Introduction

Overactive bladder syndrome (OAB) is a syndrome characterized by urinary urgency, usually with urinary frequency and nocturia, with or without UUI, as defined by the International Continence Society (ICS) and International Urogynecological Association [1]. It is a common disorder prevalent in 9 to 43% in women and is marked by worsening symptom severity and prevalence with age [2]. In Lebanon, a study assessing the prevalence of pelvic floor disorder found a 35% prevalence of OAB with “at least a little bother” among a sample of 900 women of all ages attending primary care and specialty nongynecology clinics [3]. Symptoms of OAB have a considerable impact on quality of life and negative implications on the overall wellbeing of patients, including disturbances in sleep patterns, and decreased work productivity [4]. Several studies have been aimed at identifying lifestyle factors associated with this disorder. However, most of these studies included a wide age range and women of different parity [5]. The data on OAB in young nulliparous women remain scarce. Only one study, published in 2021, investigated urinary incontinence (UI) in nulliparous university students in Turkey and concluded that the prevalence of UI is 18% in this age group [6]. The association between lower urinary tract symptoms (LUTS) and dietary factors, and nondietary behavioral factors such as cigarette smoking, alcohol, and physical activity has been assessed in many studies [5, 7,8,9]. Kawahara et al. recently published a large-scale study to determine a correlation between cigarette smoking and OAB in nonhospitalized participants [10]. The authors found a 30% prevalence of OAB in women in their third decade. This prevalence was higher than previously reported and the median age was found to be younger [10]. Although cigarette smoking was found to be associated with OAB symptoms, the unique toxicant profile of WP smoking may have a different impact on OAB symptoms and their severity. To our knowledge, no study has evaluated the association between OAB symptoms and waterpipe (WP) smoking, an increasingly popular smoking habit among young people.

A WP consists of a head where a tobacco preparation and charcoal is placed for combustion. The head is connected to a bowl containing water and a hose with a mouthpiece through which smoke is inhaled. WP, also known as hookah, narghile, argileh, shisha, and goza, has gained wide popularity over the past few years [11]. WP tobacco is sold in a wide variety of “flavors,” where mostly unregulated synthetic products are added in order to give it a pleasant taste and smell and mask the harshness and bitterness of the tobacco smoke. The cooling effect of water and the common misconception that water “filters” toxins have made WP smoking a desirable alternative to cigarette smoking [12]. Compared with cigarette smoking, WP smoking is associated with greater carbon monoxide, benzene, and high polycyclic aromatic hydrocarbon exposure [13]. In 2013, the prevalence of WP smoking among students in London (United Kingdom) was twice as common as cigarette smoking [14]. A study published in 2011 concluded that 28% of university students in Lebanon were current WP smokers and 43% had smoked WP at least once in their life [15]. It is worth noting that WP was not found to have a gender predilection, with a recent study showing that 23.4% of female students smoked WP [14]. Although less common in the US, the National Youth Tobacco Survey (NYTS) in 2016 reported that 4.8% of high school students had smoked a WP in the past 30 days [12].

Our study was aimed at assessing the prevalence of OAB symptoms among nulliparous female university students and evaluating associations of these symptoms with WP smoking and other lifestyle factors, specifically BMI, cigarette smoking, alcohol consumption, and a variety of dietary and behavioral factors, including WP smoking.

Materials and methods

This study was approved by the Institutional Review Board (IRB) at the American University of Beirut. This is a cross-sectional study conducted via the administration of a web-based questionnaire to adult healthy nulliparous female university students in Beirut, Lebanon. Data were collected between October 2017 and February 2020.

Designated personnel from four different universities were asked to select at random a percentage of nulliparous female students above 18 years of age. The questionnaire was then sent by e-mail to the participants after obtaining their consent. Exclusion criteria included a history of pelvic floor dysfunction including incontinence, irradiation, diabetes, hypertension, or cardiovascular problems, and two or more urinary infections in the past.

