Hookah Susceptibility and Transitions Over the First Year of College

Abstract

Objective:

There has been a growth in popularity of hookah (or waterpipes) among American college students, despite the health risks. This study investigated factors that predict hookah susceptibility and whether hookah susceptibility predicts hookah initiation and continued use.

Method:

The study established a cohort of 529 incoming college freshmen (51.6% female) who completed an online survey approximately 1 week before their arrival to a large U.S. university. Students were sent four follow-up surveys throughout the 2016–2017 academic year; 90.5% completed at least one follow-up survey.

Results:

A total of 13.2% of the sample had used hookah at baseline and 9.9% initiated hookah use over the course of their freshman year. Among the nonusers who had no hookah susceptibility at baseline, 30.0% came to indicate some susceptibility. Multivariable logistic regression indicated that the personality construct conscientiousness was protective against becoming susceptible, whereas coming from a rural part of the state was a risk factor. Susceptibility predicted both continued use among the baseline ever-users and initiation among the baseline never-users.

Conclusions:

These findings highlight the role of susceptibility in the trajectory of hookah use among U.S. college students.

Twenty years ago, few researchers in the United States had concerns about hookah (Knishkowy & Amitai, 2005). Since then, however, the United States has seen the emergence of hookah tobacco (“hookah”) use among its adolescent and young adult populations (Jamal et al., 2017; Salloum et al., 2017; Villanti et al., 2015). Use of hookah (also referred to as waterpipes, narghile, or shisha) appears to be particularly popular among college students (Heinz et al., 2013; Loukas et al., 2015; Shepardson & Hustad, 2016), with one review estimating that 20% of U.S. college students used hookah within the past year (Grekin & Ayna, 2012). Indeed, several studies with national samples identified college attendance as a risk factor for ever-use of hookah (Majeed et al., 2017; Salloum et al., 2017; Villanti et al., 2015).

Hookah use is a somewhat unique behavior compared with other tobacco product use. Unlike cigarette smoking, hookah use is rarely a daily behavior in the United States (Leavens et al., 2018; Robinson et al., 2018; Villanti et al., 2015). One recent nationally representative study found that among young adult past-30-day hookah users, only 4% reported daily use (Salloum et al., 2017); rather, hookah use is generally intermittent. Conversely, when hookah is used, the typical session is lengthy—lasting well over 30 minutes (Salloum et al., 2017). Hookah use is also a very social behavior in the United States, with the majority of users reporting that they always use with friends (Heinz et al., 2013). Likewise, college students report that decisions to use hookah are often driven by the social context (Roberts et al., 2017).

Researchers have speculated that the high prevalence of hookah use during college is facilitated by environmental factors such as permissive social norms surrounding substance use, the highly social nature of hookah use, and the density of hookah establishments surrounding college campuses (Kates et al., 2016; Shepardson & Hustad, 2016). But within this college context, what makes some use and others not? Although research remains ongoing on this topic, there are several factors that seem to increase the likelihood of a young adult being a hookah user, or frequent hookah user, including demographic characteristics (i.e., younger age, being male; Grekin & Ayna, 2012; Jarrett et al., 2012; Park et al., 2017; Robinson et al., 2018) and having lower risk perceptions and more positive expectancies about hookah (Creamer et al., 2016; Doran & Brikmanis, 2016; Grekin & Ayna, 2012; Hair et al., 2017; Villanti et al., 2015). There is some evidence that high-risk personality characteristics are involved, such as impulsivity (Fielder et al., 2012a). Hookah use also appears to be associated with the use of other substances (Grekin & Ayna, 2012; Haider et al., 2015; Jarrett et al., 2012; Majeed et al., 2017; Park et al., 2017; Shepardson & Hustad, 2016; Villanti et al., 2015). For example, recent studies have found overlap between hookah users and social smokers (Abudayyeh et al., 2018; Villanti et al., 2017).

Preventing hookah use is critical, as hookah use is an extremely unsafe behavior with many of the same risks as cigarette smoking (Akl et al., 2010; American Lung Association, 2011). Specifically, inhaling hookah smoke exposes an individual to high levels of nicotine, carbon monoxide, metals, and cancer-causing chemicals (Cobb et al., 2010; Shihadeh, 2003; St. Helen et al., 2014). There is also evidence that hookah may serve as a “gateway” to nicotine addiction and use of other tobacco products (Fielder et al., 2013; Jensen et al., 2010; Soneji et al., 2017). Despite these risks, few health education or preventive interventions for hookah have been developed, perhaps because it is not always clear what constructs or populations to target. More research is needed to better identify both at-risk populations and modifiable factors that could be targeted.

