The Group-based multi-trajectory model (GBMTM) extends the univariate Group-based trajectory model (GBTM) to analyse multivariate longitudinal data by identifying subgroups with similar developmental patterns across multiple outcomes. This method has gained popularity for exploring complex phenomena from developmental and relational perspectives across various empirical fields. Despite its utility, comparing GBMTM with preliminary GBTM analyses poses challenges due to potential discrepancies in trajectory characteristics such as numbers, sizes, levels, and shapes across outcomes. These differences suggest a complex data-generative process not fully understood. Our study aims to bridge this knowledge gap by examining how longitudinal data features impact class enumeration and parameter recovery in GBMTM and GBTM through extensive simulations. We highlight the influence of several factors on multivariate clustering, notably outcomes' class separation and the strength of univariate class correspondence. By addressing analytical and interpretational challenges, our findings offer practical guidelines for GBMTM, illustrated with real-world data examples.

Heavy episodic drinking (HED) is a major problem among Colombian university students. This study aims to identify the sociodemographic characteristics and motivational constructs, as defined by the I-Change model (ICM), associated with HED among university students in Colombia. A cross-sectional study was conducted with 846 university students from three universities in Colombia. Participants completed an online questionnaire that assessed sociodemographic characteristics and psychographic constructs based on the ICM. Descriptive statistics, Chi-square tests, ANOVA, and binary logistic regression analyses were performed to analyze the data. Heavy episodic drinking was more prevalent among male students, those with higher socioeconomic status, those living in their hometown, and those attending private universities in Colombia. HED was associated with lower risk perception, greater perceived advantages, and lower perceived disadvantages of consuming ten or more standard drinks. Students who engaged in HED also reported higher social norms, greater modeling and pressure from loved ones to drink, reduced self-efficacy in refusing drinking situations, and a stronger intention to engage in HED. Preventive interventions targeting university students in Colombia should specifically address the key sociodemographic and motivational factors associated with heavy episodic drinking (HED), as identified in this study.

Normative studies are needed to obtain norms for comparing individuals with the reference population on relevant clinical or educational measures. Norms can be obtained in an efficient way by regressing the test score on relevant predictors, such as age and sex. When several measures are normed with the same sample, a multivariate regression-based approach must be adopted for at least two reasons: (1) to take into account the correlations between the measures of the same subject, in order to test certain scientific hypotheses and to reduce misclassification of subjects in clinical practice, and (2) to reduce the number of significance tests involved in selecting predictors for the purpose of norming, thus preventing the inflation of the type I error rate. A new multivariate regression-based approach is proposed that combines all measures for an individual through the Mahalanobis distance, thus providing an indicator of the individual's overall performance. Furthermore, optimal designs for the normative study are derived under five multivariate polynomial regression models, assuming multivariate normality and homoscedasticity of the residuals, and efficient robust designs are presented in case of uncertainty about the correct model for the analysis of the normative sample. Sample size calculation formulas are provided for the new Mahalanobis distance-based approach. The results are illustrated with data from the Maastricht Aging Study (MAAS).

