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Prevalence and characteristics of water-pipe smoking in Canada: results from the Canadian Tobacco Use Monitoring Survey
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Original Research
Prevalence and characteristics of water-pipe smoking in Canada: results from the Canadian Tobacco Use Monitoring Survey P. Abdullah a,*, C. Costanian a, N. Khanlou b, H. Tamim a a b
Kinesiology and Health Science, York University, Toronto, Ontario, Canada School of Nursing, York University, Toronto, Ontario, Canada
article info
abstract
Article history:
Objectives: To investigate the prevalence and characteristics of water-pipe smoking (WPS)
Received 7 December 2016
nationally in Canada.
Received in revised form
Study design: This study was a cross-sectional study.
5 March 2017
Methods: Data from the Canadian Tobacco Use Monitoring Survey 2011 and 2012 was used.
Accepted 16 March 2017
Outcomes investigated were ever and current WPS. Demographic, socio-economic and smoking-related variables were included in a multivariable logistic regression model to determine associations with the outcomes.
Keywords:
Results: Prevalence of WPS was 8.9% for ever and 0.8% for current WPS (1.8% among <18
Water pipe
years old and 4.0% among 18e24 years old). The highest prevalence of ever WPS was in
Canada
Quebec (11.3%) and of current WPS in Alberta (1.2%). Age was the strongest predictor for
Smoking
WPS with an odds ratio ¼ 47.86, 95% confidence interval: 37.97e60.33 for current WPS for
Hookah
those aged <18 years compared to 35 þ years. Male gender, urban residence, being single,
Narghileh
speaking another language at home (not English/French), higher education, cigarette smoking and marijuana use were also significantly associated with increased WPS. Conclusions: Multiple factors impact WPS, with the younger population having the highest prevalence. This necessitates further research into the attitudes of this age group to better focus health promotion efforts. © 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Introduction Water-pipe smoking (WPS) (also known as hookah, shisha, narghileh) is a centuries-old tradition that is commonly practiced in multiple parts of the world including China, India and the Middle East.1 Smoke is generated by heating a piece of
charcoal placed on top of a perforated sheet of aluminium foil, underneath which a tobacco mixture (often flavoured) is located.2 This flavoured heated air is bubbled in water to cool before being inhaled by the smoker through a hose.2 Since water pipes were invented before tobacco was commonly used, the instrument itself may have been used to smoke
* Corresponding author. Tel.: þ1 289 921 9131; fax: þ1 416 736 5774. E-mail address: [email protected] (P. Abdullah). http://dx.doi.org/10.1016/j.puhe.2017.03.007 0033-3506/© 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
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other materials like hashish or opium.3 However, nowadays it is commonly used to smoke flavoured forms of tobacco around the globe including Asia, Europe and North America.4 Water-pipe tobacco smokers perceive WPS as less harmful and less addictive than traditional cigarettes.5 Contrary to these perceptions, however, WPS exposes users to numerous toxicants and chemicals that are sometimes greater in amount than those produced by cigarette smoking.6 Studies using machine generated smoke have shown that, compared to one cigarette, one episode of WPS, which typically lasts for about an hour, generates 1.7 times the nicotine, 8.4 times the carbon monoxide, 36 times the tar (dry particulate matter that is nicotine-free)6 and considerably higher amounts of heavy metals.7 Moreover, WPS and cigarette smoking yield similar amounts of various other chemicals including nitric oxide and carbonylic compounds.7 In addition, some toxicants such as benzene are mainly produced by the burning charcoal and are, therefore, present in much higher amounts in WPS compared to cigarettes.7 Consequently, WPS has been associated with numerous detrimental effects on different body systems including the cardiovascular and respiratory systems.8 Effects of WPS on the cardiovascular system include increases in heart rate and blood pressure as well as an increased risk of coronary artery disease.8 As for the respiratory system, WPS has been associated with chronic bronchitis, emphysema and chronic obstructive pulmonary disease.8 Moreover, WPS has been associated with multiple forms of cancer including lung, gastric and oesophageal cancer.8 Other negative health outcomes related to WPS include periodontal disease, obstetrical complications and poor neonatal outcomes (including low birth-weight and neonatal death).8 Global trends indicate that even though cigarette use is either stable or declining in many areas, the use of other forms of tobacco, particularly WPS, is increasing.4 A systematic review performed by Akl et al.9 showed that the prevalence of current WPS in the Middle East ranged from 2% to 25% among school students, 6e28% among university students and 9e15% among adults, the higher ends of these statistics being from studies done in Lebanon. WPS is on the rise not only globally, but also in North America.4 In the United States of America (USA), the overall prevalence of ever WPS among adults 18 years and older was 9.8%, the highest being in the District of Columbia at 17.3%.10 The prevalence of WPS among university students in the USA was 8.4% (current) and 30.4% (ever).11 Furthermore, between 2011 and 2015 WPS increased among high-school students in the USA from 4.1% to 7.2%.12 Generally speaking, the prevalence of WPS tends to be higher in males,4,9e11,13e16 high socio-economic status,4 and increases with alcohol use, cigarette smoking9,11 and in Middle Eastern or South Asian ethnicity.17 Thus far, national studies looking at WPS trends in Canada have utilised the Youth Smoking Survey (YSS) (2006e2013), which focussed on students in grades 6e12.13e15,18,19 Results from YSS 2010 reported 10.1% ever use and 4% current use of water pipes among students in grades 9e12.14 These statistics increased significantly in the YSS 2012/2013 cycle where ever use was 14.3% (42% increase) and use within the last 30 days was 5.4% (35% increase).15 These alarming statistics highlight the importance of studying WPS in Canada among other age
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groups. The objective of the present study was to determine the prevalence and characteristics of WPS among different age groups in Canada on a national scale.
