Improving Quality of Life After Thoracic Surgery Using Patient-Reported Outcomes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving Quality of Life After Thoracic Surgery Using Patient-Reported Outcomes (NCT04342260), a randomized na study. The primary outcome is Quality of Life at 12 Months.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, parallel-group study with no masking. It is listed as completed, with 113 participants enrolled. The recorded start date is 2020-04-30 and the primary completion date is 2023-11-10. The registry lists the study phase as not applicable.

Participants were assigned to Active Monitoring or Passive Monitoring. In the active arm, clinicians were to receive symptom alerts if survey responses suggested increased or worsening symptoms. In the passive arm, clinicians were not to receive symptom alerts. The study summary describes patient self-reporting of symptoms for remote monitoring by the care team, and states that the study was designed to test feasibility as well as assess quality of life, health outcomes, and service utilization.

The primary outcome is continuous: quality of life at 12 months post-discharge, described as a mean score with standard deviation. The registry also posts readmission at 3 months and overall survival at 12 months as secondary outcomes. The posted outcome counts show 50 participants for Active Monitoring and 49 for Passive Monitoring for the primary measure. The registry record does not explain how these outcome counts relate to the enrollment figure or describe participant flow between enrollment and outcome assessment.

The sponsor is UNC Lineberger Comprehensive Cancer Center. Further details about the allocation procedure, recruitment setting, eligibility criteria, delivery of the monitoring tools, and implementation of the alerts are not reported in the registry record. The presence of randomization identifies the broad study design, but does not by itself establish how assignment was generated or concealed.

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: Eligible patients who enrolled were assigned to study arms at the time of enrollment in a 1:1 ratio using block randomization with blocks of 20 participants (patients).

Overall Study

Analysis population for the primary outcome, as defined in the registry: Intent to treat population.

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 Quality of Life at 12 Months, measured over 12 months post-discharge.

The primary endpoint is quality of life 12 months after discharge, measured with the EORTC Quality of Life Questionnaire Core-30, version 3.0. The registry describes the result as a score on a 0 to 100 scale, with a higher score representing better quality of life. The outcome is summarized as a mean and standard deviation for the intent-to-treat population.

Patient-reported quality of life is relevant to a study of remote symptom monitoring because it captures participants’ reported experience rather than relying only on service-use or clinical-event measures. The study summary frames the monitoring approach as a way to assess postoperative symptoms and potential effects on quality of life, health outcomes, and service utilization. The primary endpoint therefore addresses one of the central outcomes named in the study’s stated purpose.

The registry record does not report a threshold for a clinically important difference, a scoring or missing-item procedure, or further details about when questionnaires were collected within the 12-month timeframe. Without those details, the numerical difference can be described on the posted scale, but its clinical importance and the handling of incomplete questionnaires cannot be established from the record.

7. Results Posted in the Registry

• Passive Monitoring: mean 84.02 versus 80.97 on control; difference 3.05 (95% CI -3.58 to 9.68), standardized effect d = 0.18; z-test p = 0.367.

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.

Readmission at 3 Months

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Passive Monitoring: 14.3% (7/49) versus 12.0% (6/50) on control; risk difference 2.3 percentage points (95% CI -11.0 to 15.6), risk ratio 1.19 (0.43–3.29); unadjusted two-proportion z-test p = 0.736.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Passive Monitoring and the control. The interval gives the range of effects that remain compatible with the data.

Overall Survival at 12 Months

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Passive Monitoring: 95.9% (47/49) versus 94.0% (47/50) on control; risk difference 1.9 percentage points (95% CI -6.7 to 10.5), risk ratio 1.02 (0.93–1.12); unadjusted two-proportion z-test p = 0.663.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Passive Monitoring and the control. The interval gives the range of effects that remain compatible with the data.

The registry posts two secondary outcomes: readmission at 3 months post-discharge and overall survival at 12 months post-discharge. Together with the primary quality-of-life endpoint, they address different aspects of the study’s stated interest in postoperative outcomes. Readmission captures a service-use event, while survival is a distinct patient outcome; neither is interchangeable with a patient-reported quality-of-life score.

Across the posted secondary comparisons, the uncertainty intervals include no difference. This broad pattern is consistent with the primary result in the limited sense that none of the posted comparisons clearly resolves a difference between the monitoring groups. The outcomes use different measures and timeframes, however, so they should not be treated as repeated measurements of the same effect or as evidence that one outcome validates another.

The secondary outcomes complement the primary endpoint by showing what was recorded for additional outcomes, but the primary question remains the difference in quality-of-life means at 12 months. No reported analyses are listed for the secondary outcomes. The posted comparisons are unadjusted, and the registry record does not describe a prespecified testing hierarchy or a multiplicity strategy.

