Functional Status, Morbidity and Mortality in Cemented Versus Press-Fit Hemiarthroplasty: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Functional Status, Morbidity and Mortality in Cemented Versus Press-Fit Hemiarthroplasty (NCT01114646), a randomized na study. The primary outcome is Mortality.

2. Clinical Question

3. Trial Design

This was a prospective randomized trial with a parallel-group design. The registry lists an enrollment of 130 and records the study as completed. The cemented arm lists 66 participants, and the press-fit arm lists 64. These are the posted arm counts; the record does not explain whether all participants contributed data to every outcome.

The study compares cemented hemiarthroplasty with press-fit, or uncemented, hemiarthroplasty for femoral neck fractures. Its official title specifies subcapital hip fractures. The registry background says the investigation was intended to compare morbidity, mortality, and functional outcomes. It also describes a proposed expectation of fewer adverse peri-operative outcomes with press-fit treatment and equivalent functional results at one year. These are stated aims and expectations, not findings.

The listed primary outcome is mortality, described as assessment of post-operative mortality at 1 year. The secondary outcomes include the Instrumental Activities of Daily Living and Physical Activities of Daily Living scales, and an Energy/Fatigue Scale. The record lists five outcome measures but posts two secondary outcomes. It reports no analyses for the outcome data.

The study start is recorded as 2005-03 and primary completion as 2009-05. Its phase is listed as NA. Hartford Hospital is the sponsor. The registry reports no masking, so the design should be read as an unmasked randomized comparison; it does not describe additional procedures to conceal treatment assignment. The registry record does not report details of allocation concealment, the randomization method, or whether treatment assignment was stratified.

Random allocation can help make groups comparable at baseline, but it does not guarantee balance in every characteristic, especially in a study of limited size. Interpretation also depends on follow-up, outcome ascertainment, and the analysis population. The registry record does not describe these features in enough detail to assess them. The posted data should therefore be read as a registry record of a randomized trial, rather than as a complete account of its methods or analysis.

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 Mortality, measured over 1 year.

The primary endpoint is mortality assessed after surgery at 1 year. Mortality is a direct clinical outcome: it records whether a participant died during the specified follow-up period. The registry describes the measure as post-operative mortality and labels its unit “pecent.” The arm-level values are 23.1 for cemented hemiarthroplasty and 20.1 for press-fit hemiarthroplasty.

Mortality is relevant to the trial’s stated comparison because the background identifies morbidity and mortality as concerns in the choice between cemented and press-fit implants. It is also distinct from the functional outcomes listed as secondary measures. Functional scales describe activity or fatigue; mortality records a vital status outcome. Those outcomes answer different questions and should not be treated as interchangeable evidence.

The record does not explain the exact mortality calculation, the denominator used for the posted values, how deaths were identified, or how incomplete follow-up was handled. It also does not provide a confidence interval, a comparison estimate, or a test result for the primary endpoint. Consequently, the arm values describe what the registry posts, but do not on their own show how much uncertainty surrounds the comparison or whether an observed difference is compatible with chance variation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization assigns participants to treatment groups by chance. In general, this can reduce systematic differences in prognostic factors between groups and helps support a causal comparison. It does not ensure exact balance in the characteristics of a particular trial, and its value depends on how the assignment process was carried out. The record labels this study randomized, but does not report the sequence-generation method or allocation concealment. Those details are not reported in the registry record.

A parallel design means participants are assigned to an arm and followed in that assigned group rather than crossing between treatments within the study. The registry lists a cemented hemiarthroplasty arm and a press-fit hemiarthroplasty arm. It also records no masking. In an unmasked trial, participants and clinical staff may know the assigned treatment. Knowledge of assignment can affect some aspects of care or outcome assessment, although the potential impact depends on the endpoint. The record does not explain whether mortality ascertainment was conducted by assessors unaware of treatment assignment.

The primary endpoint is mortality at 1 year. For a binary outcome such as whether death occurred during a defined follow-up, an analysis might compare event risks, estimate a difference or ratio, and report uncertainty. The registry does not report such a comparative estimate for this endpoint. It posts arm-level values of 23.1 and 20.1, with the unit written as “pecent,” and marks values as missing or not estimable for a two-arm comparison. The underlying calculation and denominator are not described. These omissions mean that a reader cannot independently assess how the entries were derived or how precisely they estimate the underlying risks.

A confidence interval is a statistical range constructed by a method that, under its assumptions, reflects uncertainty in an estimated effect. It is not a range containing a known treatment effect with certainty. For a treatment comparison, the interval helps show whether the estimate is precise enough to rule out effects that could matter. Because the registry does not post an effect estimate or interval for mortality, the precision of this comparison is not reported.

A hypothesis test summarizes how compatible the observed data are with a specified null hypothesis under a statistical model. A p-value is not the probability that the null hypothesis is true, and it does not measure the clinical importance of an effect. No p-value or test result for the primary comparison is posted in the record. It is therefore not possible to characterize the mortality comparison as statistically significant or not statistically significant based on the registry information.

