence, or whether events were judged related to an intervention. These general considerations matter when interpreting safety summaries, but the additional detail needed for such an assessment is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: insulin regulation as the primary outcome and self-reported physical functioning as a secondary outcome. It does not report an analysis plan that defines the primary contrast, a hierarchy of outcomes, or a procedure for accounting for multiple comparisons. With three randomized groups, there can be several reasonable group contrasts; the record does not say which were intended or how results across contrasts would be interpreted.

Missing-data methods are not reported in the registry record. There is no description of missing outcome measurements, follow-up completion for the primary endpoint, imputation, or sensitivity analyses. The registry’s enrollment total does not establish how many participants contributed a usable baseline or 3-month insulin measurement. It also does not say how missing physical-functioning responses were handled.

The analysis population is not specified. In particular, the record does not state whether the primary analysis included all randomized participants according to assigned group, or whether another population was used. It does not describe withdrawals, exclusions, intervention adherence, or treatment crossover. Without these details, readers cannot assess how missing observations or departures from assigned interventions may have affected the estimates.

The registry records zero analyses and does not post outcome estimates. That status should be read as an absence of posted analysis results, not as a finding that the outcomes were unchanged. The statistical analysis plan, interim analyses, and any prespecified methods for handling missing data or multiplicity are not reported in the registry record.

11. 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists serious events affecting zero participants in each of the three groups. It also lists zero deaths in each group. For other events, the counts of affected participants are 8 in Health Living Attention Control, 28 in Reduce Sitting, and 26 in Sit-to-Stand Transition. The corresponding numbers at risk are 135, 136, and 136, respectively, in the same group order.

These are group-level counts, not a description of the event types or their causes. The registry does not provide event names, onset timing, duration, severity beyond the serious-event category, or judgments about whether an event was related to an intervention. It also does not state whether participants could have experienced more than one event or how events were collected. The counts therefore should not be interpreted as rates or as a comparison of risk between groups.

Zero serious events recorded in a group means none were listed as affecting participants in that group in the registry summary. It does not establish that an intervention is free of risk, nor does it provide a precise estimate of the probability of a rare event. The record does not report a statistical safety comparison or additional detail that would support a broader safety conclusion.

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

The registry establishes that this was a randomized, parallel, three-arm study of strategies aimed at changing sitting behavior in overweight, postmenopausal women. The primary outcome was mean insulin measured from fasting blood draws at baseline and 3 months. It also identifies self-reported physical functioning as a secondary outcome and posts group-level adverse-event counts.

It does not provide the primary outcome results. There is no reported mean, treatment contrast, confidence interval, or test for insulin, and no analysis result for physical functioning. Consequently, the posted information does not establish whether insulin differed across groups, how large any difference may have been, or how precisely it was estimated. It also does not establish whether the two behavior-change approaches differed from each other or from the attention-control condition.

A trial’s design and outcome definitions are not substitutes for its results. Random assignment can support causal comparisons when implemented and analyzed appropriately, but interpretation also depends on the analysis plan, missing data, adherence, and the estimates themselves. Those details are not reported in the registry record. The record’s absence of posted analyses should not be taken as evidence that there was no effect or that the groups were equivalent.

The adverse-event summary reports zero serious events and zero deaths in each group, along with counts of participants affected by other events. Those figures are descriptive and lack event-level detail, exposure information, and a formal comparison. They do not support a definitive conclusion about comparative safety.

The appropriate reading is therefore limited: the record documents the trial’s design, target population as described in its summary, intervention aims, primary endpoint, and selected safety counts, but it does not provide enough results to determine the trial’s findings on insulin or physical functioning.

13. Why This Trial Matters Statistically

This trial poses a useful statistical contrast because its intervention groups target different features of sedentary behavior. One aims to reduce total daily sitting time, while the other aims to increase brief transitions from sitting to standing. The attention-control group receives healthy-aging education. Distinguishing these strategies requires clear definitions of the target comparison and careful reporting of outcome estimates, not simply a statement that the study was randomized.

The primary endpoint is a continuous laboratory measure collected at baseline and 3 months. Statistical interpretation of such a measure depends on the estimand: whether the comparison concerns follow-up means, changes from baseline, or an adjusted model estimate. The registry identifies the measurement and timeframe but does not report the analysis method. This illustrates why a named endpoint alone is not enough to evaluate the evidence; the estimate, uncertainty, and analysis population are also essential.

The three-group structure also makes prespecification important. A reader needs to know which comparisons answer the main question and how additional comparisons are treated. The registry does not report that plan or post results for the primary endpoint. In the absence of those elements, no inference about the relative performance of the interventions is possible from the record.

Finally, the record demonstrates the difference between a trial’s existence and a trial’s publicly reported statistical evidence. It contains design information and adverse-event counts, but no outcome analyses. For clinical researchers and biostatisticians, transparent reporting of estimands, missing-data handling, analysis populations, and uncertainty is necessary to judge what a randomized study can support. Those details are not reported in the registry record.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpreting this trial is that the registry record does not report outcome analyses. The primary endpoint is defined, but there are no posted group means, treatment contrasts, confidence intervals, or statistical tests. The record also lists zero analyses. Without those results, the magnitude, direction, and precision of the primary outcome cannot be evaluated.

The analysis plan is not described in enough detail to identify the primary comparison or the method used for the baseline and 3-month insulin measurements. The exact analysis population, handling of missing data, and treatment of participants who did not follow their assigned intervention are not reported in the registry record. These omissions limit assessment of potential bias and the population represented by any estimate.

The masking label is single, but the masked party and masking procedures are not specified. Details of random sequence generation and allocation concealment are also not reported. The registry lists intervention components, including coaching, an inclinometer, and prompting tools, but does not describe their use or adherence in sufficient detail to assess how consistently the interventions were delivered.

The record describes a design intended for 405 participants and lists enrollment of 407. It does not provide participant flow, group-specific completion, baseline characteristics, or the number with available endpoint measurements. The reason for the difference between the planned count in the summary and recorded enrollment is not reported.

Safety information is limited to counts of participants affected by serious and other events and deaths. Event descriptions, timing, attribution, and statistical comparisons are not reported. Together, these gaps mean the registry supports a description of the trial’s design and intended outcomes, but not a comprehensive evaluation of efficacy, precision, missingness, or safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Sedentary Behavior Interrupted Randomized Controlled Trial (P2) — NCT03473145.
• Registry record last updated 2025-11-03; status last verified 2025-09.
• Results first posted 2025-11-03.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03473145 is a completed, randomized, single-masked, parallel-group trial sponsored by University of California, San Diego. It lists enrollment of 407, a start date of 2018-05-30, and a primary completion date of 2022-12-31. The registry describes three groups: Health Living Attention Control, Reduce Sitting, and Sit-to-Stand Transition.

The primary outcome is mean insulin in mU/L from fasting blood draws at baseline and 3 months. Self-reported physical functioning is listed as a secondary outcome. The record lists zero analyses and does not post outcome estimates, confidence intervals, or tests. Serious events affecting participants and deaths are listed as zero in each group; other-event counts are also reported, without event-level details.

The study question and design are documented, but the registry record does not report enough analysis results to interpret the primary endpoint or compare the groups’ outcomes.