General: When several outcomes are tested, the chance of observing at least one apparently unusual result can increase, depending on how the tests relate and how they are selected. Adjustment procedures or a prespecified hierarchy can help define how multiple tests are interpreted. Without information on those choices, secondary p values should be considered exploratory or descriptive rather than treated as independent confirmatory evidence. This does not erase the results; it places them in context and cautions against giving them the same weight as a clearly prespecified primary analysis.

For the same reason, an overall pattern across outcomes should be described without claiming a single combined treatment effect. The registry record does not report a composite endpoint or a method for combining the primary and secondary outcomes. Each outcome therefore retains its own scale, timeframe, and uncertainty.

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

• Readmission at 3 Months
• Overall Survival at 12 Months

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous because it is measured on a numerical quality-of-life scale. The registry summarizes each arm using a mean and standard deviation, then posts a mean difference comparing Passive Monitoring with Active Monitoring. The estimate of 3.05 is the reported contrast; the arm means are 84.02 and 80.97, respectively. The posted confidence interval is -3.577 to 9.677, and the unadjusted p value is 0.367.

What does a mean difference describe?

General: A mean is a measure of the center of a set of numerical observations. A mean difference compares the average value in one group with the average value in another, using a stated direction for the subtraction. Here, the comparison is Passive Monitoring relative to Active Monitoring. A positive estimate means the observed mean was higher in Passive Monitoring; a negative estimate would mean it was lower. The outcome scale’s stated direction matters: higher scores indicate better quality of life.

General: A standard deviation describes how spread out individual observations are around their group mean. It is not the same as the standard error, which describes the precision of an estimated mean. The posted standard deviations, 17.06 and 16.58, reflect variation among the measured scores within the two arms. The registry also posts standard errors of 2.413 and 2.369 for the arm means as part of the comparison information.

How should the confidence interval be read?

General: A confidence interval expresses uncertainty around an estimate using a range of values compatible with the data under the interval’s statistical assumptions. A narrower interval indicates greater precision than a wider interval on the same scale. An interval that includes no difference indicates that the data do not rule out no difference at the interval’s confidence level. It does not mean that all values inside the interval are equally likely, nor does it show that the true effect must lie within the interval in every particular study.

For this comparison, the interval runs from -3.577 to 9.677. It includes no difference and extends in both directions. Thus, the estimate does not sharply distinguish a lower mean in Passive Monitoring from a higher mean. The registry does not report a clinically important difference threshold, so the interval cannot be classified against such a threshold using this record.

What does the p value add?

General: A p value describes how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the analysis assumptions held. It is not the probability that the null hypothesis is true, and it does not quantify the probability that the result occurred by chance. The unadjusted p value of 0.367 is a summary of the comparison under its statistical test; it does not communicate the range or clinical importance of plausible differences. The registry record does not identify a full analysis plan or report a multiplicity adjustment for this comparison.

The record posts no reported analyses. Consequently, the posted unadjusted comparison is the available registry result, but details such as covariate adjustment, model specification, assumptions checks, or handling of incomplete data are not reported in the registry record. No adjusted estimate should be inferred from the displayed summary statistics.

Why does outcome type matter?

General: A continuous outcome such as a questionnaire score is commonly summarized with means and measures of spread. Binary outcomes, such as whether a participant was readmitted, are summarized by counts and proportions. These outcome types answer different questions and use different effect measures. For the primary quality-of-life endpoint, the posted contrast is a mean difference in scale units. For the secondary endpoints, the registry posts risk differences between arms.

General: Statistical models also depend on features of the data, including the distribution of observations and whether observations are independent. Over-dispersion occurs when observed variation exceeds what a model assumes; if it is ignored, standard errors and uncertainty estimates can be misleading. The registry record does not report a model assessment or an over-dispersion analysis. Since the primary result is posted as a comparison of means and no reported analyses are listed, claims about model diagnostics or robustness would go beyond the record.

The randomized parallel-group design supports a comparison between the two assigned monitoring approaches, but the design label alone does not document the allocation sequence, concealment, adherence, or analysis population implementation. The primary outcome is described as intent-to-treat, while operational details about that population and the treatment of missing outcome data are not reported in the registry record.

11. Confidence Intervals and Precision

The primary mean difference is 3.05 units, with a 95% confidence interval from -3.577 to 9.677. Because the interval includes no difference and extends to both negative and positive values, it leaves uncertainty about the direction of the difference as well as its size. The point estimate is more precise when considered together with this interval than when read alone, but the interval remains broad enough to include meaningfully different possibilities on the score scale.

General: Precision concerns how tightly the data constrain an estimate. It is distinct from whether an effect is important. A narrow interval can be centered on a small difference, while a broad interval may include both small and larger differences. The interpretation of an interval also depends on the outcome scale and, where available, a benchmark for a meaningful difference. No such benchmark is reported in the registry record.

