SNPs Sets in Codifying Genes for Xenobiotics-Processing Enzymes Are Associated with COPD Secondary to Biomass-Burning Smoke.

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide; the main risk factors associated with the suffering are tobacco smoking (TS) and chronic exposure to biomass-burning smoke (BBS). Different biological pathways have been associated with COPD, especially xenobiotic or drug metabolism enzymes. This research aims to identify single nucleotide polymorphisms (SNPs) profiles associated with COPD from two expositional sources: tobacco smoking and BBS. One thousand-five hundred Mexican mestizo subjects were included in the study and divided into those exposed to biomass-burning smoke and smokers. Genome-wide exome genotyping was carried out using Infinium Exome-24 kit arrays v. 1.2. Data quality control was conducted using PLINK 1.07. For clinical and demographic data analysis, Rstudio was used. Eight SNPs were found associated with COPD secondary to TS and seven SNPs were conserved when data were analyzed by genotype. When haplotype analyses were carried out, five blocks were predicted. In COPD secondary to BBS, 24 SNPs in MGST3 and CYP family genes were associated. Seven blocks of haplotypes were associated with COPD-BBS. SNPs in the ARNT2 and CYP46A1 genes are associated with COPD secondary to TS, while in the BBS comparison, SNPs in CYP2C8, CYP2C9, MGST3, and MGST1 genes were associated with increased COPD risk.

Prevalence, attitude, knowledge, and risk perception towards COVID-19 in COPD patients associated to biomass exposure.

Chronic obstructive pulmonary disease (COPD) patients due to biomass exposure (BE-COPD) could be more affected than COPD due to tobacco smoke (TE-COPD) by the coronavirus disease 2019 (COVID-19) pandemic. The aim of this work was to determine the prevalence of COVID-19 in BE-COPD and TE-COPD and if housing conditions, poor attitude, knowledge, and risk perception towards COVID-19, particularly in BE-COPD women, could represent a risk factor for contagion.An 11% prevalence of COVID-19 was found with no significant difference between COPD groups. The BE-COPD group showed poorer socioeconomic status. No significant differences were found to be associated with SARS-CoV-2 infection regarding housing conditions, poor knowledge, attitude, and risk perception towards COVID-19. Living in urban areas and perceiving risk in COVID-19 were significantly associated with increased adherence to sanitary measures and concern of contagion. Around 40% of all patients showed poor risk perception and adherence to sanitary measures towards COVID-19.

Protective Role of Genetic Variants in HSP90 Genes-Complex in COPD Secondary to Biomass-Burning Smoke Exposure and Non-Severe COPD Forms in Tobacco Smoking Subjects.

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is an inflammatory disease characterized by airflow obstruction, commonly present in smokers and subjects exposed to noxious particles product of biomass-burning smoke (BBS). Several association studies have identified single-nucleotide polymorphisms (SNP) in coding genes related to the heat shock proteins family-genes that codify the heat shock proteins (Hsp). Hsp accomplishes critical roles in regulating immune response, antigen-processing, eliminating protein aggregates and co-activating receptors. The presence of SNPs in these genes can lead to alterations in immune responses. We aimed to evaluate the association of SNPs in the HSP90 gene complex and COPD. METHODS: We enrolled 1549 participants, divided into two comparison groups; 919 tobacco-smoking subjects (cases COPD-TS n = 294 and, controls SWOC n = 625) and 630 chronic exposed to BBS (cases COPD-BBS n = 186 and controls BBES n = 444). We genotyped 2 SNPs: the rs13296 in HSP90AB1 and rs2070908 in HSP90B1. RESULTS: Through the dominant model (GC + CC), the rs2070908 is associated with decreased risk (p < 0.01, OR = 0.6) to suffer COPD among chronic exposed BBS subjects. We found an association between rs13296 GG genotype and lower risk (p = 0.01, OR = 0.22) to suffer severe COPD-TS forms in the severity analysis. CONCLUSIONS: single-nucleotide variants in the HSP90AB1 and HSP90B1 genes are associated with decreased COPD risk in subjects exposed to BBS and the most severe forms of COPD in tobacco-smoking subjects.

SMALLa AIRWAY DISEASE IN COPD ASSOCIATED TO BIOMASS EXPOSURE.