Introduction The public health impact of a tobacco tax increase depends on the extent to which the industry passes the increase onto consumers, also known as tax-pass through. In 2020, the Netherlands announced tax increases aimed at increasing the retail price by 1 per 20 factory-made (FM) cigarettes and 2.50 per 50 g of roll-your-own (RYO) tobacco. This study examines the pass-through rate after the tax increase, and whether this differed by type of tobacco and brand segment.Aims and Methods Self-reported prices of 117 tobacco brand varieties (cigarettes = 72, RYO = 45) pre- and post-tax increases were extracted from the 2020 International Tobacco Control Netherlands Surveys (n = 2959 respondents). We calculated the tax pass-through rate per variant, examining differences between the type of tobacco and brand segments.Results On average, cigarette prices increased by 1.12 (SD = 0.49; 112% of 1) and RYO prices by 2.53 (SD = 0.60; 101% of 2.50). Evidence of differential shifting across segments was found, with evidence of overshifting in non-discount varieties. The average price of discount varieties increased by 0.20 less than non-discount varieties. Similarly, the net-of-tax price decreased in discount varieties (cigarettes = -0.02; RYO = -0.05), but increased in non-discount varieties (cigarettes = +0.14; RYO = +0.20).Conclusions Despite the large tax increase, the industry increased prices in line with or above the required level. Through differential shifting, the price gap between discount and non-discount varieties has widened, which may reduce the public health impact of the tax increase. Measures aimed at reducing price variability should be strengthened in taxation policy, such as the European Tobacco Tax Directive (TTD).Implications We found that the industry used differential shifting after a significant tobacco tax increase in the Netherlands. Prices increased more than required in higher-priced products, but not in lower-priced products. This pattern was found both for FM cigarettes and RYO tobacco. Through differential shifting, the industry undermines the potential public health impact of tobacco tax increases, by offering a relatively cheaper alternative, which discourages people to quit or reduce consumption. The revision of the European TTD provides an opportunity to address the widening price gap-both between and within product segments-across the European Union.

Abstract Background The cost of tobacco is one of the most reported reasons to quit smoking. The Netherlands increased tobacco taxes twice in the span of nine months: a €1 increase per pack in April 2020, and a €0.12 increase per pack in January 2021. This study examines to what extent people report to think about quitting due to the upcoming tax increase(s), as well as how it relates to their age, income or educational level. Additionally, we examined whether thinking about quitting was associated with quit intention and quit behaviour, and whether these associations were different for the two tax increases. Methods Longitudinal data from the International Tobacco Control (ITC) Netherlands Surveys, Cohort 2 were used (N = 5919 observations; wave 1 (February – March 2020): n = 2051; wave 2 (September – November 2020): n = 1919; wave 3 (June – July 2021): n = 1949). Generalised Estimating Equation (GEE) regressions were fit to test the associations between thinking about quitting due to the tax increase and post-tax increases in quit intention, serious quit attempts, and quitting smoking (≤ 1 cigarette a month), as well as sociodemographic variables. Results Circa half of the people who smoke reported thinking about quitting smoking due to the upcoming tax increase (Wave 1 = 51.3% (n = 1052); Wave 2 = 47.3% (n = 849)). Individuals who reported thinking about quitting smoking due to upcoming tax increase(s) were more likely to have increased their quit intention (aOR: 2.00, p ≤ .001) or have carried out a serious quit attempt (aOR:1.48, p ≤ .001) post-tax increase. More people attempted to quit smoking between wave 2 and 3 (post 2021 increase) than between wave 1 and 2 (post 2020 increase). We did not find an interaction effect between wave and thinking about quitting for quit intention, quit attempts, and quitting smoking. Conclusions Tax increases stimulate people to think about quitting. Thinking about quitting due to an upcoming tax increase was associated with more positive quit intention and serious quit attempts.

Introduction Professional behavioral counseling for smoking cessation can be delivered in many forms, which may not work equally well for everyone. We aim to explore in a real-world setting whether different delivery modes yield different rates of quit success and whether quit success varies based on gender, age, educational level, and being treated for a health condition.Aims and Methods We used monitoring data (n = 13 747) from a smoking cessation counseling provider in the Netherlands (September 2018 to August 2021) to compare differences in quit success immediately after the end of counseling and at 12-month follow-up between telephone and other modes of counseling. Participants chose which mode of counseling they received. At the 12-month follow-up, we also examined differences in quit success based on demographic characteristics and whether one is being treated for various health conditions.Results Participants of in-person group counseling and online in-company group counseling were significantly more likely to have quit immediately after the counseling compared with telephone counseling (OR = 1.25, 95% CI = 1.08-1.44; OR = 1.63, 95% CI = 1.18-2.24). Analyses revealed no significant differences in quit success between telephone and other modes of counseling after 12 months. Those treated for a respiratory or psychological condition were less likely to have maintained quit success, as were women, and participants with a lower educational level.Conclusions When chosen by oneself, the mode of smoking cessation counseling received does not appear to be important for long-term quit success. However, certain groups warrant extra support to prevent excessive program attrition and unsuccessful quit attempts.Implications Our findings suggest that when chosen by oneself, the delivery mode of smoking cessation counseling does not appear to be important for long-term quit success. This finding is of particular relevance for those who are unable to attend in-person cessation counseling due to, for instance, reduced accessibility or mobility. We also found that women, lower educated, and younger participants were more likely to dropout of the cessation program or to not have maintained a quit attempt, signaling that disparities in smoking cessation persist when standardized counseling is given, and therefore more tailored counseling may be necessary for these groups.

