[Optimal cut-point of salivary cotinine concentration to discriminate smoking status in the adult population in Barcelona]

Specific biomarker comparison in current smokers, e-cigarette users, and non-smokers

INTRODUCTION

This study aims to address the existing gap in the literature, while adding evidence, by comparing tobacco-specific biomarkers (cotinine and nitrosamines: NNK, NNAL, NNN), and other biomarkers of e-cigarette use (humectants: glycerol, 1,2-PD, 1,3-PD) according to five study groups.

METHODS

A pooling analysis including two different studies was conducted. In both analyses, we took saliva samples from smokers (n = 409) and non-smokers (n = 154), dual tobacco and e-cig users (n = 92), exclusive e-cig user with nicotine (n = 158), and exclusive e-cig users without nicotine (n = 38). We analyzed and compared the geometric means (GM) and geometric standard deviations (GSD) of the concentration of tobacco-specific biomarkers, and e-cigarette biomarkers among groups. We used log-linear models adjusted for sex and age to model the change percentage and their 95% confidence intervals.

RESULTS

Cotinine was significantly higher in nicotine consumers and in e-cigarette users without nicotine when compared to non-smokers. TSNAs were generally significantly lower in non-smokers and higher in nicotine consumers. NNN and NNAL were lower in e-cigarette users with nicotine comparted to smokers, and NNN was higher in e-cigarette users without nicotine when compared to non-smokers. No differences were found in humectant biomarkers between e-cigarette groups.

CONCLUSIONS

Although there was a reduction in TSNAs in e-cigarette exclusive users compared to smokers, and a reduction of cotinine concentrations in e-cigarette exclusive users without nicotine compared to smokers, there are still high levels of these biomarkers when compared to non-smokers, which may be a clue towards the harmful effect of e-cigarettes.

Variation in Nicotine Metabolization According to Biological Factors and Type of Nicotine Consumer

This study aims to describe the nicotine metabolite ratio among tobacco smokers and electronic cigarette (e-cigarette) users and nonusers. We analyzed pooled data from a longitudinal and a cross-sectional study of the adult population from the city of Barcelona. The final sample included information on 166 smokers, 164 e-cigarettes users with nicotine, 41 e-cigarette users without nicotine, 95 dual users (users of both products), and 508 nonusers. We used log-linear models to control for the potential confounding effect of the daily number of cigarettes smoked. Salivary nicotine metabolic rate assessment included the rate of nicotine metabolism (cotinine/nicotine) and the nicotine metabolite ratio (trans-3′-hydroxycotinine/cotinine). Exclusive users of e-cigarette without nicotine have the lowest rate of nicotine metabolism (Geometric mean: 0.08, p-values < 0.001) while cigarette smokers have the highest (Geometric mean: 2.08, p-values < 0.001). Nonusers have lower nicotine metabolic rate than cigarette smokers (Geometric means: 0.23 vs. 0.18, p-value < 0.05). Younger individuals (18−44 years) have a higher rate of nicotine metabolism than older individuals (45−64 years and 65−89) (Geometric means: 0.53 vs. 0.42 and 0.31, respectively, p-values < 0.01) and individuals with lower body mass index (21−25 kg/m2) have a higher rate of nicotine metabolism than the rest (26−30 kg/m2 and 31−60 kg/m2) (Geometric means: 0.52 vs. 0.35 and 0.36, respectively-values < 0.01). Nicotine metabolic rates are useful biomarkers when reporting smoking status and biological differences between individuals.

Changes in the salivary cotinine cut-offs to discriminate smokers and non-smokers before and after Spanish smoke-free legislation

INTRODUCTION

High levels of cotinine in non-smokers indicate passive exposure to tobacco smoke. This study aims to evaluate variations in salivary cotinine cut-offs to discriminate smokers and non-smokers before and after the implementation of smoke-free legislation (Law 28/2005 and Law 42/2010) in a sample of the adult population of Barcelona, Spain.

METHODS

This longitudinal study analyzes salivary cotinine samples and self-reported information from a representative sample (n = 676) of the adult population from Barcelona before and after the approval of smoke-free legislation. We calculated the receiver operating characteristic (ROC) curves, to obtain optimal cotinine cut-off points to discriminate between smokers and non-smokers overall, by sex and age, and their corresponding sensitivity, specificity, and area under the curve. We used linear mixed-effects models, with individuals as random effects, to model the percentage change of cotinine concentration before and after the implementation of both laws.

