Heaviness of smoking predicts smoking relapse only in the first weeks of a quit attempt: findings from the International Tobacco Control Four-Country Survey

Sex effects in predictors of smoking abstinence and neuropsychiatric adverse events in the EAGLES trial

Significance There are sex effects in abstinence outcomes across all smoking cessation medications, but there is limited information regarding sex effects on cessation-related neuropsychiatric adverse events (NPSAEs) or interactions with psychiatric status.

METHODS

Secondary analysis of data from EAGLES of 8144 adults who smoke cigarettes randomized to varenicline, bupropion, nicotine patch or placebo. Design characteristics included region (within/outside US), psychiatric cohort (absent/present), and treatment. Baseline variables included demographics, smoking history, prior use of study treatments, lifetime suicide-related history, and prior psychiatric co-morbidities and medication use. Design characteristics were forced into logistic regressions models, and then interactions among sex, design elements, and baseline characteristics were evaluated for NPSAEs and 6-month cessation outcomes.

RESULTS

Findings demonstrated a significant interaction of sex and race (p < 0.02); Black women were more likely to report NPSAEs than Black men. For cessation outcomes, there were no significant interactions with psychiatric cohort and sex. Women vs men with higher baseline levels of smoking had lower odds of continuous abstinence. Women vs men who used varenicline previously had lower odds of continuous abstinence. For 6-month point prevalence, sex interacted with baseline cigarettes per day (p < 0.01) similar to the interaction for continuous abstinence. Sex interacted with medication (p < 0.03), such that women vs men had relatively greater success at achieving point prevalence abstinence on varenicline.

CONCLUSIONS

Overall, results demonstrated important sex and racial differences in the incidence of NPSAEs, but psychiatric status did not interact with sex on cessation outcomes. Findings did support prior work demonstrating relative increased efficacy of varenicline for women.

Association Between Comorbid Psychiatric Disorders and Persistent Smoking After a Diagnosis of Chronic Obstructive Pulmonary Disease Among Patients Seeking Treatment at a Tertiary Care Hospital in India

Introduction Smoking cessation is the most effective approach to slowing down the progression of chronic obstructive pulmonary disease (COPD). Despite this, almost half of COPD patients continue to smoke after diagnosis. COPD patients with current smoking status are more likely to have concurrent psychiatric comorbidities, for instance, depression and anxiety. These psychiatric disorders can contribute to the persistence of smoking in individuals with COPD. This study aimed to investigate predictors of smoking persistence in COPD patients. Materials and methods A cross-sectional study was conducted in the Outpatient Department (OPD) of the Department of Pulmonary Medicine in a tertiary care hospital from August 2018 to July 2019. Patients with COPD were screened for their smoking status. All subjects were then personally assessed for any psychiatric comorbidity using the Mini International Neuropsychiatric Interview (MINI), the Patient Health Questionnaire-9 (PHQ-9), and the Anxiety Inventory for Respiratory (AIR) Disease. Logistic regression was performed to compute the odds ratio (OR).  Results The study included a total of 87 COPD patients. Of the 87 COPD patients, 50 were current smokers, and 37 were past smokers. COPD patients with psychiatric disorders were four times more likely to continue smoking than those without psychiatric comorbidities (OR: 4.62, 95% CI: 1.46-14.54). The results showed that increasing PHQ-9 scores by one unit in COPD patients increased the likelihood of continuing to smoke by 27 percent. Conclusion In our multivariate analysis, current depression was found as a significant predictor of continued smoking in COPD patients. The present results are consistent with reports from previous research that depressive symptoms are associated with continued smoking in patients with COPD. COPD patients who are currently smoking should be examined for psychiatric disorders and treated concurrently to achieve effective smoking cessation.

Augmented reality for extinction of cue-provoked urges to smoke: Proof of concept

OBJECTIVE

Cue-exposure therapy (CET) aims to extinguish conditioned cue reactivity (CR) to aid in smoking cessation. A key disadvantage of extant CET is its limited ability to generalize extinction to the real world. Our team developed a set of augmented reality smoking-related and neutral cues that can appear in real-time in smokers' natural environments as viewed through a smartphone screen. Prior to deployment as a clinical tool, the present study tested the ability of AR smoking cues to extinguish CR in a controlled laboratory study with an AR smartphone application developed for this project. We hypothesized that daily smokers who completed a single session of cue exposure with AR smoking cues (extinction condition) would demonstrate lower cue-provoked urge to smoke at posttest compared to those who viewed AR neutral cues (control condition).

METHOD

Daily smokers (N = 129, 46.5% female, Mage = 47.6, Mcigarettes/day = 19.1) in acute abstinence were randomized to either the extinction or control condition comprising 28 AR trials.

RESULTS

As hypothesized, we found a Time × Condition interaction indicating that posttest urge ratings were lower in the extinction condition than in the control condition (p = .034). A secondary hypothesis that participants in the extinction condition would show a longer latency to smoke when provided a cigarette was not supported.

CONCLUSIONS

These laboratory findings provide evidence supporting the potential clinical efficacy of AR cues for cue-exposure trials, setting the stage for testing in smokers' naturalistic environments. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The effect of a real-world intervention for smoking cessation in Adults with and without comorbid psychiatric and substance use disorders: A one-year follow-up study

This study evaluated short-term abstinence and prolonged abstinence following a real-world intervention for smoking cessation in a sample of 1,213 adults with nicotine dependence only (ND), nicotine dependence and past history of another substance use disorder (ND-SUD), nicotine dependence and a non-substance use mental health disorder (ND-MD), or nicotine dependence and comorbid substance use disorder and mental health disorder (ND-SUMD). Participants received six sessions of group Cognitive Behavioral Therapy (CBT) and pharmacotherapy. Abstinence was assessed following completion of treatment and at 12-month follow-up. Logistic regression and survival analyses were performed. Participants who were lost to follow-up were included as censored and baseline differences were used as covariates in multivariate analyses. Rates of short-term abstinence and prolonged abstinence were significantly different between ND and ND-SUMD (20.9% versus 36.5%; 14.9% versus 22.4%, respectively). Among participants with follow-up, 37.7% were abstinent at 12-month. Diagnostic group was not associated with abstinence at 12-month follow-up after adjusting for nicotine dependence severity, which was associated with lower likelihood of abstinence (HR=1.11;95%CI:1.03-1.19). CBT plus pharmacotherapy had a positive effect on smoking cessation among the participants in this study. Special attention should be given to adults with more severe nicotine dependence and comorbid psychiatric and substance use disorders.