Methods This study was a secondary data analysis of the data collected by Statistics Canada. For this type of study (secondary data analysis), institutional consent requirements are waived. The final two cycles (2011 and 2012) of the Canadian Tobacco Use Monitoring Survey (CTUMS), an annual survey examining tobacco use among Canadians aged 15 years or older in all 10 provinces were used for this analysis. Residents of the Yukon, Northwest territories, Nunavut and full-time residents of institutions were not included in the survey. This crosssectional survey was conducted using a two-phased stratified random sampling of telephone numbers. In the first phase, random digit sampling was used to select households. Even though only households with landlines were included in the survey, all estimates were weighted to include the 14% of the target population who do not have landlines. In the second phase, one or two individuals (or none) were selected for participation based on household composition, to increase the representation in the sample of the population most at risk (individuals belonging to 15e19 and 20e24 year age groups). Applying weights in the analysis adjusts for this increased representation. The questionnaire was administered over the phone in either English or French. Data for the 2011 cycle of CTUMS was collected between February and December of 2011, resulting in 20,703 respondents with a household response rate of 78.9% and a person response rate of 83.9%. Data for the 2012 cycle of CTUMS was collected between February and December of 2012, resulting in a total of 19,285 respondents with a household response rate of 83.5% and a person response rate of 83%. Access to this data was granted by the Research Data Centre (RDC) at York University. Additional details about this survey can be found at the CTUMS page on the Statistics Canada website.20 The two main outcomes of the current study were ‘ever use’ and ‘current use’ of water pipes, and assessed by the following yes or no questions: ‘Have you ever tried a tobacco water-pipe, also known as hookah, sheesha, nargeelay, hubble-bubble or gouza to smoke tobacco?’ and ‘In the past 30 days, have you smoked a tobacco water-pipe?’, respectively. These questions meet the definitions and criteria set forth by the Expert Panel on Water-pipe Assessment in Epidemiological Studies.21,22 Covariates examined included: demographic factorsdgender, Aboriginal status (asked by the question ‘Are tis or Inuk/ you an Aboriginal person, that is, First Nations, Me Inuit? First Nations include status and non-status Indians?’), province of residence, rural residence (information obtained from the variable ‘characteristics of the community’), marital status, language spoken at home and age; socio-economic factorsdlevel of education and current work status (asked by the question ‘Are you currently working at a job or a business?’); and smoking-related factorsdhousehold smoking (asked by the question ‘Does anyone in your household smoke cigarettes?’), cigarette smoking and marijuana use (asked by the question ‘Have you ever used or tried marijuana,
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cannabis or hashish?’). The age groups used for ever WPS were: <18, 18e24, 25e34, 35e44 or 45þ years. This was modified for current WPS due to low cell counts, and a new category was created (35þ) by merging the last two groups. The relationship between each of the covariates and the outcomes was assessed using bivariate and multivariate logistic regressions to obtain odds ratio (OR) and 95% confidence interval (95% CI). Survey weights were applied to each variable and each calculated estimate. Bootstrapping was also performed to account for the complex design of the survey. All analyses were performed using Stata Statistical Software version 13 (StataCorp, College Station, TX).
partner (OR ¼ 3.64, 95% CI: 3.06e4.33) and speaking a language other than English and French at home (OR ¼ 2.10, 95% CI: 1.79e2.46) (Table 1). Level of education was a significant predictor of current WPS among the socio-economic variables with completed university having the strongest association (OR ¼ 5.22, 95% CI: 4.25e6.41) when compared to less than secondary (Table 1). As for smoking-related variables, current and former cigarette smoking were significant predictors of current WPS with current cigarette smoking having the strongest association (OR ¼ 3.68, 95% CI: 3.15e4.30) (Table 1). Finally, marijuana use was also significantly associated with current WPS (OR ¼ 2.38, 95% CI: 2.12e2.67) (Table 1).
Results
Discussion
The total weighted sample size was 28,513,934 with an overall prevalence of 8.9% for ever WPS (n ¼ 2,518,124) and 0.8% for current WPS (n ¼ 239,034) (Table 1). Among the <18 years age group, 7.6% were ever water-pipe smokers while 1.8% were current water-pipe smokers (Table 1). Among the 18e24 years age group, 24.6% were ever water-pipe smokers while 4% were current water-pipe smokers (Table 1). The sample included 49.4% males and 67.4% individuals aged 35 years and above (Table 1). The prevalence of current cigarette smoking was 16.7% (Table 1). Looking at the 10 provinces of Canada, Quebec had the highest prevalence of ever WPS at 11.3% while the lowest prevalence of ever WPS was in Newfoundland at 3.4% (P < 0.05). On the other hand, the highest prevalence of current WPS was in Alberta at 1.2% and the lowest was in Newfoundland again, at 0.2% (P < 0.05) (Fig. 1). Results of the bivariate and multivariate analyses are shown in Table 1. At the multivariate level, statistically significant demographic predictors of ever WPS were: male gender (OR ¼ 1.59, 95% CI: 1.53e1.65), age with 18e24 years of having the strongest association (OR ¼ 12.44, 95% CI: 11.76e13.17) when compared to 45 þ years, province of residence with EasterneCentral having the strongest association (OR ¼ 1.81, 95% CI: 1.75e1.89) when compared to EasterneAtlantic, urban residence (OR ¼ 1.68, 95% CI: 1.57e1.80), having no partner (OR ¼ 1.40, 95% CI: 1.33e1.48) and speaking a language other than English or French at home (OR ¼ 1.64, 95% CI: 1.53e1.76) (Table 1). Level of education was a significant predictor of ever WPS among the socio-economic variables with completed university having the strongest association when compared to less than secondary (OR ¼ 4.80, 95% CI: 4.44e5.18) (Table 1). In terms of smoking-related variables, current and former cigarette smoking were significant predictors of ever WPS with current cigarette smoking having the strongest association (OR ¼ 1.99, 95% CI: 1.87e2.11) (Table 1). In addition, marijuana use was significantly associated with ever WPS (OR ¼ 4.72, 95% CI: 4.50e4.95) (Table 1). Statistically significant demographic predictors of current WPS at the multivariate level were: male gender (OR ¼ 2.16, 95% CI: 1.98e2.36), age with <18 years having the strongest association (OR ¼ 47.86, 95% CI: 37.97e60.33) when compared to 35 þ years of age, province of residence with WesterneBritish Columbia having the strongest association (OR ¼ 1.89, 95% CI: 1.64e2.18) when compared to EasterneAtlantic, urban community residence (OR ¼ 1.87, 95% CI: 1.70e2.75), having no