Reliability of measurement instruments providing quantitative outcomes is usually assessed by an intraclass correlation coefficient. When participants are repeatedly measured by a single rater or device, or, are each rated by a different group of raters, the intraclass correlation coefficient is based on a one-way analysis of variance model. When planning a reliability study, it is essential to determine the number of participants and measurements per participant (i.e. number of raters or number of repeated measurements). Three different sample size determination approaches under the one-way analysis of variance model were identified in the literature, all based on a confidence interval for the intraclass correlation coefficient. Although eight different confidence interval methods can be identified, Wald confidence interval with Fisher's large sample variance approximation remains most commonly used despite its well-known poor statistical properties. Therefore, a first objective of this work is comparing the statistical properties of all identified confidence interval methods-including those overlooked in previous studies. A second objective is developing a general procedure to determine the sample size using all approaches since a closed-form formula is not always available. This procedure is implemented in an R Shiny app. Finally, we provide advice for choosing an appropriate sample size determination method when planning a reliability study.

Introduction Tobacco taxation is an effective tobacco control measure because of its impact on increasing quitting and reducing consumption. Some smokers, however, may instead use price-minimising strategies, such as purchasing less-expensive brands. This study examined whether smokers’ responses to a major tobacco tax increase differed by age, income, and education. We also examined whether price played a role in quitters’ decision to quit. Material and Methods Cross-sectional data was analysed from the 2020 International Tobacco Control (ITC) Netherlands Survey, conducted 6 months after a tax increase that increased prices by circa 13%. Responses to the tax increase by smokers (N=1790) were categorised as intended (reducing consumption to reduce spending) or unintended (using only price-minimising behaviours to reduce spending). We also examined whether price was reported by quitters as a reason for quitting (N=125). We used multinomial and logistic regression to examine whether responses varied by equity variables (e.g., income) and nicotine dependence. Results In response to the tax increases, 35.6% of smokers reduced consumption and 19.3% engaged only in price-minimising behaviours. 82.1% of quitters stated that price influenced their decision to quit. Low-income individuals were more likely to reduce consumption or quit due to price, but also to purchase less expensive brands. Highly dependent smokers were less likely to reduce consumption and more likely to use price-minimising behaviours. Conclusions Increasing taxation has a positive public health benefit: four out of five quitters said price influenced their decision to quit, and more than one-third of smokers reduced their consumption, with low-income smokers being more likely to reduce consumption or quit smoking, providing further evidence that increasing tobacco taxes can reduce health inequalities caused by smoking. Price-minimising strategies were most common among highly dependent smokers.

Designing studies such that they have a high level of power to detect an effect or association of interest is an important tool to improve the quality and reproducibility of findings from such studies. Since resources (research subjects, time, and money) are scarce, it is important to obtain sufficient power with minimum use of such resources. For commonly used randomized trials of the treatment effect on a continuous outcome, designs are presented that minimize the number of subjects or the amount of research budget when aiming for a desired power level. This concerns the optimal allocation of subjects to treatments and, in case of nested designs such as cluster-randomized trials and multicenter trials, also the optimal number of centers versus the number of persons per center. Since such optimal designs require knowledge of parameters of the analysis model that are not known in the design stage, in particular outcome variances, maximin designs are presented. These designs guarantee a prespecified power level for plausible ranges of the unknown parameters and minimize research costs for the worst-case values of these parameters. The focus is on a 2-group parallel design, the AB/BA crossover design, and cluster-randomized and multicenter trials with a continuous outcome. How to calculate sample sizes for maximin designs is illustrated for examples from nutrition. Several computer programs that are helpful in calculating sample sizes for optimal and maximin designs are discussed as well as some results on optimal designs for other types of outcomes.

