Review
Shiva Kargar1, Alireza Ansari-Moghaddam1,
1Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Islamic Republic of Iran (Correspondence; S. Kargar:
Abstract
Background: Smoking is an important risk factor for various diseases, especially cancer.
Aims: To estimate the prevalence of cigarette and waterpipe smoking and its attributable fraction of cancer.
Methods:We searched Medline, Google Scholar, and PubMed for original articles published between 2000 and 2020 that reported the prevalence of waterpipe and cigarette smoking in Middle East countries. Data were analyzed using STATA version 14.
Results: We included 90 articles in this meta-analysis. The pooled prevalence of current cigarette and waterpipe smoking in Middle East countries was 17.41% and 6.92%, respectively. The prevalence of current cigarette and waterpipe smoking in men was significantly higher than in women. In the past decade, the prevalence of cigarette smoking decreased by 7.21% but the prevalence of waterpipe smoking increased by 7.80%. The highest population attributable risk was shown for oesophageal (35.0%), lung (30.50%), and gastric (8.20%) cancers.
Conclusion: The popularity of cigarette smoking is still a public health problem among adults, particularly in men in Middle East countries. About 30% of oesophageal and lung cancers in this region were attributed to cigarette smoking. The increasing trend in waterpipe smoking during the last decade is of concern. Prevention of cigarette and waterpipe smoking should be at the top of health priorities.
Keywords: prevalence, waterpipe smoking, cigarette smoking, Middle East countries, meta-analysis
Citation: Kargar S, Ansari-Moghaddam A. Meta-analysis of prevalence of cigarette and waterpipe smoking and its attributable fraction of cancer among adults in Middle East countries. East Mediterr Health J. https://doi.org/10.26719/emhj.23.077 Received: 28/04/2022; accepted: 09/02/2023
Copyright: © Authors; licensee World Health Organization. EMHJ is an open access journal. All papers published in EMHJ are available under the Creative Commons Attribution Non-Commercial ShareAlike 3.0 IGO licence (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo).
Introduction
Tobacco use is the cause of many preventable diseases and premature death worldwide (1). WHO estimates that smoking-related mortality in developed countries will decrease by 9% from 2002 to 2030, while in developing countries, it will double (2). Previous studies have shown that smoking and hookah use are associated with various diseases, such as lung cancer, oral cancer, cardiovascular disease, and respiratory disease (3). Also, regular use of tobacco can expose a person to high levels of nicotine and cause dependence (4, 5).
The high prevalence of tobacco use is of concern in Middle East Countries, especially among school and university students, and it has been increasing in the last 20 years (6, 7). Smoking prevalence is reported to be higher in men than in women (8).
WHO has identified measures to reduce tobacco use by 25% until 2025. This goal may be undermined by the increase in prevalence in different environments (9). In the last 20 years, waterpipe smoking has become more common than cigarette smoking among young people and is part of a new global epidemic of tobacco use (10). The main factors driving waterpipe use are low cost and ready availability (11). Many people believe that waterpipe smoking is less dangerous than cigarettes and is used in social gatherings (12).
The aimsof this meta-analysis were: (1) to estimate the prevalence of cigarette and waterpipe smoking among adults in Middle East countries, based on age, sex, and year of publication; and (2) to investigate the population risk of common cancers attributed to cigarette and waterpipe smoking in Middle East countries.
Methods
We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to perform this systematic review and meta-analysis (13). We searched for relevant English-language articles from 2000 to 2020 in PubMed, Google Scholar, and Medline. The search strategy used a combination of terms: smoking, cigarettes, waterpipe, hookah, tobacco, prevalence, Middle-East, and the names of countries in the Middle East.
Inclusion criteria were: (1) cross-sectional studies published from 2000 to 2020; (2) assessment of the prevalence of current, daily, occasional, and regular waterpipe and cigarette smoking in adults; and (3) reports on prevalence of waterpipe and cigarette smoking separately from other forms of smoking. Exclusion criteria were: (1) studies that were not published in English; (2) studies with specific target populations, such as high school students, university students, or pregnant women; (3) no measure of prevalence or data to calculate 95% confidence intervals (CIs); and (4) mixed reports of the prevalence of any tobacco use (cigarettes, water pipe, and smokeless tobacco). We also excluded abstracts for which we could not identify the full text after contacting the corresponding author.
Two researchers independently screened the titles and abstracts of articles to identify eligible articles. We then assessed the full text of the studies and extracted data using an Excel form. The extracted data included: names of authors; year of publication; study setting (country and location); sampling (age, method, number in population, and sex); and prevalence of cigarette and waterpipe smoking and its 95% CIs. The current smoker category included always, sometimes, occasional, daily, and regular smokers.