The objective of the present study was to investigate the prevalence and characteristics of ever and current WPS in Canada. The national prevalence of ever WPS was found to be 8.9% and current WPS was 0.8%. The findings of this study indicate that WPS varies by age, education and province of residence, where higher ORs were found in individuals who were younger, had higher levels of education and resided in the EasterneCentral provinces and British Columbia. It is concerning that despite the low prevalence of WPS in Canada, the younger population seems to make a significant percentage of ever and current water-pipe smokers. Of particular concern is the high percentage of water-pipe smokers who were between 15 and 24 years of age. To our knowledge, the present study is the first to investigate WPS across all age groups in Canada. The findings of this project highlight the importance of better directing national health promotion efforts in Canada based on age and gender among other factors. The prevalence of WPS in Canada seems to be on the lower end of the spectrum when compared to the rest of the world. Previous research on the younger Canadian population has utilised the YSS and found that in 2010, the prevalence of ever and current WPS students in grades 9e12 was 10.1% and 4%, respectively.14 These numbers increased in 2012/2013 to 14.3% for ever WPS and 5.4% for current WPS.15 The present study combined the 2011 and 2012 cycles of CTUMS and found that individuals who were 15e18 years of age have a prevalence of 7.6% of ever WPS and 1.8% of current WPS. Moreover, the present study found that the prevalence of WPS in the 18e24 years of age group was 24.6% for ever WPS and 4% for current WPS. The difference between these findings and the findings from YSS may be explained by the different populations targeted in both surveys. The YSS targeted school children in grades 6e12 and did not include Manitoba.15 In the USA, the prevalence of ever WPS in adults 18 years of age or older was found to be 9.8% (ever)10 and 8.4% (current) and 30.4% (ever) among university students.11 In addition, there seems to have been an upward trend of WPS between 2011 and 2015 among high-school students in the USA increasing from 4.1% to 7.2%.12 In other parts of the world, it appears that WPS is gaining popularity among the younger individuals on a global scale, and this concerning trend seems to be on the rise.4,6,23 The prevalence of WPS varied from 33% among university students in Pakistan9 to 21.9e22.7% among students aged 13e15 years in Eastern Europe16 and 7.8% among students in
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Table 1 e Prevalence, unadjusted and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) of ever and current water-pipe smoking (WPS) in individuals aged 15 years and above living in Canada based on the Canadian Tobacco Use Monitoring Survey (CTUMS), 2011 and 2012. Predictor
Overall %
Ever WPS %
Total Demographic variables Gender Male Female Age (years) <18 18e24 25e34 35e44 (35 þ for current WPS) 45þ Aboriginal status Yes No Province of residence EasterneAtlantic EasterneCentral WesternePrairies WesterneBritish Columbia Rural residence Urban Rural Marital status Partner No partner Language spoken at home English/French/both Other Socio-economic variables Level of education Less than secondary Completed secondary Completed community college Completed university Currently working Yes No Smoking-related variables Household smoking Yes No Cigarette smoking Current Former Never Marijuana use Yes No
100.0
8.9
49.4 50.6
Unadjusted OR (95% CI)
Current WPS Adjusted OR (95% CI)
%
Unadjusted OR (95% CI)
Adjusted OR (95% CI)
e
e
0.8
e
e
11.3 6.5
1.8 (1.79e1.90) 1.00
1.59 (1.53e1.65) 1.00
1.3 0.4
2.9 (2.68e3.14) 1.00
2.16 (1.98e2.36) 1.00
4.6 11.4 16.7 16.3 51.1
7.6 24.6 19.7 6.0 2.9
2.80 (2.65e2.95) 11.12 (10.68e11.57) 8.39 (7.95e8.85) 2.17 (2.04e2.31) 1.00
10.24 (9.48e11.06) 12.44 (11.76e13.17) 6.63 (6.24e7.04) 2.01 (1.88e2.15) 1.00
1.8 4.0 1.5 0.1 e
25.23 (21.14e30.10) 56.77 (48.12e66.97) 21.00 (17.04e25.83) 1.00
47.86 (37.97e60.33) 30.87 (25.29e37.69) 12.26 (9.90e15.18) 1.00
5.1 95.0
8.9 8.8
1.01 (0.94e1.09) 1.00
0.70 (0.65e0.76) 1.00
0.9 0.8
1.12 (0.97e1.28) 1.00
0.83 (0.73e0.96) 1.00
6.9 62.2 17.3 13.6
5.1 9.4 8.4 8.8
1.00 1.96 (1.90e2.02) 1.73 (1.68e1.78) 1.82 (1.74e1.90)
1.00 1.81 (1.75e1.89) 1.61 (1.55e1.68) 1.63 (1.55e1.72)
0.4 0.8 0.9 1.0
1.00 1.87 (1.72e2.04) 2.11 (1.95e2.27) 2.34 (2.03e2.70)
1.00 1.34 (1.22e1.46) 1.71 (1.57e1.86) 1.89 (1.64e2.18)
80.3 19.7
9.7 5.2
1.97 (1.86e2.09) 1.00
1.68 (1.57e1.80) 1.00
1.0 0.4
2.34 (2.13e2.58) 1.00
1.87 (1.70e2.05) 1.00
62.3 37.7
6.0 13.8
1.00 2.52 (2.43e2.61)
1.00 1.40 (1.33e1.48)
0.2 2.0
1.00 11.76 (10.18e13.58)
1.00 3.64 (3.06e4.33)
89.4 10.6
9.0 8.4
1.00 0.93 (0.87e0.98)
1.00 1.64 (1.53e1.76)
0.8 1.1
1.00 1.38 (1.16e1.63)
1.00 2.10 (1.79e2.46)
16.1 35.2 19.8 28.9
3.7 9.8 8.4 11.1
1.00 2.82 (2.69e2.96) 2.37 (2.24e2.51) 3.22 (3.05e3.39)
1.00 2.30 (2.15e2.47) 2.56 (2.36e2.78) 4.80 (4.44e5.18)
0.6 1.2 0.6 0.8
1.00 2.00 (1.84e2.17) 1.05 (0.91e1.20) 1.33 (1.14e1.55)
1.00 2.44 (2.14e2.77) 2.37 (1.98e2.85) 5.22 (4.25e6.41)
62.5 37.5
10.8 5.7
2.01 (1.94e2.08) 1.00
1.21 (1.16e1.25) 1.00
1.0 0.6
1.86 (1.73e1.99) 1.00
1.33 (1.23e1.44) 1.00
25.5 75.5
13.9 7.2
2.09 (2.01e2.17) 1.00
1.15 (1.09e1.22) 1.00
1.6 0.6
2.88 (2.63e3.16) 1.00
1.16 (1.02e1.32) 1.00
16.7 26.7 56.6
7.7 17.4 6.9
2.85 (2.74e2.97) 1.13 (1.08e1.18) 1.00
1.99 (1.87e2.11) 1.96 (1.87e2.06) 1.00
0.3 2.4 0.6
3.99 (3.61e4.41) 0.51 (0.44e0.58) 1.00
3.68 (3.15e4.30) 1.74 (1.48e2.03) 1.00
39.2 60.8
17.5 3.4
6.10 (5.86e6.35) 1.00
4.72 (4.50e4.95) 1.00
1.6 0.4
4.25 (3.73e4.83) 1.00
2.38 (2.12e2.67) 1.00
grades 8, 10 and 12/13 in London (United Kingdom).17 In Lebanon, the prevalence of ever WPS was extremely high: up to 66% among school students and 43% among university students.9 The popularity of WPS in the Middle East is likely due to the cultural significance of WPS in that region, where it is often practiced in social settings, be it in designated public cafes or at the individual's home.24 In terms of demographic variables, the findings of the present study indicate that male gender is associated with
higher odds of WPS. This is in line with previous research which found that WPS is more common in males.4,9e11,13e16 Moreover, the present study found that younger age is associated with WPS. Previous research has reported that older secondary students (compared to other secondary students),17 younger university students (compared to other university students)11 and adults in the 18e24 years of age range (compared to 35e44 years of age)10 have a higher prevalence of WPS. In addition, previous research has found that ethnicity
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Prevalence of WPS (%)
12
10 8 6
Ever WPS
4
Current WPS
2
0
Fig. 1 e Prevalence of ever and current water-pipe smoking (WPS) in individuals aged 15 years and above in the different provinces of Canada based on the Canadian Tobacco Use Monitoring Survey (CTUMS), 2011 and 2012. N.L.: Newfoundland and Labrador, P.E.I.: Prince Edward Island, N.B.: New Brunswick, B.C.: British Columbia.