The relative advantage of the left (LH) over the right hemisphere (RH) in processing of verbal material for most individuals is well established. Nevertheless, several studies have reported the ability of positively and negatively valenced stimuli to enhance and reverse, respectively, the usual LH>RH asymmetry. These studies, however, have used baseline stimuli that differed from emotional stimuli on two dimensions (i.e., valence and verbal/nonverbal nature), creating interpretive difficulties as to whether differences across these conditions are due to differences in valence or the verbal/nonverbal nature of the primes used in the baseline condition. In addition, these studies, along with many others in the literature, have failed to control for potential confounding effects of arousal. Emotional stimuli vary on dimensions of valence as well as arousal and arousal may be asymmetrically presented in the brain therefore contributing to observed asymmetries. Taken together, these considerations underscore the importance of controlling for both valence as well as arousal in any investigation of the effects of emotional stimuli. The objectives of the present study were twofold: (1) to employ an appropriate baseline condition to render emotional stimuli vs. baseline stimuli comparisons meaningful and (2) to examine the extent to which emotional verbal stimuli, equated for arousal level, alter the expected LH>RH asymmetry in a consonant trigram task. Results demonstrated that when LH lateralized consonant trigram presentations were preceded by a positive prime, an enhancement of the expected LH>RH asymmetry was observed. In contrast, when trigram presentations lateralized to the RH were preceded by a negative prime, a complete reversal of the typical asymmetry was found with RH>LH performance. These results are analogous to the pattern of relative hemispheric activations observed for various mood states. Controlling for arousal in studies investigating asymmetries associated with emotional processing may allow more clear interpretation of data intended to test predictions of neuropsychological models of emotion. Moreover, equating stimuli on the dimension of arousal as well as valence may shed more light on conflicting findings with regard to perception vs. expression of emotion.

To prevent mistakes in psychological assessment, the precision of test norms is important. This can be achieved by drawing a large normative sample and using regression-based norming. Based on that norming method, a procedure for sample size planning to make inference on Z-scores and percentile rank scores is proposed. Sampling variance formulas for these norm statistics are derived and used to obtain the optimal design, that is, the optimal predictor distribution, for the normative sample, thereby maximizing precision of estimation. This is done under five regression models with a quantitative and a categorical predictor, differing in whether they allow for interaction and nonlinearity. Efficient robust designs are given in case of uncertainty about the regression model. Furthermore, formulas are provided to compute the normative sample size such that individuals' positions relative to the derived norms can be assessed with prespecified power and precision. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Background The cost of tobacco is one of the most reported reasons for smoking cessation. Rather than quitting, smokers can use also strategies to reduce tobacco expenditure while continuing smoking, such as smoking less or using price-minimising strategies. The Netherlands announced to increase the price of a pack cigarettes from seven (2018) to ten euros (2023), to reduce tobacco prevalence and consumption. This study explores the self-reported strategies to reduce tobacco spending among Dutch smokers, and whether this differed per age, income, and education. Additionally, we analysed among quitters in these subgroups whether price played a role in their decision to quit. Methods Cross-sectional survey data from the International Tobacco Control (ITC) Netherlands Wave 2 (September–November 2020, N = 1915) was used. Strategies to reduce spending among smokers ( N = 1790) were: reducing consumption, bulk buying, switching to cheaper products or buying from low-taxed sources. These were collapsed into: reducing consumption (solely or in combination with other behaviours), solely price-minimising behaviours (such as buying cheaper brands), or no strategies to reduce spending. Associations between strategies and characteristics were analysed through multinomial and binary logistic regression models. Second, we explored which subgroups were more likely to report that price played a role in their decision to quit among quitters ( N = 125). Results The majority of smokers used strategies to reduce tobacco spending: 35.6% reduced consumption and 19.3% used solely price-minimising strategies. 82.1% of quitters reported that price played a role in their decision to quit. Low-income individuals were more likely to report price as a reason for quitting and reduce consumption, but also to buy cheaper products. Highly nicotine dependent smokers were more likely to use price-minimising behaviours, and less likely to reduce consumption. Conclusions The majority reported using strategies to reduce spending or that price played a role in their decision to quit. Reducing consumption was the most reported strategy. Low-income smokers were more likely to reportedly reduce consumption, buy cheaper products, or quit. Price policies have the potential to reduce socioeconomic inequalities in smoking. To discourage price-minimising behaviours, such as switching to cheaper products, reducing price differences between products should be prioritized.