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous entity that may result from different causative agents and risk factors and may follow diverse clinical courses, including COPD secondary to biomass smoke exposure. At present, this phenotype is becoming more important for two reasons: first, because at least almost half of the world's population is exposed to biomass smoke, and second, because the possibility of it being diagnosed is increasing. Biomass smoke exposure COPD affects primarily women and is related with insults to the airways occurred during early life. Although constituents of biomass smoke and tobacco smoke are similar, the physiopathological changes they induce differ depending not only on the chemical composition (related with the type of fuel used) but also on the particle size and the inhalation pattern. Evidence has shown that biomass smoke exposure affects the airway, predominantly the small airways causing anthracofibrosis and peribronchiolar fibrosis changes that will clinically translate into chronic bronchitis symptoms, with a high impact on the quality of life. In this review, we focus especially on the main epidemiological and clinical differences between COPD secondary to biomass exposure and COPD caused by tobacco exposure.

Varenicline for long term smoking cessation in patients with COPD.

BACKGROUND: Quitting smoking is key for patients with Chronic Obstructive Pulmonary Disease (COPD). Standard recommendations for quitting smoking are implemented for COPD as well. Varenicline Tartrate (VT) is the most effective drug to help quit smoking, but few studies have analysed its effectiveness. AIM OF THE STUDY: To determine the Abstinence Rate (AR) at 12 months, in COPD and non-COPD smokers. METHODS: Observational study in 31 COPD (post bronchodilator-BD FEV1/FVC <0.70) and in 63 non-COPD smokers, were invited to receive treatment with Varenicline Tartrate (VT). Fourteen subjects with COPD and 46 non-COPD subjects received additionally Cognitive-Behavioral Therapy (CBT). Abstinence rate (AR) was validated by exhaled carbon monoxide CO (COe), in addition to a phone or face-to-face interview. Motivation score was measured with a visual analogue scale (MS). RESULTS: Differences between COPD and non-COPD, mean FEV1/FVC ratio 0.52 ±â€¯0.10 vs. 0.90 ±â€¯0.15, age 60 ±â€¯10 vs. 47 ±â€¯10 years, smoking pack-years 37 ±â€¯3.5 vs. 22 ±â€¯12, and COe 16 ±â€¯11 vs. 12 ±â€¯9 ppm were statistically significant (p < 0.05); for MS the score was 93 ±â€¯11 vs. 93 ±â€¯11 and for attempts to quit (AQ) 2 ±â€¯2 vs. 2 ±â€¯3 were not. AR was not significantly different at 12 months (61.2 vs. 42.8% p = 0.072). Motivation was the only significant one-year AR predictor. CONCLUSIONS: COPD smokers had a similar response (higher tendency) to VT regardless of the presence of airflow obstruction and stronger nicotine addiction.

Genetic Variants in IL6R and ADAM19 are Associated with COPD Severity in a Mexican Mestizo Population.

Chronic obstructive pulmonary disease (COPD) is a complex and multifactorial disease with a strong genetic component. Our objective is to identify the genetic variants associated with COPD risk and its severity in Mexican Mestizo population. We evaluated 1285 single-nucleotide polymorphisms (SNPs) of candidate genes in 299 smokers with COPD (COPD-S) and 531 smokers without COPD (SWOC) using an Illumina GoldenGate genotyping microarray. In addition, 251 ancestry informative markers were included. Allele A of rs2545771 in CYP2F2P is associated with a lower risk of COPD (p = 4.02E-10, odds ratio [OR] = 0.104, confidence interval [CI] 95% 0.05-0.18). When the COPD group was stratified by severity according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD; levels III + IV vs. I + II), 3 SNPs (rs4329505 and rs4845626 in interleukin 6 receptor [IL6R] and rs1422794 in a disintegrin and metalloproteinase domain 19 [ADAM19]) were associated with a lower risk of suffering the most severe stages of the disease. rs2819096 in the surfactant protein D (SFTPD) gene was associated with a higher risk of COPD GOLD III + IV (p = 7.79E-03, OR = 1.80, CI 95% 1.16-2.79). Finally, the haplotype in IL6R was associated with a lower risk of suffering from more severe COPD, whereas the haplotype in ADAM19 was associated with a higher risk (p = 7.40E-03, OR = 2.83, CI 95% 1.20-6.86) of suffering from the severe stages of the disease. Our data suggest that there are alleles and haplotypes in the IL6R, ADAM19, and SFTPD genes associated with different severity stages of COPD; in CYP2F2P, rs25455771 is associated with a lower risk of COPD.