In order to ensure a power of 80% of detecting a significant association between OAB and WP smoking with an OR of 2, a target sample size of 440 participants was required. This was based on the prevalence of WP smoking in university students in Lebanon [15] and on the prevalence of OAB symptoms among women younger than 40 [3]. The sample size was inflated to 2,900 participants in order to account for eligibility and nonresponse.

A web-based questionnaire was developed to assess the presence, severity, and degree of bother of the following OAB symptoms: urgency, frequency, nocturia, and UUI (Appendix 1). The following variables were evaluated: BMI, WP smoking, cigarette smoking, coffee, and tea consumption with and without artificial sweeteners, current alcohol consumption and consumption of soft drinks (diet and regular), as well as “energy drinks.” Finally, the participants who reported smoking WP were asked about their willingness to decrease, or stop WP smoking if it were shown to have an impact on OAB symptoms.

Exposure to WP smoking was assessed using the standardized measures and terminology proposed by Maziak et al., as follows [17]: those who have had one or two inhalations in their lifetime were considered as “ever smoking” and those who have smoked at least once in the previous month were considered as “current smokers.” “Former smoking” was used to describe someone who is not currently smoking but has smoked at least once a month for 3 consecutive months. Pattern of exposure was described as daily, weekly, or monthly. The age at smoking and whether they engage in WP “sharing” was also noted.

Symptoms of OAB were assessed using the Bristol Female Lower Urinary Tract Symptoms Questionnaire (BFLUTS), which is a validated and widely used tool to study the prevalence and impact of lower urinary tract symptoms [18]. A Likert scale was used to quantify the degree of bother.

The raw data were summarized and processed using IBM SPSS (Statistical Product and Service Solutions) Statistics (version 27). Descriptive statistics, reported as frequencies, were used to describe the cigarette smoking, WP smoking, and dietary habits of the study population. Pearson’s Chi-squared test was performed to analyze the association between representative indicators of lifestyle factors and each of the following: bothersome frequency, urgency, nocturia, and UUI. Multiple logistic regression analysis was performed to determine the independent contribution of each risk factor to the previously stated symptoms of frequency, urgency, nocturia, and UUI, which were all measured as binary.

Results

A web-based questionnaire was sent to 2,900 female university students. Responses were obtained from 767 (26.4%). The mean age of the sample was 22 (±5.06). A little less than one-third (29.5%) of the participants reported having ever smoked WP and 12.9% to have ever smoked at least 100 cigarettes. The largest proportion of surveyed female students had a normal BMI (66.8% with BMI 18.5–25) and 22.5% were overweight or obese. The majority of the sample drank coffee, with the highest proportion drinking 1–2 cups per day. Consuming soft drinks and lifetime alcohol consumption were both common (61.0% and 44.1%) (Table 1). The prevalence of OAB symptoms including urinary frequency, nocturia, urgency, and UUI is reported in Table 2. The most frequently reported symptom was nocturia (47.5%; CI 43.95–51.06) followed by bothersome urinary frequency (32.3%; CI 64.30–70.95). Urgency and urinary leakage were reported in 25.5% (CI 21.79-27.94) and 24.7% (CI 21.79–27.94) of participants respectively. Finally, 69.2% of WP smokers reported that they would at least decrease WP smoking if it were found to be linked to their urinary symptoms.

Table 1 Distribution of a sample of female university students (N = 767) by demographic characteristics and behavioral factors. In some categories the total is less than 767 owing to missing data
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Table 2 Distribution of a sample of female university students (N = 767) by reporting of overactive bladder symptoms. In some categories the total is less than 767 owing to missing data
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Bivariate analysis

Table 3 reports on the crude association between symptoms of OAB and BMI, WP smoking, cigarette smoking, alcohol consumption, coffee and tea consumption with and without artificial sweeteners, regular and diet soft drinks, and “energy drinks.” Bothersome frequency was only statistically significantly associated with artificial sweetener in coffee or tea consumers (OR:1.96, CI 1.17–3.29, p value 0.010). Consuming alcohol in the previous month was associated with significantly lower odds of nocturia (OR: 0.47, CI 0.29–0.74, p value 0.001) and urgency (OR: 0.53, CI 0.30–0.94, p value 0.030). Urgency was significantly associated with smoking one or more WP per week (OR: 2.01, CI 1.01–3.96, p value 0.044). Obesity, cigarette smoking, and “energy drinks” consumption were significantly associated with experiencing urine leakage (OR: 1.87, 2.37, and 1.44 respectively).