Late detection of oral cancer (OC) cases in Saudi Arabia is concerning. It reduces survival rate and complicates treatment. The ISAC intervention was developed to bridge the gaps observed in dentists' practice of OC examination and patient education. The ISAC stands for I, informing patients of OC screenings; S, screening for OC; A, advising high-risk patients to quit risk factors; and C, connecting patients to advanced services. This study tested the potential effect of the ISAC in influencing dentists' cognitive and behavioral skills, to enhance early detection and prevention of OC. A quasi-experimental study was conducted among dental interns (DIs) at dental setting to test the effect on comprehensive oral cancer examination score (COCE), awareness, self-efficacy, descriptive-norms, and self-reported behavior. Data were collected through triangulation of methods pre and post the intervention at two-months. Multiple linear mixed effects regression models were utilized for data analysis. Between October 2020 and April 2021, 47 DIs participated in the study. The final model showed the significant effects of time (ISAC) on COCE (95% CI = 25.12-29.42, P < .001). DIs had a significant improvement in awareness, self-efficacy, descriptive norms, and self-reported behavior. The findings showed promising effects of the intervention toward the early detection and prevention of OC. Dentists, dental organizations, and policymakers in areas with a high risk of OC could benefit from the current intervention which contributes to capacity building and improved community health. A pragmatic study with a robust design is needed to test the effectiveness of the intervention on a wider scale.

People who try to quit smoking might relapse depending on certain contextual factors (e.g., drinking coffee). Ecological momentary assessment (EMA) was used to investigate contextual factors during temptation and lapse episodes. Contextual factors included what participants did (activities), who they were with (social environment), and where they were (location). Participants ( N = 103) were smokers motivated to quit within three months. The EMA protocol ( N EMA = 6,457) began on a self-determined quit day and lasted 14 days. Generalized linear mixed models were performed to assess the association between each contextual factor and temptations and lapses. Various contextual factors were positively associated with temptations (e.g., sexual intercourse) and lapses (e.g., being outdoors) relative to random assessments. Lapses relative to temptations were mainly associated with social contextual factors (e.g., being with friends). How contextual factors can be addressed in (just-in-time) relapse prevention interventions should be the focus of future studies.

The use of longitudinal finite mixture models (FMMs) to identify latent classes of individuals following similar paths of temporal development is gaining traction in applied research. However, FMM's users may be unaware of how data features as well as the inappropriate specification of the model's covariance structure impacts class enumeration. To elucidate this, we investigated model fit-criteria curve behaviour across an array of data conditions and covariance structures. Fit statistic patterns were variable among the fit criteria and across a range of data conditions. This variability was greatly attributable to the level of class separation and the presence/absence of random effects. Our findings support some widely held notions (e.g. BIC outperforms other criteria) while debunking others (adding random effects is not always the solution). Based on the obtained results, we present guidelines on how the behaviour of fit criteria curves can be used as a diagnostic aid during class enumeration.