Electronic cigarettes. A position statement of the forum of international respiratory societies.

BACKGROUND: Awareness and usage of electronic cigarettes has exponentially increased during the last few years, especially among young people and women in some countries. The rapid acceptance of electronic cigarettes may be attributed in part to the perception created by marketing and the popular press that they are safer than combustible cigarettes. GOALS: To alert and advise policy makers about electronic cigarettes and their potential hazards. METHODS: Using The Union's position paper on electronic cigarettes as the starting template, the document was written using an iterative process. Portions of the manuscript have been taken directly from the position papers of participating societies. RESULTS: Because electronic cigarettes generate less tar and carcinogens than combustible cigarettes, use of electronic cigarettes may reduce disease caused by those components. However, the health risks of electronic cigarettes have not been adequately studied. Studies looking at whether electronic cigarettes can aid smoking cessation have had inconsistent results. Moreover, the availability of electronic cigarettes may have an overall adverse health impact by increasing initiation and reducing cessation of combustible nicotine delivery products. CONCLUSIONS: The health and safety claims regarding electronic nicotine delivery devices should be subject to evidentiary review. The potential benefits of electronic cigarettes to an individual smoker should be weighed against potential harm to the population of increased social acceptability of smoking and use of nicotine, the latter of which has addictive power and untoward effects. As a precaution, electronic nicotine delivery devices should be restricted or banned until more information about their safety is available. If they are allowed, they should be closely regulated as medicines or tobacco products.

FEV1 decline in patients with chronic obstructive pulmonary disease associated with biomass exposure.

RATIONALE: Biomass exposure is an important risk factor for chronic obstructive pulmonary disease (COPD). However, the time-course behavior of FEV1 in subjects exposed to biomass is unknown. OBJECTIVES: We undertook this study to determine the FEV1 rate decline in subjects exposed to biomass. METHODS: Pulmonary function was assessed every year in a Mexican cohort of patients with COPD associated with biomass or tobacco during a 15-year follow-up period. MEASUREMENTS AND MAIN RESULTS: The mean rate of decline was significantly lower for the biomass exposure COPD group (BE-COPD) than for the tobacco smoke COPD group (TS-COPD) (23 vs. 42 ml, respectively; P < 0.01). Of the TS-COPD group, 11% were rapid decliners, whereas only one rapid decliner was found in the BE-COPD group; 69 and 21% of smokers versus 17 and 83% of the BE-COPD group were slow decliners and sustainers, respectively. A higher FEV1 both as % predicted and milliliters was a predictive factor for decline for BE-COPD and TS-COPD, whereas reversibility to bronchodilator was a predictive factor for both groups when adjusted by FEV1% predicted and only for the TS-COPD group when adjusted by milliliters. CONCLUSIONS: In the biomass exposure COPD group the rate of FEV1 decline is slower and shows a more homogeneous rate of decline over time in comparison with smokers. The rapid rate of FEV1 decline is a rare feature of biomass-induced airflow limitation.

Nicotine Addiction Development: From Epidemiology to Genetic Factors.

BACKGROUND: Nicotine addiction is a complex and multifactorial disease affecting the central nervous system and consists of a set of characteristic symptoms and signs. OBJECTIVE: The objective of this study was to provide an overview on smoking and the complexity of dependency, with special emphasis on the involvement of genetic factors, including neurexin and nicotinic cholinergic receptor genes. METHODS: The following two aspects are discussed in the present article: (i) epidemiology in Mexico; and (ii) a review of the published literature on genetic association studies using the National Center for Biotechnology Information (NCBI) database of the USA as a search tool. The search key words were: nicotine, smoking, dependence, genetic, tobacco, neurobiology and GWAS. The publication period of the reviewed articles was January 2005 to July 2015. RESULTS: There are numerous studies that provide evidence of the involvement of a genetic component that contributes to the risk of developing nicotine addiction, but the multifactorial nature of addiction requires coordinated research from multiple disciplines. CONCLUSION: Research is needed on the factors associated with genetic risk for nicotine addiction and their interaction with environmental factors.

COPD phenotypes in biomass smoke- versus tobacco smoke-exposed Mexican women.

