The Effect of Resistance Training on Proprotein Subtilisin Convertase Kexin 9 Level After Coronary Bypass Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Resistance Training on Proprotein Subtilisin Convertase Kexin 9 Level After Coronary Bypass Surgery (NCT02674659), a randomized na study. The primary outcome is PCSK-9 Level.

2. Clinical Question

This is a question about a measured laboratory outcome after rehabilitation, not a direct comparison of subsequent cardiovascular events. The randomized allocation supports an intervention-versus-comparator framing, but interpretation still depends on the recorded outcome data, how participants were analyzed, and the precision of the estimate. The registry does not report the rationale for selecting PCSK-9 as the primary outcome or whether a particular change was considered clinically important. Those points are not reported in the registry record.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group study of resistance training added to cardiac rehabilitation after coronary bypass surgery. In a parallel design, participants are assigned to one program or the other, rather than cycling through both programs. One group received conventional rehabilitation with aerobic training only; the other received conventional rehabilitation with aerobic and resistance training. The registry does not say who was masked, so the meaning of single masking cannot be specified further.

The record lists an enrollment of 87 and marks the study as completed. It gives a start date of 2016-02-10 and a primary completion date of 2016-09-23. The primary outcome population is described as patients who completed the rehabilitation program. The posted primary-outcome summaries include 39 participants in the control group and 40 in the intervention group. The registry also reports safety figures with different group denominators, and secondary-outcome summaries with their own denominators. The record does not explain the reasons for those differences.

The primary endpoint was assessed 3-4 weeks after completion of 12 sessions of cardiac rehabilitation, using a blood sample and an ELISA method. The registry identifies PCSK-9 level as a continuous measure and reports group means and standard deviations. It also lists eight secondary outcomes, including lipid measures, body mass index, fasting blood glucose, and blood pressure. Numerical summaries and comparisons are available for Low Density Lipoprotein, Body Mass Index, and High-Density Lipoprotein in the record; numerical comparisons for the other listed secondary outcomes are not reported in the registry record.

The registry does not report the original design assumptions, a sample-size justification, the identity of the masked party, or the detailed statistical analysis plan. It also does not describe whether allocation was concealed or how the random sequence was generated. These features cannot be inferred from the fact that the study is labeled randomized and single-masked.

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: There is no specific run-in period for every patient enrolled in this study. If they meet the inclusion criteria, they will be randomly assigned to the intervention or control group.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Patients who completed the cardiac rehabilitation program

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 PCSK-9 Level, measured over 3-4 weeks (after completion of 12 sessions of cardiac rehabilitation program).

The primary endpoint is the mean PCSK-9 level in blood, measured in ng/ml, among patients who completed cardiac rehabilitation. The registry defines the measurement as occurring 3-4 weeks after 12 rehabilitation sessions and states that blood samples were assessed using ELISA. The endpoint is continuous: each participant contributes a measured value, and the results are summarized as group means with standard deviations.

As a general statistical point, a continuous laboratory measure can capture variation across participants and can be compared between randomized groups using a difference in group means. That makes it suitable for expressing the direction and magnitude of an average contrast. In this study, the chosen contrast is the average PCSK-9 level in the intervention group relative to the average in the aerobic-only control group at the stated assessment time.

The registry identifies PCSK-9 as the primary outcome but does not explain why it was selected, what biological or clinical interpretation the investigators intended, or what size of difference would be important to patients. Those rationales and thresholds are not reported in the registry record. A laboratory endpoint is not itself a measure of symptoms, survival, or later cardiovascular events. Consequently, the result describes a difference in the measured marker at the reported follow-up point; it does not by itself establish what that difference means for longer-term health.

7. Results Posted in the Registry

• Intervention Group: mean 322.53 versus 377.50 on control; difference -54.97 (95% CI -104.99 to -4.95), standardized effect d = -0.49; z-test p = 0.031.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Low Density Lipoprotein

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Group: mean 96.20 versus 106.30 on control; difference -10.10 (95% CI -20.93 to 0.73), standardized effect d = -0.39; z-test p = 0.068.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Group and the control. The interval gives the range of effects that remain compatible with the data.

Body Mass Index

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Group: mean 24.70 versus 25.30 on control; difference -0.60 (95% CI -1.84 to 0.64), standardized effect d = -0.20; z-test p = 0.343.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Group and the control. The interval gives the range of effects that remain compatible with the data.

