降低与烟草相关的肺癌风险：无 AB 卡瓦的随机临床试验

安慰剂比较：安慰剂对照

药品：安慰剂

这只手臂上的参与者将每天口服 3 次一粒安慰剂胶囊，持续 28 天。

实验性的：卡瓦干预

药品：卡瓦

这只手臂上的参与者将服用一粒卡瓦胶囊（每粒胶囊含有 75 毫克卡瓦内酯），每天口服 3 次，持续 28 天。

Urinary Total Nicotine Equivalents

Measure urinary total nicotine equivalents (TNE). TNE is the sum of nicotine and its metabolites in a participant's urine. TNE was measured at baseline (on Day 1 of treatment), after 1 and 2 weeks on treatment, at the end of treatment, at 4 weeks after end of treatment and at 8 weeks after end of treatment.

Reinforcing Effects of Smoking

Determine if participants experience reinforcing effects of smoking using the Modified Cigarette Evaluation Questionnaire. Subjects respond with a whole number numerical value from 1 to 7 for each item. The item responses are used to determine 5 scores: smoking satisfaction, psychological reward, aversion, enjoyment of respiratory tract sensations and craving reduction. Each score is either the response to a single item (for the enjoyment of respiratory tract sensations and craving reduction scores) or is calculated as the mean of multiple individual item responses (for the smoking satisfaction, psychological reward, and aversion scores). Possible values for each score range from a minimum of 1 and a maximum of 7. A higher value is worse for the smoking satisfaction, psychological reward and craving reduction scores. A lower value is worse for the aversion score. A higher score for the respiratory tract sensations score means greater enjoyment of respiratory tract sensations.

Participant Reported Number of Cigarettes Smoked Weekly

Determine the participant reported number of cigarettes smoked weekly. The number of cigarettes smoked was measured by having participants document how many cigarettes they smoked in the past week on a calendar. Participants completed this at baseline (day 1 of treatment), at 1 week and 2 weeks after beginning treatment, and at the end of treatment.

Participant Urge to Smoke

Measure participant urge to smoke using the Brief Questionnaire on Smoking Urges (QSU-Brief). The QSU-Brief is a 10-item scale, assessing the features of craving, including the anticipation of relief of nicotine withdrawal, anticipation of positive outcomes of smoking, desire to smoke, and intention to smoke. Participants respond with a score from 1 (best) to 7 (worst) for each item. Possible total scores range from 10 to 70, with a higher score meaning a greater urge to smoke. Participants completed the QSU-Brief at baseline (day 1 of treatment), at 1 week and 2 weeks after beginning treatment, and at the end of treatment.

Nicotine Dependency

Measure participant nicotine dependency using the Fagerström Test for Nicotine Dependence (FTND). The FTND is a 6-item scale measuring the level of nicotine dependency or addiction. It assesses how soon tobacco use begins each day, which cigarettes during the day a person could do without, how smokers cope in places where they cannot smoke, and how frequently and how deeply they smoke. Responses for each item are given either 0 points or 1 point for 4 items and 0-3 points for 2 items, with more points meaning a greater nicotine dependency. Possible total scores range from 0 to 10 points, with a higher score meaning a greater nicotine dependency. Participants completed the FTND at baseline (day 1 of treatment), at 1 week and 2 weeks after beginning treatment, and at the end of treatment.

Perceived Stress

Measure participant perceived stress using the Perceived Stress Scale (PSS). The PSS is a 10-item scale measuring the perception of stress. It is a measure of the degree to which situations in one's life are appraised as stressful. The scale also includes a number of direct queries about current levels of experienced stress. Participants respond to each item with a score of 0 ("never") to 4 ("very often"). A higher score is worse for the 6 items assessing negative outcomes, such as how often participants felt nervous and stressed and a lower score is worse for the 4 items assessing positive outcomes, such as how often participants felt on top of things. Possible total scores range from 0 to 40, with a higher score meaning higher perceived stress. Participants completed the PSS at baseline (day 1 of treatment), at 1 week and 2 weeks after beginning treatment, and at the end of treatment.

Severity of Insomnia

Measure severity of participant insomnia using the Insomnia Severity Scale. The Insomnia Severity Scale is a 7-item self-report questionnaire assessing the nature, severity, and impact of insomnia. Participants respond to each item with a score of 0 (best) to 4 (worst). Possible total scores range from 0 to 28, with a higher score meaning more severe insomnia. Participants completed the Insomnia Severity Scale at baseline (day 1 of treatment), at 1 week and 2 weeks after beginning treatment, and at the end of treatment.

Compliance Score Percentage

Evaluate subject compliance with the kava intervention, as measured by the compliance score percentage. The compliance score percentage was calculated by dividing the total number of kava or placebo capsules actually consumed across all visits by the total number of kava or placebo capsules expected to be consumed across all visits and multiplying the result by 100.

Participant Compliance Status

Determine participant compliance status, defined as whether the number of kava or placebo capsules expected to be returned matched the number of kava or placebo capsules actually returned by a participant across all visits, with "Yes" indicating a match and "No" indicating a mismatch.