The primary outcome counts are 50 for Active Monitoring and 49 for Passive Monitoring. The registry enrollment is 113, and the record does not explain how enrollment relates to these outcome counts. It also does not describe missingness, the number of questionnaires available at the 12-month assessment beyond the posted counts, or the method used to address incomplete data. This limits the ability to assess whether the precision reflects all randomized participants or only those with outcome information.

The p value of 0.367 should not be used as a substitute for the confidence interval. It gives no direct description of the range of differences compatible with the data. The interval is the more informative summary for seeing the uncertainty in the estimated mean difference, while the absence of a reported clinically important threshold limits judgments about practical relevance.

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 sample-size figures are planning illustrations based on the observed effect, not the trial’s own design calculations. The assumptions listed for these illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row considers detecting a stated fraction of the observed effect. These are planning assumptions; the trial’s original sample-size justification and design assumptions are not reported in the registry record.

For the continuous primary outcome and the posted binary outcomes, the figures are participants per arm. They are not totals across both arms and are not event counts. The columns for 80% and 90% power describe the number of participants per arm that the planning calculation estimates would be needed to have, respectively, an 80% or 90% chance of detecting the specified effect under the listed assumptions if that effect were the true one. A higher target power generally requires more participants for a given effect.

The rows for 100%, 75%, and 50% of the observed effect represent progressively smaller effects to detect. Smaller effects require more participants, because they are harder to distinguish from random variation. The observed effect used as the starting point comes from the posted comparison; it is not a claim about a true or clinically important effect.

These calculations are not observed power. They are hypothetical planning illustrations and do not show the probability that this completed study detected its true effect. The trial’s own sample-size rationale is not reported in the registry record, so the planning calculations should not be interpreted as evidence of the study’s intended recruitment target or as a substitute for the confidence intervals around the posted results.

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 = 3.050; pooled standard deviation σ = 16.824.
2. n = 2 × (1.96 + 0.842)² × 16.824² / 3.050² = 477.6, rounded up to 478 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 <- 3.05                      # observed difference in means
sigma <- 16.8241859532546                     # 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(4342260)
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 = 478 (80% power), 640 (90% power)
 75% of observed effect: n per arm = 850 (80% power), 1,137 (90% power)
 50% of observed effect: n per arm = 1,911 (80% power), 2,558 (90% power)
power.t.test: 478.6 
Simulated power at n = 478 per arm: 0.802 (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 quality of life at 12 months as the primary outcome and posts readmission at 3 months and overall survival at 12 months as secondary outcomes. It reports seven outcome measures in total, but does not provide a complete description of all outcome measures in the available record. No reported analyses are listed. The registry record does not state whether a testing hierarchy, family-wise error procedure, false-discovery approach, or other multiplicity strategy was planned.

General: Multiplicity matters when several hypotheses are tested because the chance of at least one apparently noteworthy result may rise as the number of tests increases. A plan can address this by identifying one primary test, ordering outcomes, adjusting significance thresholds, or treating secondary analyses as exploratory. Without a stated plan, it is difficult to know whether a displayed p value was intended as confirmatory evidence or as a descriptive comparison. The unadjusted p values should therefore be read as individual comparisons, not as a complete multiplicity-controlled analysis.

The primary population is described as intent to treat. The record does not report how that population was operationalized, whether all randomized participants were included in the primary analysis, or how participants without a 12-month score were handled. It also does not report imputation, complete-case analysis, sensitivity analysis, or reasons for missing observations. These details are important because missing outcome data can affect both the estimated difference and its uncertainty, depending on why data are missing and how they are handled.

The registry gives 113 as enrollment and posts primary outcome counts of 50 and 49 in the two arms. It does not explain the relationship between these figures or provide a participant-flow account. The design is randomized and unmasked, but details of allocation concealment and adherence are not reported in the registry record. No assumptions about the original statistical plan, interim analyses, missing-data methods, or covariate adjustment can be established from the posted information.

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

The result shows that the observed mean quality-of-life score was higher in Passive Monitoring than in Active Monitoring at 12 months, with a posted mean difference of 3.05 units. Its confidence interval ranges from -3.577 to 9.677, so the data are compatible with differences in either direction. The registry result therefore does not settle whether the underlying mean score was higher in one group or the other.

This is not the same as showing that the approaches are equivalent. Equivalence or non-inferiority requires a prespecified margin and an analysis designed to test that margin. No such margin or analysis is reported in the registry record. Nor does an unadjusted p value of 0.367 establish the probability that there is no difference. The p value and confidence interval describe uncertainty in different ways, and neither on its own establishes clinical importance.