High-Density Lipoprotein

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Group: mean 37.40 versus 36.10 on control; difference 1.30 (95% CI -1.83 to 4.43), standardized effect d = 0.17; z-test p = 0.416.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Group and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists eight secondary outcomes, spanning lipid measures, body mass index, fasting blood glucose, and systolic and diastolic blood pressure. Numerical group summaries and comparisons are available for Low Density Lipoprotein, Body Mass Index, and High-Density Lipoprotein. Numerical comparisons for the other listed measures are not reported in the registry record. The available secondary results do not show a consistent, clearly separated pattern across all reported measures.

In general, secondary outcomes can help describe whether the primary result sits within a broader set of measured changes, but they do not replace the primary endpoint. They may also have different scales, variability, and precision, so their estimates should be interpreted on their own terms. The primary result concerns PCSK-9, while the available secondary comparisons concern other continuous measures. Agreement or lack of agreement among these outcomes does not establish the biological or clinical meaning of the primary marker difference.

The reported secondary comparisons are unadjusted. When several outcomes are examined, the chance of obtaining one or more apparently notable results can increase. Unless a multiplicity strategy is prespecified and reported, isolated secondary p-values generally carry less inferential weight than a primary result designated in advance. The registry does not report a multiplicity adjustment or a hierarchy for testing secondary outcomes.

The record also does not provide numerical analyses for every listed secondary measure, so the broader pattern cannot be fully assessed. The missing comparisons should not be interpreted as showing no difference; their results are simply not reported in the registry record. Taken together, the available secondary outcomes can be viewed as descriptive context, not as independent confirmation of a clinically important effect or a substitute for longer-term outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Low Density Lipoprotein
• Body Mass Index
• High-Density Lipoprotein
• Total Cholesterol
• Triglyceride
• Fasting Blood Glucose
• Systolic Blood Pressure
• Diastolic Blood Pressure

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is a continuous measurement, and the registry reports its mean and standard deviation in each group. The comparison is expressed as a mean difference: the intervention-group mean minus the control-group mean. With this sign convention, a negative estimate means the intervention group’s observed mean is lower. The reported estimate is -54.97 ng/ml. This is an absolute difference on the outcome’s measurement scale, not a percentage change or a standardized effect.

What the group summaries describe

A mean is the arithmetic average of the recorded measurements in a group. It provides a compact description of the group’s central level, but it does not show every participant’s value or the shape of the measurements’ distribution. The standard deviation describes how dispersed individual values are around the group mean. It is not the standard error of the mean and it is not a confidence interval. A larger standard deviation indicates more variation among participants, while the standard error concerns the precision of an estimated mean.

The registry reports standard deviations of 118.9 ng/ml for the control group and 107.5 ng/ml for the intervention group. The observed group means are 377.5 ng/ml and 322.5 ng/ml, respectively. These summaries help distinguish the average contrast from the participant-to-participant variability. In general, variability and the number of observations both affect the precision of a comparison; the standard deviations alone do not determine whether the estimate is precise.

What the mean difference expresses

The mean difference keeps the units of the outcome, so the primary estimate is interpretable in ng/ml. It addresses the difference between group averages rather than the difference for every participant. A group-level contrast cannot show whether all individuals changed in the same direction, and the registry does not report individual trajectories. The interpretation also depends on the endpoint timing: these measurements were defined for 3-4 weeks after completion of 12 cardiac rehabilitation sessions.

The comparison reports a 95% confidence interval from -105.0 to -4.947 ng/ml. In general, a confidence interval combines the estimate with its statistical uncertainty under an analysis procedure. A narrower interval indicates greater precision for the estimated contrast; a wider interval indicates less precision. The interval is not a range containing 95% of participants’ measurements. It is also not a probability statement that assigns a 95% chance to this particular fixed contrast after the data have been observed.

How to read the p-value

The unadjusted p-value is 0.031. In general, a p-value describes how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the assumptions of the test. It does not measure the probability that the null hypothesis is true, the probability that the finding is due to chance, or the size or importance of an effect. The registry does not identify the exact test used to obtain the primary p-value, so a specific test procedure should not be inferred.