plays a role in the distribution of WPS. It has been found that ethnicities such as South Asian,17 Middle Eastern,17 Latin14,15 and Asian14 all have positive associations with WPS when compared to Caucasians. Since CTUMS does not have a variable for ethnicity, direct association of this important factor with WPS could not be studied. However, the present study utilised the ‘language spoken at home’ variable to gain some insight into the role of cultural differences on WPS and found that individuals who speak a language other than English or French at home were more likely to be ever or current waterpipe smokers. In addition, the present study found that WPS is associated with urban residence and residing in the EasterneCentral provinces and British Columbia. This can be explained by immigration trends in Canada, which in 2011 indicated that the majority of immigrants came from Asia (including the Middle East) and that the top three provinces receiving immigrants were Ontario, Quebec and British Columbia.25 Furthermore, these immigrants were more likely to inhabit large urban centres than Canadian born individuals.25 In terms of socio-economic variables, the present study found that higher education was significantly associated with WPS, depicted by higher ORs for university education than those found for other categories. According to a report based on the National Household Survey (2011) published by Statistics Canada, individuals with higher income often have higher education.26 This would mean that more financial resources are available to more educated individuals to fund this habit, which we speculate is more expensive than cigarette smoking due to the fact that WPS often takes place in public cafes. However, this observation needs to be further examined in future research. As for smoking-related variables, the present study found that marijuana use and current cigarette smoking were significantly associated with WPS. Whether marijuana use triggers other types of smoking or vice versa is difficult to determine, however, there is evidence that cigarette smoking
and binge drinking are also associated with marijuana use.27 In addition, marijuana can be consumed by several methods including smoking joints and water pipes28 which are similar vessels to those used for cigarette smoking and tobacco WPS, respectively. In addition, marijuana can be smoked alone or in combination with tobacco28 which supports the notion that marijuana and tobacco smoking may facilitate the use of one another. The limitations of the present study include the crosssectional design, which prevents any inference about causation. Moreover, CTUMS does not include all the variables that can play a role in WPS which can introduce a confounding effect of factors such as ethnicity and immigration status. Additionally, individuals living in institutions as well as residents of the Northwest Territories, Nunavut and the Yukon were not included in the survey population, making our results not generalisable to these individuals. Furthermore, since this was a survey that relied on self-reported data there is a potential for information bias. However, it has been shown that self-reported data can be used as a valid estimate of tobacco use in Canadians of different ages.29 In addition, the sampling of CTUMS was performed to over represent the younger population; however, this was resolved by applying weights to each variable making sample representative of the Canadian population. Another strong point of the present study is the large sample size that was included. Finally, to the our knowledge, this is the first study to look at all age groups in Canada, as a whole, making the findings of the present study an important baseline for future research in this area. In conclusion, WPS is associated with multiple demographic, socio-economic and smoking-related factors. Age, education and even the province/region of residence play an important role in current and ever WPS which calls for better directed national health promotion efforts. Since WPS seems to be quite prevalent among the younger age groups, future research can aim at understanding the reasons behind the increasing popularity of WPS is in the younger population
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when compared to older adults. This can be done, for example, through qualitative studies where youth are asked regarding the reasons why they engage (or do not engage) in WPS.
4.
Author statements 5.
Author contributions PA contributed to hypothesis conception, data analysis, interpretation of results and manuscript write-up. CC and NK contributed to critical revisions of the manuscript. HT supervised hypothesis conception, data analysis and interpretation and provided critical revisions of the manuscript.
6.
Acknowledgements The authors would like to thank the staff working at the RDC at York University and for the individuals responsible for CTUMS. Although the present research and analysis are based on data from Statistics Canada, the opinions expressed do not represent the views of Statistics Canada.
Ethical approval
7.
8.
None sought.
Funding
9.
This work was supported by the LaMarsh centre for child and youth research, York University.
Competing interests
10.
None declared.
Statement on the welfare of animals
11.
The article does not contain any studies with animals performed by any of the authors.
Informed consent 12.
For this type of study formal consent is not required.
references 13. 1. Maziak W, Ward KD, Afifi Soweid RA, Eissenberg T. Tobacco smoking using a waterpipe: a re-emerging strain in a global epidemic. Tob Control [Internet] 2004 Dec;13(4):327e33. [cited 2015 Aug 22]. Available from: http://www.pubmedcentral.nih.gov/ articlerender.fcgi?artid¼1747964&tool¼pmcentrez&rendertype¼ abstract. 2. Maziak W. The global epidemic of waterpipe smoking. Addict Behav [Internet] 2011 Jan;36(1e2):1e5. [cited 2015 Sep 17]. Available from:/pmc/articles/PMC4135081/?report¼abstract. 3. American Lung Association. An emerging deadly trend: waterpipe tobacco use. Tob Policy Trend Alert [Internet]
14.