Statistical analysis
We performed a random-effect meta-analysis to obtain pooled smoking prevalence estimates with 95% CIs. The I2 statistic was used to assess heterogeneity between studies. To explore the sources of heterogeneity, we conducted subgroup analyses by sex, country, residence, and age. Visual examination of the funnel plot and Egger’s test were performed to identify publication bias. All analyses were conducted by STATA-14 statistical software (Stata Corp., College Station, TX, USA). We calculated population attributable risks for common types of cancer, such as gastric, lung, ovarian, bladder, colorectal, oesophageal, liver, and kidney cancers, related to smoking in Middle East countries in males and females, using the formula: PAR = P (RR 1) / P (RR 1) + 1. The relative risk (RR) of cancer caused by smoking was obtained from a previously published meta-analysis, and prevalence (P) was estimated from studies identified in this meta-analysis. RR and 95% CI for gastric, lung, ovarian, bladder, colorectal, oesophageal, liver, and kidney cancers were 1.53 (1.42–1.65), 3.59 (3.25–3.96), 1.05 (0.95–1.16), 1.22 (1.06–1.4), 1.14 (1.10–1.18), 4.18 (3.42–5.12), 1.51 (1.37–1.67), and 1.39 (1.28–1.51), respectively (14–21).
Quality assessment
Loney et al. provided a tool for critical assessment of prevalence studies, which was used to assess the quality of the included studies (22). This instrument included 8 criteria: methodology (1, design; 2, sampling frame; 3, sample size; 4, outcome measures; 5, measurement; 6, response rate); interpretation of results (7, prevalence with CIs and detailed subgroup analysis); and applicability of results (8, are the study subjects and setting similar to those of interest?). The studies received 1 point for each criterion that was met. High-quality studies were rated 7 or 8, medium-quality studies 4–6, and low-quality studies 0–3.
Ethical considerations
The Ethics Committee of Zahedan University of Medical Sciences approved this study (IR.ZAUMS.REC.1401.214).
Results
We identified 1091 articles from the database search; 442 were duplicates, and 372 were excluded because of unrelated titles and after reading the abstract. We assessed the full text of 277 articles, and 187 were excluded for the following reasons: no cross-sectional study, did not measure prevalence rate, insufficient information, focus on specific populations, reports of prevalence of any tobacco use, and absence of full text. Finally, 90 articles were eligible for inclusion in the meta-analysis. Figure 1 shows the flowchart of the study selection. Most of the studies were conducted in the Islamic Republic of Iran (n = 33), Jordan (n = 12), and Saudi Arabia (n = 9). Overall, 744 960 participants aged ≥ 15 years were included in the meta-analysis. The sample size for the studies ranged from 46 to 170 430.
Quality assessment
Fifteen studies were categorized as high quality, 63 as moderate quality, and 12 as low quality. The low-quality studies had the highest pooled prevalence of current cigarette smokers (19.29%, 13.83–26.91%), followed by the moderate-quality studies (18.89%, 15.77–22.63%), and high-quality studies (12.44%, 7.03–22.0%). We found no indication of heterogeneity among the studies (P = 0.37).
Publication bias
The funnel plot revealed a little asymmetry (Figure 2). The P value for Egger’s test was 0.98, implying no publication bias.
Prevalence of current cigarette and waterpipesmoking
The overall pooled prevalence of current cigarette and waterpipe smoking among adults in 17 Middle East countries was 17.41% (95% CI: 13.76–22.03) and 6.92% (95% CI: 3.70–12.93), respectively (Figure 3 and Table 1). The highest prevalence of current cigarette smoking was seen in Iraq (32.0%, 95% CI: 20.20–50.69) and Cyprus (31.40%, 95% CI: 25.86–38.13). The lowest prevalence was in Bahrain (2.60%, 95% CI: 0.70–6.60) and Qatar (8.86%, 95% CI: 6.28–12.48) (P ˂ 0.001, I2 = 93.2%). The highest prevalence for waterpipe smoking was in Iraq (25.0%, 95% CI: 19.10–31.60) and Palestine (20.90%, 95% CI: 17.40–24.70). The lowest prevalence was in Oman (1.10%, 95% CI: 0.60–1.90) and Syrian Arab Republic (1.30%, 95% CI: 0.90–1.90).There was some heterogeneity among the studies (P ˂ 0.001, I2 = 96.7%).
According to sex, 24.86% of men and 4.09% of women smoked cigarettes and 9.55% of men and 5.05% of women smoked waterpipes (Table 1). Therefore, the prevalence of current cigarette and waterpipe smoking in men (P ˂ 0.001,I2 = 99.2%) was significantly higher than in women (P = 0.03, I2 = 77.3%). The prevalence of current cigarette smoking was highest among the age groups 30–39 (16.92%) and 40–49 (14.66%) years, and lowest among the age groups 18–29 (12.98%) and ≥ 60 (8.84%) years, but the difference was not significant (P = 0.28). In contrast, waterpipe smoking was most prevalent in the age groups 18–29 (4.0%) and 30–39 (3.60%) years, and least prevalent in the age groups 50–59 (0.76%) and ≥ 60 (0.84%) years (P ˂ 0.001, I2 = 88.7%). The rural population had a higher prevalence of cigarette smoking and a lower prevalence of waterpipe smoking than the urban population had, but these differences were not significant (P = 0.91, P = 0.66). The prevalence of cigarette smoking decreased from 22.25% (95% CI: 17.48–28.33) during 2008–2011 to 15.04% (95% CI: 11.20–20.21) during 2016–2020. The prevalence of waterpipe smoking increased from 6.03% (95% CI: 3.96–9.17) (P ˂ 0.001, I2 = 83.9%) to 13.83% (95% CI: 9.68–19.76) (P= 0.002, I2 =80.9%) during the same period of time.