Associations of tobacco cigarette use and dependence with substance use disorder treatment completion by sex/gender and race/ethnicity

INTRODUCTION

Individuals with substance use disorders (SUD) are approximately five times more likely to smoke cigarettes than the general population. Individuals who smoke cigarettes have greater odds of SUD relapse compared to individuals who do not smoke cigarettes, but we know little about how cigarette use is related to SUD treatment completion overall by sex/gender or race/ethnicity.

METHODS

This study examined 2855 adults (71.98 % male; >70 % racial/ethnic minority) in outpatient and residential SUD treatment at a New York-based treatment agency over a six-month period in 2018.

RESULTS

Overall, approximately three-fourths of SUD treatment-seeking participants smoked cigarettes, with high rates across sex/gender and racial/ethnic groups. Nicotine dependence did not differ by sex/gender, and White Non-Hispanic adults had the highest levels of nicotine dependence across racial/ethnic groups. Those who smoked cigarettes were significantly less likely to complete treatment compared to those who did not smoke cigarettes (OR = 0.69; 95 % CI: 0.58, 0.82). The study found no overall differences in SUD treatment completion and length of stay by sex/gender or race/ethnicity.

CONCLUSIONS

Given the high prevalence of cigarette smoking and lower odds of completing SUD treatment, the current system of care for SUD treatment may be enhanced by addressing cigarette smoking from onset of treatment.

Cost-Effectiveness of a Telephone-Based Smoking Cessation Randomized Trial in the Lung Cancer Screening Setting

BACKGROUND

There are limited data on the cost-effectiveness of smoking cessation interventions in lung cancer screening settings. We conducted an economic analysis embedded in a national randomized trial of 2 telephone counseling cessation interventions.

METHODS

We used a societal perspective to compare the short-term cost per 6-month bio-verified quit and long-term cost-effectiveness of the interventions. Trial data were used to micro-cost intervention delivery, and the data were extended to a lifetime horizon using an established Cancer Intervention Surveillance and Modeling Network lung cancer model. We modeled the impact of screening accompanied by 8 weeks vs 3 weeks of telephone counseling (plus nicotine replacement) vs screening alone based on 2021 screening eligibility. Lifetime downstream costs (2021 dollars) and effects (life-years gained, quality-adjusted life-years [QALYs]) saved were discounted at 3%. Sensitivity analyses tested the effects of varying quit rates and costs; all analyses assumed nonrelapse after quitting.

RESULTS

The costs for delivery of the 8-week vs 3-week protocol were $380.23 vs $144.93 per person, and quit rates were 7.14% vs 5.96%, respectively. The least costly strategy was a 3-week counseling approach. An 8-week (vs 3-week) counseling approach increased costs but gained QALYs for an incremental cost-effectiveness ratio of $4029 per QALY. Screening alone cost more and saved fewer QALYs than either counseling strategy. Conclusions were robust in sensitivity analyses.

CONCLUSIONS

Telephone-based cessation interventions with nicotine replacement are considered cost-effective in the lung screening setting. Integrating smoking cessation interventions with lung screening programs has the potential to maximize long-term health benefits at reasonable costs.

Genotypic Differences in the Effects of Menthol on Nicotine Intake and Preference in Mice

Menthol has been shown to exacerbate elements of nicotine addiction in humans and rodents; however, the mechanisms mediating its effects are not fully understood. This study examined the impact of genetic factors in menthol’s effects on oral nicotine consumption by comparing two inbred mouse strains with differing sensitivities to nicotine. C57BL/6J (B6J) mice are nicotine-preferring, while DBA/2J (D2J) mice are not. While the effects of menthol on oral nicotine consumption have been highlighted in B6J mice, it is unknown if they extend to the D2J strain as well. Consequently, adolescent (PND 21) and adult (PND 63), male and female D2J mice were subjected to the nicotine two-bottle choice (2BC) paradigm with orally and systemically administered menthol. Then, we evaluated its impact on nicotine pharmacological responses in conditioned reward and nociception after systemic administration and, lastly, investigated the potential involvement of the TAAR1 gene and α7 nAChRs in menthol’s effects. Menthol failed to enhance oral nicotine consumption in adult and adolescent female and male D2J mice. Moreover, this lack in effect was not due to nicotine concentration, oral aversion to menthol, or basal preference for nicotine. Menthol also failed to augment nicotine reward or enhance nicotine-induced antinociception in D2J mice, demonstrating that genetic background plays a significant role in sensitivity to menthol’s effects on nicotine. Furthermore, TAAR1 or α7 nAChRs did not seem to mediate menthol’s differential effects in D2J mice. These findings support the existence of genotype-specific mechanisms that may contribute to the variable effects of menthol in different populations.

Factors Associated with Quit Interest and Quit Attempts among Young Adult JUUL Users

Despite reports suggesting young people are interested in quitting e-cigarettes, little work has examined predictors of quit outcomes. This study aimed to identify factors associated with quit outcomes among JUUL e-cigarette users in a longitudinal sample of young adults. We assessed undergraduate past-30-day JUUL users during autumn 2018 (N = 225); Our outcomes included short-term quit attempts and interest (spring 2019), and long-term quit attempts (spring 2020). We used logistic regression to examine the associations between our outcomes and JUUL use characteristics, other tobacco use, and sociodemographic factors. Findings indicated 76% of users were interested in quitting JUUL, and more than 40% reported a quit attempt. Quit outcomes were not related to sociodemographics. Short-term quit outcomes were more likely among freshmen and less likely among recent cigarillo users. Heavy JUUL users were more likely to report short- and long-term quit attempts, but JUUL device owners were less likely to report short- and long-term quit attempts. Higher nicotine dependence reduced the likelihood of a long-term quit attempt. There is a need for policy level actions that address tobacco control among this population. Findings suggest a range of unique factors that can inform such policies and programs to curb young adult e-cigarette use.

Predictive Power of Dependence Measures for Quitting Smoking. Findings From the 2016 to 2018 ITC Four Country Smoking and Vaping Surveys

INTRODUCTION

To test whether urges to smoke and perceived addiction to smoking have independent predictive value for quit attempts and short-term quit success over and above the Heaviness of Smoking Index (HSI).

