Walking Aids in the Management of Hip Osteoarthritis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Walking Aids in the Management of Hip Osteoarthritis (NCT00506714), a non-randomized na study. The primary outcome is Gait Velocity.

2. Clinical Question

The study title refers to walking aids in hip osteoarthritis, while the brief summary describes a purpose involving knee osteoarthritis. The arm descriptions instead specify hip osteoarthritis and healthy participants. This difference in wording should be kept in mind when interpreting the record; the reason for it is not reported in the registry record.

3. Trial Design

The registry lists this as a completed, parallel-model study with non-randomized allocation and no masking. Enrollment is 26. The start is recorded as 2007-07 and primary completion as 2009-07. The phase is listed as NA. The sponsor is the Arthritis Foundation.

The described participant groups are adults with hip osteoarthritis and healthy adults. The hip osteoarthritis group is described as walking with and without a single point cane at baseline and after four weeks. The healthy group is described as walking without a cane at baseline. These descriptions do not establish that the healthy participants were intended as a directly comparable control group. The registry specifically cautions that the arms are not a like-for-like control comparison because allocation was non-randomized.

Non-randomized allocation means the record does not describe random assignment to groups. Consequently, differences between groups may reflect participant characteristics or other differences, as well as any differences associated with cane use. The record does not report how participants entered each group, whether the same participants completed every walking condition, or whether any order of walking conditions was assigned.

The registry lists three outcome measures and zero analyses. It identifies gait velocity at baseline as the primary outcome, with a mean and standard deviation as the specified summary. Two secondary outcome titles concern gait velocity, including gait velocity with a cane in hip osteoarthritis participants. Numerical outcome results, analysis estimates, and details of the statistical analysis plan are not reported in the registry record. The record also does not report a protocol, sample-size justification, interim analyses, or the reasons for the discrepancy between the title and brief summary.

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

Analysis population for the primary outcome, as defined in the registry: Analysis was per protocol

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 Gait Velocity, measured over Baseline.

The primary endpoint is gait velocity, a continuous measure reported in centimeters per second. It represents how quickly a participant walks under the specified assessment conditions. The registry identifies the primary outcome timeframe as baseline and specifies a mean with standard deviation as its summary, with the analysis population described as per protocol.

Gait velocity can be used as a quantitative description of walking performance. As a continuous endpoint, it retains information across the measured scale rather than reducing walking performance to categories. A mean describes the center of the observed measurements, while a standard deviation describes how dispersed individual measurements are around that mean. These are general interpretations of the statistical summaries specified in the record, not claims about the study's observed values.

The endpoint description does not state a numerical mean or standard deviation, nor does it report a treatment contrast, confidence interval, or test result. The outcome title alone does not establish whether the primary question concerns cane use, differences between participant groups, or another comparison. The record also does not give measurement equipment, walking distance, repeated-trial procedures, or assessor details. These aspects of endpoint measurement and interpretation are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry specifies a continuous primary outcome summarized by a mean and standard deviation. These are descriptive statistics. The mean gives a measure of the central value of observed gait-velocity measurements. The standard deviation conveys how much individual measurements vary around that center. Both help characterize a distribution, but neither alone estimates a difference between conditions or groups. No numerical values for either summary are reported in the registry record.

What does a confidence interval convey?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method used. Its width communicates precision: a narrower interval indicates greater precision than a wider interval, when the methods and scale are comparable. A confidence interval is not a guarantee that the true value lies within the particular interval. The registry record does not report a confidence interval for the primary outcome, so the precision of any outcome contrast cannot be assessed from the posted results.

What would a significance test address?

In general, a significance test evaluates how compatible observed data are with a specified null hypothesis under the test's assumptions. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of an effect. Interpretation depends on the planned contrast, analysis method, assumptions, and multiplicity of testing. No primary-outcome p-value or analysis method is reported in the registry record. The listing of zero analyses means the record does not present an analysis result to interpret.

Why does the allocation method matter?

Random allocation, when used, is intended to balance measured and unmeasured participant characteristics across assigned groups on average. This record states that allocation was non-randomized, so that protection cannot be assumed. Group differences may be associated with the intervention condition, but they may also reflect differences in who entered each group. The registry cautions against treating the groups as a like-for-like control comparison. It does not report covariate adjustment, matching, or another method to address this issue.

The arm descriptions also imply different assessment patterns: adults with hip osteoarthritis are described as walking with and without a cane at baseline and after four weeks, while healthy participants are described as walking without a cane at baseline. In general, observations from the same participant are related rather than independent. Analyses of repeated measurements may need to account for that relationship. The record does not state whether the same participants contributed to all conditions, how repeated measurements were handled, or which contrast was the primary one.

