Heart Rate Variability Biofeedback for Smoking Cessation Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Heart Rate Variability Biofeedback for Smoking Cessation Treatment (NCT05224050), a na phase 2 study. The primary outcome is Intervention Feasibility: Participant Ratings of Effectiveness.

2. Clinical Question

3. Trial Design

This was an open trial of heart rate variability biofeedback for smoking cessation treatment, registered as NCT05224050. It is listed as Phase 2 and as a single-group study. The record identifies Rutgers, The State University of New Jersey, as sponsor, and Tobacco Smoking as the condition. Enrollment was 28. The study started on 2021-11-29, reached primary completion on 2023-06-15, and is recorded as completed.

All participants in the trial's intervention group were to receive individualized resonance-breathing training using biofeedback, cognitive-behavioral smoking cessation treatment, and up to 8-weeks of transdermal nicotine patch. The brief description characterizes the intervention as adapted and primarily virtual and remote. Since all participants received the combined package, the study design does not permit a direct estimate of the separate effects of biofeedback, counseling, or nicotine patch.

Allocation is listed as NA, masking as none, and the model as single-group. There is no randomized comparator in the record. Consequently, changes in ratings or smoking behavior over time, if reported, would describe participants' outcomes during the intervention and follow-up rather than a controlled contrast. Changes could not by themselves distinguish intervention effects from other influences, such as time, expectations, or concurrent changes in participants' circumstances.

The registry lists 11 outcome measures and 7 analyses. It identifies changes in total emotional distress and several smoking-behavior outcomes among the secondary outcomes. The registry record does not report the protocol, a statistical analysis plan, sample-size justification, or details of any interim analyses. Those design details should not be inferred from the study's Phase 2 label or its completion status.

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: The intervention involved 7 sessions (2 in-person and 5 virtual remote) scheduled over a 6-week period. All participants received individualized heart rate variability biofeedback at each session, smoking cessation therapy during 6 of the sessions, and 8 weeks of transdermal nicotine patches.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Data on the Intent-to-treat N=28 participants who completed the baseline session and were enrolled in the study.

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 Intervention Feasibility: Participant Ratings of Effectiveness, measured over Week 1 (i.e., treatment initiation), Week 6 (i.e., end of treatment/1-month post-quit), and Week 16 (i.e., 3-MFU).

The primary endpoint is a self-reported rating of perceived intervention effectiveness. Four items ask whether the intervention helped participants quit smoking and manage emotional distress. Each item uses a Likert-type scale from 0=completely disagree to 4=completely agree. The mean total score is computed by averaging the items at each timepoint, and the scale ranges from 0-4; higher scores indicate greater perceived intervention efficacy.

Ratings were planned at Week 1 (treatment initiation), Week 6 (end of treatment/1-month post-quit), and Week 16 (3-MFU). These repeated assessments can describe how participants' perceptions are distributed across the treatment and follow-up period. In a feasibility study, acceptability and participants' views of the intervention can help characterize whether the treatment package is experienced as relevant and useful. Such ratings are subjective perceptions, however, and are not equivalent to verified smoking abstinence or a causal estimate of treatment benefit.

The registry record describes the measure but does not report observed mean scores or standard deviations at these timepoints. It therefore does not establish the level of perceived effectiveness or how much participant ratings varied.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help clarify what this kind of study can and cannot establish. The explanations below are general statistical context unless they refer explicitly to details reported in the registry record.

What does a mean score represent?

For a continuous outcome, a mean describes the arithmetic average of the recorded values. Here, each participant's total score is formed by averaging four self-report items, and the registry describes reporting a mean total score for each assessment timepoint. The score's stated range is 0-4, with higher values representing greater perceived intervention efficacy. A mean can summarize the overall level of responses, but it does not show whether participants gave similar ratings or whether responses were concentrated at the ends of the scale.