The record lists an enrollment of 130, with 66 in the cemented arm and 64 in the press-fit arm. Group size affects the amount of information available, but size alone does not determine precision; the number of observed outcomes, follow-up completeness, outcome variability, and analysis method also matter. The registry does not report a sample-size justification or a planned power calculation for the trial. That information is not reported in the registry record.

The record’s planning assumptions describe illustrations based on the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such calculations are planning scenarios, not observed power and not evidence that the original trial was designed around those assumptions. The assumptions also say the target effect is a stated fraction of the observed effect. Without a reported effect estimate or the actual illustration values, no particular planning requirement can be interpreted. A sample-size illustration does not change the evidential limits of the posted results.

For count outcomes, variation can sometimes exceed what a simple model assumes. In general, over-dispersion means that observed variability is greater than the model’s expected variability; ignoring it can make standard errors too small and intervals too narrow. This trial’s posted primary outcome is classified as count-other, and the registry does not provide a fitted model or dispersion estimate. It would therefore be inappropriate to claim that over-dispersion was assessed or addressed. The relevant general point is that the analysis model should match the way the outcome was collected and the variability in the data.

Finally, an intention-to-treat analysis generally compares participants according to their randomized assignment, while a per-protocol analysis may focus on participants who followed assigned treatment. These approaches answer related but not identical questions and can be affected differently by nonadherence and missing outcomes. The registry record does not say which analysis population was used. It also does not report how crossovers, withdrawals, or incomplete follow-up were handled. Without these details, the analysis cannot be reproduced or fully evaluated from the posted record.

10. Multiplicity, Missing Data and Analysis Populations

The record lists five outcome measures and identifies mortality at 1 year as the primary outcome. It names two secondary outcomes: the Instrumental Activities of Daily Living and Physical Activities of Daily Living scales, and the Energy/Fatigue Scale. The record does not post numerical results for the secondary outcomes, and it does not explain why the number of listed outcome measures differs from the number of posted secondary outcomes.

When a study evaluates multiple outcomes or makes multiple statistical comparisons, the chance of obtaining an apparently notable result by chance can increase. Statistical plans may address this through a prespecified hierarchy, adjustment, or a clear distinction between confirmatory and exploratory outcomes. Such a multiplicity strategy is not reported in the registry record. No adjustment should be assumed, and the available entries do not allow an assessment of how multiple testing was handled.

The registry lists no analyses for the outcome data. It does not specify the analysis population, whether participants were analyzed by randomized assignment, or how protocol deviations and treatment changes were handled. It also does not describe missing-data methods, the amount of missing follow-up, or whether participants with incomplete outcome information were excluded. These details matter because incomplete follow-up can affect estimates, particularly when the likelihood of missingness is related to outcome or treatment.

The enrollment and arm counts do not establish that all participants contributed to the primary endpoint. The record does not provide outcome-specific denominators or a participant flow account. Therefore, the completeness of the mortality data and the handling of missing outcomes cannot be assessed from the registry record. No assumptions about missingness or analysis populations should be inferred from the posted group sizes.

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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death (1.6%).

The registry reports serious adverse event figures by arm. In the cemented arm, 1 serious event is listed among 66 at risk; in the press-fit arm, 1 is listed among 64 at risk. The record also lists other adverse events as 11 among 66 at risk in the cemented arm and 8 among 64 at risk in the press-fit arm. These are registry counts, not comparative estimates, and the record provides no uncertainty intervals or statistical tests for them.

The serious adverse event term listed is Death, with a registry value of 1.6%. The record does not explain how this summary relates to the arm-specific serious event figures. It should not be assumed that the term-level value uses the same population, time window, or calculation as the primary mortality endpoint. The adverse event entries also do not provide definitions, event timing, severity criteria, or information about whether multiple events could be recorded for a participant.

Serious adverse event reporting and a primary mortality outcome are not automatically interchangeable. Their definitions and ascertainment can differ, and an adverse event count may not represent the same measure as mortality at 1 year. The registry record does not provide the detail needed to reconcile these entries. The figures are best read as descriptive safety reporting, not as evidence of a statistically established difference between treatments.

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

The registry records a randomized comparison of cemented and press-fit hemiarthroplasty, with mortality at 1 year as the primary endpoint. It posts arm-level mortality values of 23.1 and 20.1, respectively, and gives the unit as “pecent.” It also posts serious and other adverse event counts by arm. These entries describe the available registry results and safety counts, but they are not accompanied by a reported comparative effect estimate or uncertainty measure.

The result does not establish that either approach reduces mortality relative to the other. Without an effect estimate, confidence interval, or statistical test, the degree of uncertainty in the comparison cannot be quantified. The values also do not establish equivalence: a conclusion of equivalence requires a suitable design and analysis with a prespecified margin and adequate precision. No equivalence margin or such analysis is reported in the registry record.