We hypothesised that biomass smoke exposure is associated with an airway-predominant chronic obstructive pulmonary disease (COPD) phenotype, while tobacco-related COPD is associated with an emphysema-predominant phenotype. In this cross-sectional study, female never-smokers with COPD and biomass exposure (n=21) and female ex-cigarette smokers with COPD without biomass exposure (n=22) completed computed tomography (CT) at inspiration and expiration, pulmonary function, blood gas, exercise tolerance, and quality of life measures. Two radiologists scored the extent of emphysema and air trapping on CT. Quantitative emphysema severity and distribution and airway wall thickness were calculated using specialised software. Women in the tobacco group had significantly more emphysema than the biomass group (radiologist score 2.3 versus 0.7, p=0.001; emphysema on CT 27% versus 19%, p=0.046; and a larger size of emphysematous spaces, p=0.006). Women in the biomass group had significantly more air trapping than the tobacco group (radiologist score 2.6 and 1.5, respectively; p=0.02) and also scored lower on the symptom, activities and confidence domains of the quality of life assessment and had lower oxygen saturation at rest and during exercise (p<0.05). Biomass smoke exposure is associated with less emphysema but more air trapping than tobacco smoke exposure, suggesting an airway-predominant phenotype.

FEV1 inversely correlates with metalloproteinases 1, 7, 9 and CRP in COPD by biomass smoke exposure.

BACKGROUND: Matrix metalloproteinases (MMPs) and C-reactive protein (CRP) are involved in chronic obstructive pulmonary disease (COPD) pathogenesis. The aim of the present work was to determine plasma concentrations of MMPs and CRP in COPD associated to biomass combustion exposure (BE) and tobacco smoking (TS). METHODS: Pulmonary function tests, plasma levels of MMP-1, MMP-7, MMP-9, MMP-9/TIMP-1 and CRP were measured in COPD associated to BE (n = 40) and TS (n =40) patients, and healthy non-smoking (NS) healthy women (controls, n = 40). RESULTS: Plasma levels of MMP-1, MMP-7, MMP-9, and MMP-9/TIMP-1 and CRP were higher in BE and TS than in the NS healthy women (p <0.01). An inverse correlation between MMP-1, MMP-7, MMP-9, MMP-9/TIMP-1 and CRP plasma concentrations and FEV1 was observed. CONCLUSIONS: Increase of MMPs and CRP plasma concentrations in BE suggests a systemic inflammatory phenomenon similar to that observed in COPD associated to tobacco smoking, which may also play a role in COPD pathogenesis.

Fractional Exhaled Nitric Oxide (FeNO) in Biomass Smoke-Associated Chronic Obstructive Pulmonary Disease.

Chronic Obstructive Pulmonary Disease (COPD) is a disease characterized by local and systemic inflammation independently of the risk factor; during the exacerbations, such inflammation is accentuated and amplified. A practical inflammatory marker and one with an applicable predictive value in the follow-up has been sought. FeNO has shown an excellent performance in that respect within the context of asthma and has also been studied in tobacco-smoke COPD (COPD-TS). In Biomass-smoke COPD (COPD-BS), this, to our knowledge, has not been evaluated. OBJECTIVE: To measure FeNO levels in patients with COPD-BS and to compare these with those of patients with stable COPD-TS and in healthy controls. METHODS: Transversal, observational, descriptive, comparative, and analytical study. A total of 57 patients, including 23 with COPD-BS, 17 with COPD-TS, and 17 healthy control subjects. The measurement of FeNO was carried out on all of these by means of the on-line chemiluminescence technique; the values were expressed in parts per billion (ppb) for their analysis. RESULTS: It was observed that the FeNO values were similar between COPD-BS and COPD-TS and were significantly different between the healthy and stable COPD (both groups). No correlation was found between pulmonary function and symptoms with FeNO in any of the groups. CONCLUSIONS: The level of FeNO in stable COPD is found to be increased in a similar manner in COPD-BS and COPD-TS, with a significant difference on comparing it with that of the healthy subjects.

sRAGE levels are decreased in plasma and sputum of COPD secondary to biomass-burning smoke and tobacco smoking: Differences according to the rs3134940 AGER variant.