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youth: findings from the 2012/2013 Youth Smoking Survey. Cancer Causes Control [Internet] 2015 Jun;26(6):831e8. [cited 2015 Sep 7]. Available from: http://www.pubmedcentral.nih. gov/articlerender.fcgi? artid¼4438198&tool¼pmcentrez&rendertype¼abstract. Jawad M, Lee JT, Millett C. Waterpipe tobacco smoking prevalence and correlates in 25 Eastern Mediterranean and Eastern European countries: cross-sectional analysis of the Global Youth Tobacco Survey. Nicotine Tob Res [Internet] 2015;18(4):395e402. Available from: http://ntr.oxfordjournals. org/content/early/2015/05/26/ntr.ntv101.short. Jawad M, Wilson A, Lee JT, Jawad S, Hamilton FL, Millett C. Prevalence and predictors of water pipe and cigarette smoking among secondary school students in London. Nicotine Tob Res [Internet] 2013 Dec 1;15(12):2069e75. [cited 2015 Nov 7]. Available from: http://ntr.oxfordjournals.org/ content/15/12/2069.short. Cole AG, Leatherdale ST. The association between senior student tobacco use rate at school and alternative tobacco product use among junior students in Canadian secondary schools. Tob Induc Dis [Internet] 2014 Jan;12(1):8. [cited 2015 Sep 17]. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi? artid¼4012246&tool¼pmcentrez&rendertype¼abstract. Minaker LM, Ahmed R, Hammond D, Manske S. Flavored tobacco use among Canadian students in grades 9 through 12: prevalence and patterns from the 2010e2011 youth smoking survey. Prev Chronic Dis [Internet] 2014 Jan;11:E102. [cited 2015 Sep 18]. Available from: http://www.pubmedcentral.nih.gov/ articlerender.fcgi? artid¼4068113&tool¼pmcentrez&rendertype¼abstract. Canada S. Canadian Tobacco Use Monitoring Survey (CTUMS) [Internet]. [cited 2015 Oct 27]. Available from: http://www23. statcan.gc.ca/imdb/p2SV.pl?Function¼getSurvey& SurvId¼97504&InstaId¼135461&SDDS¼4440. Maziak W, Ward KD, Afifi Soweid RA, Eissenberg T. Standardizing questionnaire items for the assessment of
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Available online at www.sciencedirect.com
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Original Research
Prevalence and characteristics of water-pipe smoking in Canada: results from the Canadian Tobacco Use Monitoring Survey P. Abdullah a,*, C. Costanian a, N. Khanlou b, H. Tamim a a b
Kinesiology and Health Science, York University, Toronto, Ontario, Canada School of Nursing, York University, Toronto, Ontario, Canada
article info
abstract
Article history:
Objectives: To investigate the prevalence and characteristics of water-pipe smoking (WPS)
Received 7 December 2016
nationally in Canada.
Received in revised form
Study design: This study was a cross-sectional study.
5 March 2017
Methods: Data from the Canadian Tobacco Use Monitoring Survey 2011 and 2012 was used.
Accepted 16 March 2017
Outcomes investigated were ever and current WPS. Demographic, socio-economic and smoking-related variables were included in a multivariable logistic regression model to determine associations with the outcomes.
Keywords:
Results: Prevalence of WPS was 8.9% for ever and 0.8% for current WPS (1.8% among <18
Water pipe
years old and 4.0% among 18e24 years old). The highest prevalence of ever WPS was in
Canada
Quebec (11.3%) and of current WPS in Alberta (1.2%). Age was the strongest predictor for
Smoking
WPS with an odds ratio ¼ 47.86, 95% confidence interval: 37.97e60.33 for current WPS for
Hookah
those aged <18 years compared to 35 þ years. Male gender, urban residence, being single,
Narghileh
speaking another language at home (not English/French), higher education, cigarette smoking and marijuana use were also significantly associated with increased WPS. Conclusions: Multiple factors impact WPS, with the younger population having the highest prevalence. This necessitates further research into the attitudes of this age group to better focus health promotion efforts. © 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Introduction Water-pipe smoking (WPS) (also known as hookah, shisha, narghileh) is a centuries-old tradition that is commonly practiced in multiple parts of the world including China, India and the Middle East.1 Smoke is generated by heating a piece of
charcoal placed on top of a perforated sheet of aluminium foil, underneath which a tobacco mixture (often flavoured) is located.2 This flavoured heated air is bubbled in water to cool before being inhaled by the smoker through a hose.2 Since water pipes were invented before tobacco was commonly used, the instrument itself may have been used to smoke
* Corresponding author. Tel.: þ1 289 921 9131; fax: þ1 416 736 5774. E-mail address: [email protected] (P. Abdullah). http://dx.doi.org/10.1016/j.puhe.2017.03.007 0033-3506/© 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
p u b l i c h e a l t h 1 4 8 ( 2 0 1 7 ) 1 0 2 e1 0 8
other materials like hashish or opium.3 However, nowadays it is commonly used to smoke flavoured forms of tobacco around the globe including Asia, Europe and North America.4 Water-pipe tobacco smokers perceive WPS as less harmful and less addictive than traditional cigarettes.5 Contrary to these perceptions, however, WPS exposes users to numerous toxicants and chemicals that are sometimes greater in amount than those produced by cigarette smoking.6 Studies using machine generated smoke have shown that, compared to one cigarette, one episode of WPS, which typically lasts for about an hour, generates 1.7 times the nicotine, 8.4 times the carbon monoxide, 36 times the tar (dry particulate matter that is nicotine-free)6 and considerably higher amounts of heavy metals.7 Moreover, WPS and cigarette smoking yield similar amounts of various other chemicals including nitric oxide and carbonylic compounds.7 In addition, some toxicants such as benzene are mainly produced by the burning charcoal and are, therefore, present in much higher amounts in WPS compared to cigarettes.7 Consequently, WPS has been associated with numerous detrimental effects on different body systems including the cardiovascular and respiratory systems.8 Effects of WPS on the cardiovascular system include increases in heart rate and blood pressure as well as an increased risk of coronary artery disease.8 As for the respiratory system, WPS has been associated with chronic bronchitis, emphysema and chronic obstructive pulmonary disease.8 Moreover, WPS has been associated with multiple forms of cancer including lung, gastric and oesophageal cancer.8 Other negative health outcomes related to WPS include periodontal disease, obstetrical complications and poor neonatal outcomes (including low birth-weight and neonatal death).8 Global trends indicate that even though cigarette use is either stable or declining in many areas, the use of other forms of tobacco, particularly WPS, is increasing.4 A systematic review performed by Akl et al.9 showed that the prevalence of current WPS in the Middle East ranged from 2% to 25% among school students, 6e28% among university students and 9e15% among adults, the higher ends of these statistics being from studies done in Lebanon. WPS is on the rise not only globally, but also in North America.4 In the United States of America (USA), the overall prevalence of ever WPS among adults 18 years and older was 9.8%, the highest being in the District of Columbia at 17.3%.10 The prevalence of WPS among university students in the USA was 8.4% (current) and 30.4% (ever).11 Furthermore, between 2011 and 2015 WPS increased among high-school students in the USA from 4.1% to 7.2%.12 Generally speaking, the prevalence of WPS tends to be higher in males,4,9e11,13e16 high socio-economic status,4 and increases with alcohol use, cigarette smoking9,11 and in Middle Eastern or South Asian ethnicity.17 Thus far, national studies looking at WPS trends in Canada have utilised the Youth Smoking Survey (YSS) (2006e2013), which focussed on students in grades 6e12.13e15,18,19 Results from YSS 2010 reported 10.1% ever use and 4% current use of water pipes among students in grades 9e12.14 These statistics increased significantly in the YSS 2012/2013 cycle where ever use was 14.3% (42% increase) and use within the last 30 days was 5.4% (35% increase).15 These alarming statistics highlight the importance of studying WPS in Canada among other age
103
groups. The objective of the present study was to determine the prevalence and characteristics of WPS among different age groups in Canada on a national scale.