AIMS AND METHODS

Data were from the International Tobacco Control Four Country Smoking and Vaping Wave 1 (2016) and Wave 2 (2018) surveys. About 3661 daily smokers (daily vapers excluded) provided data in both waves. A series of multivariable logistic regression models assessed the association of each dependence measure on odds of making a quit attempt and at least 1-month smoking abstinence.

RESULTS

Of the 3661 participants, 1594 (43.5%) reported a quit attempt. Of those who reported a quit attempt, 546 (34.9%) reported short-term quit success. Fully adjusted models showed that making quit attempts was associated with lower HSI (adjusted odds ratio [aOR] = 0.81, 95% confidence interval [CI] = 0.73 to 0.90, p < .001), stronger urges to smoke (aOR = 1.08, 95% CI = 1.04 to 1.20, p = .002), and higher perceived addiction to smoking (aOR = 0.52, 95% CI = 0.32 to 0.84, p = .008). Lower HSI (aOR = 0.57, 95% CI = 0.40 to 0.87, p < .001), weaker urges to smoke (aOR = 0.85, 95% CI = 0.76 to 0.95, p = .006), and lower perceived addiction to smoking (aOR = 0.55, 95% CI = 0.32 to 0.91, p = .021) were associated with greater odds of short-term quit success. In both cases, overall R2 was around 0.5.

CONCLUSIONS

The two additional dependence measures were complementary to HSI adding explanatory power to smoking cessation models, but variance explained remains small.

IMPLICATIONS

Strength of urges to smoke and perceived addiction to smoking may significantly improve prediction of cessation attempts and short-term quit success over and above routinely assessed demographic variables and the HSI. Stratification of analyses by age group is recommended because the relationship between dependence measures and outcomes differs significantly for younger (aged 18-39) compared to older (aged older than 40) participants. Even with the addition of these extra measures of dependence, the overall variance explained in predicting smoking cessation outcomes remains very low. These measures can only be thought of as assessing some aspects of dependence. Current understanding of the factors that ultimately determine quit success remains limited.

A dynamic modelling analysis of the impact of tobacco control programs on population-level nicotine dependence

According to the 'hardening hypothesis', average nicotine dependence will increase as less dependent smokers quit relatively easily in response to effective public health interventions, so that sustained progress in reducing smoking prevalence will depend on shifting the emphasis of tobacco control programs towards intensive treatment of heavily dependent smokers (who comprise an increasing fraction of continuing smokers). We used a system dynamics model of smoking behaviour to explore the potential for hardening in a population of smokers exposed to effective tobacco control measures over an extended period. Policy-induced increases in the per capita cessation rate are shown to lead inevitably to a decline in the proportion of smokers who are heavily dependent, contrary to the hardening hypothesis. Changes in smoking behaviour in Australia over the period 2001‒2016 resulted in substantial decreases in current smoking prevalence (from 23.1% in 2001 to 14.6% in 2016) and the proportion of heavily dependent smokers in the smoking population (from 52.1% to 36.9%). Public health interventions that have proved particularly effective in reducing smoking prevalence (tobacco tax increases, smoke-free environment legislation, antismoking mass media campaigns) are expected to also contribute to a decline in population-level nicotine dependence.

Cigarette-smoking characteristics and interest in cessation in patients with head-and-neck cancer

Purpose

Many patients diagnosed with head-and-neck cancer are current or former smokers. Despite the well-known adverse effects of smoking, continuation of smoking during cancer treatment is associated with reduced efficacy of that treatment and with cancer recurrence. In the present study, we examined smoking characteristics in patients with head-and-neck cancer near the time of cancer treatment.

Methods

A prospective cohort of patients with head-and-neck cancer who attended a dental oncology clinic before receiving cancer treatment at a regional cancer centre were invited to participate in a study that involved completing an interviewer-administered questionnaire to assess smoking characteristics, intention to quit, motivation to quit, and strategies perceived to potentially aid in successful cessation.

Results

The study enrolled 493 ever-smokers, with a response rate of 96.1% and a self-reported current smoker rate of 37.1% (n = 183). Most of the current smokers reported high nicotine dependence, with 84.7% (n = 155) indicating a time to first cigarette of 30 minutes or less. Most had previously attempted to quit smoking (77.0%), and many had prior unsuccessful quit attempts before resuming smoking again. Most were interested in quitting smoking (85.8%), and many (70.5%) were seriously considering quitting smoking within the subsequent 30 days.

Conclusions

Patients with head-and-neck cancer reported high nicotine dependence and high interest in cessation opportunities near the time of treatment for cancer. Those results might provide support for provision of smoking cessation opportunities.

Do stress, life satisfaction, depression and alcohol use predict quitting among Aboriginal and Torres Strait Islander smokers?

OBJECTIVE

To examine whether baseline measures of stress, life satisfaction, depression and alcohol use predict making or sustaining quit attempts in a national cohort of Aboriginal and Torres Strait Islander smokers.

METHODS

We analysed data from the nationally representative quota sample of 1,549 Aboriginal and Torres Strait Islander adults who reported smoking at least weekly in the Talking About The Smokes baseline survey (April 2012-October 2013) and the 759 who completed a follow-up survey a year later (August 2013-August 2014).

RESULTS

More smokers who reported negative life satisfaction, feeling depressed, higher stress or drinking heavily less often than once a week at baseline made a quit attempt between the baseline and follow-up surveys. In contrast, of these smokers who had made quit attempts between surveys, more who reported higher stress were able to sustain abstinence for at least one month; other associations were inconclusive. Conclusions and implications for public health: Health staff and Aboriginal and Torres Strait Islander smokers need not see being more stressed as an obstacle to quitting among Aboriginal and Torres Strait Islander people. Health staff should emphasise the benefits to mental health that come with successfully quitting smoking.

