- Research objectives
This research project is a key research and development program of China in 2017, and the research object is 685 patients with tobacco dependence who were successively enrolled in the group to receive smoking cessation intervention services from December 2018 to December 2019. Through the launch of smoking cessation publicity activities in 19 communities in Beijing, smokers who are willing to quit smoking were recruited, and smokers who signed up for the activity were screened. The investigators and doctors in the smoking cessation clinic conducted one-to-one face-to-face questionnaire surveys, carbon monoxide blowing tests, and lung function tests on smokers included in the study. Based on the examination results, the doctor formulated a specific plan for smoking cessation intervention for each research subject, including whether to take smoking cessation drugs, the daily dose of drugs, the schedule of daily smoking reduction, and precautions. Throughout the research process, the subjects will receive a three-month smoking cessation intervention service and six-month follow-up. From March 2020 to April 2020, the research team recruited and trained telephone investigators to learn about the current smoking status and willingness to quit smoking of study subjects during the epidemic period through one-to-one telephone follow-up.
Throughout the research process, the inclusion criteria of the research subjects were: ① 18 years old and above; ② Residents of Beijing community; ③ Smokers, including regular smokers (referring to smoking more than 1 cigarette a day, continuous or cumulative 6 months[4]), occasional smokers (referring to smoking cigarettes more than 4 times a week, but less than one cigarette per day on average); ④ Can communicate fluently and be willing to be investigated. The exclusion criteria are ①below 18 years old; ②non-smokers; ③not able to communicate fluently; ④reluctant to be investigated. The final telephone survey followed up 565 smoking cessation subjects. In this study, "successfully quit smoking" refers to the rate of quitting smoking at 7 days, that is, the subjects self-reported that they stopped smoking ≥7d[5], and "did not completely quit smoking" refers to people who are still smoking at the time of the survey, including those who have quit smoking but relapse .
- Research content
The pre-epidemic survey included: (1) Socio-demographic information, including information such as age, gender, marital status, education level, average monthly income level, nature of household registration, job type, etc.; (2) Tobacco use, including daily smoking, smoking age, etc.; (3) Nicotine Dependence Assessment Scale (FTND); (4) Assessment scale of willingness to quit smoking.
The contents of the telephone survey during the epidemic include: (1) In the past two weeks, what was the daily time spent at home? The answers include almost all day, 80-90% of the time, 50-80% of the time, and less than 50% of the time; (2) Which words can describe the psychological feelings brought about by the recent epidemic? The answers include doubts, anxiety, panic, depression, calm, and almost as usual. Among them, the "calm" emotional state refers to the research subject's ability to think rationally about the epidemic, and "almost as usual" refers to the attitude of indifferent and indifferent; (3) The smoking behaviour of the subjects who quit smoking during the period, including the daily smoking amount and whether it is due to the epidemic regenerate the idea of wanting to smoke (if you have quit smoking, then relapse); (4) Nicotine Dependence Assessment Scale (FTND); (5) If you are still smoking, the main reason for smoking behaviour, the answer includes: refreshing, relieving sorrow and boredom, leisure time, social entertainment, imitating curiosity, elder influence, stress relief, other habits such as smoking addiction, etc.; (6) Smoking cessation willingness assessment scale.(See the supplementary file for the full contents of the questionnaire.
In the Fagerstrom Test of Nicotine Dependence (FTND), the scale consists of 6 items, and each item is scored from 0 to 3 points, representing the least degree of dependence on the heaviest degree of dependence. The degree of nicotine dependence is judged according to the total score of 6 items, which can be divided into 3 degrees of dependence: mild: 0-3 points; moderate: 4-6 points; severe: 7 points or more. The Cronbach’s a coefficient of the Chinese version of the Nicotine Dependence Scale is 0.658[6], indicating that its internal consistency is relatively reliable. The smoking cessation willingness assessment scale in this study was designed by the members of the research team to evaluate the study subjects' willingness to quit smoking. The scale contains ten items, using Likert's 5-point scoring standard, "very non-conforming" is rated as 1 point, "comparatively non-conforming" is rated as 2 points, "general" is rated as 3 points, and "relatively consistent" is rated as 4 points and "very consistent" is rated as 5 points. The higher the score, the stronger the willingness to quit smoking. In this study, by calculating the total score of each research object, it was divided into very low willingness to quit smoking (total score <10 points), relatively low (10 points £ total score <19 points), and general (20 points £ total score <29 points), relatively high (30 points £ total score <39 points), very high (total score ³ 40 points) five groups. After testing, the Cronbach's a coefficient of the scale is 0.805, the KMO value is 0.895, and the Bartlett value is 872.096 (P<0.001). After the maximum variance is rotated, the four factors are extracted and the cumulative explanation is 86%, indicating that the scale has good reliability and validity[1-2].