Susceptibility to cigarette smoking has long been understood as a key predictor of future cigarette smoking (Choi et al., 2001; Jackson, 1998; Unger et al., 1997) and is often used as both a means of identifying vulnerable youth (Kowitt et al., 2018; Primack et al., 2015; Trinidad et al., 2017) as well as a construct to target with intervention (Bier et al., 2016; Zawahir et al., 2013). This construct can be defined as the cognitive predisposition to smoke, as indicated by the absence of a firm decision against smoking (Pierce et al., 1996). There is some evidence that susceptibility may predict hookah initiation during college (Lipkus et al., 2015). However, it is important to establish whether hookah susceptibility predicts movement along the hookah uptake trajectory—both initiation and continued use. In turn, it is important to establish what factors themselves predict hookah susceptibility. Answering these questions may help to better inform future prevention work.

To investigate the role of hookah susceptibility, the present study established a cohort of matriculating college undergraduates who were surveyed multiple times throughout their freshman year. These surveys allowed us to prospectively assess changes in hookah-related behaviors and cognitions, including susceptibility. Our first objective was to determine predictors of becoming susceptible to hookah use. There is some evidence that hookah susceptibility is associated with other substance use, risk-taking traits, and male gender (Lipkus et al., 2015). Therefore, we hypothesized that indicators of greater conscientiousness, greater peer use, and demographic characteristics (especially male gender) would be predictive of becoming susceptible. Our second objective was to determine predictors of hookah initiation and progression. Given the predictive utility of susceptibility for cigarette smoking, we hypothesized that greater susceptibility would predict both continued hookah use and incidence of hookah use during the first year of college.

Method

Participants and recruitment

All study procedures were approved by the University Institutional Review Board. One week before campus move-in day (and 9 days before the start of the fall 2016 semester), the research team contacted 1,000 incoming freshman students at a large university in Ohio. This list of 1,000 students was provided by the Office of the University Registrar and was a random sample of the incoming class, stratified by gender, first-generation college status, and in- versus out-of-state family residence. All students on the list were age 18 or older so they could consent to study participation. These students were sent an email inviting them to participate in a research study on health behaviors, and were provided with a link to an online survey. As described further in the Results section, 529 participants completed this survey (53% response rate).

Procedures

The baseline survey began with an online consent form, followed by the baseline items. Because this survey was administered before campus move-in day, it allowed us to assess students’ behaviors before their arrival on campus. All participants who responded to the initial baseline survey were invited to complete subsequent follow-up surveys throughout the 2016–2017 academic year. There were four follow-up surveys: One in September (approximately 1 month into the fall semester), one in December, one in March, and one in June (following the completion of the spring semester).

At each data collection point, participants were sent a link to the online survey. Participants were given an approximately 1-week period to complete the survey and were sent multiple reminders during this period. The baseline survey was designed to take about 15 minutes to complete, and follow-up surveys 5–10 minutes. Students received a $20 online gift card for the baseline survey and $10 online gift cards for each follow-up survey.

Measures

Hookah use.

At all waves, participants were asked, “Have you ever used hookah (also known as waterpipes or shisha)?” (yes, no). Those indicating ever-use of hookah were asked about use in the past 30 days. Participants who reported never having used hookah at baseline were coded for whether they reported use during any of the follow-up surveys (initiation). Participants who reported ever-use at baseline were coded for whether they reported past-30-day use during a follow-up (continued use).

Addiction and respiratory symptoms.

Among participants who indicated ever-use of hookah, addiction was assessed at baseline with the U.S. Waterpipe Dependence Scale (α = .50; Sidani et al., 2016). We also assessed respiratory symptoms at baseline with the American Thoracic Society Questionnaire (α = .77) (Cassidy et al., 2015). Participants were additionally asked, “When you use hookah, how often do you feel a head rush, dizzy, or light-headed?” (never, sometimes, always).

Susceptibility to future hookah use.