The receptor for advanced glycation end products (RAGE) and its gene (AGER) have been related to lung injury and inflammatory diseases, including chronic obstructive pulmonary disease (COPD). We aimed to evaluate the association of rs2071288, rs3134940, rs184003, and rs2070600 AGER single-nucleotide variants and the soluble-RAGE plasma and sputum levels with COPD secondary to biomass-burning smoke (BBS) and tobacco smoking. Four groups, including 2189 subjects, were analyzed: COPD secondary to BBS exposure (COPD-BBS, n = 342), BBS-exposed subjects without COPD (BBES, n = 774), tobacco smoking-induced COPD (COPD-TS, n = 434), and smokers without COPD (SWOC, n = 639). Allelic discrimination assays determined the AGER variants. The sRAGE was quantified in plasma (n = 240) and induced-sputum (n = 72) samples from a subgroup of patients using the ELISA technique. In addition, a meta-analysis was performed for the association of rs2070600 with COPD susceptibility. None of the studied genetic variants were found to be associated with COPD-BBS or COPD-TS. A marginal association was observed for the rs3134940 with COPD-BBS (p = 0.066). The results from the meta-analysis, including six case-control studies (n = 4149 subjects), showed a lack of association of rs2070600 with COPD susceptibility (p = 0.681), probably due to interethnic differences. The sRAGE plasma levels were lower in COPD-BBS compared to BBS and in COPD-TS compared to SWOC. The sRAGE levels were also lower in sputum samples from COPD-BBS than BBES. Subjects with rs3134940-TC genotypes exhibit lower sRAGE plasma levels than TT subjects, mainly from the COPD-BBS and SWOC groups. The AGER variants were not associated with COPD-BBS nor COPD-TS, but the sRAGE plasma and sputum levels are related to both COPD-BBS and COPD-TS and are influenced by the rs3134940 variant.

Characterization of the lung microbiome and inflammatory cytokine levels in women exposed to environmental risk factors: A pilot study.

INTRODUCTION: Lung microbiome dysbiosis affects the immune system balance and promotes lung inflammation. We aimed to characterize and compare the lung bacteriome composition and the cytokine profile in women with normal lung function exposed to risk factors for chronic lung diseases (tobacco smoking and biomass-burning smoke exposure). METHODS: We included women with biomass-burning smoke exposure (BE, n = 11) and current smokers women (TS, n = 10). The bacteriome composition was performed in induced sputum, sequencing the 16 rRNA gene. Cytokine levels were measured using enzyme-linked immunosorbent assay multiplex assay in the supernatant of induced sputum. For quantitative variables, we used medians and minimum and maxim values. For the amplicon sequence variants (ASV) differential abundance testing between groups. RESULTS: At the taxa level, the phylum Proteobacteria was found in a higher proportion in the TS group concerning BE (p = .045); however, after the false discovery rate adjustment, this difference was not retained (p = .288). We found a higher concentration of IL-1ß in the TS group than in the BE group (248.6 vs. 177.9 pg/mL, p = .010). Women with high biomass-burning smoke exposure in an hour per day had a positive correlation with the abundance of Bacteroidota (ρ = 0.71, p = .014) and Fusobacteriota (ρ = 0.73, p = .011). FEV1/FVC had a positive correlation with an abundance of Bacteroidota, Proteobacteria, and Fusobacteria (ρ = 0.74, p = .009, ρ = 0.85, p = .001, and ρ = 0.83, p = .001, respectively). In tobacco smoking, women had a positive correlation (ρ = 0.77, p = .009) between cigarettes per day and Firmicutes' abundance. CONCLUSION: Compared to biomass-burning smoke-exposed women, current smokers have poor lung function and high levels of IL-1ß in sputum. Women with biomass-burning smoke exposure present an increased abundance of Bacteroidota and Fusobacteriota.

Can pictorial warning labels on cigarette packages address smoking-related health disparities? Field experiments in Mexico to assess pictorial warning label content.

OBJECTIVE: The objective of this study was to determine the most effective content of pictorial health warning labels (HWLs) and whether educational attainment moderates these effects. METHODS: Field experiments were conducted with 529 adult smokers and 530 young adults (258 nonsmokers; 271 smokers). Participants reported responses to different pictorial HWLs printed on cigarette packages. One experiment involved manipulating textual form (testimonial narrative vs. didactic) and the other involved manipulating image type (diseased organs vs. human suffering). RESULTS: Tests of mean ratings and rankings indicated that pictorial HWLs with didactic textual forms had equivalent or significantly higher credibility, relevance, and impact than pictorial HWLs with testimonial forms. Results from mixed-effects models confirmed these results. However, responses differed by participant educational attainment: didactic forms were consistently rated higher than testimonials among participants with higher education, whereas the difference between didactic and testimonial narrative forms was weaker or not statistically significant among participants with lower education. In the second experiment, with textual content held constant, greater credibility, relevance, and impact was found for graphic imagery of diseased organs than imagery of human suffering. CONCLUSIONS: Pictorial HWLs with didactic textual forms seem to work better than those with testimonial narratives. Future research should determine which pictorial HWL content has the greatest real-world impact among consumers from disadvantaged groups, including assessment of how HWL content should change to maintain its impact as tobacco control environments strengthen and consumer awareness of smoking-related risks increases.

