Heart Rate Variability Biofeedback for Smoking Cessation

Number of intervention sessions attended out of 10 possible sessions.

Effectiveness was assessed via self-report ratings on four items assessing the intervention in terms of helping them quit and manage emotional distress, rated on a 0=completely disagree to 4=completely agree Likert-type scale. Higher scores on this scale are indicative of greater perceived intervention efficacy. Mean scores obtained following the first intervention session and 3-month follow-up session are reported.

Appropriateness was assessed via self-report ratings on two items assessing the intervention in terms of comprehension and fit, rated on a 0=completely disagree to 4=completely agree Likert-type scale. Higher scores on this scale are indicative of greater perceived intervention appropriateness. Mean scores obtained following the first intervention session and 3-month follow-up session are reported.

Ease of the Intervention was assessed via self-report ratings on three items assessing ease of use and fit into daily lifestyle, rated on a 0=completely disagree to 4=completely agree Likert-type scale. Higher scores on this scale are indicative of greater perceived ease of the intervention and fit into daily lifestyle. Mean scores obtained following the first intervention session and 3-month follow-up session are reported.

Satisfaction and liking were assessed via self-report ratings on five items assessing satisfaction with learning the intervention, liking the intervention, breathing techniques, nicotine replacement, and recommending the intervention to friends, rated on a 0=completely disagree to 4=completely agree Likert-type scale. Higher scores on this scale are indicative of greater intervention acceptability. Mean scores obtained following the first intervention session and 3-month follow-up session are reported.

Quit status was assessed on Quit day via self-reported abstinence and carbon monoxide analysis of breath sample (CO <8 ppm). Given carbon monoxide analysis of breath may not be a valid indicator of cessation within the first 24 hours, we suggest interpretation of this outcome on Quit day with caution.

Sustained smoking cessation was evaluated at study termination (i.e., 3-month follow-up) via self-reported abstinence, carbon monoxide analysis ( CO <8 ppm), and salivary cotinine (<10 ng/mL).

Cigarettes Smoked Per Day (CPD) assessed via the well established Timeline Followback calendar interview were used to measure changes in smoking behavior from Week 0 (i.e., Baseline) through Week 3 (i.e., Quit date) and Week 16 (i.e., 3-month follow-up).

Self-reported change in emotional distress was evaluated via the 21-item, Depression, Anxiety and Stress Scale (DASS-21). The DASS-21 is composed of three self-report scales that measure the emotional states of depression, anxiety and stress. Items are rated on a Likert-type scale (0=Did not apply to me at all, to 3=Applied to me very much, or most of the time). Scores for depression, anxiety and stress are calculated by summing the scores for the relevant items. The severity ratings are as follows Depression: Normal 0-4, Mild: 5-6, Moderate: 7-10, Severe: 11-13, Extremely Severe: 14-21. Stress: Normal: 0-7, Mild: 8-9, Moderate: 10-12, Severe: 13-16, Extremely Severe: 17-21. Anxiety: Normal: 0-3, Mild: 4-5, Moderate: 6-7, Severe: 8-9, Extremely Severe: 10-21. Total scores are computed by summing the subscales. Total scores for the DASS-21 range from 0-63. For all scales, higher scores are indicative of greater emotional distress and less change in total distress symptoms over time.