“Unadjusted” means the displayed p-value is not described as corrected for considering multiple outcomes or comparisons. Whether a correction was planned or performed is not reported in the registry record. The p-value should therefore be read alongside the estimate, its interval, the endpoint’s prespecified role, and the other outcomes in the trial, rather than as a stand-alone verdict.

Variation and over-dispersion

As a general statistical concept, over-dispersion means that the observed variability is greater than a model expects. It matters because a model that understates variability can report standard errors that are too small and intervals that are too narrow. The registry reports standard deviations for this continuous endpoint but does not describe an over-dispersion assessment, a distributional diagnostic, or a model that addresses it. No conclusion about over-dispersion can be drawn from the record alone. For continuous measurements, the relevant question is whether the analysis accounts adequately for the observed distribution and variability; the registry does not report diagnostic details.

What the record does not specify

The randomized, parallel design identifies the broad comparison, but the registry does not report the specific inferential test, any covariate adjustment, the handling of missing measurements, or the population used for each formal analysis. It does not report whether an intention-to-treat approach was used, whether participants were analyzed according to assigned group, or how participants who did not complete rehabilitation were treated. The primary population is described as people who completed the program, but that wording alone does not establish all analysis decisions.

The record contains no reported analyses in its analyses listing, even though outcome summaries and a comparison with an unadjusted p-value are posted. Thus the numerical comparison can be described, but the full path from randomization and measurement to the inferential result is not documented. General statistical explanations in this discussion describe how these quantities are ordinarily interpreted; they do not fill in details of the study’s unreported methods.

11. Confidence Intervals and Precision

The primary mean-difference estimate is -54.97 ng/ml, with a 95% confidence interval from -105.0 to -4.947 ng/ml. The interval is entirely negative, so every value within the reported interval represents a lower mean in the intervention group under the stated intervention-minus-control direction. The interval does not include zero. The unadjusted p-value is 0.031.

The interval is wide relative to the estimate: it ranges from a comparatively modest difference to a substantially larger difference on the same measurement scale. This means the direction is more clearly estimated than the exact magnitude. The result does not pin down a single effect size, and the endpoints of the interval should not be treated as equally likely values or as a guarantee about the true difference.

In general, a confidence interval reflects the uncertainty in an estimate under the statistical method and assumptions used. It does not show the spread of participant-level PCSK-9 measurements; the group standard deviations describe that spread. The interval also does not account automatically for uncertainty due to unreported analysis choices, missing data, or multiple outcomes. The registry does not provide enough methodological detail to evaluate those sources of uncertainty.

Precision is therefore best understood in two parts: the posted estimate favors a lower group mean for the intervention group, while the plausible size of that difference remains broad. The registry does not report a threshold for a clinically important PCSK-9 difference, so the interval cannot be classified against such a threshold from the record alone.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total participants across both arms and not total events. They are illustrations based on the observed primary effect, using a two-sided significance level of 0.05, equal allocation between the two groups, and a normal approximation. Each planning row considers detecting a stated fraction of the observed effect. The original trial’s design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the planned number of participants per arm under those assumptions to have an 80% chance of detecting the specified effect if that effect were the true one. The 90% power column uses a higher target chance of detection and therefore calls for more participants per arm under the same planning framework. For example, the planning illustration for 100% of the observed effect gives 67 participants per arm for 80% power and 90 participants per arm for 90% power. These figures are planning targets, not a description of the randomized group sizes.

The other rows consider 75% and 50% of the observed effect. Smaller effects are harder to distinguish from sampling variation, so detecting them at the same power generally requires more participants. The figures are calculated from the observed effect and should not be read as evidence that the trial was designed around that effect. This is not observed power: it is a forward-looking planning illustration under the listed assumptions, not a measure of how likely the study was to find its observed result.

The registry reports enrollment of 87, while the primary outcome summaries include 39 and 40 participants in the two groups. Those observed counts are distinct from the planning illustrations. The record does not explain the difference or report how the original recruitment target was set.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -54.970; pooled standard deviation σ = 113.269.
2. n = 2 × (1.96 + 0.842)² × 113.269² / -54.970² = 66.7, rounded up to 67 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -54.97                      # observed difference in means
sigma <- 113.26945978277                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2674659)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 67 (80% power), 90 (90% power)
 75% of observed effect: n per arm = 119 (80% power), 159 (90% power)
 50% of observed effect: n per arm = 267 (80% power), 357 (90% power)
power.t.test: 67.6 
Simulated power at n = 67 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies PCSK-9 level as the primary outcome and lists eight secondary outcomes. Considering more than one outcome raises a multiplicity issue: if many hypotheses are tested, some results may appear statistically notable by chance even when no corresponding effect exists. Statistical plans may address this through a hierarchy of outcomes, adjusted significance thresholds, or other procedures. Such choices affect how p-values and confidence intervals should be interpreted across a family of tests.

