Use of Pedometers to Measure and Increase Walking Among Patients With ESRD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of Pedometers to Measure and Increase Walking Among Patients With ESRD (NCT02623348), a randomized na study. The primary outcome is Physical Activity.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. The intervention was behavioral: participants in the pedometer arm were given pedometers and instructions to increase physical activity based on pedometer output. The usual-care arm was described as receiving no intervention. The study focused on patients with end-stage renal disease and was summarized as a trial among patients on dialysis.

The registry lists enrollment as 60. The posted primary outcome summaries report 27 participants in the pedometer arm and 26 in the usual-care arm. These are the arm-specific counts attached to the outcome summaries; the record does not explain the difference between those counts and the enrollment listing or state how many participants contributed data at each time point.

The primary outcome was physical activity, measured as change in steps per day from pedometer at baseline and 12 weeks. The registry identifies the reported arm summaries as medians with 95% confidence intervals. The sponsor's reported analysis is identified as linear mixed modeling and as a superiority analysis, with p < 0.01. A model coefficient, its confidence interval, and further detail about the model specification are not reported in the registry record.

The study is listed as completed, with a start of 2015-12 and primary completion of 2018-06. Its phase is listed as NA. The registry also lists outcomes related to physical performance, self-reported function, daily activities, symptoms, muscle mass, endothelial function, vitality, and SDNN. The record does not report further details about allocation procedures, masking of outcome assessment, or the operational conduct of the study.

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: Baseline assessment performed prior to random assignment

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 Physical Activity, measured over Baseline and 12 weeks.

The primary endpoint measures change in daily step count from baseline to 12 weeks, using pedometer readings. It is a measure of physical activity in steps per day, rather than a direct measure of health status or physical capacity. A change endpoint focuses on how the measured activity at follow-up compares with the participant's baseline measurement.

The registry reports the endpoint as a median for each arm, accompanied by a 95% confidence interval. A median describes the middle of the observed distribution and is less affected by extreme values than an arithmetic mean. That can be useful when individual changes vary widely or when the distribution is skewed. The interval communicates uncertainty around the reported median; it is not, by itself, an interval for the difference between arms.

Pedometer steps provide a direct, count-based way to quantify walking-related activity. The registry does not report the device model, wear-time rules, adherence requirements, or procedures for handling incomplete readings. It therefore cannot establish precisely how each participant's step count was collected or how missing measurements were treated.

The endpoint is recorded at baseline and 12 weeks. This identifies the intended observation period but does not establish whether all participants had measurements at both time points. The registry record does not report a separate follow-up schedule for the primary outcome, the definition of a valid measurement, or whether the analysis used all observed readings or a selected subset.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a change measure summarized by arm using medians and 95% confidence intervals. General statistical interpretation: a median identifies the midpoint of an observed distribution, so half of the measured values lie on either side of it. Unlike a mean, a median is not pulled as strongly by a small number of unusually large or small observations. This can make it a useful summary when changes in activity are unevenly distributed. It also means that an arm median does not describe every participant's response or the spread of all individual changes.

A confidence interval communicates uncertainty in an estimate under the method used to calculate it. General statistical interpretation: repeated use of the same procedure would produce intervals that cover the target parameter at the stated rate, assuming the method's conditions hold. A 95% confidence interval is not a range that contains 95% of individual participant values, and it is not a probability statement about a particular interval after it has been calculated. The registry reports intervals for the arm summaries. It does not report a confidence interval for the between-arm effect, so the arm intervals should not be treated as a substitute for one.

The sponsor identifies linear mixed modeling as the method for its superiority analysis. General statistical interpretation: a mixed model can represent relationships among repeated observations from the same participant, while estimating an average pattern or contrast under a specified model. Such models can be useful for longitudinal measurements because observations from one person are not independent of one another. The exact model structure, covariates, assumptions, estimation procedure, and handling of missing observations are not reported in the registry record. No particular model specification can therefore be inferred from the method label alone.

The registry labels the sponsor's result as a superiority analysis and reports p < 0.01. General statistical interpretation: a p-value describes how incompatible the observed data are with a specified null hypothesis under the analysis model, when that hypothesis and model assumptions hold. A small p-value is not the probability that the null hypothesis is true, and it does not indicate the size of an effect. Because the registry does not report the model estimate or its confidence interval, the reported p-value cannot show how many steps/day separate the groups or how precisely that contrast was estimated.

Randomization is intended, in general, to make assigned groups comparable on average at the time of allocation, including with respect to factors not measured by investigators. It does not guarantee that every observed characteristic will be balanced, particularly in a trial with limited enrollment. The registry identifies the allocation as randomized but does not report the sequence-generation method, concealment procedures, or baseline characteristics. The record also indicates no masking, so participants and study personnel were not masked according to the registry entry. Further information about whether outcome assessors were masked is not reported in the registry record.