How should sample-size illustrations be understood?

Any sample-size figures associated with the record are planning illustrations based on an observed effect, with the stated assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration describes the number of participants per arm for a target power when detecting a stated fraction of the observed effect. It is not a description of the trial's actual design justification or an estimate of observed power. The registry record does not report its own sample-size justification. Because no numerical outcome estimate is posted, these planning calculations should not be read as evidence about the outcome or as a substitute for reported results.

More generally, sample-size calculations depend on the target effect, variability, allocation, analysis, and chosen error and power assumptions. Changing these assumptions changes the planning requirement. A calculation based on an observed effect is especially dependent on the stability of that estimate; it does not show that the study had a particular probability of detecting an effect after completion. The record does not provide enough information to assess the original design rationale or whether the planned enrollment was adequate for the primary question.

The statistical methods described in the registry are limited to the outcome summary and the general assumptions stated for sample-size illustrations. The model for the primary endpoint, handling of missing measurements, adjustment for multiple outcomes, and any prespecified subgroup or sensitivity analyses are not reported in the registry record. Without those details and numerical results, statistical significance, precision, and robustness cannot be evaluated from the record.

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("Group 1", "Group 2")
n   <- c(13, 13)
m   <- c(107.5, 79.7)
sp  <- c(14.3, 9.9)
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  Group 1  13  107.500  14.300  98.859  116.141
CARM  Group 2  13  79.700  9.900  73.717  85.683

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, including the primary gait-velocity outcome and secondary outcomes titled “Gait Velocity With a Cane in Hip OA Subjects” and “Gait Velocity.” It also lists zero analyses. The record does not describe a multiplicity strategy, such as how testing across outcomes or comparisons was handled. In general, testing multiple questions can increase the chance of at least one apparently unusual result if each is interpreted without regard to the others. The registry does not report inferential results that would allow this concern to be assessed.

The primary outcome population is described as per protocol. The number of participants included in that population is not reported in the registry record. Nor does the record give participant flow, reasons for exclusions, the number with missing measurements, or how missing data were handled. It is therefore unclear from the posted information whether the primary analysis included all enrolled participants who met a defined criterion or a subset with available measurements.

The arm descriptions include assessments at baseline and after four weeks for adults with hip osteoarthritis, but only baseline walking without a cane for healthy adults. The record does not state how incomplete repeated measurements would be treated or how the analysis distinguished within-participant observations from comparisons between groups. It also does not report an intention-to-treat population or another defined analysis population. These omissions limit evaluation of the analysis set and the consequences of missing data.

In general, missing-data methods and analysis-population definitions matter because they determine which observations contribute to an estimate and which assumptions are used for absent measurements. No specific method can be attributed to this study from the registry record.

12. Safety Results

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

Other (non-serious) adverse events

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

The adverse-event listing records Group 1 with 13 participants at risk and zero serious adverse events. Group 2 is also listed with 13 participants at risk and zero serious adverse events. These are the posted serious-event counts for the listed groups. The record does not provide serious-event terms, and the number of deaths is recorded as null rather than as a numerical count.

The other-adverse-event fields list zero participants at risk in each group and zero affected participants. A zero at-risk count does not provide an evaluable denominator for interpreting other adverse events. It should not be read as evidence that no other adverse events occurred among the enrolled participants. The registry does not explain why these fields have zero at-risk counts.

These safety figures are counts as recorded, not a comparison showing that risk was equal between groups. The non-randomized design also means the groups are not established as like-for-like controls. The record does not report event definitions, ascertainment procedures, follow-up completeness, or a safety analysis method. The listed serious-event counts should therefore be interpreted narrowly, without extending them to outcomes or participants not represented in those fields.

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

The record establishes that a completed, non-randomized study was registered with a primary outcome of baseline gait velocity in cm/s. It describes adults with hip osteoarthritis walking with and without a single point cane at baseline and after four weeks, and healthy adults walking without a cane at baseline. It also identifies a per-protocol outcome population and specifies mean and standard deviation summaries.

The record does not report the numerical primary outcome results. Consequently, it cannot support a description of the observed average gait velocity, its variability, or a difference between walking conditions or participant groups. There is no posted estimate, confidence interval, or p-value for the primary outcome. The zero analyses listed in the record further means that no analysis result is presented for interpretation.

This absence of numerical results is not evidence that there was no difference or no change. It means the registry record does not permit those conclusions. Likewise, a study description and an outcome title do not establish whether the intervention was beneficial, harmful, or unchanged in relation to the outcome. No medical advice or treatment conclusion follows from the posted information.