A multiplicity procedure is not reported in the registry record. The primary comparison includes an unadjusted p-value of 0.031, and the available secondary comparisons also report unadjusted p-values. The record does not say whether the primary outcome was the sole confirmatory test, whether secondary outcomes were exploratory, or how the investigators intended to interpret multiple findings. It would therefore be inappropriate to assume either that an adjustment was made or that no adjustment was planned outside the registry record.

Missing-data handling is also not reported. The record defines the primary population as patients who completed the rehabilitation program, and the primary-outcome summaries include 39 control participants and 40 intervention participants. Safety figures use 43 and 44 participants at risk, while the listed secondary summaries use 43 and 44 per group. The registry does not explain why these denominators differ, whether measurements were unavailable, or whether participants were excluded for other reasons. The figures alone do not identify the cause.

The record does not describe imputation, complete-case analysis, sensitivity analyses, or any other approach to missing outcomes. It also does not specify whether the analysis followed intention-to-treat principles, analyzed participants as randomized, or restricted analyses to those completing rehabilitation. The stated completion-based primary population is relevant, but it does not answer all of these questions.

These reporting gaps limit assessment of the robustness of the inferential results. They do not change the posted group summaries, but they make it harder to judge whether the analysis population was comparable across groups, how missing values may have influenced the estimate, and how the set of outcomes informed the reported p-values. Those details are not reported in the registry record.

15. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: acute heart failure (2.3%).

The registry reports serious adverse events for 43 control participants at risk and 44 intervention participants at risk. One participant in each group is listed as having a serious adverse event. Deaths are reported as 0 in each group. These are counts as recorded in the safety results; they do not establish the cause of an event or whether it was related to rehabilitation.

For other adverse events, the registry lists 2 affected participants among 43 at risk in the control group and 0 among 44 at risk in the intervention group. The record’s serious-event terms include Acute heart failure at 2.3%. It does not provide enough detail in the listed term to assign that percentage to a particular group or to infer further event details.

Adverse-event counts should be read with their denominators and the scope of follow-up in mind. The registry does not explain the event collection procedure, severity criteria beyond the serious-event category, attribution process, or duration of safety follow-up. Small event counts also provide limited information about uncommon harms. These figures describe what is posted in the registry; they are not a complete assessment of safety or evidence about clinical benefit.

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

The primary result describes a lower mean PCSK-9 level in the group assigned to aerobic plus resistance training than in the group assigned to aerobic training only, at the assessment after 12 rehabilitation sessions. The mean difference is -54.97 ng/ml, and the 95% confidence interval is -105.0 to -4.947 ng/ml. The estimate is a comparison of group averages for the registry-defined population of patients who completed rehabilitation.

That result does not, by itself, show that the observed difference is clinically important. The registry record does not state a threshold for clinical importance or explain how a change in PCSK-9 should translate into a patient-relevant outcome. It also does not report later cardiovascular events as the primary endpoint. A difference in a laboratory measurement should not be treated as proof of a difference in symptoms, disease progression, or survival.

The result also does not establish how long any measured difference persists. The endpoint is assessed at a defined time after the rehabilitation sessions, and longer-term follow-up for the primary measure is not described. Nor does the posted comparison tell whether each participant’s value changed in the same direction; group means can differ even when individual responses vary.

Randomized allocation is an important feature for comparing groups, but the registry does not report the details needed to fully evaluate allocation procedures, masking, analysis populations, missing data, or the statistical plan. The uncertainty interval reflects statistical precision under the comparison method, but it does not resolve those reporting limitations. The unadjusted nature of the p-value and the presence of multiple listed outcomes also matter when interpreting the strength of the inferential evidence.

The appropriate conclusion is limited to the reported measurement and study population: the posted data show a lower average PCSK-9 level in the intervention group at the specified assessment, with a confidence interval that excludes zero. They do not establish a clinical benefit, a mechanism, a durable effect, or an effect on outcomes not reported. No medical decision should be based on this laboratory comparison alone.