At all waves, all participants were asked a series of five questions assessing their interest in future use, which were based on the susceptibility items from the Smoking Uptake Continuum (Choi et al., 2001) and the willingness items from the prototype/willingness model (Gibbons et al., 2003), but re-worded to concern hookah rather than cigarettes. Questions included, “Do you intend to smoke tobacco from a hookah sometime in the next year?” and, following a vignette about a group of one’s friends ending up at a hookah cafe, “How willing would you be to go to the hookah cafe and try a few puffs?” All five items were assessed on 1–7 scales and responses were aggregated to form our measure of susceptibility (α = .92).

Knowledge about hookah.

To assess knowledge about hookah and its health risks, participants were provided at baseline with a series of eight statements, and were asked whether each was true or false. Statements included “hookah smoke contains tar” and “by passing through water, hookah smoke is completely cleaned of toxins.” The correct true/false response to a statement was coded as 1, and incorrect responses and “don’t know” responses were coded as 0. Scores were then summed to provide a 0–8 hookah knowledge scale (α = .79).

Risk perceptions.

All participants were asked at baseline about their perceived risk of getting addicted to nicotine if they continued (or began) to use hookah and their perceived risk of getting serious health problems in their lifetime from hookah tobacco smoking if they continued (or began) to use it. These two items were assessed on a 1–7 scale (1 = no chance, 7 = certain to happen).

Other tobacco use.

All participants were asked at baseline about their ever use, and past-30-day use of the following products: cigarettes, cigars, cigarillos, smokeless tobacco, ecigarettes, pipes, and bidis or kreteks (combined to indicate any nonhookah tobacco use). Participants were also asked to indicate which tobacco product was the first they had ever tried.

Other substance use.

All participants were asked at baseline about past-30-day use of alcohol, and ever-use and past-30-day use of marijuana.

Personality characteristics and social risk factors.

Personality characteristics assessed at baseline included sensation seeking (α = .79; Eysenck & Eysenck, 1977; Zuckerman et al., 1978) and the 10-item personality inventory (Gosling et al., 2003), which is a brief measure of the big five personality domains (openness, conscientiousness, extraversion, agreeableness, and emotional stability; for each domain, the pairwise correlations between items > .14, ps ≤ .001). Peer use of hookah was assessed as the mean of two items asking about how many friends ever used hookah, and how many used hookah at least a few times a month (1 = none, 5 = almost all; r = .63, p < .001). Participants were also asked whether they had seen any advertising for hookah (coded as yes, no) and how important the social aspect of smoking was to them (1 = not at all important, 7 = very important).

Demographic characteristics.

Age, gender, race/ethnicity, country of birth, and socioeconomic status were all assessed at baseline. Socioeconomic status was measured in terms of three indicators: social class growing up, current social class (Harrell et al., 2013), and parental education (assessed separately for mother and father). Responses to these four indicators were z scored and aggregated to create our measure of socioeconomic status (α = .74). At the final follow-up, participants were asked if they lived in Ohio before starting at the university and, if yes, what county they lived in. Responses were coded according to existing state classifications (Aly et al., 2016): urban, suburban, rural, or out of state.

Analyses

Analyses began with descriptive statistics to characterize the overall sample, as well as the subsample of hookah users. We then used univariate and multivariable logistic regressions to determine predictors of (a) the transition to susceptibility among baseline nonsusceptible never-users, (b) initiation of hookah use among the baseline never-users, and (c) continued hookah use among the baseline ever-users. Predictors in the univariate models included demographics, personality characteristics, social risk factors, other tobacco/substance use, risk perceptions, hookah knowledge, addiction, and the American Thoracic Society Questionnaire. All multivariable models controlled for gender, race/ethnicity, and socioeconomic status, and included predictors that were statistically significant in the univariate analyses. Participants who did not complete any follow-up surveys (i.e., those who only participated at baseline) were excluded from the logistic regression analyses. When analyzing the subsample of hookah ever-users, a z-scored continuous measure of susceptibility demonstrated a normal distribution. However, for all other subsamples, the measure was highly skewed; in these instances, susceptibility was dichotomized according to the commonly used cutoffs (0 = no susceptibility, >0 = some susceptibility; Chassin et al., 2002; Tyc et al., 2009).

