Background
Cigarette smoking causes serious health, economic, and social problems throughout the world. Tobacco smoke is a toxic and carcinogenic mixture of more than 5,000 chemicals including nicotine, cyanide, benzene, formaldehyde, methanol, acetylene, and ammonia [
1]. Smoking has major adverse effects on almost every organ system in the body, accounting for more than 10% of deaths from all causes and 30% of deaths from cancer (including 87% of lung cancer deaths) worldwide [
2]. Smoking is also responsible for many other health problems include heart and blood vessel disease, stroke and cataracts [
3]. According the Global Burden of Disease study, smoking causes tremendous disability, estimated at 2,276 disability-adjusted life years (DALYs) per 100,000 [
4].
Cigarette smoking in China is particularly problematic because China has the largest population of smokers in the world, with over 350 million current smokers in 2012 [
5]. More than 50% of males over the age of 15 smoke in China [
6]. In addition, due to failed efforts to reduce or ban smoking in public places, many non-smokers (mostly children and women) also experience health problems from second hand exposure to tobacco smoke [
7,
8]. The number of deaths attributed to tobacco use has now reached 1.2 million per year in China, and the death toll is predicted to increase to 2 million in the near future without effective efforts to reduce smoking [
9].
Smoking cessation, however, is extremely difficult because of the highly addictive nature of nicotine. Among regular smokers, withdrawal symptoms occur within two hours of the last cigarette, peaking within 24–48 hours and sometimes lasting for weeks or months [
10]. Symptoms include an intense craving for another cigarette, feelings of tension and irritability, trouble concentrating, lethargy (while at the same time having difficulty falling asleep), and a decrease in motor performance, all of which drive the person to continue smoking. Thus, not only must efforts be directed at stopping people from smoking but on preventing the onset of smoking in youth. Social and cultural factors may help in this regard – particularly religion.
All major world religions place a high value on human life, and for that reason often discourage cigarette smoking, even though they may not prohibit it entirely [
11]. Consequently, religious involvement is known to be an important predictor of health behaviors and substance use. Studies have found that higher religiosity is associated with a lower rate of tobacco, alcohol and illicit drug use [
12-
14], especially among youth [
15]. In fact, a recent review of the literature concluded that greater religious involvement was associated with a lower risk of tobacco use [
12]. Persons who attend religious services weekly or more have a 25% lower risk of smoking compared than those who attend less frequently. Even among those who smoke, religious attendance is inversely related to number of cigarettes smoked per day [
16]. Prospective studies also find that religious involvement predicts lower rates of smoking in the future. For example, a prospective study of 4,569 individuals between ages 20 and 32 found that a higher frequency of religious attendance at baseline predicted a lower probability of both current smoking or smoking initiation during a 3-year follow-up [
17]. Infrequent religious attendees are reported to be nearly twice as likely as frequent attendee to use smokeless tobacco (which is becoming more and more popular these days) [
18].
Faith-based public health efforts to reduce smoking have been reported in several regions of the U.S [
19]. For example, the Partnership for a Healthy Mississippi (PHM) is a program funded by churches and other faith-based organizations whose goal is to prevent youth from taking up the habit of smoking. This program has been very successful, resulting in a 25% decrease in high school students’ cigarette use. In fact, during a two year evaluation period, students’ use of any form of tobacco product dropped by 23% [
20]. Similarly, another study found that the smoking cessation rate in a county where a church-based intervention was implemented was almost twice that compared to control counties within rural areas that had high concentrations of African Americans [
21].
Although, researchers have shown increased interest in religion and tobacco use in recent years, there has been little research reported from non-Christian areas of the world and from developing countries [
22]. Moreover, reports from studies on the effects of religious involvement on the cessation of cigarette smoking (or history of prior smoking) have not been consistent in different ethnic groups [
23,
24].