Table 3 Unadjusted odds ratios and 95% confidence intervals of occurrence of urinary symptoms and BMI, waterpipe and cigarette smoking patterns, alcohol drinking, energy drinks, artificial sweeteners, and diet/regular soft drink intake
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Multivariate analysis

A multivariate binary logistic regression analysis using variables showed p value <0.2 at the bivariate level in addition to variables that were deemed to be clinically relevant. Table 4 summarizes the adjusted results.

Table 4 Adjusted odds ratios and 95% confidence intervals of urinary symptoms and selected associated behavioral factors (BMI, waterpipe and cigarette smoking patterns, alcohol drinking, energy drinks and artificial sweeteners, and diet/regular soft drink intake
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Women who smoked less than once per week and women who smoked once or more than once per week were compared with women who have never smoked WP. OAB symptoms were not found to be significantly associated with WP smoking in women who smoked less than once per week. However, frequent smokers, namely women who smoked WP more than once per week, were found to be twice as likely to experience urgency as women who have never smoked (adjusted OR: 2.12 CI 1.00–4.48, p value < 0.048). Current cigarette smokers were significantly more likely to experience UUI more frequently than noncigarette smokers (adjusted OR: 1.95, CI 1.05–3.65, p value < 0.034).

The BMI was found to be the strongest independent associated risk factor for UUI (adjusted OR: 2.05 CI 1.37–3.05, p value < 0.001). Overweight and obese women as a group were twice as likely to experience symptoms of urinary leakage as their normal weight counterparts.

Women who drink coffee or tea with and without artificial sweeteners were compared with women who do not drink coffee or tea. Drinking coffee or tea with an artificial sweetener was found to be significantly associated with bothersome frequency (adjusted OR: 1.95, CI 1.15–3.32, p value 0.013). The effect of alcohol consumption in the past month was found to be significantly associated with lower odds of having nocturia and urgency (adjusted OR: 0.52, CI 0.32–0.85, p value 0.009 and OR 0.48, CI 0.26–0.87, p value: 0.017 respectively). Finally, the consumption of either regular soft drinks or diet soft drinks as well as energy drinks was not found to be significantly associated with any OAB symptoms in the adjusted model.

Discussion

Our study shows that OAB symptoms are common in young healthy nulliparous women. BMI is an established risk factor for both stress urinary incontinence and UUI [6, 8]. Our findings are in agreement with a recent meta-analysis that concluded that BMI was significantly higher in women with OAB [5].

Similar to others’ findings, current cigarette smoking in younger women was associated with an increased prevalence of UUI [10]. Kawahara et. al reported that cigarette smoking cessation was found to decrease the prevalence of UUI and urgency symptoms [10]. However, in our opinion, multiple confounding variables, in addition to recall bias, limit the relevance of this conclusion. Longitudinal studies are needed to answer this question with more certainty.

Our study shows a high prevalence of WP smoking among young female students with approximately one-third of our sample having smoked at least once in their lifetime. A comparable prevalence in the eastern Mediterranean region has been reported in the literature [16, 19]. Our study shows that young women who smoke WP were twice as likely to report symptoms of urgency. WP smoking is a social activity with sessions that often last more than 1 h. Although the peak nicotine plasma level is the same in WP and cigarette smoking, the effective exposure to nicotine, and presumably to other “toxins” could be higher owing to the longer sessions of WP smoking [20]. Furthermore, WP generates 35 times more carbon monoxide (CO) than cigarette smoking [12, 21].

The IUGA/ICS 2010 joint report on terminology of female pelvic floor dysfunction defines frequency as a complaint that micturition occurs more frequently during waking hours that previously deemed normal by the woman [1]; consequently, we used “bothered by frequency” as an outcome correlate to OAB symptoms instead of the number of micturition events per day.