Results

Sample characteristics

Table 1 provides descriptive statistics for the sample at baseline. Average age was 18.6 years (SD = 0.7) and the sample was 51.6% female and 76.1% non-Hispanic White. Among the 1,000 participants invited to participate in the study, enrollment (vs. non-enrollment) at baseline was not related to gender, first-generation college status, or in- versus out-of-state family residence. At baseline, 53.7% of the sample reported having had alcohol within the past 30 days; 27.8% had ever used marijuana, and 35.7% had ever used a tobacco product.

Table 1.

Characteristics of the incoming freshman sample at baseline

Characteristic	n	% or M (SD)
Race/ethnicity	528
White, non-Hispanic		76.0%
Black, non-Hispanic		4.2%
Hispanic		3.4%
Asian		12.9%
Other race/ethnicity		3.4%
Gender	529
Female		51.6%
Male		48.0%
Other gender response		0.4%
Area	386
Urban		29.7%
Suburban		11.3%
Rural		12.3%
Out of state		16.3%
Age (years)	527	18.6 (0.7)
Socioeconomic status	528	0.0 (0.7)
Country of birth	527
Outside the United States		9.8%
United States		89.8%
Baseline hookah status	529
Ever-user		13.2%
Susceptible never-user		39.1%
Nonsusceptible never-user		47.6%
Ever other tobacco use	529
No		68.6%
Yes		31.4%
Past-30-day use alcohol	528
No		46.1%
Yes		53.7%
Ever blunt use	528
No		81.5%
Yes		18.3%
Ever marijuana use	528
No		87.0%
Yes		12.9%
Sensation seeking	528	2.2 (0.6)
Openness	528	5.3 (1.0)
Conscientiousness	528	5.4 (1.1)
Extraversion	528	4.2 (1.5)
Agreeableness	528	4.8 (1.2)
Emotional stability	528	4.8 (1.4)
Seen advertisements for hookaha	70
No		55.7%
Yes		44.3%
Peer hookah use	528	1.7 (0.7)
Like social aspect of using	529
No		70.1%
Yes		29.9%
Perceived risk of addiction	529	4.1 (1.6)
Perceived risk of health problems	529	4.6 (1.3)
Hookah knowledge	529	4.9 (2.4)
Addictiona	70
No symptoms		82.9
Some symptoms		17.1
ATSQ	528	10.7 (3.4)

Notes: Prevalence values may not sum to 100% due to missing data; ATSQ = American Thoracic Society Questionnaire.

^aQuestion only asked of ever-users of hookah.

Overall, 90.5% of the sample participated in at least one follow-up survey. Specific retention rates for the September, December, March, and June follow-ups were 82.6%, 76.0%, 75.6%, and 69.8%, respectively. Among the 529 participants who completed the baseline survey, completing at least one follow-up (vs. never completing any follow-ups) was not related to any of the demographic variables, baseline hookah use, or baseline susceptibility to hookah.

Becoming susceptible

There were 223 students who reported no susceptibility to hookah use at baseline and who never reported hookah use at any data collection period (this value of 223 excludes those students who did not complete a follow-up survey). Among this subsample of baseline nonsusceptible never-users, 30% transitioned into reporting some susceptibility for hookah use. Univariate analyses indicated that several factors assessed at baseline were predictive of becoming susceptible. When these factors were included in a multivariable logistic regression that also controlled for gender, race/ethnicity, and socioeconomic status, only baseline conscientiousness and area growing up remained significant (Table 2). Specifically, every 1-point increase on the 7-point conscientiousness scale predicted a 30% reduction in the odds of becoming susceptible to hookah (odds ratio [OR] = 0.70, 95% CI [0.49, 0.99], p = .043). Further, when compared with students who grew up in a rural part of the state, students who grew up in all other areas (urban, suburban, and out of state) had lower odds of becoming susceptible to hookah (68%, 73%, and 72% reduction, respectively; ps ≤ .02).

Table 2.