RESULTS

The mean salivary cotinine concentration was significantly lower post-2010 law (-85.8%, p < 0.001). The ROC curves determined that the optimal cotinine cut-off points for discriminating non-smokers and smokers were 10.8 ng/mL (pre-2005 law) and 5.6 ng/mL (post-2010 law), with a post-2010 law sensitivity of 92.6%, specificity of 98.4%, and an area under the curve of 97.0%. The post-2010 law cotinine cut-off points were 5.6 ng/mL for males and 1.9 ng/mL for females.

CONCLUSION

The implementation of Spanish smoke-free legislation was effective in reducing secondhand smoke exposure and, therefore, also in reducing the cut-off point for salivary cotinine concentration. This value should be used to better assess tobacco smoke exposure in this population.

Measuring cigarette dependence: A comparison of two scales in two different groups of smokers

INTRODUCTION

The Fagerström Test for Cigarette Dependence (FTCD) and the Cigarette Dependence Scale (CDS) are usually used to assess cigarette dependence in clinical- and population-based studies. Our objective was to compare these two scales within groups of smokers from both contexts.

METHODS

The study was observational with smokers from a representative sample of the adult general population (n=188) and smokers attending a smoking cessation clinic in Barcelona, Spain (n=759). The FTCD and the CDS-5 (short version of 5 items) were used to assess cigarette dependence. We compared the standardized median scores obtained with both scales within each group of smokers by selected variables. To this aim, we re-scaled the scores of both scales to allow their comparison and assess their correlation within both groups.

RESULTS

The scores obtained with both scales were highly correlated within both groups of smokers (p<0.001), indicating good agreement in the assessment of cigarette dependence. Nevertheless, higher standardized CDS-5 scores were observed more frequently in the population group overall (3.9 vs FTCD score=3.7, p=0.001), among women (4.5 vs 4.2; p<0.001), in the youngest group of smokers (3.9 vs 3.2; p<0.007) and in light smokers (time to the first cigarette >60 min; 1.7 vs 1.1; p<0.001).

CONCLUSIONS

While the CDS-5 scored higher more frequently in the population group, the FTCD scored higher more frequently in the clinical group. These differences should be considered when designing either clinical- or population-based studies.

Third-hand exposure at homes: Assessment using salivary cotinine

BACKGROUND/OBJECTIVES

While exposure to secondhand smoke (SHS) is a well-established problem, exposure to third-hand smoke (THS) is scanty known and needs to be studied. The objective of this work is to characterize salivary cotinine concentrations among people who self-reported exposure to SHS and THS at home.

METHODS

Cross-sectional study of a representative sample (n = 736) of the adult population (≥16 years) from the city of Barcelona carried out in 2013-2014. A questionnaire on tobacco use and passive exposure was administered, and a saliva sample was collected for cotinine determination. For this study, the information of the non-smoker participants who provided saliva sample (n = 519) was used. The geometric means (GM) and geometric standard deviations (GSD) of the cotinine concentration were compared according to the type of self-reported exposure at home: (1) Not exposed to SHS or THS; (2) Exposed to SHS and THS; and (3) Only exposed to THS. We used log-linear models to compare the cotinine concentration of each exposed group with respect to the unexposed group, adjusting for sex, age, educational level, and tobacco exposure in other settings.

RESULTS

The GM of the salivary cotinine concentration was 0.34 ng/ml (GSD = 0.16) among individuals reporting SHS and THS exposure, 0.22 ng/ml (GSD = 0.15) among those reporting only THS exposure and 0.11 ng/ml (GSD = 0.04) among those who declared not to be exposed to SHS nor THS (p-value for trend <0.001). The regression model showed a statistically significant increase in cotinine concentration among those exposed to SHS and THS (188% higher, 95% CI: 153%; 223%), and only exposed to THS (106% higher, IC95. %: 74.5%; 137.0%) when comparing with the unexposed group. No statistically significant differences in cotinine concentration were observed between those exposed to SHS and THS compared to the THS group (-25.8%, 95% CI: -69.5%; 17.9%).