China has a large population with many different religious groups, including Buddhists, Taoists, Muslims, Jews, Christians, and a variety of other Chinese religions [
25]. In the past 10 years, there has been a rapid increase in the percentage of Chinese who claim some type of religious practice (from 7.0% in 2001 to 23.9% in 2007) [
26]. According to the Pew Research Center, over 40% of people in mainland China in the year 2010 were affiliated with at least one religion. More than seven-in-ten (73%) members of folk religions in the world and half (50%) of the world’s Buddhists live in China [
27]. Also, there are over twenty million Muslims (1.8% of total population) distributed throughout China [
27].
More and more research is focusing on the relationship between religious involvement and health in China [
28]. For example, a large cohort study of Chinese older adults revealed that the risk of dying was 24% lower among those who frequently participated in religious activities compared to those who did not participate [
29,
30]. Likewise, a strong positive relationship between religious participation and subjective well-being was found in a Chinese sample, with this study showing that religion had a particularly strong effect on well-being in men [
31]. Another study, this one in young Chinese women, found that higher religiosity was associated with fewer depressive symptoms and less suicidal ideation [
32,
33]. Little research, however, has focused on the relationship between religious involvement and cigarette smoking in China.
The present study examined the association between religious involvement and tobacco use in a large representative sample of community-dwelling adults in Western China. The objectives of this study were (1) to examine the association between religious involvement and tobacco use (current smoking, past smoking, and tobacco abuse/dependence); and (2) to explore associations between religiosity and tobacco use in Muslims compared to non-Muslims.
Methods
Data source and participants
Data for this study are drawn from an epidemiological study of mental disorders in the province of Ningxia located in Western China, where Muslims makes up 35% of the total population (6.4 million) [
34]. Inclusion criteria were age 18 years or older and residence for at least six months or longer at the current address. Exclusion criteria were significant impairment caused by brain injury, brain tumor and/or craniotomy or dementia, being in the acute phase of a stroke, any severe illness, any obvious cognitive disabilities, or the presence of deafness, aphasia or other language barriers.
Sample selection and procedure
Participants were identified in three stages. First, 62 primary sample units (PSU) were selected from 2,209 villages and 393 neighborhood communities using a probability proportionate to size (PPS) method [
35]. Second, depending on the total number of households in the selected PSU, 60 to 210 households were systematically identified from each PSU resulting in a total of 6,890 households being selected. Third, interviewers visited sample households and used a Kish selection table [
36] to identify one eligible participant from each households. A total of 6,476 participants were approached to conduct a face-to-face interview. 414 households were not found participants because no one could be located during the period of study.
Subsampling was used in most surveys to reduce respondent burden by dividing the interview into two stages. In the Stage I interview, which was administered to all respondents, information was collected on demographics and tobacco use. The World Health Organization Composite International Diagnostic Interview (WHO-CIDI) used for mental disorders assessment during this stage. A total of 5,810 participants (89.7%) completed the Stage I interview. Stage II included assessments of risk factors, services sought, religious involvement, and identification of additional disorders that were either of secondary importance or were too time consuming to assess in the full sample. A computer program was used to select participants who completed Stage I interviews to take part in the Stage II survey. The program which divided respondents into three groups based on their Part I responses. First, all respondents who (1) met lifetime criteria for at least one mental disorders assessed in Part I, or (2) met sub-threshold lifetime criteria for a mental disorders and sought treatment for it at some time in their life, were selected to complete Part II of the evaluation. Second, a probability sample was selected of 59% of respondents who did not meet criteria for membership in the first group, but gave responses in Part I indicating that they (1) ever met subthreshold criteria for Part I disorders, or (2) ever sought treatment for any emotional or substance abuse problem, or (3) ever had suicidal ideation, or (4) used psychotropic medications in the past 12 months to treat emotional problems. Third, a 25% random sample of respondents without mental disorders or emotional problems was selected to receive the Part II evaluation [
37]. The present study consisted of 2,770 participants who completed the Stage II interviews.
