The Effect of Priming of Questionnaire Content on Grip Strength in Patients With Hand and Upper Extremity Illness: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Priming of Questionnaire Content on Grip Strength in Patients With Hand and Upper Extremity Illness (NCT02493127), a randomized na study. The primary outcome is Difference in Grip Strength Measured With Dynamometer.

2. Clinical Question

The study asks whether questionnaire content is associated with grip-strength measurements in patients with hand and upper extremity illness. Its rationale, as stated in the registry summary, is to determine the association between priming and measurements of hand function such as grip strength. The primary null hypothesis states that best-of-three grip strength as a percentage of the opposite hand does not differ between the groups. Secondary null hypotheses concern last-of-three grip strength as a percentage of the opposite hand and changes before and after completing questionnaires.

The clinical question is therefore about measurement in the context of questionnaire completion. It does not, on the information in the registry record, address whether either questionnaire improves hand function or changes the underlying illness. The numerical results needed to evaluate the intended group comparisons are not reported in the registry record.

3. Trial Design

The registry record describes a randomized, double-masked, parallel-group study, marked as completed. Enrollment is listed as 122. The record lists the phase as NA. The study is sponsored by Massachusetts General Hospital and is recorded as starting in 2015-06, with primary completion in 2015-08.

The two arm descriptions identify a Standard PCS group and a Positive PCS group. Both descriptions include grip-strength measurements; the distinction is whether participants complete the standard PCS or the positively adjusted PCS. Grip Strength also appears as a registered intervention name, but the record does not describe it as a separate randomized arm. Further details of allocation procedures are not reported in the registry record.

In general, random allocation is intended to make assigned groups comparable on average with respect to factors present before the intervention. It does not guarantee that groups will be identical, and the value of randomization for interpreting a result depends on how assignment was carried out and on how participants were retained and analyzed. Details of sequence generation, concealment, and implementation are not reported in the registry record.

The record labels the study double-masked but does not state which people were masked or how masking was maintained. That matters for an experiment involving questionnaire content and a measurement that could be influenced by expectations or measurement procedures. The record also does not describe the setting, participant flow, or the number assigned to each arm. The adverse-event listings give at-risk counts of 60 in each arm, but those listings alone do not establish the full allocation or analysis populations.

The study's stated measurement occasion is Day 1. Each participant is described as completing grip-strength measurement 3 times on the non-affected hand at enrollment. The registry record does not provide a fuller visit schedule or explain how those repeated measurements were combined for each registered outcome.

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:

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 Difference in Grip Strength Measured With Dynamometer, measured over Day 1.

The registered primary outcome is titled Difference in Grip Strength Measured With Dynamometer. Its unit is pounds, its measure type is a mean, and its dispersion is a standard deviation. The stated timeframe is Day 1. The description says that grip strength of the non-affected hand was measured 3 times at enrollment and that the reported results represent an increase or decrease in mean grip strength and maximum grip strength after completing the intervention.

Grip strength is a quantifiable measure of hand function. In general, using a dynamometer provides a standardized way to record force, while repeated attempts can reflect variation in effort or measurement. The registry summary separately frames its primary hypothesis around the best of three attempts as a percentage of the opposite hand. It also describes a secondary comparison based on the last attempt and a before-and-after comparison.

These descriptions do not establish a single unambiguous endpoint definition. The registered primary outcome description emphasizes a post-intervention difference in pounds and refers to mean and maximum grip strength; the summary emphasizes best-of-three grip strength relative to the opposite hand. The registry record does not explain whether the opposite-hand percentage, the raw pound measure, the mean, or the maximum is the primary analysis variable. No endpoint estimates or standard deviations are reported in the registry record, so the size and precision of any group contrast cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a randomized, double-masked, parallel-group design. These terms describe different features of a trial. Randomization concerns how participants are assigned to groups; masking concerns awareness of assigned group; and a parallel design means groups proceed under their assigned conditions rather than crossing between conditions. In general, randomization can reduce systematic differences in baseline characteristics, but it does not remove the need to document allocation, follow-up, and analysis. The record does not describe the specific procedures used for randomization or masking.

What does a mean difference represent?

The primary outcome is identified as a mean of a continuous measure, with grip strength measured in pounds. A difference between group means would describe the average separation in the measured outcome, in the stated unit, for the groups being compared. Its interpretation depends on the precise outcome definition and time point. The registered description refers to an after-intervention difference, but the summary frames the primary hypothesis as best-of-three grip strength relative to the opposite hand. Those are not clearly interchangeable definitions, and the record does not say which was used in an analysis.

A mean is useful for describing the central level of a continuous measurement. It can, however, conceal variation among participants or be affected by unusual values. The registry lists standard deviation as the dispersion measure. In general, a standard deviation describes how spread out individual measurements are around the mean; it is not the same as the uncertainty around a group mean or a group difference. No means or standard deviations are reported in the registry record, so neither the observed group separation nor the variability can be assessed.

Why do repeated attempts matter?