Abstinence and retention outcomes in a smoking cessation program among individuals with co-morbid substance use and mental disorders

Tobacco use is the leading cause of preventable death in the world. Although cigarette smoking prevalence has decreased, there are still disparities in morbidity and mortality experienced by individuals with substance use and/or mental disorders when compared to general population. The aim of this study was to compare treatment outcomes between three subgroups of smokers: individuals with substance use disorder (SUD-only), individuals with mental disorder without substance use disorders (MD-only), and individuals with co-morbid substance use and mental disorder (SUD + MD). Data of 498 smokers enrolled in a 6-week smoking cessation program in Brazil were analyzed. Sociodemographic, medical and tobacco use information were collected at baseline. Treatment included group cognitive behavioral therapy (CBT) and pharmacotherapy. The primary outcome was defined as "self-report 4-week quitter" (SR4WQ), a standardized measure to assess treatment success. Retention to treatment was also investigated. Associations between groups were analyzed using unadjusted and adjusted logistic regression models. The results showed that SUD + MD had worse outcomes when compared to the other two groups. After adjusting for level of smoking dependence and the use of medication, abstinence and retention to treatment of SUD-only became equivalent to SUD + MD. Because tobacco and other substance addictions share similar mechanisms, having history of SUD might impair successful results of conventional smoking programs. There is a need to further investigate specific variables associated with treatment success for a more resistant subgroup of individuals in mental health and perhaps to invest in more intensive actions, such as the use of combined pharmacotherapy and adapted CBT approaches.

Indicators of cigarette smoking dependence and relapse in former smokers who vape compared with those who do not: findings from the 2016 International Tobacco Control Four Country Smoking and Vaping Survey

BACKGROUND AND AIMS

It has been proposed that many smokers switch to vaping because their nicotine addiction makes this their only viable route out of smoking. We compared indicators of prior and current cigarette smoking dependence and of relapse in former smokers who were daily users of nicotine vaping products ('vapers') or who were not vaping at the time of survey ('non-vapers').

DESIGN

Cross-sectional survey-based comparison between vaping and non-vaping former smokers, including a weighted logistic regression of vaping status onto predictor variables, adjusting for covariates specified below.

SETTING

United States, Canada, Australia and England.

PARTICIPANTS

A total of 1070 people aged 18+ years from the 2016 International Tobacco Control (ITC) Four Country Smoking and Vaping Wave 1 Survey who reported having ever been daily smokers but who stopped less than 2 years ago and who were currently vapers or non-vapers.

MEASUREMENTS

Dependent variable was current vaping status. Predictor variables were self-reported: (1) smoking within 5 minutes of waking and usual daily cigarette consumption, both assessed retrospectively; (2) current perceived addiction to smoking, urges to smoke and confidence in staying quit. Covariates: country, sample sources, sex, age group, ethnicity, income, education, current nicotine replacement therapy use and time since quitting.

FINDINGS

Vapers were more likely than non-vapers to report: (1) having smoked within 5 minutes of waking [34.3 versus 15.9%, adjusted odds ratio (aOR) = 3.74, 95% confidence interval (CI) = 1.99, 7.03), χ2  = 16.92, P < 0.001]; having smoked > 10 cigarettes/day (74.4 versus 47.2%, aOR = 4.39, 95% CI = 2.22, 8.68), χ2  = 18.18, P < 0.001); (2) perceiving themselves to be still very addicted to smoking (41.3 versus 26.2%, aOR = 2.89, 95% CI = 1.58, 5.30, χ2  = 11.87, P < 0.001) and feeling extremely confident about staying quit (62.1 versus 36.6%, aOR = 3.22, 95% CI = 1.86, 5.59, χ2  = 17.36, P < 0.001). Vapers were not more likely to report any urges to smoke than non-vapers (27.7 versus 38.8%, aOR = 0.86, 95% CI = 0.44, 1.65, χ2  = 0.21, P = 0.643).

CONCLUSIONS

While former smokers who currently vape nicotine daily report higher levels of cigarette smoking dependence pre- and post-cessation compared with former smokers who are current non-vapers, they report greater confidence in staying quit and similar strength of urges to smoke.

C57BL/6 Substrain Differences in Pharmacological Effects after Acute and Repeated Nicotine Administration

Tobacco smoking is the major cause of disability and death in the United States and around the world. In addition, tobacco dependence and addiction express themselves as complex behaviors involving an interplay of genetics, environment, and psychological state. Mouse genetic studies could potentially elucidate the novel genes and/or gene networks regulating various aspects of nicotine dependence. Using the closely related C57BL/6 (B6) mice substrains, recent reports have noted phenotypic differences within C57BL/6J (B6J) and C57BL/6N (B6N) mice for some drugs of abuse: alcohol, opiates, and cocaine. However, the differences in nicotine’s effects have not yet been described in these substrains. We examined the phenotypic differences in these substrains following the acute and repeated administration of nicotine in several pharmacological measures, including locomotion (after acute and repeated exposure), body temperature, nociception, and anxiety-like behaviors. We report substrain differences in the pharmacological effects of acute and repeated nicotine administration in the B6 substrains. Overall, we show enhanced nicotine sensitivity to locomotion, hypothermia, antinociception, and anxiety-like behaviors in the B6J mouse substrain compared to B6N. In the repeated administration paradigm, both the B6N and B6J substrains showed no sensitized locomotor responses after repeated exposure to nicotine at the two doses tested. This study thus provides evidence that the B6 mouse substrains may be useful for genetic studies to elucidate some of the genetic variants involved in tobacco dependence and addiction.

Comparisons of early and delayed abstainers and its effects on long-term smoking cessation in Taiwan

Background

Different quitting trajectories may reflect the stages of behavior change among smokers. The nature of quitting patterns could help the public health sector to design appropriate cessation plans. This study compared demographic, health, and behavioral characteristics and the effects of long-term abstinence between early and delayed abstainers.

Methods

We retrospectively sampled 142 abstainers from smoking cessation clinic participants for a study conducted from January 1 to December 31, 2017. Baseline information was obtained at the first clinic visit, and phone interviews were conducted 2 weeks, 3 months, and 6 months later. The 7-day point prevalence abstinence was employed for measuring their quitting status. We defined early abstainers as those who attained abstinence by second week and delayed abstainers as those who had done so by the third month. We compared their characteristics and 6-month quit rates and examined potential predictors between the two quitting patterns.

Results

One hundred forty-two participants were included with 87 (61.3%) early abstainers and 55 (38.7%) delayed abstainers. Early abstainers were older with more comorbidities, presenting longer smoking duration, higher exhaled carbon monoxide (CO) concentration and Fagerstrom Test of Cigarette Dependence (FTCD) scores. The 6-month abstinence rate was high for both quitting patterns with no significant difference (83.9% versus 81.8%, p = 0.7462). Higher FTCD scores and exhaled CO concentration were potential predictors for early abstainers with adjusted odds ratio 1.16 (95% confidence interval [CI], 1.01–1.33) and 1.04 (95% CI, 1.00–1.08) respectively.