The standard deviation describes the spread of individual scores around their mean. A larger standard deviation indicates greater variation among participants' scores, while a smaller one indicates that scores are more clustered. The standard deviation is not the same as the precision of the estimated mean. Precision also depends on how many observations contribute and on the analysis method. The registry record identifies the standard deviation as the measure of dispersion for the primary endpoint, but the numerical means and standard deviations are not reported in the record.

How should repeated timepoints be understood?

Assessments at Week 1, Week 6, and Week 16 offer a way to describe participants' ratings at different stages: treatment initiation, end of treatment/1-month post-quit, and 3-MFU. Because these are measurements from participants followed over time, interpreting changes requires knowing which observations were included at each timepoint and how within-participant relationships were handled. Scores from the same participant may be related, so treating all timepoint observations as independent would not generally represent that structure. The registry record does not report the model or other statistical procedure used to analyze repeated ratings.

Even when a within-person change is estimated, a single-group study does not provide the counterfactual comparison needed to identify what would have happened to the same participants without the intervention. As general statistical context, an uncontrolled time trend can reflect the intervention, other events over time, changes in who provides data, or measurement effects. The design therefore supports description of outcomes during the intervention, not a randomized causal contrast.

What does a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate under a specified statistical model and sampling procedure. It gives readers a range of values compatible with the data and method, rather than a guarantee that the true value lies in that range. A narrow interval indicates greater precision than a wide interval, all else equal. A confidence interval around a mean rating would help readers assess the precision of that mean; an interval around a comparison would address uncertainty in that comparison. The registry record does not report confidence intervals for the primary endpoint in the registry record.

A confidence interval cannot repair limitations in the design. In a single-group trial, a precise estimate of the participants' average rating would still not establish what the ratings would have been under a different treatment or without treatment. Statistical precision and causal identification are distinct questions.

What does the planning illustration mean?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. It describes the target effect as a stated fraction of the observed effect. These are planning assumptions, not features that change the actual single-group design. The illustration is not the trial's own sample-size justification, and the registry record does not report that justification.

A sample-size calculation asks how many participants per arm a hypothetical comparison would require under specified assumptions to reach a target power for a chosen effect. It is a prospective planning exercise, not a measure of the power actually achieved in the completed trial. It cannot establish that an observed result is true or clinically important. The numerical outputs for the planning illustration are not reported in the registry record for this analysis, and they should not be inferred.

In general, calculations using a normal approximation depend on assumptions about the outcome distribution and the comparison. Equal allocation is an assumed design choice for the hypothetical two-arm planning exercise; it does not describe this study's observed allocation, which is listed as NA. Any planning values based on an observed effect also depend on how that effect was estimated. If an observed estimate is imprecise, calculations built from it can also be unstable. The registry record does not report enough information to assess these assumptions further.

Why does over-dispersion matter?

As general statistical context, over-dispersion occurs when observed variability is greater than a model assumes. For count outcomes, for example, a model that underestimates variability can produce standard errors that are too small and uncertainty intervals that are too narrow. A model that accommodates extra variability may better reflect the data. The primary endpoint in this trial is a bounded mean score, not a reported count outcome, and the registry record does not describe an over-dispersion adjustment. The concept should not be taken to mean that such an issue was observed in this trial.

Overall, sound interpretation depends on the reported estimates, their uncertainty, the analysis population, and the method used. The registry record describes the primary measure and participant availability, but does not report the endpoint estimates or sufficient analysis details to reconstruct the statistical analysis.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Week 1 (Treatment Initiation)", "Week 6 (End of Treatment)", "Week 16 (3-MFU)")
n   <- c(27, 18, 16)
m   <- c(3.02, 3.29, 2.8)
sp  <- c(0.59, 0.59, 0.9)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Week 1 (Treatment Initiation)  27  3.020  0.590  2.787  3.253
CARM  Week 6 (End of Treatment)  18  3.290  0.590  2.997  3.583
CARM  Week 16 (3-MFU)  16  2.800  0.900  2.320  3.280