Each participant is described as completing grip-strength measurement 3 times on the non-affected hand at enrollment. The brief summary specifies the best attempt for the primary hypothesis and the last attempt for a secondary hypothesis. Selecting the maximum, using the last attempt, and averaging repeated attempts are distinct ways of summarizing repeated measurements. They can answer different questions and need not produce the same estimate. The record does not report the full outcome definitions for all five measures or state exactly how the attempts were incorporated into each result.

Repeated measurements on the same participant are related rather than independent observations. In general, an analysis of repeated measurements should account for that within-participant relationship if it treats the measurements separately. Reducing attempts to a prespecified summary, such as the best attempt, creates a participant-level value but still requires a clearly stated rule. The registry record does not report whether the analyses used participant-level summaries, a repeated-measures model, or another approach.

What does a confidence interval tell a reader?

In general, a confidence interval gives a range of values compatible with the observed data under the assumptions of a statistical method. For a group difference, it communicates uncertainty about the estimated contrast as well as its direction and plausible size. A narrow interval indicates greater precision than a wide interval, but the meaning depends on the outcome and analysis. No confidence intervals or other uncertainty estimates are reported in the registry record. Thus, the precision of any effect cannot be evaluated.

A p-value, when reported, assesses how compatible data are with a specified null model under the assumptions of the test. It does not measure the probability that the null hypothesis is true, and it does not describe the size or clinical importance of an effect. The registry record lists zero analyses and gives no p-values. It is not possible to infer a statistical conclusion from the null hypotheses alone.

How should planning calculations be read?

The planning assumptions describe illustrations based on the observed effect, rather than the trial's own design justification. They use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect set as a stated fraction of the observed effect. General sample-size calculations estimate the number of participants needed under chosen assumptions to detect a target effect with a chosen level of statistical power. Such estimates depend on the effect size, variability, test procedure, allocation, and other assumptions.

These calculations are planning illustrations, not observed power and not evidence that a study did or did not detect an effect. Their interpretation also depends on the underlying observed effect and its uncertainty. The registry record does not report the observed outcome estimates or the trial's own sample-size justification. It therefore does not support a numerical conclusion about the adequacy of the planned enrollment or the precision achieved.

Why can variation beyond a simple model matter?

In general, over-dispersion means that observed variation is greater than a statistical model assumes. A model that understates variation can make uncertainty appear smaller than it is. This concept is especially relevant to outcomes whose variance is not well captured by a chosen model; it is not a finding reported for this continuous grip-strength outcome. The registry record does not identify a statistical model or provide diagnostics, so no model adequacy assessment can be made.

For continuous outcomes, the choice of model can depend on the distribution of measurements, the design, and whether baseline or repeated values are included. Adjustment for baseline measures can sometimes improve precision, but it must be specified and appropriately conducted. The record does not report whether an adjusted or unadjusted analysis was used, which covariates were considered, or how assumptions were checked. Any explanation of these methods is general rather than a description of the analysis actually performed.

10. Multiplicity, Missing Data and Analysis Populations

The registry summary gives a primary null hypothesis and secondary null hypotheses concerning last-of-three grip strength and before-and-after measurements. It also lists five outcome measures. When multiple outcomes or comparisons are examined, the chance of at least one apparently unusual result can increase. In general, a statistical plan may address this through prespecification, a hierarchy of outcomes, or an adjustment for multiple testing. The registry record does not report whether any such approach was planned or used, or how the five measures relate to the stated hypotheses.

The distinction between primary and secondary outcomes matters because the primary question is usually the principal basis for interpretation, while secondary outcomes can offer supporting or exploratory information. Here, the summary's primary definition and the registered primary outcome description are not fully aligned. The record does not report a statistical analysis plan explaining the endpoint hierarchy, the handling of the repeated attempts, or whether the hypotheses were tested as described.

Missing-data methods are not reported in the registry record. The record does not describe participant withdrawals, incomplete grip-strength measurements, missing questionnaire data, imputation, or sensitivity analyses. Without participant flow and analysis-population details, it is not possible to assess whether all randomized participants contributed to the reported outcomes or whether exclusions could affect the comparisons.

The record also does not state whether analyses followed intention-to-treat principles, used a per-protocol population, or applied another definition of the analysis set. These choices can affect interpretation because they define which participants contribute to each estimate. No analysis methods are listed, so the handling of missing observations, protocol deviations, and multiplicity remains unclear.

11. 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 listings report zero serious adverse events among 60 at risk in the Standard PCS group and zero among 60 at risk in the Positive PCS group. They also report zero other adverse events among 60 at risk in each group. These are the counts recorded for the listed groups; they should not be read as proof that no adverse events occurred outside the registry's recorded categories or reporting procedures.

Deaths are not reported in the registry record. The listings do not provide event descriptions or further detail about collection and follow-up. A count of zero in these records does not establish that the study had sufficient follow-up or size to detect uncommon harms, and the counts alone do not establish a safety comparison between groups.

These safety figures should be read separately from the grip-strength outcomes. They do not answer whether questionnaire content was associated with a change in grip-strength measurement. Nor do they establish that either questionnaire is safe or harmful in other settings or populations. The registry record gives no further safety analysis or interpretation.