The reported arm-specific participant counts are outcome-summary counts, not a complete account of follow-up. General statistical interpretation: if observations are missing, the effects on estimates depend on why they are missing and how the analysis handles them. Complete-case analysis, imputation, and model-based use of available repeated measurements can lead to different results under different assumptions. The registry does not state which missing-data approach was used, whether all randomized participants were included, or whether the primary analysis followed assigned groups.

Planning calculations, when based on an observed effect, are hypothetical illustrations rather than observed trial results or observed power. General statistical interpretation: a planning estimate depends on assumptions about the target effect, variability, allocation, significance level, and analysis method. The stated illustration assumptions for this record include a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. Such calculations do not establish the trial's original design rationale. The registry does not report the original sample-size justification, and the planning assumptions should not be interpreted as the trial's own protocol or as evidence that the study had a particular probability of detecting an effect.

More generally, modeling can account for the structure represented in the model, but it cannot resolve uncertainty about unreported design details, outcome collection, or missingness. Reading the sponsor's result alongside the arm-level summaries is therefore useful, while keeping the distinction clear between a modeled inferential test and descriptive medians. Neither the reported p-value nor the arm summaries alone provide a complete account of the magnitude, precision, or robustness of the group comparison.

10. Analyses Reported by the Sponsor

The sponsor's own analysis is reported as linear mixed modeling and is labeled a superiority analysis, with p < 0.01. This is the inferential result to use when describing the sponsor's analysis. The registry record does not provide the model-based contrast, confidence interval, or enough model detail to reproduce that analysis independently.

The posted primary-outcome values are arm-specific medians and their 95% confidence intervals. They are descriptive summaries, not a recalculated two-arm comparison. In this case, a recalculation is not available from the posted summary statistics: the record indicates that values are missing or not estimable for a two-arm comparison of this median-type endpoint. The sponsor's own analysis therefore takes precedence over any attempted unadjusted re-calculation.

The sponsor's reported p-value should not be mistaken for an effect size. Without a reported model estimate and its interval, the registry does not convey the numerical magnitude or precision of the modeled between-arm result. The arm medians can be described separately, but they cannot fill in those missing quantities or be treated as equivalent to the model's result.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists secondary outcomes covering physical performance, self-reported physical functioning, change in activities of daily living, symptom burden on the Dialysis Symptoms Index, total body muscle mass adjusted by height squared, endothelial function, vitality, and SDNN. It reports nine secondary outcomes as posted and one analysis. These entries show that the trial assessed outcomes beyond the primary physical-activity measure, but the registry record does not report how the outcomes were prioritized in analysis or how multiplicity was handled.

Multiplicity arises when several hypotheses or outcomes are tested. General statistical interpretation: conducting multiple tests can increase the chance that at least one result appears unusual under its null hypothesis. Procedures such as adjusting significance thresholds or specifying a hierarchy can address this issue, but the registry does not state whether any such approach was used. The reported p-value should therefore be read as the sponsor's recorded result, without assuming that it was adjusted for the listed secondary outcomes or that it was not.

The record does not report a statistical analysis plan, prespecified hypothesis hierarchy, interim analyses, or sample-size justification. It also does not state whether any outcomes were added, removed, or redefined after the study began. The absence of those details limits assessment of selective reporting and the relationship between the planned and reported analyses.

Missing-data handling and analysis populations are also not described. The record does not report how many participants had primary outcome observations at each measurement time, why measurements may have been unavailable, whether imputation was used, or whether participants were analyzed according to randomized assignment. General statistical interpretation: conclusions can depend on these choices when follow-up data are incomplete. The difference between the registry's enrollment listing and the arm-specific counts attached to the primary-outcome summaries is not explained, so those figures cannot be used to infer a specific missing-data pattern or analysis population.

These omissions do not alter the results that are posted, but they prevent a full appraisal of multiplicity control, missingness assumptions, and the population underlying the analysis. Details on these points are not reported in the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports no serious adverse events in either arm. It lists other adverse events affecting 6 in the pedometer arm and 2 in usual care. Deaths are listed as 1 in the pedometer arm and 0 in usual care. These are counts as recorded in the safety information; they do not establish that an event was caused by the assigned intervention.

The registry lists 30 participants at risk in each arm for the adverse-event summaries. The record does not give serious adverse-event terms, and no top serious-event terms are listed. It also does not report event descriptions, severity grades, timing, relatedness assessments, or the rules used to classify and collect adverse events. The counts alone cannot explain the clinical circumstances or whether an event occurred during or after intervention exposure.

General statistical interpretation: sparse event counts can be imprecise, and a comparison of counts is not by itself a complete safety analysis. The registry does not provide a formal between-arm safety estimate or an uncertainty interval. These figures should therefore be read as the posted descriptive safety counts, not as proof of equivalence or as evidence that any intervention caused or prevented an event.

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

The result addresses a focused question: how physical activity, measured by steps per day, changed from baseline to 12 weeks among participants assigned to pedometers compared with those assigned to usual care. The registry reports arm-level median changes and a sponsor-conducted linear mixed-model superiority analysis with p < 0.01. Those details describe what was measured and what inferential result was recorded.