Background: Multi-problem households (MPHs) are less physically active, eat less healthy, have higher perceived stress and worse self-reported health. A health promotion program was developed for MPHs targeting self-reported health, physical activity, healthy nutrition and engagement in social networks. This paper described the effectiveness of this program. Methods: A quasi-experimental study was conducted in the city Apeldoorn in the Netherlands with assessments at baseline and after six months. The primary outcome was self-reported health. Secondary outcomes were physical activity, fruit and vegetable consumption, social contacts, loneliness, mental health, BMI and lifestyle index. Data were analyzed with multilevel linear regression analyses. Results: A total of 116 respondents signed up for participation, of which 90 respondents (77.6%) completed the follow-up questionnaire. No differences were found between the control and intervention group on self-reported health (p=0.84). No differences were found between the groups on fruit consumption (p=0.34), but a significant interaction of group×time×health literacy was found (p=0.02). Follow-up analyses showed that only for participants with high health literacy significant differences in fruit consumption were found between control and intervention group at post-test (ß=8.059, p=0.02). No significant differences were found on other outcomes. Conclusions: Recruiting sufficient participants was a challenge. Significant differences in fruit consumption were found among individuals with a relatively high health literacy and none for the other primary and secondary outcome measures. Our outcomes indicate that health promotion programs, as well as their reachability, need to be further tailored to the needs of MPH.

Background: Health recommender systems (HRSs) are intelligent systems that can be used to tailor digital health interventions. We compared two HRSs to assess their impact providing smoking cessation support messages. Methods: Smokers who downloaded a mobile app to support smoking abstinence were randomly assigned to two interventions. They received personalized, ratable motivational messages on the app. The first intervention had a knowledge-based HRS (n = 181): it selected random messages from a subset matching the users’ demographics and smoking habits. The second intervention had a hybrid HRS using collective intelligence (n = 190): it selected messages applying the knowledge-based filter first, and then chose the ones with higher ratings provided by other similar users in the system. Both interventions were compared on: (a) message appreciation, (b) engagement with the system, and (c) one’s own self-reported smoking cessation status, as indicated by the last seven-day point prevalence report in different time intervals during a period of six months. Results: Both interventions had similar message appreciation, number of rated messages, and abstinence results. The knowledge-based HRS achieved a significantly higher number of active days, number of abstinence reports, and better abstinence results. The hybrid algorithm led to more quitting attempts in participants who completed their user profiles.

Introduction Macroeconomic studies have shown that young individuals who smoke, and have a low socioeconomic status respond more strongly to price increases. Most of this evidence stems from research on factory-made (FM) cigarettes. With the rising popularity of roll-your-own (RYO) tobacco, there is a need for studies on cigarette demand that distinguish between both. Aims and Methods This study examined whether individual demand differed for FM and RYO tobacco, and across age, and socioeconomic (income and education) groups. Purchase tasks for FM and RYO cigarettes were included in the 2020 International Tobacco Control (ITC) Netherlands Survey. Adults who smoke daily (n = 1620) stated how many cigarettes they would smoke in 24 hours across eight prices. Four demand indices were derived: intensity (consumption at zero costs), alpha (rate of change in elasticity), P-max (turning point elasticity), and breakpoint (lowest price where consumption equals zero). The indices were tested for subgroup differences. Results Individuals who smoke RYO tobacco indicated higher intensity, and greater alpha than individuals who smoke FM cigarettes. Participants aged 25-39 had lower P-max, and 18-24 year olds displayed higher breakpoints. Participants with low income displayed higher intensity, and lower P-max than other income groups. No associations were found with education. Conclusions Individuals who smoke RYO tobacco indicated higher price sensitivity than those smoking FM cigarettes, supporting the need to harmonize tobacco taxation. Taxation may be especially beneficial to reducing consumption among individuals with a low income or smoke RYO tobacco. Substantially higher prices are needed in the Netherlands to achieve the desired results. Implications Individuals who smoke daily were willing to pay substantially higher prices than the current market prices, indicating the room and need for much higher taxation levels. Demand for RYO tobacco was more sensitive to price changes than demand for FM cigarettes. Taxation should be raised at equivalent rates for FM and RYO cigarettes. Taxation appears to be especially effective in reducing consumption among people who smoke RYO tobacco and low-income individuals. It remains important to combine increased taxation with other tobacco control measures.