Methods This study was a secondary data analysis of the data collected by Statistics Canada. For this type of study (secondary data analysis), institutional consent requirements are waived. The final two cycles (2011 and 2012) of the Canadian Tobacco Use Monitoring Survey (CTUMS), an annual survey examining tobacco use among Canadians aged 15 years or older in all 10 provinces were used for this analysis. Residents of the Yukon, Northwest territories, Nunavut and full-time residents of institutions were not included in the survey. This crosssectional survey was conducted using a two-phased stratified random sampling of telephone numbers. In the first phase, random digit sampling was used to select households. Even though only households with landlines were included in the survey, all estimates were weighted to include the 14% of the target population who do not have landlines. In the second phase, one or two individuals (or none) were selected for participation based on household composition, to increase the representation in the sample of the population most at risk (individuals belonging to 15e19 and 20e24 year age groups). Applying weights in the analysis adjusts for this increased representation. The questionnaire was administered over the phone in either English or French. Data for the 2011 cycle of CTUMS was collected between February and December of 2011, resulting in 20,703 respondents with a household response rate of 78.9% and a person response rate of 83.9%. Data for the 2012 cycle of CTUMS was collected between February and December of 2012, resulting in a total of 19,285 respondents with a household response rate of 83.5% and a person response rate of 83%. Access to this data was granted by the Research Data Centre (RDC) at York University. Additional details about this survey can be found at the CTUMS page on the Statistics Canada website.20 The two main outcomes of the current study were ‘ever use’ and ‘current use’ of water pipes, and assessed by the following yes or no questions: ‘Have you ever tried a tobacco water-pipe, also known as hookah, sheesha, nargeelay, hubble-bubble or gouza to smoke tobacco?’ and ‘In the past 30 days, have you smoked a tobacco water-pipe?’, respectively. These questions meet the definitions and criteria set forth by the Expert Panel on Water-pipe Assessment in Epidemiological Studies.21,22 Covariates examined included: demographic factorsdgender, Aboriginal status (asked by the question ‘Are tis or Inuk/ you an Aboriginal person, that is, First Nations, Me Inuit? First Nations include status and non-status Indians?’), province of residence, rural residence (information obtained from the variable ‘characteristics of the community’), marital status, language spoken at home and age; socio-economic factorsdlevel of education and current work status (asked by the question ‘Are you currently working at a job or a business?’); and smoking-related factorsdhousehold smoking (asked by the question ‘Does anyone in your household smoke cigarettes?’), cigarette smoking and marijuana use (asked by the question ‘Have you ever used or tried marijuana,
104
p u b l i c h e a l t h 1 4 8 ( 2 0 1 7 ) 1 0 2 e1 0 8
cannabis or hashish?’). The age groups used for ever WPS were: <18, 18e24, 25e34, 35e44 or 45þ years. This was modified for current WPS due to low cell counts, and a new category was created (35þ) by merging the last two groups. The relationship between each of the covariates and the outcomes was assessed using bivariate and multivariate logistic regressions to obtain odds ratio (OR) and 95% confidence interval (95% CI). Survey weights were applied to each variable and each calculated estimate. Bootstrapping was also performed to account for the complex design of the survey. All analyses were performed using Stata Statistical Software version 13 (StataCorp, College Station, TX).
partner (OR ¼ 3.64, 95% CI: 3.06e4.33) and speaking a language other than English and French at home (OR ¼ 2.10, 95% CI: 1.79e2.46) (Table 1). Level of education was a significant predictor of current WPS among the socio-economic variables with completed university having the strongest association (OR ¼ 5.22, 95% CI: 4.25e6.41) when compared to less than secondary (Table 1). As for smoking-related variables, current and former cigarette smoking were significant predictors of current WPS with current cigarette smoking having the strongest association (OR ¼ 3.68, 95% CI: 3.15e4.30) (Table 1). Finally, marijuana use was also significantly associated with current WPS (OR ¼ 2.38, 95% CI: 2.12e2.67) (Table 1).
Results
Discussion
The total weighted sample size was 28,513,934 with an overall prevalence of 8.9% for ever WPS (n ¼ 2,518,124) and 0.8% for current WPS (n ¼ 239,034) (Table 1). Among the <18 years age group, 7.6% were ever water-pipe smokers while 1.8% were current water-pipe smokers (Table 1). Among the 18e24 years age group, 24.6% were ever water-pipe smokers while 4% were current water-pipe smokers (Table 1). The sample included 49.4% males and 67.4% individuals aged 35 years and above (Table 1). The prevalence of current cigarette smoking was 16.7% (Table 1). Looking at the 10 provinces of Canada, Quebec had the highest prevalence of ever WPS at 11.3% while the lowest prevalence of ever WPS was in Newfoundland at 3.4% (P < 0.05). On the other hand, the highest prevalence of current WPS was in Alberta at 1.2% and the lowest was in Newfoundland again, at 0.2% (P < 0.05) (Fig. 1). Results of the bivariate and multivariate analyses are shown in Table 1. At the multivariate level, statistically significant demographic predictors of ever WPS were: male gender (OR ¼ 1.59, 95% CI: 1.53e1.65), age with 18e24 years of having the strongest association (OR ¼ 12.44, 95% CI: 11.76e13.17) when compared to 45 þ years, province of residence with EasterneCentral having the strongest association (OR ¼ 1.81, 95% CI: 1.75e1.89) when compared to EasterneAtlantic, urban residence (OR ¼ 1.68, 95% CI: 1.57e1.80), having no partner (OR ¼ 1.40, 95% CI: 1.33e1.48) and speaking a language other than English or French at home (OR ¼ 1.64, 95% CI: 1.53e1.76) (Table 1). Level of education was a significant predictor of ever WPS among the socio-economic variables with completed university having the strongest association when compared to less than secondary (OR ¼ 4.80, 95% CI: 4.44e5.18) (Table 1). In terms of smoking-related variables, current and former cigarette smoking were significant predictors of ever WPS with current cigarette smoking having the strongest association (OR ¼ 1.99, 95% CI: 1.87e2.11) (Table 1). In addition, marijuana use was significantly associated with ever WPS (OR ¼ 4.72, 95% CI: 4.50e4.95) (Table 1). Statistically significant demographic predictors of current WPS at the multivariate level were: male gender (OR ¼ 2.16, 95% CI: 1.98e2.36), age with <18 years having the strongest association (OR ¼ 47.86, 95% CI: 37.97e60.33) when compared to 35 þ years of age, province of residence with WesterneBritish Columbia having the strongest association (OR ¼ 1.89, 95% CI: 1.64e2.18) when compared to EasterneAtlantic, urban community residence (OR ¼ 1.87, 95% CI: 1.70e2.75), having no