- Statistical analysis
This study uses IBM SPSS Statistics 25.0 for data propensity score matching and statistical analysis. Propensity Score Matching (PSM) is a statistical method commonly used to process observational research data. This method is used to reduce the influence of data bias and confounding variables in the study, so as to affect the experimental group and the control group make a more reasonable comparison. It is suitable for two situations. The first is the re-observation study, where the number of individuals that can be directly compared between the control group and the test group is very small; the second is that there are more parameters to measure individual characteristics and select the same or similar parameters comparison is more difficult. This research is the second case. In this study, it was divided into two groups: those who had quit before the epidemic and those who had not completely quit before the epidemic. Nearest neighbour matching (NNM) was used, based on the propensity score of the subjects in the groups. Based on the propensity score of the study subjects in the group who had quit smoking before the epidemic, the subjects who did not completely quit smoking before the epidemic were searched for the object closest to the score, and matched 1:1. The calliper value of the propensity score is set to 0.02. The matching process uses whether or not to quit smoking before the epidemic as the dependent variable. The matching conditions include education level, whether to take smoking cessation drugs, and whether to receive regular follow-up, etc. Finally, 197 pairs were successfully matched.
In addition, this study also used descriptive analysis methods to calculate the overall distribution of home time, psychological and emotional state, smoking behaviour, and willingness to quit smoking among the smoking cessation subjects during the epidemic. All measurement data used Kolmogorov-Smirnov test for normality test; non-normal distribution variables were represented by M (P25, P75), and Mann-Whitney rank sum test was used for comparison between groups. Categorical variables are expressed in frequency (%).Chi-squared test, rank sum test and Fisher exact probability method were used to analyze the correlation between home isolation time, psychological and emotional status, reasons for smoking, changes in smoking volume before and during the epidemic, willingness to quit and other factors of the matched population who quit smoking. Spearman rank correlation was used to analyse the correlation between the study participants’ willingness to quit smoking and their daily home time during the epidemic. The difference was statistically significant when P<0.05.
- Analyse ideas
The success of smoking cessation is affected by many factors, including different smoking status, motivation to quit, the availability of appropriate techniques and methods, and the temptation situation during smoking cessation[3]. After the outbreak of the new crown virus pneumonia, the results of the telephone follow-up suggest that the distribution of daily smoking of the test patients during the epidemic and the distribution before the epidemic is statistically significant (P<0.001), are shown in Table 1. Among them, the daily smoking of 159 smoking patients changed from before the epidemic, as shown in Table 2. This reminds us that during the epidemic, long-term self-isolation of study subjects at home and changes in their psychological and emotional state in the face of the epidemic may affect the smoking cessation behaviour of the patients who quit smoking.
However, in this study, the subjects had received three-month smoking cessation services and a six-month follow-up, and the time overlapped with the epidemic period. Among them, the use of smoking cessation drugs, regular follow-up, and other factors may also affect the process of smoking cessation, as shown in Figure 1. To control the influence of related confounding factors, indicators with discrepancies in demographic information and the main content of smoking cessation intervention services are used as matching conditions for propensity score matching. After matching, the relevant factors can be controlled, and then the relationship between home time, relapse thoughts, psychological emotions and changes in smoking behaviour can be further analyzed.
- Ethical approval
The study protocol is performed in accordance with the relevant guidelines. This study has been approved by the Medical Ethics Committee of Capital Medical University (Z2019SY007), and an informed consent form has been signed with the subjects before the investigation. Additionally, this study has been registered on the official website of the China Clinical Trial Registration Centre (ChiCTR1900024991).