Odds ratios (ORs) and 95% confidence intervals (CIs) for multivariable logistic regressions testing predictors of transitioning to susceptibility, ever use, and continued use

	Nonsusceptible to susceptible		Never-use to ever-use		Ever-use to continued use
Variable	OR	[95% CI]	OR	[95% CI]	OR	[95% CI]
Gender (ref.: male)	1.05	[0.51, 2.18]	0.96	[0.44, 2.06]	0.47	[0.08, 2.70]
Race/ethnicity (ref.: non-White)	1.91	[0.79, 4.63]	0.41	[0.16, 1.04]	0.12	[0.02, 0.95]*
Socioeconomic status	0.98	[0.60, 1.59]	1.08	[0.64, 1.84]	0.75	[0.26, 2.12]
Ever other tobacco use (ref.: yes)	0.45	[0.15, 1.39]	0.65	[0.27, 1.56]
Past-30-day use alcohol (ref.: yes)			0.46	[0.17, 1.21]	10.70	[0.76, 150.24]
Ever blunt use (ref.: yes)			0.42	[0.13, 1.42]
Ever marijuana use (ref.: yes)			1.26	[0.40, 3.92]
Sensation seeking			0.72	[0.35, 1.47]
Conscientiousness	0.70	[0.49, 0.99]*
Extraversion			1.23	[0.93, 1.62]
Agreeableness					0.50	[0.24, 1.06]
Seen advertisements (ref.: no)					0.44	[0.09, 2.31]
Peer hookah use Area			1.97	[1.18, 3.27]**	2.32	[0.85, 6.34]
Urban	0.32	[0.13, 0.81]*
Suburban	0.27	[0.09, 0.79]*
Out of state	0.28	[0.10, 0.80]*
Baseline susceptibility (ref.: no)			3.27	[1.20, 8.91]*
Baseline susceptibility (continuous)					2.35	[1.11, 4.97]*
Like social aspect of using (ref.: yes)			1.04	[0.46, 2.37]
Perceived risk of addiction			1.07	[0.78, 1.48]
Perceived risk of health problems			0.72	[0.50, 1.04]
Hookah knowledge			1.20	[1.01, 1.42]*
Addiction (ref.: no indicators)					3.93	[0.22, 70.82]
ATSQ					1.14	[0.90, 1.46]

Notes: Blank spaces in the table indicate where a variable was not included in the multivariable model due to the variable not being significant in the univariate model. Ref. = reference; ATSQ = American Thoracic Society Questionnaire.

^*p < .05;

^**p < .01.

Hookah initiators

Among the students who reported never using hookah at baseline and completed a follow-up, 9.9% initiated use over their freshman year. Univariate analyses indicated that several factors assessed at baseline were predictive of initiation. When these factors were included in a multivariable logistic regression that also controlled for gender, race/ethnicity, and socioeconomic status, three factors remained significantly associated with a higher likelihood of use: greater knowledge about hookah (OR = 1.20, 95% CI [1.01, 1.42], p = .04), a higher prevalence of hookah use in the peer group (OR = 1.97, 95% CI [1.18, 3.27], p < .01), and higher susceptibility to future use (OR = 3.27, 95% CI [1.20, 8.91], p = .02). Thus, participants with some baseline susceptibility for hookah use had 3.3 times greater odds of initiating hookah use over the course of freshman year compared with those with no baseline susceptibility.

Baseline hookah users

At baseline, 13.2% of the sample reported having ever used hookah. For more than half (52.9%) of the ever-users, hookah was the first tobacco product ever tried; the next most-common first products were e-cigarettes (12.9%), cigarettes (10.0%), and cigarillos (10.0%). Among the participants who reported ever-use at baseline, 34.9% reported past-30-day use during one of the follow-ups. Univariate logistic regressions showed that several factors assessed at baseline were predictive of continued use. However, when these factors were included in a multivariable logistic regression that also controlled for gender, race/ethnicity, and socioeconomic status, only two factors were significant. First, students with higher susceptibility toward future use were more likely to continue using (OR = 2.35, 95% CI [1.11, 4.97], p = .03); specifically, for every 1-unit increase in susceptibility, students had 2.4 times greater odds of continuing to use. Second, non-Hispanic White students were less likely to continue using compared with students reporting another race/ethnicity (OR = 0.12, 95% CI [0.02, 0.95], p = .04).