The objective of the present study was to investigate the prevalence and characteristics of ever and current WPS in Canada. The national prevalence of ever WPS was found to be 8.9% and current WPS was 0.8%. The findings of this study indicate that WPS varies by age, education and province of residence, where higher ORs were found in individuals who were younger, had higher levels of education and resided in the EasterneCentral provinces and British Columbia. It is concerning that despite the low prevalence of WPS in Canada, the younger population seems to make a significant percentage of ever and current water-pipe smokers. Of particular concern is the high percentage of water-pipe smokers who were between 15 and 24 years of age. To our knowledge, the present study is the first to investigate WPS across all age groups in Canada. The findings of this project highlight the importance of better directing national health promotion efforts in Canada based on age and gender among other factors. The prevalence of WPS in Canada seems to be on the lower end of the spectrum when compared to the rest of the world. Previous research on the younger Canadian population has utilised the YSS and found that in 2010, the prevalence of ever and current WPS students in grades 9e12 was 10.1% and 4%, respectively.14 These numbers increased in 2012/2013 to 14.3% for ever WPS and 5.4% for current WPS.15 The present study combined the 2011 and 2012 cycles of CTUMS and found that individuals who were 15e18 years of age have a prevalence of 7.6% of ever WPS and 1.8% of current WPS. Moreover, the present study found that the prevalence of WPS in the 18e24 years of age group was 24.6% for ever WPS and 4% for current WPS. The difference between these findings and the findings from YSS may be explained by the different populations targeted in both surveys. The YSS targeted school children in grades 6e12 and did not include Manitoba.15 In the USA, the prevalence of ever WPS in adults 18 years of age or older was found to be 9.8% (ever)10 and 8.4% (current) and 30.4% (ever) among university students.11 In addition, there seems to have been an upward trend of WPS between 2011 and 2015 among high-school students in the USA increasing from 4.1% to 7.2%.12 In other parts of the world, it appears that WPS is gaining popularity among the younger individuals on a global scale, and this concerning trend seems to be on the rise.4,6,23 The prevalence of WPS varied from 33% among university students in Pakistan9 to 21.9e22.7% among students aged 13e15 years in Eastern Europe16 and 7.8% among students in
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Table 1 e Prevalence, unadjusted and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) of ever and current water-pipe smoking (WPS) in individuals aged 15 years and above living in Canada based on the Canadian Tobacco Use Monitoring Survey (CTUMS), 2011 and 2012. Predictor
Overall %
Ever WPS %
Total Demographic variables Gender Male Female Age (years) <18 18e24 25e34 35e44 (35 þ for current WPS) 45þ Aboriginal status Yes No Province of residence EasterneAtlantic EasterneCentral WesternePrairies WesterneBritish Columbia Rural residence Urban Rural Marital status Partner No partner Language spoken at home English/French/both Other Socio-economic variables Level of education Less than secondary Completed secondary Completed community college Completed university Currently working Yes No Smoking-related variables Household smoking Yes No Cigarette smoking Current Former Never Marijuana use Yes No
100.0
8.9
49.4 50.6
Unadjusted OR (95% CI)
Current WPS Adjusted OR (95% CI)
%
Unadjusted OR (95% CI)
Adjusted OR (95% CI)
e
e
0.8
e
e
11.3 6.5
1.8 (1.79e1.90) 1.00
1.59 (1.53e1.65) 1.00
1.3 0.4
2.9 (2.68e3.14) 1.00
2.16 (1.98e2.36) 1.00
4.6 11.4 16.7 16.3 51.1
7.6 24.6 19.7 6.0 2.9
2.80 (2.65e2.95) 11.12 (10.68e11.57) 8.39 (7.95e8.85) 2.17 (2.04e2.31) 1.00
10.24 (9.48e11.06) 12.44 (11.76e13.17) 6.63 (6.24e7.04) 2.01 (1.88e2.15) 1.00
1.8 4.0 1.5 0.1 e
25.23 (21.14e30.10) 56.77 (48.12e66.97) 21.00 (17.04e25.83) 1.00
47.86 (37.97e60.33) 30.87 (25.29e37.69) 12.26 (9.90e15.18) 1.00
5.1 95.0
8.9 8.8
1.01 (0.94e1.09) 1.00
0.70 (0.65e0.76) 1.00
0.9 0.8
1.12 (0.97e1.28) 1.00
0.83 (0.73e0.96) 1.00
6.9 62.2 17.3 13.6
5.1 9.4 8.4 8.8
1.00 1.96 (1.90e2.02) 1.73 (1.68e1.78) 1.82 (1.74e1.90)
1.00 1.81 (1.75e1.89) 1.61 (1.55e1.68) 1.63 (1.55e1.72)
0.4 0.8 0.9 1.0
1.00 1.87 (1.72e2.04) 2.11 (1.95e2.27) 2.34 (2.03e2.70)
1.00 1.34 (1.22e1.46) 1.71 (1.57e1.86) 1.89 (1.64e2.18)
80.3 19.7
9.7 5.2
1.97 (1.86e2.09) 1.00
1.68 (1.57e1.80) 1.00
1.0 0.4
2.34 (2.13e2.58) 1.00
1.87 (1.70e2.05) 1.00
62.3 37.7
6.0 13.8
1.00 2.52 (2.43e2.61)
1.00 1.40 (1.33e1.48)
0.2 2.0
1.00 11.76 (10.18e13.58)
1.00 3.64 (3.06e4.33)
89.4 10.6
9.0 8.4
1.00 0.93 (0.87e0.98)
1.00 1.64 (1.53e1.76)
0.8 1.1
1.00 1.38 (1.16e1.63)
1.00 2.10 (1.79e2.46)
16.1 35.2 19.8 28.9
3.7 9.8 8.4 11.1
1.00 2.82 (2.69e2.96) 2.37 (2.24e2.51) 3.22 (3.05e3.39)
1.00 2.30 (2.15e2.47) 2.56 (2.36e2.78) 4.80 (4.44e5.18)
0.6 1.2 0.6 0.8
1.00 2.00 (1.84e2.17) 1.05 (0.91e1.20) 1.33 (1.14e1.55)
1.00 2.44 (2.14e2.77) 2.37 (1.98e2.85) 5.22 (4.25e6.41)
62.5 37.5
10.8 5.7
2.01 (1.94e2.08) 1.00
1.21 (1.16e1.25) 1.00
1.0 0.6
1.86 (1.73e1.99) 1.00
1.33 (1.23e1.44) 1.00
25.5 75.5
13.9 7.2
2.09 (2.01e2.17) 1.00
1.15 (1.09e1.22) 1.00
1.6 0.6
2.88 (2.63e3.16) 1.00
1.16 (1.02e1.32) 1.00
16.7 26.7 56.6
7.7 17.4 6.9
2.85 (2.74e2.97) 1.13 (1.08e1.18) 1.00
1.99 (1.87e2.11) 1.96 (1.87e2.06) 1.00
0.3 2.4 0.6
3.99 (3.61e4.41) 0.51 (0.44e0.58) 1.00
3.68 (3.15e4.30) 1.74 (1.48e2.03) 1.00
39.2 60.8
17.5 3.4
6.10 (5.86e6.35) 1.00
4.72 (4.50e4.95) 1.00
1.6 0.4
4.25 (3.73e4.83) 1.00
2.38 (2.12e2.67) 1.00
grades 8, 10 and 12/13 in London (United Kingdom).17 In Lebanon, the prevalence of ever WPS was extremely high: up to 66% among school students and 43% among university students.9 The popularity of WPS in the Middle East is likely due to the cultural significance of WPS in that region, where it is often practiced in social settings, be it in designated public cafes or at the individual's home.24 In terms of demographic variables, the findings of the present study indicate that male gender is associated with