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

The registry record documents a randomized comparison of standard and positively adjusted PCS questionnaires, with grip-strength measurement as the outcome of interest. It specifies the intended primary and secondary questions in the study summary and describes a Day 1 measurement protocol involving 3 attempts. These details help identify the research question, but they do not provide the results needed to judge the observed group differences.

No numerical outcome estimates, measures of variability, confidence intervals, or p-values are reported in the registry record. Therefore, the posted information does not show whether grip strength was higher in either group, how large any difference was, or how precisely it was estimated. It also does not establish that there was no difference. A null hypothesis written in a registry is a statement of the question, not a result.

The outcome definitions also warrant care. The summary defines the primary hypothesis using best-of-three grip strength as a percentage of the opposite hand, while the primary outcome description refers to post-intervention grip strength in pounds and changes in mean and maximum grip strength. Without clarification of the analyzed endpoint, even a numerical estimate would need to be linked to its exact measurement and comparison before it could be interpreted.

In general, a trial about measurement can inform whether a measurement process is associated with questionnaire context. It does not automatically establish an effect on underlying hand function, symptoms, or illness. The registry record does not report enough results or analysis details to draw a conclusion about such an association. The planning assumptions likewise should not be treated as evidence of observed power or as a substitute for trial findings.

13. Why This Trial Matters Statistically

This study raises a statistical issue that can arise whenever an outcome is measured after participants encounter different questionnaire wording: the measurement process itself may be the subject of investigation. The registry summary explicitly frames the objective as determining the association between priming and measurements of hand function such as grip strength. That makes clear endpoint definition and timing central to interpreting the question.

Grip strength is measured repeatedly in the described protocol, and the summary identifies different ways of using those attempts: best-of-three for the primary hypothesis and last-of-three for a secondary hypothesis. These summaries represent different measurement choices. Distinguishing them is important because a conclusion about one summary need not apply automatically to another. The registry record does not provide results or sufficient analysis detail to determine whether those choices led to similar estimates.

The record also illustrates why consistency between a summary hypothesis and an outcome definition matters. A percentage of opposite-hand strength and an absolute measurement in pounds do not express the outcome in the same way. A result should be interpreted in relation to the exact measurement, comparison, and time point that generated it. In this case, the descriptions do not fully establish that alignment.

Finally, the record separates a study's conceptual question from the evidence available to answer it. Randomization and masking are valuable design features in general, but their labels alone do not provide an effect estimate or establish precision. The lack of posted statistical analyses means readers cannot assess the magnitude, uncertainty, or consistency of the results. This is a useful reminder that a registered hypothesis and a completed study are not substitutes for reported outcome data.

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 main limitation for interpretation is that numerical outcome results are not reported in the registry record. The record lists five outcome measures but zero analyses. It gives no group means, standard deviations, effect estimates, confidence intervals, or p-values. Without them, the direction, size, and precision of any result cannot be evaluated.

The primary outcome is not described consistently across the summary and outcome entry. The summary refers to best-of-three grip strength as a percentage of the opposite hand, whereas the primary outcome description specifies a difference in grip strength of the non-affected hand in pounds and refers to mean and maximum values after intervention. The record does not clarify which definition governed the primary analysis.

Important design and analysis details are also not reported in the registry record. These include the randomization procedures, the identities of people who were masked, participant flow, arm-specific allocation, analysis populations, missing-data handling, and statistical methods. The record does not state whether baseline measurements were used in adjusted analyses or whether multiplicity was addressed across the outcomes and comparisons.

The description says grip strength was measured 3 times at enrollment and refers to post-intervention outcomes, but it does not fully explain how repeated attempts or before-and-after measurements were incorporated. This leaves uncertainty about the estimand, the exact contrast, and the relationship between the primary and secondary questions. The registry record also does not report detailed eligibility criteria or participant characteristics, limiting assessment of the population to which findings might apply.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Effect of Priming of Questionnaire Content on Grip Strength in Patients With Hand and Upper Extremity Illness — NCT02493127.
• Registry record last updated 2017-04-13; status last verified 2017-03.
• Results first posted 2017-04-13.
• 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

The registry record describes a completed, randomized, double-masked, parallel-group study of standard versus positively adjusted PCS questionnaires in patients with hand and upper extremity illness. Enrollment is listed as 122, the sponsor is Massachusetts General Hospital, and the recorded study period runs from 2015-06 to primary completion in 2015-08.

The stated objective is to assess whether priming is associated with grip-strength measurements. The summary identifies primary and secondary hypotheses involving best-of-three, last-of-three, and before-and-after measurements. The registered primary outcome description and the summary do not fully align on whether the primary measure is an absolute pound value or a percentage of the opposite hand.

Five outcome measures are listed, but zero analyses are reported. Numerical grip-strength results and their uncertainty are not reported in the registry record, so no conclusion about the observed group difference or its precision can be drawn. Serious and other adverse-event listings record zero events in the groups, while deaths are not reported in the registry record.