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures and 7 analyses. It does not report a multiplicity adjustment, a hierarchy of confirmatory outcomes, or a prespecified strategy for controlling the chance of false-positive findings across analyses. When multiple outcomes or analyses are examined, the chance of at least one apparently notable result can increase if each is interpreted as a separate test. As general statistical context, a prespecified plan can clarify which outcomes are confirmatory and how multiple comparisons are handled. The absence of such details in the registry record means the approach cannot be assessed; it does not establish that no plan existed outside the record.

The primary endpoint is described as a mean score at Week 1, Week 6, and Week 16. The record does not specify whether the primary analysis targeted a particular timepoint, a change between timepoints, or a model combining repeated observations. It also does not report hypothesis tests or confidence intervals for this endpoint. The statistical analysis plan and the handling of multiple timepoint comparisons are not reported in the registry record.

Missing data are relevant because endpoint availability differs across the reported assessments. The record states that n=27 had Week 1 data among the 28 enrolled, n=18 had Week 6 data among the n=19 who completed treatment, and n=16 completed the measure at the 3-month follow up. These figures do not explain why observations were unavailable or whether missingness was related to participant experience or outcomes. The record does not report imputation, a complete-case analysis, sensitivity analyses, or another method for addressing missing data.

The analysis population is also not reported in the registry record. The availability counts should not be mistaken for a statement about an intention-to-treat analysis, a per-protocol analysis, or another defined analysis set. Without the analysis population and missing-data approach, the risk that estimates reflect a selected subset of participants cannot be evaluated.

12. 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.

The registry lists the HRVB-SCT group with 28 participants at risk for serious adverse events and 28 at risk for other adverse events. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths. No top serious adverse-event terms are listed.

These are the reported counts for the categories recorded in the registry, not a complete description of every symptom or experience during treatment. A zero count means no events were reported in that category in this record; it does not establish that no adverse experiences occurred or that the intervention has no risk. The record does not provide event definitions, details of ascertainment, timing, severity grading, relatedness assessments, or information about events that may not meet the registry's reporting thresholds.

There is no comparison group for interpreting safety differences. These figures therefore describe the reported experience in the enrolled group and cannot establish whether event rates differ from those under another treatment or no treatment. The safety counts should be read alongside the study's open, single-group design and the limits of the adverse-event details reported in the registry record.

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

This trial addresses a practical research question: whether an adapted, primarily virtual intervention combining heart rate variability biofeedback, cognitive-behavioral smoking cessation treatment, and nicotine patch can be studied with participant reports and follow-up outcomes. Its primary measure asks participants how effective they perceive the intervention to be in helping with quitting and managing emotional distress. That is a relevant feasibility-oriented perspective, but it is not itself proof of smoking cessation or a direct measure of treatment efficacy.

The registry record gives the primary endpoint's scale, assessment timepoints, and data availability. It does not report the observed mean scores or standard deviations. As a result, the registry entries do not show whether participants rated the intervention favorably, how much ratings varied, or whether ratings changed over time. The record also lists smoking behavior and emotional distress among secondary outcomes, but does not report their numerical results in the registry record for this analysis.

The single-group design matters to any interpretation of change. Because there was no concurrent randomized comparator, participant outcomes during and after treatment cannot establish what would have occurred under another approach. Self-reported ratings may reflect perceived benefit, but they can also be influenced by expectations and the experience of participating. This design is useful for describing an intervention experience, but does not isolate the causal contribution of the treatment package.

The trial also combines multiple components. Its design cannot determine whether biofeedback, smoking cessation therapy, nicotine patch, or their combination accounts for any observed response. The record's serious adverse-event figures are zero in the listed categories, but they do not establish an absence of all adverse experiences or prove safety.