The findings do not provide a numerical model-based difference between arms or a confidence interval for that difference. The reported arm medians and their confidence intervals cannot be used as a replacement for the missing contrast. The sponsor's p-value does not identify the size of the effect, while the separate arm summaries do not show the uncertainty around the model-based comparison. The registry therefore gives an incomplete account of the magnitude and precision of the primary comparison.

The result also does not establish how much the finding depends on outcome completeness, analysis-population choices, or the assumptions of the mixed model. Information about missing-data procedures, model details, and the analyzed population is not reported in the registry record. The enrollment listing and the arm-specific primary-outcome counts are not reconciled in the record.

More broadly, a change in pedometer-measured steps is a behavioral outcome, not a direct measure of every aspect of physical function, symptoms, or health. The registry lists several secondary outcomes, but their results and multiplicity handling are not described in the registry record for this account. Nor do the posted primary endpoint results establish effects on unreported outcomes or longer-term patterns beyond the stated baseline-to-12-week timeframe.

The appropriate reading is limited to the recorded outcome summaries, the sponsor's reported test, and the uncertainty created by omitted analysis details. The registry does not support claims beyond that specific study question and those reported data.

14. Why This Trial Matters Statistically

This trial is statistically instructive because it places an arm-level descriptive summary beside a model-based inferential result. Medians can be useful for activity changes when the distribution is uneven, while a linear mixed model can address repeated measurements under its specified assumptions. These methods answer related but different questions. The medians summarize each arm; the model's superiority test evaluates a group comparison.

The registry reports the p-value but not the model-based effect estimate or its confidence interval. That makes the distinction between statistical evidence and effect magnitude especially important. A p-value alone cannot show the size of a difference, and the confidence intervals around separate arm medians do not supply the missing interval for the comparison. The record also illustrates why a descriptive contrast should not be substituted for an analysis that cannot be recalculated from the posted summaries.

It also highlights the importance of reporting the analysis population and missing-data methods. Enrollment and outcome-summary counts are not interchangeable, and the registry does not explain their relationship. Without details on missing measurements, model specification, or analysis populations, readers cannot fully judge how robust the primary result is to those choices.

Finally, a trial with several secondary outcomes raises questions about multiplicity and prespecification. The registry lists secondary measures but does not report how multiple analyses were handled. Clear reporting of the analysis plan, model estimates with uncertainty intervals, outcome completeness, and multiplicity procedures would make the inferential result easier to assess and reproduce. These are general reporting considerations; they do not imply that any particular unreported procedure was or was not used in this trial.

15. Limitations

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

The registry provides limited detail about the primary analysis. It names linear mixed modeling and reports a superiority p-value, but does not report a model coefficient, confidence interval, model specification, covariates, or assumptions. The reported arm medians are not a substitute for the missing model-based contrast, and a two-arm re-calculation is not available from the posted median summaries.

The outcome-count information is not fully reconciled. Enrollment is listed as 60, while the primary outcome summaries give arm-specific counts of 27 and 26. The registry record does not explain the difference or say how many participants had usable observations at baseline and 12 weeks. Missing-data methods and the analysis population are not reported, so the extent and handling of incomplete outcome data cannot be assessed.

The record describes random allocation and no masking, but does not give details about sequence generation, allocation concealment, or whether outcome assessors were masked. It also does not describe the pedometer device, measurement procedures, wear-time rules, adherence, or the specific usual-care context. These omissions limit understanding of how the activity endpoint was collected and how consistently the intervention was delivered.

Multiplicity procedures, the statistical analysis plan, interim analyses, and the original sample-size rationale are not reported in the registry record. The listed secondary outcomes therefore cannot be interpreted with knowledge of a prespecified hierarchy or adjustment strategy. The safety record includes counts but not event descriptions, severity, relatedness, or a formal comparative safety analysis. Together, these gaps limit assessment of precision, reproducibility, missingness, and the context of reported events.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Use of Pedometers to Measure and Increase Walking Among Patients With ESRD — NCT02623348.
• Registry record last updated 2019-10-02; status last verified 2019-09.
• Results first posted 2019-10-02.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT02623348 is a completed randomized, parallel-group trial with no masking, listed for patients with end-stage renal disease. Participants in the pedometer arm received pedometers and instructions to increase activity based on pedometer output; usual care was described as no intervention. Enrollment is listed as 60, with start in 2015-12 and primary completion in 2018-06.

The primary outcome was change in steps per day from baseline to 12 weeks, reported as arm-specific medians with 95% confidence intervals. The sponsor's analysis is identified as linear mixed modeling and a superiority analysis, with p < 0.01. A model-based effect estimate and confidence interval are not reported in the registry record, and the median summaries do not allow a two-arm re-calculation.

The registry also lists secondary outcomes and descriptive safety counts. Details on missing-data handling, analysis populations, multiplicity, and the model specification are not reported in the registry record.