Air quality in Mexico City during the COVID-19 lockdown possibly decreased COPD exacerbations.

The reduction of air pollution during the #COVID19 lockdown in Mexico City possibly reduced the exacerbation rate in #COPD patients due to biomass and tobacco despite that the self-isolation was not as strict as expected. https://bit.ly/3Iyv98t.

Clinical and microbiological characteristics and inflammatory profile during an exacerbation of COPD due to biomass exposure. A comparison with COPD due to tobacco exposure.

BACKGROUND: Patients with biomass exposure-related COPD (BE-COPD) is a prevalent disease in developing countries and requires a detailed study of its clinical and inflammatory characteristics, specifying interventions that may differ from tobacco exposure-related COPD (TE-COPD). The objective was to describe clinical characteristics, biomarkers of inflammation, T-helper cells, and microbiological agents during a COPD exacerbation in BE-COPD in comparison with TE-COPD. METHODS: A prospective observational study in patients with moderate or severe exacerbation was recruited either in the emergency room or the COPD clinic. At enrollment, nasopharyngeal swabs and sputum were collected to identify viral and bacterial pathogens. Blood samples were also collected to measure inflammatory biomarkers and T-helper cells levels. Days of hospitalization and mechanical ventilation requirement was evaluated. RESULTS: Clinical characteristics, vaccination history, hospitalization, history of exacerbations, and microbiological pattern between BE-COPD and TE-COPD were similar. The Th2 profile was higher in BE-COPD than in TE-COPD (2.10 [range 1.30-3.30] vs. 1.40 [range 1.20-1.80], p = 0.001). The Th2/Th1 ratio was higher in BE-COPD than TE-COPD (1.22 [range 0.58-2.57 ] vs. 0.71 [range 0.40-1.15], p = 0.004). The need of mechanical ventilation (MV) was higher in TE-COPD than BE-COPD (13% vs. 31.1%, p = 0.01). Nonvaccination history and high CRP levels were significantly associated with hospitalization [OR 1.48 (CI 95% 1.30-4.61, p = 0.005) and OR 1.17 (CI 95% 1.10-1.24, p = 0.001), respectively]. CONCLUSIONS: Clinical characteristics, inflammatory markers, and microbiological isolates were similar in both groups but BE-COPD show a tendency to present higher inflammatory Th2 cells and low requirement MV compared with TE-COPD.

Consumption of single cigarettes and quitting behavior: a longitudinal analysis of Mexican smokers.

BACKGROUND: Previous cross-sectional research has suggested single cigarettes could either promote or inhibit consumption. The present study aimed to assess the effects of single cigarette availability and consumption on downstream quit behavior. METHODS: We analyzed population-based, longitudinal data from adult smokers who participated in the 2008 and 2010 administrations of the International Tobacco Control Policy Evaluation Survey in Mexico. RESULTS: At baseline, 30% of smokers saw single cigarettes for sale on a daily basis, 17% bought singles at their last purchase, and 7% bought singles daily. Smokers who most frequently purchased singles, both in general and specifically to control their consumption, were no more likely to attempt to quit over the 14 month follow-up period than those who did not purchase singles. Frequency of buying singles to reduce consumption had a non-monotonic association with being quit at followup. The odds of being quit was only statistically significant when comparing those who had not bought singles to reduce consumption with those who had done so on a more irregular basis (AOR = 2.30; 95% CI 1.19, 4.45), whereas those who did so more regularly were no more likely to be quit at followup. Frequency of self-reported urges to smoke upon seeing singles for sale was unassociated with either quit attempts or being quit at followup. CONCLUSIONS: These results suggest that the relationship between singles consumption and quit behavior is complex, with no clear evidence that singles either promote or inhibit downstream quit behavior.