尼古丁依赖性高可预测戒烟期间体重增加

《PLoS One》杂志8月21日在线发表的一项研究显示，尼古丁成瘾严重的吸烟者在尝试戒烟时明显更易出现体重增加。

日本京都医疗中心的Maki Komiyama医生及其同事纳入2007年7月~2011年11月间到国立医院组织京都医疗中心戒烟诊所就诊且成功戒烟的132例男性和54例女性(平均59.6岁)。在这186例在门诊接受尼古丁替代治疗后成功戒烟的患者中，平均体重指数(BMI)在初次就诊时为23.5 kg/m2，在治疗开始后3个月时显著增至23.9 kg/m2。多因素分析发现，Fagerstrom尼古丁依赖测验(FTND)评分高(提示重度依赖)是BMI增加的最显著预测因素(采用性别校正的标准化系数) (PLoS One 2013 Aug. 21[doi:10.1371/journal.pone.0072010])。

除了2例患者未接受药物治疗之外，其余所有入组的患者均接受口服伐尼克兰(95例)或尼古丁贴片（89例）治疗。伐尼克拉组与尼古丁贴片组在BMI增幅方面无差异，但伐尼克拉组的尼古丁依赖性较高。

单因素分析发现的与BMI增加显著相关的其他因素包括甘油三酯水平、高密度脂蛋白胆固醇和每日吸烟量。多因素分析进一步发现，甘油三酯水平和FTND评分是戒烟后BMI增加的确定因素，并且FTND评分是最显著的确定因素。FTND评分≥8(量表评分范围为1~10分)与较大的戒烟后BMI增幅相关，并且该增幅与FTND评分≤7情况下观察到的BMI增幅相比，具有统计学显著性。研究者表示，高FTND评分是BMI增加的最重要确定因素，这一结果支持戒烟后体重增加是尼古丁戒断症状之一的假设。至于甘油三酯升高与体重增加之间的关联，其机制尚不明确，有待进一步研究。

研究者还表示，已知戒烟可降低心血管和癌症风险及降低全因死亡率，而戒烟后体重增加可导致葡萄糖耐受不良风险增加和肺功能从戒烟中获益减少。对体重增加的担忧也可导致戒烟失败。不过，存在预防戒烟后体重增加的可能性。通过提高预测哪些患者可能在戒烟治疗期间出现体重增加的能力及在体重增加开始时进行相应的体重控制，可改善患者转归。该研究结果可能有助于鉴别此类患者。虽然该研究证实戒烟治疗后BMI显著增加，但BMI增幅仅为0.4 kg/m2 (1.1 kg)，明显小于既往研究在主动戒烟者中观察到的增幅(2.8~3.8 kg)。需进行额外研究，以确定对戒烟后体重增加启动干预的适当时机。

该研究获国立医院组织和辉瑞健康研究基金会临床研究补助金支持。研究者表示研究中所用的伐尼克兰由辉瑞生产，但这未改变他们对PLoS One所有数据和材料分享政策的依从性。

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By: SHARON WORCESTER, Cardiology News Digital Network

Smokers who are heavily addicted to nicotine are significantly more likely to gain weight when they try to quit, researchers report.

Investigators studying 186 patients who successfully quit smoking after receiving nicotine replacement therapy at an outpatient clinic found that mean body mass index increased significantly from 23.5 kg/m2 at an initial consultation to 23.9 kg/m2 at 3 months after the start of therapy. A high Fagerstrom Test for Nicotine Dependence (FTND) score, indicating severe dependency, was found on multivariate analysis to be the strongest predictor of increase (using a gender-adjusted standardized coefficient).

Dr. Maki Komiyama of Kyoto (Japan) Medical Center and colleagues reported their findings online Aug. 21 in the open access journal PLoS One (PLoS One 2013 Aug. 21 [doi:10.1371/journal.pone.0072010]).

The findings are important because, while smoking cessation is known to reduce cardiovascular and cancer risk and to reduce all-cause mortality, associated weight gain is linked with greater risk of glucose intolerance and a reduction in the beneficial effects that quitting has on pulmonary function. Concerns about weight gain also can lead to a failure to quit smoking, they said.

"Even if one is expected to experience post-cessation weight gain, quitting smoking still leads to a reduced cardiovascular risk. However, there is also a possibility that if one can prevent post-cessation weight gain, then this will further reduce the cardiovascular risk due to having ceased smoking," they wrote.

Thus, they continued, the ability to predict which patients are likely to gain weight during smoking cessation therapy – and performing weight control accordingly at the outset – could lead to improved outcomes, and the findings of this study may be useful for discriminating such patient groups.

Study participants were 132 men and 54 women with a mean age of 59.6 years who visited the smoking cessation clinic at the National Hospital Organization Kyoto Medical Center between July 2007 and November 2011 and successfully quit smoking.

Other factors found on univariate analysis to be significantly associated with BMI increase included triglyceride level, high-density lipoprotein cholesterol, and daily cigarette consumption. "To further investigate ... we performed multivariate analysis. The results demonstrated that the triglyceride level and FTND score were factors determining the post-cessation BMI increase, and that the FTND score was the strongest one," the investigators wrote.

An FTND score of 8 or more (on a scale of 1-10) was associated with larger postcessation BMI increase, and the increase was statistically significant when compared with the level of BMI increase in those with a score of 7 or less, they noted.

"The result that a high FTND score was the most important determinant of a BMI increase supports the hypothesis that post-cessation weight gain is one of the nicotine withdrawal symptoms," they said.

As for the association between triglyceride elevation and weight gain, the mechanism is not clearly understood and requires further study, they noted.

With the exception of two patients who did not receive medical treatment, study participants were treated with either oral varenicline (95 patients) or nicotine patch (89 patients). No difference was seen between the varenicline and nicotine patch groups with respect to BMI increase, but the varenicline group had higher nicotine dependency.

They also noted that, in their study, "although a significant increase in BMI was confirmed after smoking-cessation therapy, the BMI increase was only 0.4 kg/m2 (1.1 kg), which is much smaller than reported in previous studies for people who quit smoking on their own initiative (2.8-3.8 kg)."

Additional study is needed to determine the appropriate timing for initiating interventions against post–smoking cessation weight gain, they noted.

This study was supported by a grant-in-aid for clinical research from the National Hospital Organization and the Pfizer Health Research Foundation. The authors reported that one study drug (varenicline) is manufactured by Pfizer but confirmed "that this does not alter their adherence to all the PLoS One policies on sharing data and materials."