The design also constrains interpretation. Allocation was non-randomized, and the registry cautions that the groups are not a like-for-like control comparison. Even if a numerical contrast were available, differences between groups could not automatically be attributed to cane use. The record does not report adjustment methods or sufficient analysis detail to resolve this concern.

The title and arm descriptions refer to hip osteoarthritis, but the brief summary refers to knee osteoarthritis. The reason for that discrepancy is not reported in the registry record. This matters for identifying the intended study population, and should not be silently resolved by choosing one description over the other. Overall, the record supports a description of the registered question and design, but not an estimate of the intervention's effect or the precision of such an estimate.

14. Why This Trial Matters Statistically

This record illustrates why a registry description and a results analysis are different kinds of evidence. The study has a stated clinical context, intervention, outcome, and design, but the primary outcome's numerical result is not reported in the registry record. Without an estimate and a measure of its precision, readers cannot assess the observed gait-velocity values or the uncertainty around a contrast.

The non-randomized allocation is also central to statistical interpretation. A difference between groups in a non-randomized study may reflect participant differences as well as the condition being compared. The registry itself warns that the groups are not a like-for-like control comparison. This makes it particularly important to know the exact comparison and any adjustment strategy; those details are not reported.

The different assessment descriptions create further analytic questions. The hip osteoarthritis participants are described as walking with and without a cane at baseline and after four weeks, while healthy participants are described as walking without a cane at baseline. Within-participant comparisons and comparisons between groups answer different questions and generally require different treatment of the data. The registry does not identify the primary contrast or explain how the observations were analyzed.

The mismatch between the hip osteoarthritis title and arm descriptions and the knee osteoarthritis brief summary is another reason to read registry fields carefully. It does not establish which description is erroneous. Finally, the safety listing illustrates the importance of denominators: the serious-event counts are paired with at-risk counts, while the other-event fields show zero at risk. These fields cannot be interpreted as equivalent evidence of absence. Together, these features show why design, analysis details, endpoint results, and data completeness all matter when judging what a clinical trial record can establish.

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 most direct limitation is that the registry does not report numerical results for the primary outcome. Mean gait velocity and its standard deviation are specified as the intended summary, but no values, contrasts, confidence intervals, or p-values are posted. The record lists zero analyses, leaving no inferential result to evaluate.

The clinical description is internally inconsistent: the title and participant descriptions concern hip osteoarthritis, while the brief summary refers to knee osteoarthritis. The reason for this discrepancy is not reported in the registry record. The discrepancy makes the intended clinical population less clear from the record alone.

Allocation is non-randomized, and the registry cautions that the groups are not a like-for-like control comparison. The record does not explain group assignment or report adjustment methods. The described assessment schedules also differ between the hip osteoarthritis and healthy groups. Details about measurement procedures, the primary contrast, repeated-measures analysis, and participant flow are not reported.

Although total enrollment is listed as 26, the primary outcome analysis population is described only as per protocol. The number analyzed and reasons for any exclusions or missing measurements are not reported in the registry record. The record does not provide the original sample-size justification, a statistical analysis plan, interim analyses, or a multiplicity approach. The sample-size assumptions associated with planning illustrations do not establish the study's actual design rationale or the precision of its unreported outcome.

Safety fields require caution too: the other-adverse-event groups have zero participants at risk, and deaths are recorded as null. The record does not explain these entries or report the relevant ascertainment details. These limitations concern what can be concluded from the registry record, not necessarily what may exist in other study materials.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Walking Aids in the Management of Hip Osteoarthritis — NCT00506714.
• Registry record last updated 2012-10-04; status last verified 2012-09.
• Results first posted 2012-09-28.
• 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

NCT00506714 is listed as completed, with non-randomized allocation, no masking, and a parallel model. Enrollment is 26; the start is recorded as 2007-07 and primary completion as 2009-07. The sponsor is the Arthritis Foundation.

The title concerns walking aids in hip osteoarthritis. The intervention is a single point cane. Adults with hip osteoarthritis are described as walking with and without a cane at baseline and after four weeks; healthy adults are described as walking without a cane at baseline. The brief summary refers to knee osteoarthritis, unlike the title and arm descriptions.

The primary outcome is baseline gait velocity in cm/s, summarized as a mean and standard deviation in a per-protocol population. Numerical outcome results are not reported in the registry record, and zero analyses are listed. The registry cautions that the non-randomized groups are not a like-for-like control comparison. Serious adverse events are recorded as zero in each listed group, with 13 at risk in each; the other-event fields list zero at risk.