Stimulus-specific random effects inflate false-positive classification accuracy in multivariate-voxel-pattern-analysis: A solution with generalized mixed-effects modelling.

When conducting multivariate-voxel pattern analysis (MVPA), researchers typically compute the average accuracy for each subject and statistically test if the average accuracy is different from the chance level across subjects (by-subject analysis). We argue that this traditional by-subject analysis leads to inflated Type-1 error rates, regardless of the type of machine learning method used (e.g., support vector machine). This is because by-subject analysis does not consider the variance attributed to the idiosyncratic features of the stimuli that have a common influence on all subjects (i.e., the random stimulus effect). As a solution, we proposed the use of generalized linear mixed-effects modelling to evaluate average accuracy. This method only requires post-classification data (i.e., it does not consider the type of classification methods used) and is easily implemented in the analysis pipeline with common statistical software (SPSS, R, Python, etc.). Using both statistical simulation and real fMRI data analysis, we demonstrated that the traditional by-subject method indeed increases Type-1 error rates to a considerable degree, while generalized mixed-effects modelling that incorporates random stimulus effects can indeed maintain the nominal Type-1 error rates.

Correction to: Influenza vaccination effectiveness for people aged under 65 years in Japan, 2013/ 2014 season: application of a doubly robust method to a large-scale, real-world dataset.

After publication of the original article [1], in Table 1, in the second and third column, "Vacnee" and "Non-vacnee" should be replaced with "Vaccinee" and "Non-vaccinee".

Influenza vaccination effectiveness for people aged under 65 years in Japan, 2013/2014 season: application of a doubly robust method to a large-scale, real-world dataset.

BACKGROUND: Influenza vaccination is recognized as a primary public health intervention which prevents the illness of patients and relieves the societal burdens of influenza for medical community as well as the economy. To date, no effectiveness study of influenza vaccination has been conducted including a large population with a wide age span, in Japan. Here, we evaluated the clinical effectiveness of influenza vaccination in a large Japanese population. METHODS: We conducted a cohort study using a large-scale claims database for employee health care insurance plans. Vaccination status was identified using plan records for influenza vaccination subsidies. We excluded people aged 65 years or more because of the unavailability of vaccination records. Effectiveness of vaccination in preventing influenza and its complication was evaluated with doubly robust methods using inversed probability treatment weighting to adjust health conscious behaviours and other confounders. RESULTS: During the 2013/2014 influenza season, 369,425 subjects with age range from 1 to 64 years were eligible. Vaccination rate was 39.5% and an estimated odds ratio (OR) for influenza onset was 0.775 after doubly robust adjustment. Age-stratified ORs were significantly reduced in all age groups; lowest in subjects aged 1 to 4 years (0.600) and highest in those aged 13 to 19 (0.938). ORs for all the influenza complication outcomes were also statistically significant (0.403-0.709). CONCLUSIONS: We confirmed the clinical effectiveness of influenza vaccination in people aged 1 to 64 years. Influenza vaccination significantly prevented influenza onset and was more effective in reducing secondary risks of influenza complications.

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells-Dawson Polyoxometalate.

A novel compound containing a hexacalcium cluster cation, one carbonate anion, and one calcium cation assembled on a trimeric trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM), [{Ca6(CO3)(µ3-OH)(OH2)18}(P2W15Ti3O61)3Ca(OH2)3]19- (Ca7Ti9Trimer), was obtained as the Na7Ca6 salt (NaCa-Ca7Ti9Trimer) by the reaction of calcium chloride with the monomeric trititanium(IV)-substituted Wells-Dawson POM species "[P2W15Ti3O59(OH)3]9-" (Ti3Monomer). Ti3Monomer was generated in situ under basic conditions from the separately prepared tetrameric species with bridging Ti(OH2)3 groups and an encapsulated Cl- ion, [{P2W15Ti3O59(OH)3}4{µ3-Ti(H2O)3}4Cl]21- (Ti16Tetramer). The Na7Ca6 salt of Ca7Ti9Trimer was characterized by complete elemental analysis, thermogravimetric (TG) and differential thermal analyses (DTA), FTIR, single-crystal X-ray structure analysis, and solution 183W and 31P NMR spectroscopy. X-ray crystallography revealed that the [Ca6(CO3)(µ3-OH)(OH2)18]9+ cluster cation was composed of six calcium cations linked by one µ6-carbonato anion and one µ3-OH- anion. The cluster cation was assembled, together with one calcium ion, on a trimeric species composed of three tri-Ti(IV)-substituted Wells-Dawson subunits linked by Ti-O-Ti bonds. Ca7Ti9Trimer is an unprecedented POM species containing an alkaline-earth-metal cluster cation and is the first example of alkaline-earth-metal ions clustered around a titanium(IV)-substituted POM.