The study summary states that the study was designed to examine feasibility and possible effects on quality of life, health outcomes, and service utilization. The posted outcome comparisons provide numerical estimates for the primary quality-of-life endpoint and two secondary endpoints, but the registry record does not post a separate feasibility result or a full analysis report. The available results should therefore be understood as registry-posted summaries rather than a complete assessment of every stated study aim.

General: A randomized comparison can help estimate differences between assigned groups, but interpretation still depends on how participants were randomized, retained, measured, and analyzed. The registry identifies a randomized design and an intent-to-treat primary population, but does not report several operational details needed to assess those processes. In particular, details of missing data and the relationship between enrollment and outcome counts are not available.

The results do not establish that either monitoring approach improves or worsens quality of life, readmission, or survival. They describe observed group summaries and comparisons, with uncertainty. The lack of a definitive difference in these posted estimates should not be converted into a claim of no effect, just as the direction of a point estimate should not be treated as proof of benefit or harm.

16. Why This Trial Matters Statistically

This trial is statistically interesting because it compares two monitoring approaches that differ in whether clinicians receive symptom alerts. The contrast is focused on an operational feature of remote monitoring, while the primary outcome is a patient-reported measure of quality of life. That pairing makes interpretation depend on both the score’s scale and the uncertainty in the between-group estimate.

The primary result illustrates why a point estimate alone is incomplete. The posted difference is positive for Passive Monitoring relative to Active Monitoring, but its confidence interval spans values in both directions. The interval makes the uncertainty visible and discourages treating the observed direction as a settled conclusion. It also shows why a p value should not replace an estimate and its interval.

The study also has outcomes with different statistical forms: a continuous quality-of-life score and binary event outcomes. These require different summaries and effect measures, and their results should not be collapsed into one interpretation without a stated method. The secondary outcomes broaden the questions considered, but multiplicity and the absence of reported analyses limit the strength of confirmatory conclusions that can be drawn from them.

Finally, the record highlights the difference between an observed comparison and a sample-size planning illustration. The planning figures are based on fractions of the observed effect under stated assumptions; they are not evidence of the trial’s original design rationale and are not observed power. The registry does not report the original sample-size justification. Clear separation of estimation, uncertainty, outcome priority, and planning assumptions is essential when interpreting a completed trial’s posted results.

17. 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 specific to this registry record constrain interpretation. The study is listed as unmasked, and the record does not describe procedures to reduce the possibility that knowledge of monitoring assignment influenced symptom reporting, clinical responses, or outcome assessment. The primary endpoint is patient-reported, making collection and completion procedures relevant, but these details are not reported in the registry record.

The record gives an enrollment of 113, while the posted primary outcome counts are 50 for Active Monitoring and 49 for Passive Monitoring. It does not explain how these counts relate to enrollment or provide participant flow, reasons for unavailable outcomes, or a missing-data approach. This prevents a full assessment of the outcome analysis population and possible missingness.

The record does not report a clinically important difference threshold for the quality-of-life scale. As a result, the statistical estimate and interval can be described, but a judgment about clinical importance cannot be anchored to a stated threshold. Further scoring details, including handling of incomplete questionnaires, are also not reported.

No reported analyses are listed. The registry does not provide the full statistical analysis plan, covariate adjustments, model diagnostics, multiplicity procedure, interim analysis details, or the original sample-size justification. Allocation generation and concealment details are not reported either. These absences do not establish that such procedures were not used; they mean that they cannot be assessed from the registry record.

The registry lists deaths in the adverse-event information as 3 for Active Monitoring and 2 for Passive Monitoring, while the secondary survival outcome is separately posted as a participant count. The record does not provide additional context for interpreting the adverse-event entries alongside the survival endpoint. These reporting and documentation limits should be kept distinct from the observed numerical comparisons.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Improving Quality of Life After Thoracic Surgery Using Patient-Reported Outcomes — NCT04342260.
• Registry record last updated 2025-02-20; status last verified 2025-01.
• Results first posted 2025-02-20.
• 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.

21. Record Summary

The registry record describes a completed randomized, parallel-group study without masking, enrolling 113 participants. It compares Active Monitoring, in which clinicians received symptom alerts for increased or worsening symptoms, with Passive Monitoring, in which clinicians did not receive alerts. The study summary describes remote patient symptom reporting and aims that include feasibility, quality of life, health outcomes, and service utilization.

The primary outcome is mean EORTC QLQ-C30 quality-of-life score at 12 months post-discharge, with higher scores representing better quality of life. The posted mean difference for Passive Monitoring relative to Active Monitoring is 3.05, with a 95% confidence interval from -3.577 to 9.677 and an unadjusted p value of 0.367. Readmission at 3 months and overall survival at 12 months are also posted as secondary outcomes.

The registry record does not list reported analyses or explain the relationship between enrollment and the primary outcome counts. Details of the original sample-size rationale, multiplicity, and missing-data handling are not reported in the registry record.