Conclusions

Our results associated early abstainers with older age, more comorbidities and higher nicotine dependence. Both groups achieved good long-term abstinence maintenance. Although early abstainers may achieve earlier reduction of health risks, smokers could still benefit from long-term abstinence if they can manage to quit smoking even at later phases of cessation courses.

Predictors and reasons for starting and sustaining quit attempts in a national cohort of Aboriginal and Torres Strait Islander smokers

INTRODUCTION AND AIMS

The national prevalence of daily smoking among the Aboriginal and Torres Strait Islander population is 39% but falling. We explore factors associated with starting and sustaining quit attempts, and reasons given for quitting.

DESIGN AND METHODS

We analysed data from the nationally representative quota sample of 759 Aboriginal and Torres Strait Islander adults who reported smoking at least weekly in the Talking About The Smokes baseline survey (April 2012-October 2013) who completed a follow-up survey a year later (August 2013-August 2014).

RESULTS

Having made more quit attempts, more recent quit attempts in the past, motivational attitudes, having been encouraged to quit by a health professional and having noticed tobacco advertising were associated with making a quit attempt between surveys. Having made longer quit attempts in the past, non-daily smoking and quit self-efficacy were associated with sustaining abstinence. But neither having made more quit attempts in the past nor dependence was associated with sustaining abstinence. Health concerns, price and setting an example to children were the most common reasons given by smokers and ex-smokers for quitting.

DISCUSSION AND CONCLUSIONS

Different factors predict making and sustaining quit attempts among Aboriginal and Torres Strait Islander smokers. We need to rethink current messages that just encourage Aboriginal and Torres Strait Islander smokers to keep making quit attempts by increasing motivation to quit, as motivation and making more quit attempts does not predict eventual success. We could focus more on increasing smokers' confidence that they can successfully quit.

Social networks and quitting in a national cohort of Australian Aboriginal and Torres Strait Islander smokers

INTRODUCTION AND AIMS

Health behaviours, such as smoking and quitting, spread person-to-person through social networks. We explore how social networks are associated with making and sustaining quit attempts for at least 1 month among Aboriginal and Torres Strait Islander smokers.

DESIGN AND METHODS

We analysed data from the nationally representative quota sample of 759 Aboriginal and Torres Strait Islander adults who reported smoking at least weekly in Talking About The Smokes baseline survey (April 2012-October 2013) who completed a follow-up survey a year later (August 2013-August 2014).

RESULTS

At baseline, 41% of smokers reported that all of their five closest family or friends smoked, but 62% reported that family or friends had provided encouragement to quit. Fewer smokers with other adult smokers in their household at baseline made a quit attempt between surveys (OR 0.63, 95% CI 0.45-0.87). Fewer smokers who had made an attempt between surveys sustained abstinence for at least 1 month if all of their five closest friends smoked (OR 0.60, 95% CI 0.37-0.97). Perceived support to quit in your social network was associated with making and sustaining a quit attempt.

DISCUSSION AND CONCLUSIONS

Exposure to smoking in the social networks of Aboriginal and Torres Strait Islander smokers is an obstacle to quitting, but there is also considerable support for quitting from within these same social networks. Health staff could consider encouraging smokers to draw on the few non-smokers within their social networks as role models to increase their confidence in quitting.

Kick.it: The development of an evidence-based smoking cessation smartphone app

Currently, the evidence for mobile health (mHealth) smoking cessation interventions is limited and heterogeneous, warranting the need for innovative rigorously developed solutions. The aim of this study was to describe the development of a smoking cessation smartphone application (app) developed using evidence-based principles. The app (Kick.it) was designed using the Intervention Mapping framework, incorporating an extensive literature review and qualitative study, in combination with the Behavioural Change Taxonomy v1, the Theoretical Domains Framework, and the Persuasive System Design framework. Kick.it provides quit smoking education, skills training, motivational content and self-regulation functionality for smokers, as well as their social support network. By logging cravings and cigarettes smoked, users will create their own smoking profile, which will be used to provide tailored interventions. It hosts a social network to allow 24/7 social support and provides in-app tools to help with urges to smoke. The app aims to motivate smokers to retry if they slip-up or relapse, allowing them to learn from previous smoking cessation attempts. Rather than basing the app on a singular behavioral change approach, Kick.it will use elements stemming from a variety of behavioral approaches by combining methods of multiple psychological theories. The use of best-practice intervention development frameworks in conjunction with evidence-based behavioral change techniques is expected to result in a smartphone app that has an optimal chance of helping people to quit smoking.

Smoking cessation in pregnancy: a continuing challenge in the United States

Despite significant population level declines, smoking during pregnancy remains a major public health issue in the United States (US). Approximately 360,000-500,000 smoke-exposed infants are born yearly, and prenatal smoking remains a leading modifiable cause of poor birth outcomes (e.g. birth < 37 gestational weeks, low birth weight, perinatal mortality). Women who smoke during pregnancy are more likely to be younger and from disadvantaged socioeconomic and racial and ethnic groups, with some US geographic regions reporting increased prenatal smoking rates since 2000. Such disparities in maternal prenatal smoking suggests some pregnant women face unique barriers to cessation. This paper reviews the current state and future direction of smoking cessation in pregnancy in the US. We briefly discuss the etiology of smoking addiction among women, the pathophysiology and effects of tobacco smoke exposure on pregnant women and their offspring, and the emerging issue of electronic nicotine delivery systems. Current population-based and individual smoking cessation interventions are reviewed in the context of pregnancy and barriers to cessation among US women. Finally, we consider interventions that are on the horizon and areas in need of further investigation.

Do predictors of smoking relapse change as a function of duration of abstinence? Findings from the United States, Canada, United Kingdom and Australia

AIMS

To estimate predictors of time to smoking relapse and test if prediction varied by quit duration.

DESIGN

Longitudinal cohort data from the International Tobacco Control Four-Country survey with annual follow up collected between 2002 and 2015.

SETTING

Canada, United States, United Kingdom and Australia.

PARTICIPANTS

A total of 9171 eligible adult smokers who had made at least one quit attempt during the study period.

MEASUREMENTS

Time to relapse was the main outcome. Predictor variables included pre-quit baseline measures of nicotine dependence, smoking and quitting-related motivations, quitting capacity and social influence, and also two post-quit measures, use of stop-smoking medications and quit duration (1-7 days, 8-14 days, 15-31 days, 1-3 months, 3-6 months, 6-12 months, 1-2 years and 2+ years), along with socio-demographics.