Table 2 shows the population attributable risk of smoking for common types of cancer.The highest risk overall was for oesophageal cancer (35.0%), followed by lung (30.50%) and gastric (8.26%) cancers, and in both men and women. Also, because of the higher prevalence of smoking in men, the cancer burden associated with smoking was higher in men than in women.
Discussion
This meta-analysis showed that, between 2000 and 2020, ~20% of adults in the Middle East were cigarette smokers and ~7% were waterpipe users.The study demonstrated that waterpipe and cigarette smoking was more popular in Iraq, Cyprus, and Palestine. In comparison, the lowest prevalence of waterpipe and cigarette smoking was in Oman and Bahrain. Socioeconomic status and different customs and cultures may explain these differences in prevalence.
In this study, the prevalence of cigarette and waterpipe smoking was significantly higher in men than in women. This pattern was similar to other studies, including in Europe (8, 23), which may have been due to the social acceptance of men’s smoking habits. Another study confirmed that men smoke more than women do, regardless of age group (school children, university students, and adults) (24). In previous studies, smoking habits were related to various factors such as age, sex, and level of education (25), and prevalence was higher in people of lower socioeconomic status (26). In this study, the prevalence of cigarette smoking in rural populations was higher than in urban populations, but this difference was not significant. Our results showed that the prevalence of cigarette smoking increased from age 18–29 to 50–59 years, which is consistent with other related studies (27–29). In our study, most cigarette smokers were in the age groups of 30–39 (16.92%) and 40–49 (14.66%) years, and the prevalence was lower in people aged ≥ 60 years. This decrease in cigarette smoking could have resulted from attributable diseases and mortality and a better understanding of the dangers of smoking, and health literacy in the older age group.
The highest prevalence of waterpipe smoking was in the 18–29 and 30–39 years age groups. Other studies also showed that the prevalence of waterpipe smoking among young people has increased (30). This may have been because of the spread of waterpipe smoking as a recreational activity and a lack of awareness or understanding of the health risks in the younger age groups (31). There is a misconception that waterpipe smoking is less harmful than cigarette smoking and this has led to its social acceptance (32). Also, according to our results, the prevalence of waterpipe smoking has increased in the last decade and the prevalence of cigarette smoking has decreased. Other studies have shown that tobacco use has been declining in recent years and the use of alternative tobacco products including e-cigarettes and waterpipes has increased (33).
Smoking increases the risk of some types of cancer, including gastric, lung, and kidney cancers (34, 35). Accordingly, this study demonstrated that 35% of esophageal cancer, 30% of lung cancer, and 8% of gastric cancer in Middle East countries was attributed to cigarette smoking. Additionally, because of the higher prevalence of smoking in men, the burden of smoking-related cancers was also higher in men than in women.
There were a few limitations to this study that should be addressed before interpreting the findings. First, we used the results from self-reporting studies on cigarette and waterpipe smoking, and the categories reported differed (e.g. current, ever, daily, occasional, and regular). Second, the numbers of studies varied between countries. Third, the study populations differed in age distribution, sociodemographic characteristics, workplace and occupation, which might have caused differences in cigarette and waterpipe smoking prevalence. Fourth, the attributable risk was calculated using unadjusted relative risk, even though there were potential confounders, such as blood pressure, diabetes, and socioeconomic status, that could have affected the relationship between smoking and cancer.
Conclusion
This meta-analysis showed that the prevalence of cigarette smoking was high in adults, especially men, in Middle East countries. The increasing trend in the prevalence of waterpipe smoking in the last decade and among young people is worrying and emphasizes that prevention programmes should be at the top of health priorities. The high percentage of esophageal, lung, and gastric cancers in the Middle East was also related to smoking. Therefore, comprehensive tobacco use control programmes are needed to reduce the harm caused by tobacco use in Middle East countries.
Conflict of interest: The authors have no conflicts of interest to disclose.
Funding: There was no source of funding for this project.
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Table 1. Prevalence of current smoking in Middle East countries
Table 2. Population attributable risk of smoking for common types of cancer
Figure 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)
Figure 2. Funnel plot to check for publication bias.
Figure 3. Overall prevalence of current smoking in Middle East countries.