Data on caffeinated beverages and OAB symptoms have been conflicting [8]. This could be due to different concentrations of caffeine in different coffees and teas, or to confounding factors often present among caffeinated beverage consumers. In spite of this, the International Consultation on Incontinence recommends caffeine reduction in women who experience urinary symptoms [23]. In our study, coffee and tea consumers had higher odds of experiencing bothersome frequency, but this association was only significant for those who used artificial sweeteners. Caffeine is not only present in coffee and tea but is also in different foods and beverages including chocolate and sodas. In a four-way crossover trial conducted among college students in the USA in 2005, consumption of diet Coke and caffeine-free diet Coke was associated with an increase in urgency and frequency, compared with carbonated water or classic Coke. This finding suggests that the consumption of artificial sweeteners, rather than the caffeine, is the likely culprit behind OAB symptoms [23]. By the same token, it could be that the artificial sweetener in coffee and tea rather than the caffeine itself is responsible for OAB.

Alcohol use in the past month was not associated with OAB symptoms but was associated with a decrease in nocturia and urgency. Some studies have reported a positive association of alcohol with OAB, whereas others have reported an inverse association [5]. In a 2019 meta-analysis, alcohol consumption was not found to be significantly associated with OAB [5]. Shiri et al. assessed the effect of alcohol consumption on nocturia and found that men who consumed 150 g of alcohol per week were at a lower risk of nocturia than abstainers [24]. The effect of alcohol consumption on nocturia needs to be elucidated in further studies.

Although in a recent meta-analysis, carbonated drinks, especially diet beverages containing artificial sweeteners, were found to increase OAB symptoms [7], we could not determine any significant association between “energy drink” intake, soft drink intake, and any of the OAB symptoms. Özgür Yeniel et al. concluded that consumption of carbonated beverages was associated with OAB symptoms only when consumed in “excessive amounts” [21]. It is also important to mention that soft drinks include a variety of brands that vary in their composition and in the concentration of their ingredients. This could theoretically explain the inconsistent effects, in different studies, of the consumption of soft drinks on the symptoms of OAB.

Our study has many limitations. This was a web-based questionnaire, which limited the response rate to 26%. However, this response rate is typical of e-mail-based surveys [25]. Our results are applicable in the geographic context where the study was conducted and cannot be generalized, especially in view of the established genetic and environmental aspects of OAB. Whether or not WP smokers and cigarette smokers were more inclined to participate in the study is a possibility. Therefore, selection bias cannot be absolutely ruled out. Furthermore, the cross-sectional design of this study does not allow determination of a cause–effect relationship between the variables but rather only allows inference of a possible correlation between the variables.

In our analysis, we included the frequency but not the duration of WP smoking “sessions.” These sessions are variable, and could last from minutes to hours, with a large variability in the quantity of inhaled smoke. Future studies should include, in addition to the frequency of WP smoking, the duration of the WP smoking session. Our questionnaire did not differentiate between carbonated and noncarbonated drinks, as the question addressed the consumption of “soft drinks.” Consequently, it is difficult to compare our results with those of most studies that specifically evaluated the effect of carbonated drinks on OAB. Similarly, the question regarding “energy drinks” lumped together drinks with and without alcohol. Ideally, the composition and concentration of different ingredients in these beverages should be known in order to estimate their effect on the symptoms of OAB. This, however, entails including a very large number of participants who are regular consumers of specific brands.

In conclusion, symptoms of OAB are common among young nulliparous women. UUI has the strongest correlation with elevated BMI. Urgency is associated with WP smoking, and bothersome frequency with artificial sweeteners used with coffee and tea. Soft drinks and “energy drinks” were not found to be significantly associated with OAB symptoms. Our results could help to establish the path for larger studies to evaluate behavioral factors associated with OAB in this specific population of nulliparous young women. Finally, our results highlight the need for more awareness campaigns regarding the toxic effect of WP smoking and its association with OAB.