Face-to-face computer assisted personal interviews (CAPI) [
38] were carried out by lay interviewers from Ningxia Medical University. Interviewers were trained in a 7-day session by our research team. The training covered general interviewing techniques, review of the questionnaire, post-interview editing, and in- and out-of-classroom exercises. Ninety trainees passed the final test and were selected as interviewers, forty-one of them are male, and forty-nine of them are female. These interviewers then were sent into the field to administer the survey. The survey was designed as anonymous. The potential risks and benefits of the survey were described by the interviewer and the participant was asked to provide their consent by checking a box on computer screen with the response (1 = I agree to participate in the study; 5 = I do not agree to participate in the study). If the response was “I do not agree”, the CAPI program was immediately terminated automatically. The institutional review board of the Ningxia Medical University approved the study.
Dependent variables
Cigarette smoking was assessed in terms of (1) current smoking, but without a tobacco use disorders, (2) past history of smoking (but not current use), and (3) tobacco use disorders (tobacco abuse/tobacco dependent). Smoking was measured by asking, “Are you a current smoker, ex-smoker, or have you never smoked?” here we defined the smoking as “lasting at least two months when you smoked at least once per week”. ICD-10 of Tobacco Use Disorders were diagnosed using the WHO-CID, a structured diagnostic interview that is widely used to identify mental disorders in community populations [
39]. A Chinese version of the CIDI was produced by translating and back-translating the English version using the standard WHO protocol. Culture adaptation and modification research have verified the validity of this version [
40].
Independent variables
Religious involvements
Religious involvement was determined using measures of religious importance, attendance, and affiliation. Religious importance was measured with a single question that asked, “In general, how important are religious or spiritual beliefs in your daily life?” Responses options ranged from not at all important (1) to very important (4). Religious attendance was assessed using a single question that asked, “How often do you usually attend religious activities?” Responses ranged from never (1) to more than once a week (5). Finally, religious affiliation was determined by asking, “What is your religious preference?” Religious affiliation was coded for analysis into four categories: 1 = none, 2 = Chinese religion (i.e., Buddhist, Daoist, etc.), 3 = Western religion (i.e., Christian, Catholic, etc.), and 4 = Muslim.
Participants were divided into high and low religiosity in the following manner. High religiosity was defined as (1) attending religious activities at least 2–3 times per month and (2) indicating that religious or spiritual beliefs were very important in daily life. All other participants were placed in the low religiosity category.
Health variables
Anxiety disorders and mood disorders were assessed using the WHO-CIDI. Anxiety disorders include agoraphobia, generalized anxiety disorder, obsessive-compulsive disorder, panic disorder, social phobia, specific phobia, and neurasthenia. Mood disorders assessed were unipolar depressive disorder and bipolar disorder.
Physical health characteristics assessed were overall self-rate physical health (good vs. poor), self-rated chronic body pain (yes vs. no), type II diabetes (yes vs. no), and hypertension (yes vs. no).
Socio-demographic variables
Socio-demographic information collected included age, gender, education, marital status (married vs. unmarried), residence (rural vs. urban), ethnicity (Han vs. Hui), experience of migration from other areas of China (yes vs. no), and geographical region (developed vs. undeveloped).
Statistical analyses
Analyses were performed using the Statistical Analysis System (SAS) 8.2 software (SAS Institute Inc). Differences in socio-demographic, physical, mental, religious, and smoking characteristics between males and females were examined using the Student’s t-test for continuous variables and the chi-square statistic for categorical variables. Differences by demographic characteristics, physical and mental health, and religious group and level of involvement across the three smoking categories (current, past, smoking disorder) were examined using one-way-analysis of variance (ANOVA) for continuous variables and the chi-square statistic for categorical variables. Three separate logistic regression models were used to examine correlations between religious involvement and smoking status. The final logistic regression model was then repeated in males to compare Muslims and non-Muslims (smoking exposure rate in females was too low for this comparison). Unstandardized beta and standard errors were calculated for all models. Given the exploratory nature of these analyses, statistical significance was set at 0.05 without correction for multiple comparisons.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
WZ participated in the design of the study and done the data collection, also, wrote the first draft of the manuscript. HK participated in the design of the study, conducted the statistical analysis and helped to draft the manuscript. SA provided summaries of previous research studies and edited the text. All authors read and approved the final manuscript.