Introduction To date, there is no consensus on which anterior surgical technique is more cost-effective in treating cervical degenerative disc disease (CDDD). The most commonly used surgical treatment for patients with single- or multi-level symptomatic CDDD is anterior cervical discectomy with fusion (ACDF). However, new complaints of radiculopathy and/or myelopathy commonly develop at adjacent levels, also known as clinical adjacent segment pathology (CASP). The extent to which kinematics, surgery-induced fusion, natural history, and progression of disease play a role in the development of CASP remains unclear. Anterior cervical discectomy with arthroplasty (ACDA) is another treatment option that is thought to reduce the incidence of CASP by preserving motion in the operated segment. While ACDA is often discouraged, as the implant costs are higher while the clinical outcomes are similar to ACDF, preventing CASP might be a reason for ACDA to be a more cost-effective technique in the long term. Methods and analysis In this randomized controlled trial, patients will be randomized to receive ACDF or ACDA in a 1:1 ratio. Adult patients with single- or multi-level CDDD and symptoms of radiculopathy and/or myelopathy will be included. The primary outcome is cost-effectiveness and cost-utility of both techniques from a healthcare and societal perspective. Secondary objectives are the differences in clinical and radiological outcomes between the two techniques, as well as the qualitative process surrounding anterior decompression surgery. All outcomes will be measured at baseline and every 6 months until 4 years post-surgery. Discussion High-quality evidence regarding the cost-effectiveness of both ACDA and ACDF is lacking; to date, there are no prospective trials from a societal perspective. Considering the aging of the population and the rising healthcare costs, there is an urgent need for a solid clinical cost-effectiveness trial addressing this question. Trial registration ClinicalTrials.gov NCT04623593. Registered on 29 September 2020.

Abstract Background Effectiveness of tobacco taxation can be undermined through smokers applying price-minimizing behaviours rather than quitting or reducing consumption. Common price-minimizing strategies are buying cheaper tobacco [discount brands or roll-your-own (RYO) tobacco], bulk buying and cross-border purchasing. This study analyses trends in and factors associated with such behaviours in four European countries from 2006 to 2020. Methods Data came from adult smokers participating in the International Tobacco Control (ITC) Surveys conducted between 2006 and 2020 in England (9 waves, n = 768–4149), France (4 waves, n = 1415–1735), Germany (5 waves, n = 513–1515) and the Netherlands (10 waves, n = 1191–2177). Country-specific generalized estimating equation regression models were fit to assess trends in smoking RYO tobacco, discount brands, bulk buying and cross-border purchasing within the European Union. Results Buying discount brands or RYO tobacco was the most common strategy in all countries, except France. Except for buying discount brands, estimates of price-minimizing behaviours were highest in France (2019: RYO = 27.2%, discount brands = 17.3%, bulk buying = 34.1%, cross-border purchasing = 34.2%), and lowest in Germany (2018: RYO = 18.6%, discount brands = 43.7%, bulk buying = 8.0%, cross-border purchasing = 9.8%). Direction and magnitude of trends differed by country, and behaviour. Young smokers were less likely to buy in bulk. Low-income and low-education smokers were more likely to purchase RYO tobacco or discount brands. The association with discount brands was not found for French low-income smokers. Conclusions Smoking cheaper tobacco is the most prevalent price-minimizing strategy in three countries (England, Germany and Netherlands), and more prevalent among low-income individuals. Harmonizing prices across products and countries would reduce switching to cheaper tobacco.