In short, the registry record documents a completed open trial and a defined feasibility endpoint, along with available-data counts. It does not provide the endpoint estimates needed to judge participants' ratings, and it does not support a controlled estimate of treatment effect. These distinctions separate what the study was designed to describe from what its posted results can establish.

14. Why This Trial Matters Statistically

Feasibility-oriented studies can address practical questions that precede a definitive comparison: whether a treatment package can be delivered in its intended format, whether participants provide the planned assessments, and how participants perceive the experience. The trial's focus on an adapted, primarily virtual intervention makes those questions relevant to the design of subsequent research. Its primary measure explicitly asks about perceived help with quitting and managing emotional distress, rather than treating participant experience as interchangeable with an objective cessation outcome.

The statistical value of this record also lies in what it makes visible about interpretation. A defined score, assessment schedule, and participant availability counts help readers understand what was intended to be measured. At the same time, an endpoint description cannot substitute for estimates of the endpoint itself. With no reported mean scores or standard deviations in the available record, readers cannot assess the level or precision of the primary ratings.

The design offers a useful example of why different evidence questions should remain distinct. Descriptive ratings can characterize participants' experience; smoking outcomes can describe behavior; and a randomized comparison is needed to estimate a treatment contrast with stronger causal interpretation. An open, single-group trial may inform planning and identify issues for further study, but its structure does not answer all of these questions at once.

Finally, the record illustrates why analysis details matter. Missing-data handling, the analysis population, repeated-measures methods, and multiplicity strategy affect how results should be read. Those details are not reported in the registry record. Calling them out is not a claim that the study handled them improperly; it identifies information needed for a fuller statistical appraisal.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation for interpreting the endpoint is that the registry record describes the measure but does not report its observed mean scores or standard deviations. The registry entries therefore do not permit assessment of the endpoint's magnitude or precision. No numerical primary endpoint result should be inferred from the scale definition or data-availability counts.

The open, single-group design has no concurrent control comparison. It cannot separate outcomes associated with the intervention from changes over time or other influences. The intervention is a package of biofeedback, cognitive-behavioral smoking cessation treatment, and nicotine patch, so the design also cannot identify the contribution of individual components.

Endpoint data were available for n=27 at Week 1, n=18 at Week 6 among treatment completers, and n=16 at the 3-month follow up. The registry record does not explain why data were unavailable, describe how missing observations were handled, or identify the analysis population. If participants with and without follow-up data differ in relevant ways, estimates based on available data may not represent all enrolled participants; whether that occurred cannot be determined from the record.

The registry lists multiple outcomes and analyses but does not report a multiplicity strategy or detailed statistical analysis plan. It also does not report the protocol, sample-size justification, interim analyses, participant characteristics beyond the available enrollment information, or detailed intervention adherence. These omissions limit assessment of prespecification, generalizability, and analytic choices. The record's zero adverse-event counts should likewise be interpreted within the scope of the categories and reporting detail it provides.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Heart Rate Variability Biofeedback for Smoking Cessation Treatment — NCT05224050.
• Registry record last updated 2024-05-01; status last verified 2024-04.
• Results first posted 2024-05-01.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT05224050 is a completed Phase 2, open, single-group trial sponsored by Rutgers, The State University of New Jersey. It enrolled 28 participants and studied a primarily virtual intervention combining individualized heart rate variability biofeedback, cognitive-behavioral smoking cessation treatment, and up to 8-weeks of transdermal nicotine patch.

The primary endpoint was participants' self-reported perceived effectiveness on a 0-4 scale, assessed at Week 1, Week 6, and Week 16. The registry reports data availability counts of n=27, n=18, and n=16 at those assessments, respectively, with the Week 6 count among participants who completed treatment. Observed mean scores and standard deviations are not reported in the registry record.

The record lists 11 outcome measures and 7 analyses, but does not report the statistical analysis plan or missing-data approach. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths in the listed group. The single-group design does not provide a randomized comparison.