FINDINGS

All factors were predictive of relapse within the first 6 months of quitting but only wanting to quit, quit intentions and number of friends who smoke were still predictive of relapse in the 6-12-month period of quitting [hazard ratios (HR) = 1.20, P < 0.05; 1.13, P < 0.05; and 1.21, P < 0.001, respectively]. Number of friends smoking was the only remaining predictor of relapse in the 1-2 years quit period (HR = 1.19, P = 0.001) with none predictive beyond the 2-year quit period. Use of stop-smoking medications during quit attempts was related negatively to relapse during the first 2 weeks of quitting (HR = 0.71-0.84), but related positively to relapse in the 1-6-month quit period (HR = 1.29-1.54). Predictive effects of all factors showed significant interaction with quit duration except for perceiving smoking as an important part of life, prematurely stubbing out a cigarette and wanting to quit.

CONCLUSIONS

Among adult smokers in the United States, Canada, United Kingdom and Australia, factors associated with smoking relapse differ between the early and later stages of a quit attempt, suggesting that the determinants of relapse change as a function of abstinence duration.

Cannabis use among two national samples of Aboriginal and Torres Strait Islander tobacco smokers

INTRODUCTION AND AIMS

There is a concern that cannabis use is an important barrier to reducing Aboriginal and Torres Strait Islander smoking. We investigate the associations of cannabis use and tobacco smoking and quitting in two large national samples.

DESIGN AND METHODS

The 2012-2013 National Aboriginal and Torres Strait Islander Health Survey was a national stratified random household survey conducted between April 2012 and February 2013, and included 2580 adult Aboriginal and Torres Strait Islander smokers. The Talking About The Smokes Project interviewed a national quota sample of 1301 Aboriginal and Torres Strait Islander adult smokers between August 2013 and August 2014. Both surveys asked about tobacco smoking and quitting, cannabis use and socio-demographic factors.

RESULTS

Both surveys estimated that cannabis use is common among Aboriginal and Torres Strait Islander smokers (National Aboriginal and Torres Strait Islander Health Survey: 32%, Talking About The Smokes: 24%). Both surveys found a higher prevalence of cannabis use among smokers who were male, younger, unemployed or who more frequently consumed five or more alcoholic drinks in a day. However, the two surveys provided inconsistent evidence about whether cannabis use is associated with not quitting smoking tobacco.

DISCUSSION AND CONCLUSIONS

We did not find consistent evidence in this setting that cannabis use is an obstacle to quitting tobacco smoking. Nevertheless, we would still recommend that clinicians counselling Aboriginal and Torres Strait Islander tobacco smokers about quitting talk about cannabis use because its use is common and almost all mix it with tobacco.

Pain-related anxiety as a predictor of early lapse and relapse to cigarette smoking

Although emerging research suggests that pain-related anxiety may play a role in the maintenance of tobacco dependence, no previous work has examined pain-related anxiety as a predictor of smoking cessation outcomes. The current study aimed to test the hypothesis that pain-related anxiety would predict early lapse and relapse to cigarette smoking. These data were collected in the context of a primary study examining the role of emotional vulnerabilities in smoking cessation. The current analyses were conducted among 55 daily cigarette smokers who attempted to quit without psychosocial or pharmacological cessation aids. Pain-related anxiety was assessed at baseline using the Pain Anxiety Symptom Scale-20 (PASS-20). Early lapse and relapse were assessed using timeline follow-back procedures. Cox regression analyses indicated that pain-related anxiety was a significant predictor of both early smoking lapse and relapse such that for every 1-point increase on the PASS-20, the risk of early lapse increased by 3.7% and the risk of early relapse increased by 3.6%. These effects were evident above and beyond the variance accounted for by tobacco dependence, past 4-week pain severity, anxiety sensitivity, and the presence of current Axis I psychopathology. Kaplan-Meier survival analyses further revealed that among early lapsers, greater pain-related anxiety predicted a more rapid trajectory to lapse. Pain-related anxiety was also a significant predictor of early lapse when the sample was limited to smokers with past 4-week pain. These findings lend empirical support to the notion that pain-related anxiety may contribute to the maintenance of tobacco dependence among smokers who experience varying levels of pain intensity. (PsycINFO Database Record

The social determinants and starting and sustaining quit attempts in a national sample of Aboriginal and Torres Strait Islander smokers

OBJECTIVE

To assess whether social, economic and demographic measures are associated with initiating and sustaining quit attempts in a national sample of Aboriginal and Torres Strait Islander smokers.

METHODS

We analysed data from 759 adults who reported smoking at least weekly in the Talking About The Smokes baseline survey (April 2012 - October 2013) and completed a follow up survey a year later (August 2013 - August 2014).

RESULTS

Almost none of the standard baseline socioeconomic indicators predicted making or sustaining quit attempts. However, becoming employed was associated with making quit attempts (OR 1.88) and both becoming employed (OR 3.03) and moving to purchase a home (OR 2.34) were both positively associated with sustaining abstinence of one month or more. More smokers who had insufficient money for food or essentials because of money spent on cigarettes had made a quit attempt (OR 1.47) and sustained abstinence of one month or more (OR 1.74).

CONCLUSIONS AND IMPLICATIONS

Disadvantage does not seem to have pervasive negative effects on quitting. We should be more optimistic in our tobacco control activities with the most disadvantaged among Aboriginal and Torres Strait Islander smokers. Increasing personal empowerment (e.g. getting a job) may lead to at least short-term improvements in quitting.