higher odds of WPS. This is in line with previous research which found that WPS is more common in males.4,9e11,13e16 Moreover, the present study found that younger age is associated with WPS. Previous research has reported that older secondary students (compared to other secondary students),17 younger university students (compared to other university students)11 and adults in the 18e24 years of age range (compared to 35e44 years of age)10 have a higher prevalence of WPS. In addition, previous research has found that ethnicity
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p u b l i c h e a l t h 1 4 8 ( 2 0 1 7 ) 1 0 2 e1 0 8
Prevalence of WPS (%)
12
10 8 6
Ever WPS
4
Current WPS
2
0
Fig. 1 e Prevalence of ever and current water-pipe smoking (WPS) in individuals aged 15 years and above in the different provinces of Canada based on the Canadian Tobacco Use Monitoring Survey (CTUMS), 2011 and 2012. N.L.: Newfoundland and Labrador, P.E.I.: Prince Edward Island, N.B.: New Brunswick, B.C.: British Columbia.
plays a role in the distribution of WPS. It has been found that ethnicities such as South Asian,17 Middle Eastern,17 Latin14,15 and Asian14 all have positive associations with WPS when compared to Caucasians. Since CTUMS does not have a variable for ethnicity, direct association of this important factor with WPS could not be studied. However, the present study utilised the ‘language spoken at home’ variable to gain some insight into the role of cultural differences on WPS and found that individuals who speak a language other than English or French at home were more likely to be ever or current waterpipe smokers. In addition, the present study found that WPS is associated with urban residence and residing in the EasterneCentral provinces and British Columbia. This can be explained by immigration trends in Canada, which in 2011 indicated that the majority of immigrants came from Asia (including the Middle East) and that the top three provinces receiving immigrants were Ontario, Quebec and British Columbia.25 Furthermore, these immigrants were more likely to inhabit large urban centres than Canadian born individuals.25 In terms of socio-economic variables, the present study found that higher education was significantly associated with WPS, depicted by higher ORs for university education than those found for other categories. According to a report based on the National Household Survey (2011) published by Statistics Canada, individuals with higher income often have higher education.26 This would mean that more financial resources are available to more educated individuals to fund this habit, which we speculate is more expensive than cigarette smoking due to the fact that WPS often takes place in public cafes. However, this observation needs to be further examined in future research. As for smoking-related variables, the present study found that marijuana use and current cigarette smoking were significantly associated with WPS. Whether marijuana use triggers other types of smoking or vice versa is difficult to determine, however, there is evidence that cigarette smoking
and binge drinking are also associated with marijuana use.27 In addition, marijuana can be consumed by several methods including smoking joints and water pipes28 which are similar vessels to those used for cigarette smoking and tobacco WPS, respectively. In addition, marijuana can be smoked alone or in combination with tobacco28 which supports the notion that marijuana and tobacco smoking may facilitate the use of one another. The limitations of the present study include the crosssectional design, which prevents any inference about causation. Moreover, CTUMS does not include all the variables that can play a role in WPS which can introduce a confounding effect of factors such as ethnicity and immigration status. Additionally, individuals living in institutions as well as residents of the Northwest Territories, Nunavut and the Yukon were not included in the survey population, making our results not generalisable to these individuals. Furthermore, since this was a survey that relied on self-reported data there is a potential for information bias. However, it has been shown that self-reported data can be used as a valid estimate of tobacco use in Canadians of different ages.29 In addition, the sampling of CTUMS was performed to over represent the younger population; however, this was resolved by applying weights to each variable making sample representative of the Canadian population. Another strong point of the present study is the large sample size that was included. Finally, to the our knowledge, this is the first study to look at all age groups in Canada, as a whole, making the findings of the present study an important baseline for future research in this area. In conclusion, WPS is associated with multiple demographic, socio-economic and smoking-related factors. Age, education and even the province/region of residence play an important role in current and ever WPS which calls for better directed national health promotion efforts. Since WPS seems to be quite prevalent among the younger age groups, future research can aim at understanding the reasons behind the increasing popularity of WPS is in the younger population
p u b l i c h e a l t h 1 4 8 ( 2 0 1 7 ) 1 0 2 e1 0 8
when compared to older adults. This can be done, for example, through qualitative studies where youth are asked regarding the reasons why they engage (or do not engage) in WPS.
4.
Author statements 5.
Author contributions PA contributed to hypothesis conception, data analysis, interpretation of results and manuscript write-up. CC and NK contributed to critical revisions of the manuscript. HT supervised hypothesis conception, data analysis and interpretation and provided critical revisions of the manuscript.
6.
Acknowledgements The authors would like to thank the staff working at the RDC at York University and for the individuals responsible for CTUMS. Although the present research and analysis are based on data from Statistics Canada, the opinions expressed do not represent the views of Statistics Canada.
Ethical approval
7.
8.
None sought.
Funding
9.
This work was supported by the LaMarsh centre for child and youth research, York University.
Competing interests
10.
None declared.
Statement on the welfare of animals
11.
The article does not contain any studies with animals performed by any of the authors.
Informed consent 12.
For this type of study formal consent is not required.
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