17. Why This Trial Matters Statistically

This trial is statistically useful as an example of how an intervention can be evaluated using a continuous laboratory endpoint in a randomized parallel-group design. The primary contrast is expressed in the measurement’s original units, making its direction and scale interpretable without converting it into a standardized effect. Reporting group means, standard deviations, a mean difference, and a confidence interval allows readers to distinguish the estimated contrast from variability among participants and uncertainty around the estimate.

The record also illustrates why a p-value should not be read alone. The unadjusted p-value is 0.031, while the confidence interval communicates the range of values compatible with the reported comparison under its statistical assumptions. The interval helps convey that the direction is clearer than the exact magnitude. The registry’s multiple listed outcomes also demonstrate why a primary outcome and a multiplicity plan matter when interpreting a collection of results.

There are important limits to what can be learned statistically from registry reporting. The original sample-size justification, analysis plan, missing-data approach, and multiplicity strategy are not reported. The primary outcome population is defined by completion of rehabilitation, but the record does not explain the different outcome denominators or the analysis population in more detail. These omissions reduce reproducibility and make it harder to assess whether the inferential comparison followed a prespecified procedure.

The planning illustrations provide a separate statistical lesson: sample-size requirements depend on the effect size selected for planning and the desired power. They are not observed power and do not establish what assumptions guided the trial’s original design. Overall, the study offers a concrete comparison with a measurable endpoint, while also showing why transparent reporting of methods and analysis populations is essential for judging precision and reliability.

18. 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.

Several limitations are specific to the information recorded for this trial. The primary outcome is defined for participants who completed cardiac rehabilitation, but the record does not explain how many randomized participants completed the program or why the primary outcome denominators differ from the safety denominators. The available counts do not establish whether the difference reflects missing blood samples, eligibility decisions, or another reason. These details are not reported in the registry record.

The registry identifies the study as single-masked but does not state who was masked or how masking was maintained. It labels allocation randomized but does not describe sequence generation or allocation concealment. For a behavioral intervention involving exercise programs, the practical details of masking may be particularly relevant to measurement and participation, but the record does not describe them. The actual procedures should not be inferred from the design labels.

The primary result is a laboratory measurement taken at one stated assessment period after rehabilitation. The record does not report longer-term PCSK-9 results or clinical event outcomes as the primary endpoint. It also does not explain the rationale for selecting this measure or identify a clinically important difference. The statistical comparison therefore has limited reach beyond the measured outcome and time point.

Analysis details are sparse. The registry does not report the statistical test, covariate adjustments, missing-data methods, analysis population, or multiplicity procedure. Although an unadjusted p-value and confidence interval are posted, the underlying analysis plan is not reported. Several secondary outcomes are listed, but numerical comparisons for all listed outcomes are not reported in the registry record.

The safety results are counts with limited contextual information. Event ascertainment, relatedness, follow-up duration, and detailed event-level reporting are not described. The small number of reported serious events cannot fully characterize uncommon harms. These limitations concern the scope and transparency of the available record, and should not be mistaken for findings that the relevant procedures or outcomes did not exist.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: The Effect of Resistance Training on Proprotein Subtilisin Convertase Kexin 9 Level After Coronary Bypass Surgery — NCT02674659.
• Registry record last updated 2020-01-21; status last verified 2020-01.
• Results first posted 2019-12-09.
• 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.

22. Record Summary

The registry record describes a completed randomized, single-masked, parallel-group study of resistance training added to conventional cardiac rehabilitation after coronary bypass surgery. The control group received aerobic training only; the intervention group received aerobic and resistance training. Enrollment is listed as 87.

The primary endpoint was mean PCSK-9 level in ng/ml, measured from a blood sample after 12 rehabilitation sessions, at 3-4 weeks. The posted comparison reports a mean difference of -54.97 ng/ml for intervention minus control, with a 95% confidence interval from -105.0 to -4.947 ng/ml and an unadjusted p-value of 0.031. The primary outcome population is described as patients who completed rehabilitation.

The record lists eight secondary outcomes and reports numerical comparisons for three. It also posts adverse-event counts. The original sample-size justification, detailed statistical plan, missing-data handling, and multiplicity approach are not reported in the registry record.