Preliminary evaluation of a telephone-based smoking cessation intervention in the lung cancer screening setting: A randomized clinical trial

Incorporating effective smoking cessation interventions into lung cancer screening (LCS) programs will be essential to realizing the full benefit of screening. We conducted a pilot randomized trial to determine the feasibility and efficacy of a telephone-counseling (TC) smoking cessation intervention vs. usual care (UC) in the LCS setting. In collaboration with 3 geographically diverse LCS programs, we enrolled current smokers (61.5% participation rate) who were: registered to undergo LCS, 50-77 years old, and had a 20+ pack-year smoking history. Eligibility was not based on readiness to quit. Participants completed pre-LCS (T0) and post-LCS (T1) telephone assessments, were randomized to TC (N=46) vs. UC (N=46), and completed a final 3-month telephone assessment (T2). Both study arms received a list of evidence-based cessation resources. TC participants also received up to 6 brief counseling calls with a trained cessation counselor. Counseling calls incorporated motivational interviewing and utilized the screening result as a motivator for quitting. The outcome was biochemically verified 7-day point prevalence cessation at 3-months post-randomization. Participants (56.5% female) were 60.2 (SD=5.4) years old and reported 47.1 (SD=22.2) pack years; 30% were ready to stop smoking in the next 30 days. TC participants completed an average of 4.4 (SD=2.3) sessions. Using intent-to-treat analyses, biochemically verified quit rates were 17.4% (TC) vs. 4.3% (UC), p<.05. This study provides preliminary evidence that telephone-based cessation counseling is feasible and efficacious in the LCS setting. As millions of current smokers are now eligible for lung cancer screening, this setting represents an important opportunity to exert a large public health impact on cessation among smokers who are at very high risk for multiple tobacco-related diseases. If this evidence-based, brief, and scalable intervention is replicated, TC could help to improve the overall cost-effectiveness of LCS.

TRIAL REGISTRATION

NCT02267096, https://clinicaltrials.gov.

Persistence and amplitude of cigarette demand in relation to quit intentions and attempts

INTRODUCTION

The cigarette purchase task (CPT) is a method that can be used to assess the relative value of cigarettes. Based on cigarettes purchased across a price range, five derived metrics (Omax, Pmax, breakpoint, intensity, and elasticity) can assess cigarette demand. A study with adolescent smokers found that these could be reduced to two latent factors: persistence (price insensitivity) and amplitude (volumetric consumption). We sought to replicate this structure with adult smokers and examine how these variables relate to cessation efforts.

METHOD

Web-based survey conducted in 2014 among adult (18 years and above) current daily cigarette smokers (N = 1194). Participants completed the CPT, Fagerstrom Test for Nicotine Dependence (FTND), reported past-year quit attempts, and future quit intentions. We included published scales assessing perceived prevalence of smoking, social reactivity, smoker identity, and risk perception.

RESULTS

Our analysis supported two latent variables, persistence and amplitude, which correlated positively with FTND. Persistence was correlated with several psychosocial factors and was higher among those intending to quit very soon, but did not vary by number of past-year quit attempts. Amplitude differed across quit attempts and intention (p < 0.001) and, in multivariable models, was significantly associated with lower 30-day quit intention (OR = 0.76, p = 0.001).

CONCLUSIONS

Persistence and amplitude factors characterized CPT data in adults, discriminated known groups (e.g., smokers by intentions to quit), and were positively associated with nicotine dependence. Factor scores also appear to relate to certain psychosocial factors, such as smoker identity and perceptions of risk. Future research should examine the predictive validity of these constructs.

Smoking and environmental characteristics of smokers with a mental illness, and associations with quitting behaviour and motivation; a cross sectional study

Background

Persons with a mental illness are less likely to be successful in attempts to quit smoking. A number of smoking and environmental characteristics have been shown to be related to quitting behaviour and motivation of smokers generally, however have been less studied among smokers with a mental illness. This study aimed to report the prevalence of smoking characteristics and a variety of physical and social environmental characteristics of smokers with a mental illness, and explore their association with quitting behaviour and motivation.

Methods

A cross-sectional descriptive study was undertaken of 754 smokers admitted to four psychiatric inpatient facilities in Australia. Multivariable logistic regression analyses were undertaken to explore the association between smoking and environmental characteristics and recent quitting behaviour and motivation.

Results

Participants were primarily daily smokers (93 %), consumed >10 cigarettes per day (74 %), and highly nicotine dependent (51 %). A third (32 %) lived in a house in which smoking was permitted, and 44 % lived with other smokers. The majority of participants believed that significant others (68–82 %) and health care providers (80–91 %) would be supportive of their quitting smoking. Reflecting previous research, the smoking characteristics examined were variously associated with quitting behaviour and motivation. Additionally, participants not living with other smokers were more likely to have quit for a longer duration (OR 2.02), and those perceiving their psychiatrist to be supportive of a quit attempt were more likely to have had more quit attempts in the past six months (OR 2.83).

Conclusions

Modifiable characteristics of the physical and social environment, and of smoking, should be considered in smoking cessation interventions for persons with a mental illness.

Predictors of Successful Quitting among Thai Adult Smokers: Evidence from ITC-SEA (Thailand) Survey

This study uses longitudinal data from the International Tobacco Control Southeast Asia (ITC-SEA Thailand) survey to explore patterns and predictors of successful quitting among Thai adult smokers as a function of time quit. A cohort of a representative sample of 2000 smokers was surveyed four times from 2005 to 2009. A sample of 1533 individuals provided data for at least one of the reported analyses. Over the four years of follow-up, 97% made attempts to quit. Outcomes were successful quitting/relapse: (a) quit attempts of at least one month (short-term relapse, 43%) (57% remaining quit); (b) surviving at least six months (medium-term) (31%); (c) relapse between one and six months (45%); (d) having continuously quit between Waves 3 and 4 (sustained abstinence) (14%); and (e) relapse from six months on (44%) compared to those who continuously quit between Waves 3 and 4 (56%). Predictors for early relapse (<1 month) differ from longer-term relapse. Age was associated with reduced relapse over all three periods, and was much stronger for longer periods of abstinence. Cigarette consumption predicted relapse for short and medium terms. Self-assessed addiction was predictive of early relapse, but reversed to predict abstinence beyond six months. Previous quit history of more than one week was predictive of early abstinence, but became unrelated subsequently. Self-efficacy was strongly predictive of abstinence in the first month but was associated with relapse thereafter. Some determinants of relapse change with time quit, but this may be in somewhat different to patterns found in the West.

Past quit attempts in a national sample of Aboriginal and Torres Strait Islander smokers

OBJECTIVES

To describe past attempts to quit smoking in a national sample of Aboriginal and Torres Strait Islander people, and to compare their quitting activity with that in the general Australian population.

DESIGN, SETTING AND PARTICIPANTS

The Talking About The Smokes (TATS) project used a quota sampling design to recruit participants from communities served by 34 Aboriginal community-controlled health services and one community in the Torres Strait. We surveyed 1643 smokers and 78 recent quitters between April 2012 and October 2013. Baseline results for daily smokers (n = 1392) are compared with results for daily smokers (n = 1655) from Waves 5 to 8.5 (2006-2012) of the Australian International Tobacco Control Policy Evaluation Project (ITC Project).