Nor do the posted entries resolve the trial’s functional outcome question. The registry describes IADL and PADL and Energy/Fatigue outcomes, but does not post their numerical results. The stated expectation that functional results would be equivalent at one year is a proposed hypothesis, not a reported finding. Likewise, the proposed expectation concerning peri-operative outcomes should not be mistaken for an observed result.

The absence of a reported comparison is not evidence that the treatments have identical effects. It means the registry record does not supply the information needed to distinguish a small or uncertain difference from a more precisely estimated one. Interpretation is further limited by the lack of detail on outcome denominators, follow-up completeness, missing-data handling, and analysis population.

In practical statistical terms, the available entries support a descriptive account of the trial arms and posted outcome values. They do not support a firm claim about comparative effectiveness or safety. A fuller assessment would require the trial’s analysis methods, complete outcome reporting, and estimates with uncertainty. These conclusions concern the statistical information in the registry record, not a recommendation about treatment.

13. Why This Trial Matters Statistically

This trial addresses an important statistical challenge in clinical research: a randomized comparison may be registered as completed, yet the posted outcome entries may not include the estimates needed to judge the comparative evidence. The study identifies a clear contrast between cemented and press-fit hemiarthroplasty and specifies mortality at 1 year as its primary endpoint. However, the record does not post a two-arm comparison estimate, an uncertainty interval, or a test result.

That distinction matters because arm-level values alone do not show the precision of a treatment comparison. The statistical question is not only what values were observed in each arm, but also how those values were analyzed, how much uncertainty remains, and whether the analysis respects the trial design and outcome definition. Without a comparative estimate, readers cannot use the posted results to distinguish a stable pattern from one that could plausibly vary across repeated studies.

The record also illustrates why endpoints and analysis populations need clear reporting. Mortality, serious adverse events, and functional scales capture different aspects of outcome. Their definitions, follow-up windows, denominators, and missing-data rules affect interpretation. The listed serious adverse event term and arm counts cannot be assumed to represent the same measure as the primary mortality endpoint.

Finally, planning calculations should be kept separate from observed evidence. The registry’s stated sample-size assumptions describe planning illustrations, not the trial’s original design or observed power. This distinction prevents a hypothetical planning scenario from being mistaken for evidence that the study had a particular ability to detect an effect. Transparent reporting of protocol methods, analysis decisions, effect estimates, and uncertainty is essential for readers to evaluate what a randomized trial can establish.

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 registry record gives limited detail about how participants were selected and followed. It does not report full eligibility criteria, baseline characteristics, or a participant flow account. Although the record lists enrollment and arm counts, it does not provide outcome-specific denominators or explain whether all randomized participants contributed to mortality data.

The primary outcome is described as post-operative mortality at 1 year, but the calculation behind the posted values is not specified. The unit is recorded as “pecent,” and the record does not explain the numerator, denominator, or handling of incomplete follow-up. It also does not provide a comparative effect estimate, confidence interval, or test result. As a result, the precision and statistical significance of the primary comparison cannot be assessed.

Details of randomization, allocation concealment, outcome ascertainment, and analysis are not reported. The record identifies the trial as randomized and unmasked, but it does not state the method used to generate assignments, whether assignment was concealed, or whether mortality assessment was independent of treatment knowledge. It also does not describe adherence, treatment crossover, protocol deviations, or the analysis population.

The record lists secondary functional outcomes but does not post their results. It lists five outcome measures while posting two secondary outcomes, and does not explain the relationship between those entries. A multiplicity plan is not reported. Missing-data procedures and the amount of missing outcome information are also not reported. These limitations restrict interpretation of both the primary comparison and the broader aims concerning morbidity and function.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Functional Status, Morbidity and Mortality in Cemented Versus Press-Fit Hemiarthroplasty — NCT01114646.
• Registry record last updated 2018-08-07; status last verified 2013-03.
• Results first posted 2018-08-07.
• 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

NCT01114646 is a completed, prospective randomized parallel trial sponsored by Hartford Hospital. It compares cemented with press-fit hemiarthroplasty for subcapital hip fractures and reports no masking. The recorded enrollment is 130, with arm counts of 66 for cemented hemiarthroplasty and 64 for press-fit hemiarthroplasty. The study start is 2005-03, and primary completion is 2009-05.

The primary outcome is post-operative mortality at 1 year. The registry posts arm values of 23.1 and 20.1, with the unit recorded as “pecent,” but does not provide a comparative effect estimate, confidence interval, or test result. It lists serious and other adverse event counts by arm, while the relation between the serious event term Death and the arm-specific figures is not explained. Functional scales are listed as secondary outcomes, but numerical results are not posted. The analysis population, missing-data approach, and multiplicity plan are not reported in the registry record.