CONCLUSIONS/RECOMMENDATIONS

People exposed to third-hand smoke at home had quantifiable cotinine levels in saliva. No differences in cotinine levels were found between those exposed to second-hand and third-hand smoke at home. The reduction of exposure to third-hand smoke at home should be put into the agenda of tobacco control.

Assessing progress in protecting non-smokers from secondhand smoke

OBJECTIVE

To examine trends in population exposure to secondhand smoke (SHS) and consider two exposure metrics as appropriate targets for tobacco control policy-makers.

DESIGN

Comparison of adult non-smokers' salivary cotinine data available from 11 Scottish Health Surveys between 1998 and 2016.

METHODS

The proportions of non-smoking adults who had measurable levels of cotinine in their saliva were calculated for the 11 time points. The geometric mean (GM) concentrations of cotinine levels were calculated using Tobit regression. Changes in both parameters were assessed for the whole period and also for the years since implementation of smoke-free legislation in Scotland in 2006.

RESULTS

Salivary cotinine expressed as a GM fell from 0.464 ng/mL (95% CI 0.444 to 0.486 ng/mL) in 1998 to 0.013 ng/mL (95% CI 0.009 to 0.020 ng/mL) in 2016: a reduction of 97.2%. The percentage of non-smoking adults who had no measurable cotinine in their saliva increased by nearly sixfold between 1998 (12.5%, 95% CI 11.5% to 13.6%) and 2016 (81.6%, 95% CI 78.6% to 84.6%). Reductions in population exposure to SHS have continued even after smoke-free legislation in 2006.

CONCLUSIONS

Scotland has witnessed a dramatic reduction in SHS exposure in the past two decades, but there are still nearly one in five non-smoking adults who have measurable exposure to SHS on any given day. Tobacco control strategies globally should consider the use of both the proportion of non-smoking adults with undetectable salivary cotinine and the GM as targets to encourage policies that achieve a smoke-free future.

Assessment of salivary cotinine concentration among general non-smokers population: Before and after Spanish smoking legislations

BACKGROUND

In Spain, two smoke-free laws have been passed (Law 28/2005 and Law 42/2010).This study evaluates the association between Spanish smoking legislations and the second-hand smoke (SHS) exposure in an adult non-smoking population cohort in Barcelona (Spain).

METHODS

This is a longitudinal study, before and after the implementation of two national smoking bans, in a representative sample of adults (≥16years old) from Barcelona (Spain) surveyed in 2004-2005 and followed up in 2013-2014 (n=736). We only analyzed non-smokers (n=397). We obtained 9ml of saliva sample for analysis of cotinine, a biomarker of recent tobacco exposure. We calculated geometric means of salivary cotinine concentration and their geometric standard deviation. We used linear mixed effect models, with individuals as random effects, to model the percentage change in salivary cotinine concentration and their 95% confidence intervals.

RESULTS

The percentage of participants with saliva samples with measurable concentrations of cotinine fell from 92.4% to 64.2% after both Spanish smoking legislations. The geometric mean of salivary cotinine concentration significantly decreased 88% (from 0.98ng/mL to 0.12ng/mL, p<0.001) after the implementation of the two Spanish smoke-free legislations. The decrease of the GM salivary cotinine concentration was statistically significant independently of the sociodemographic variables.

CONCLUSION

There was a large reduction in the salivary cotinine concentration among adult non-smokers and higher cotinine concentrations among those declaring exposure to SHS at home after both legislations. Moreover, after both Spanish smoke-free laws salivary cotinine concentration was homogenized according to sociodemographic variables.

Secondhand smoke in outdoor settings: smokers' consumption, non-smokers' perceptions, and attitudes towards smoke-free legislation in Spain

OBJECTIVE

To describe where smokers smoke outdoors, where non-smokers are exposed outdoors to secondhand smoke (SHS), and attitudes towards smoke-free outdoor areas after the implementation of national smoke-free legislation.

DESIGN

This cross-sectional study was conducted between June 2011 and March 2012 (n=1307 participants).

SETTING

Barcelona, Spain.

PARTICIPANTS

Representative, random sample of the adult (≥16 years) population.

PRIMARY AND SECONDARY OUTCOMES

Proportion of smoking and prevalence of exposure to SHS in the various settings according to type of enclosure. Percentages of support for outdoor smoke-free policies according to smoking status.