MAIN OUTCOME MEASURES

Ever having tried to quit, tried to quit in the past year, sustained a quit attempt for 1 month or more.

RESULTS

Compared with the general population, a smaller proportion of Aboriginal and Torres Strait Islander daily smokers had ever tried to quit (TATS, 69% v ITC, 81.4%), but attempts to quit within the past year were similar (TATS, 48% v ITC, 45.7%). More Aboriginal and Torres Strait Islander daily smokers than those in the general population reported sustaining past quit attempts for short periods only. Aboriginal and Torres Strait Islander smokers whose local health services had tobacco control resources were more likely to have tried to quit, whereas men and people who perceived they had experienced racism in the past year were less likely. Younger smokers, those who had gone without essentials due to money spent on smoking, and those who were often unable to afford cigarettes were more likely to have tried to quit in the past year, but less likely to have ever sustained an attempt for 1 month or more. Smokers who were unemployed, those who had not completed Year 12 and those from remote areas were also less likely to sustain a quit attempt.

CONCLUSIONS

Existing comprehensive tobacco control programs appear to be motivating Aboriginal and Torres Strait Islander smokers to quit but do not appear to overcome challenges in sustaining quit attempts, especially for more disadvantaged smokers and those from remote areas.

Dependence in a national sample of Aboriginal and Torres Strait Islander daily smokers

OBJECTIVES

To examine indicators of nicotine dependence in a national sample of Aboriginal and Torres Strait Islander daily smokers and their association with sustaining a quit attempt for at least 1 month, and to make comparisons with a national sample of Australian daily smokers.

DESIGN, SETTING AND PARTICIPANTS

The Talking About The Smokes project used a quota sampling design to recruit 1392 daily smokers from communities served by 34 Aboriginal community-controlled health services and one community in the Torres Strait from April 2012 to October 2013. These were compared with 1010 daily smokers from the general Australian population surveyed by the International Tobacco Control Policy Evaluation Project from September 2011 to February 2012.

MAIN OUTCOME MEASURES

Cigarettes per day (CPD), time to first cigarette, Heaviness of Smoking Index (HSI), other indicators of dependence, and whether smokers had ever sustained a quit attempt for at least 1 month.

RESULTS

There was little difference in the mean HSI scores for Aboriginal and Torres Strait Islander and other Australian daily smokers. A higher proportion of Aboriginal and Torres Strait Islander daily smokers smoked ≤ 10 CPD (40% v 33.4%), but more also smoked their first cigarette within 30 minutes of waking (75% v 64.6%). Lower proportions of Aboriginal and Torres Strait Islander smokers reported having strong urges to smoke at least several times a day (51% v 60.7%) or that it would be very hard to quit (39% v 47.9%). Most Aboriginal and Torres Strait Islander smokers reported experiencing difficulties during their most recent quit attempt. All indicators of dependence, except CPD and strong urges, were positively associated with not having made a sustained quit attempt. Reported difficulties during the most recent quit attempt were more strongly associated with being unable to sustain quit attempts than were traditional measures of dependence.

CONCLUSION

Aboriginal and Torres Strait Islander smokers' experiences of past attempts to quit may be more useful than conventional indicators of nicotine dependence in understanding their dependence.

Does non-smoker identity following quitting predict long-term abstinence? Evidence from a population survey in England

AIMS

'Categorical self-labels' (e.g. thinking of oneself as a smoker or non-smoker) are important aspects of identity that can have a fundamental influence on behaviour. To explore the role identity aspects relating to smoking can play in smoking cessation and relapse, this study assessed the prospective associations between taking on a non-smoker identity following quitting and long-term abstinence.

METHODS

A representative sample of 574 ex-smokers in England who quit smoking in the past year was followed-up at three (N=179) and six months (N=163). Post-quit identity relating to smoking ('I still think of myself as a smoker' or 'I think of myself as a non-smoker'), and demographic and smoking-related characteristics were assessed at baseline. Self-reported smoking abstinence was assessed at follow-ups.

RESULTS

Non-smoker identity was reported by 80.3% (95%CI 76.8-83.4) of recent ex-smokers. Younger age (p=0.017) and longer abstinence (p<0.001) were independently associated with a post-quit non-smoker identity. After adjusting for covariates, non-smoker identity (p=0.032) and length of abstinence at baseline (p<0.001) were associated with continued abstinence at three month follow-up, and baseline length of abstinence (p=0.003) predicted continued abstinence at six months.

CONCLUSIONS

The majority of people who quit smoking recently consider themselves as non-smokers. Younger people and those who have been abstinent for longer are more likely to take on a non-smoker identity. Ex-smokers who make this mental transition following a quit attempt appear more likely to remain abstinent in the medium term than those who still think of themselves as smokers.

Do cravings predict smoking cessation in smokers calling a national quit line: secondary analyses from a randomised trial for the utility of 'urges to smoke' measures

Background

Single-item urges to smoke measures have been contemplated as important measures of nicotine dependence This study aimed to prospectively determine the relationships between measures of craving to smoke and smoking cessation, and compare their ability to predict cessation with the Heaviness of Smoking Index, an established measure of nicotine dependence.

Methods

We conducted a secondary analysis of data from the randomised controlled PORTSSS trial. Measures of nicotine dependence, ascertained before making a quit attempt, were the HSI, frequency of urges to smoke (FUTS) and strength of urges to smoke (SUTS). Self-reported abstinence at six months after quitting was the primary outcome measure. Multivariate logistic regression and Receiver Operating Characteristic (ROC) analysis were used to assess associations and abilities of the nicotine dependence measures to predict smoking cessation.

Results

Of 2,535 participants, 53.5% were female; the median (Interquartile range) age was 38 (28–50) years. Both FUTS and HSI were inversely associated with abstinence six months after quitting; for each point increase in HSI score, participants were 16% less likely to have stopped smoking (OR 0.84, 95% C.I 0.78-0.89, p < 0.0001). Compared to participants with the lowest possible FUTS scores, those with greater scores had generally lower odds of cessation (p across frequency of urges categories=0.0026). SUTS was not associated with smoking cessation. ROC analysis suggested the HSI and FUTS had similar predictive validity for cessation.

Conclusions

Higher FUTS and HSI scores were inversely associated with successful smoking cessation six months after quit attempts began and both had similar validity for predicting cessation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13011-015-0011-8) contains supplementary material, which is available to authorized users.