Discussion

This study followed a cohort of freshman undergraduates over their first year of college to assess prevalence and changes in hookah-related behaviors and cognitions. For our first objective, we found that conscientiousness and a rural upbringing were the only significant predictors of transitioning to hookah susceptibility. Specifically, students high on conscientiousness were at low risk for hookah use—they had no susceptibility at baseline and remained nonsusceptible throughout the duration of the study period. This finding is consistent with previous studies indicating that conscientiousness is associated with a lower risk of cigarette smoking (Adams & Nettle, 2009; Malouff et al. 2006). The finding that growing up in a rural area was a risk factor for becoming susceptible does not appear to have been reported previously (although urban/rural designation is not assessed as often as other demographic factors). One possible explanation for this relation is that hookah cafes may be less common in rural areas, such that young people from rural areas (compared with those from more densely populated areas) experience a greater increase in hookah exposure and access when they matriculate to college. Contrary to our hypothesis, gender and other substance use did not predict a change in susceptibility in the multivariable models. Movement from being nonsusceptible to susceptible indicates that future movement along the uptake trajectory (e.g., to experimentation or continued use) may be possible. Therefore, better understanding the predictors of transitioning to hookah susceptibility will be a key area for future research.

Supporting the hypothesis for our second objective, susceptibility was a strong predictor of both continued hookah use among baseline ever-users and initiation of hookah use among baseline never-users. Thus, as with cigarette smoking, susceptibility to hookah use appears to be a strong antecedent to use progression. It is worth noting, however, that it is atypical to assess susceptibility among users—generally, it tends to be assessed among nonusers and experimenters only. It is thus possible that, when assessing susceptibility as a predictor of continued use among ever-users, the construct of “susceptibility” means something slightly different. Our definition of continued hookah use (“past-30-day use at any follow-up”) was likewise not a validated measure; further, as follow-up surveys were not conducted every 30 days, it is possible that we missed some instances of use and our results are underestimates of actual hookah use. This limitation illustrates the difficulty of assessing intermittent behaviors like hookah use.

Overall, 9.9% of baseline never-users initiated during the study. This increase is not as sharp as what has been reported for some college samples (e.g., Fielder et al., 2012b, reported 22% of nonusers initiated during their first year of college; Shepardson & Hustad, 2016, reported 13.8% during their first month). One potential reason for this somewhat lower rate is that hookah use may have declined in the United States; this possibility is supported by recent reports that hookah use among middle and high school students, although increasing from 2011 to 2015, reduced somewhat in 2016 (Jamal et al., 2017). Alternatively, the present findings may be unique to our sample, as hookah use is comparatively lower in Ohio than in other states (Park et al., 2017), and students have a variety of other social activities in which they could choose to participate.

Nevertheless, our finding that nearly 10% of baseline nonusers initiated hookah use over their freshman year is a concern, as is our finding that 30% of baseline nonsusceptible never-users came to indicate some hookah susceptibility. Further, we found that hookah was the most common first-tried tobacco product; this differs from studies in recent years, in which cigarettes were the most common first-tried product (Kulak et al., 2018; Meier et al., 2015). Overall, these prevalence estimates are a concern because of the risks inherent in hookah smoking, as well as hookah’s potential to serve as a gateway for initiation of other tobacco products (Akl et al., 2010; American Lung Association, 2011; Cobb et al., 2010; Fielder et al., 2013; Jensen et al., 2010; Shihadeh, 2003; Soneji et al., 2017; St. Helen et al., 2014). There are currently very few interventions that target hookah use (Maziak et al., 2015; Momenabadi et al., 2018). Thus, there is a clear need for greater development and dissemination of hookah prevention and intervention programs; universities should consider incorporating such programs into their existing campus-based substance use prevention programs. The present findings suggest that program development and evaluation would benefit by using susceptibility as a means of identifying meaningful subgroups. Changes in susceptibility status should likewise be monitored, as susceptibility appears to be predictive of use and continued use.

Hookah has presented many challenges to tobacco regulatory efforts. It will be important for research and policy to continue addressing these challenges, which include where and how to adhere warning labels to hookah products; correcting loopholes that permit hookah cafes to operate despite smoke-free ordinances; and intervening when hookah cafes mix tobacco flavors without undergoing the premarket review process. Beyond these immediate needs, future regulatory measures could include bans on all flavored products—a policy that was recently upheld in San Francisco.

Overall, this study demonstrated a progression in hookah uptake—from nonsusceptible, to susceptible, to first use, to continued use. The numbers of students reporting hookah use at each wave of the present study were too low to examine more complex transitions, use patterns, or classes of users; future prospective studies could answer these questions with larger cohorts or by recruiting only hookah-susceptible individuals. Larger prospective cohorts may also shed more light on the patterns of intermittent use characteristic of many hookah users. As hookah remains popular among young people in the United States, it will be critical to stay abreast of this unsafe, and in many ways unique, form of tobacco use.