RESULTS

Smokers reported smoking outdoors most in bars and restaurants (54.8%), followed by outdoor places at work (46.8%). According to non-smokers, outdoor SHS exposure was highest at home (42.5%) and in bars and restaurants (33.5%). Among non-smoking adult students, 90% claimed exposure to SHS on university campuses. There was great support for banning smoking in the majority of outdoor areas, which was stronger among non-smokers than smokers. Over 70% of participants supported smoke-free playgrounds, school and high school courtyards, and the grounds of healthcare centres.

CONCLUSIONS

Extending smoking bans to selected outdoor settings should be considered in further tobacco control interventions to protect non-smokers from SHS exposure and to establish a positive model for youth. The majority of public support for some outdoor smoke-free areas suggests that it is feasible to extend smoking bans to additional outdoor settings.

Impact of the Spanish smoke-free legislation on adult, non-smoker exposure to secondhand smoke: cross-sectional surveys before (2004) and after (2012) legislation

Background

In 2006, Spain implemented a national smoke-free legislation that prohibited smoking in enclosed public places and workplaces (except in hospitality venues). In 2011, it was extended to all hospitality venues and selected outdoor areas (hospital campuses, educational centers, and playgrounds). The objective of the study is to evaluate changes in exposure to secondhand smoke among the adult non-smoking population before the first law (2004-05) and after the second law (2011–12).

Methods

Repeated cross-sectional survey (2004–2005 and 2011–2012) of a representative sample of the adult (≥16 years) non-smoking population in Barcelona, Spain. We assess self-reported exposure to secondhand smoke (at home, the workplace, during leisure time, and in public/private transportation vehicles) and salivary cotinine concentration.

Results

Overall, the self-reported exposure to secondhand smoke fell from 75.7% (95%CI: 72.6 to 78.8) in 2004-05 to 56.7% (95%CI: 53.4 to 60.0) in 2011–12. Self-reported exposure decreased from 32.5% to 27.6% (−15.1%, p<0.05) in the home, from 42.9% to 37.5% (−12.6%, p = 0.11) at work/education venues, from 61.3% to 38.9% (−36.5%, p<0.001) during leisure time, and from 12.3% to 3.7% (−69.9%, p<0.001) in public transportation vehicles. Overall, the geometric mean of the salivary cotinine concentration in adult non-smokers fell by 87.2%, from 0.93 ng/mL at baseline to 0.12 ng/mL after legislation (p<0.001).

Conclusions

Secondhand smoke exposure among non-smokers, assessed both by self-reported exposure and salivary cotinine concentration, decreased after the implementation of a stepwise, comprehensive smoke-free legislation. There was a high reduction in secondhand smoke exposure during leisure time and no displacement of secondhand smoke exposure at home.

Development of an ultrasensitive immunochromatography test to detect nicotine metabolites in oral fluids

Passive exposure to tobacco smoke causes a variety of illnesses ranging from allergic responses to cancer. Assessment of exposure to second-hand tobacco smoke (SHS), particularly among vulnerable populations enables intervention and prevention of future disease. A minimally invasive oral fluids-based onsite test to detect such exposure would create a valuable tool for researchers and clinicians. Here we describe the development of a test that uses an inexpensive reader that utilizes a CMOS image sensor to reliably quantify a reporter signal and determine nicotine exposure. The rapid lateral flow test consists of a nitrocellulose strip with a control line containing goat anti-rabbit IgG, used as an internal standard, and a test line containing BSA-cotinine conjugate. To run the test, diluted sample containing antibodies against cotinine, the major metabolite of nicotine, is mixed with protein A-gold nanoparticles and placed on the sample pad. As the sample runs up to the nitrocellulose pad, antibodies in the running buffer bind to available cotinine. If cotinine is absent, the antibodies will bind to the BSA-cotinine derivative immobilized on the test line, resulting in an intense purple-red band. The concentration of cotinine equivalents in the sample can be estimated from interpretation of the test line. In this article we describe the effect of different cotinine derivatives, oral fluid pretreatment, and application and running buffers on assay sensitivity. The test can reliably detect as little as 2 ng mL(-1) cotinine equivalents. The assay is sensitive, simple, rapid, inexpensive, and easily implementable in point-of-care facilities to detect second-hand smoke exposure.