Are Partial Workplace Smoking Bans as Effective as Complete Smoking Bans? A National Population-Based Study of Smoke-Free Policy Among Japanese Employees.

INTRODUCTION: Although complete workplace smoking bans are generally recommended rather than partial bans, the latter are widespread in many countries, especially Japan. Our objective was to compare complete workplace smoking bans and partial bans for associations with employee smoking and secondhand smoke (SHS)-related discomfort/ill-health. We also evaluated complete bans versus no ban and partial bans versus no ban. METHODS: Eleven thousand ninety eligible employees (weighted number: 34 353 241) aged 20-64 years in 2011 (response rate: 62.5%) were analyzed using a nationally-representative, population-based cross-sectional study. Adjusted prevalence ratios for self-reported current smoking and SHS-related discomfort/ill-health according to workplace smoke-free policies were calculated, using conventional regression and propensity score (PS) weighting (targeting population of average treatment effect among both treated [TET] and untreated [TEU]). RESULTS: Both conventional regressions and PS weighting analyses showed complete bans were significantly associated with lower prevalence of current smoking and perceived SHS-related discomfort/ill-health among nonsmokers than partial or no ban. In contrast, partial bans were not significantly associated with either outcome compared with no ban. Using several PS trimming levels, we found interesting differences between TET and TEU in a comparison between partial and no ban: that is, significant associations in TET estimations, but none in TEU estimations. CONCLUSIONS: Although complete smoking bans were associated with lower levels of employee smoking and SHS-related discomfort/ill-health compared with no smoking ban, partial bans were not. Findings from PS weighting of TEU suggest that partial workplace bans may not be any more effective for Japanese employees than no ban. Therefore, complete bans may be strongly recommended for future implementation, but careful interpretation of the data is necessary because of the cross-sectional study design.

Long-term radiographic evaluation of risk factors related to implant treatment: suggestion for alternative statistical analysis of marginal bone loss.

OBJECTIVE: Secular change in marginal bone loss (MBL), which is the index adopted for implant success criteria, has often been used to evaluate risk factors. However, the need to revise these criteria has recently been indicated due to rapid developments in implant treatment. The purpose of this study was to evaluate risk factors by analyzing MBL with an alternative statistical method. MATERIAL AND METHODS: The analyses were performed on the outcomes of 366 patients with 1,902 implants during an average follow-up period of 84.8 months (with a maximum follow-up of 258 months). Instead of evaluating annual MBL, time was calculated as one of the explanatory variables because the correlation between MBL and time was small (correlation coefficient of 0.09010). Analysis of covariance (ANCOVA) was used for exploratory assessment of each factor, and multiple regression analysis was then utilized to identify risk factors. The multiple regression analysis was performed twice, once among all implants and another in which one implant per patient was randomly selected. RESULTS: As a result of multiple regression analysis, smoking habits showed a significant effect on MBL. Age, sex, diabetes mellitus, implant positions, guided bone regeneration, and sinus floor elevation did not affect MBL. IMZ® implants were associated with significantly higher MBL than were ANKYLOS® and SPI® implants. There was no significant difference between Straumann® and other implants. CONCLUSION: Our results showed that another statistical process, which eliminated the effect of time rather than comparing annual MBL, could be applied to evaluate MBL because the correlation between MBL and time was small.

Synthesis and Molecular Structure of a Water-Soluble, Dimeric Tri-Titanium(IV)-Substituted Wells-Dawson Polyoxometalate Containing Two Bridging (C5Me5)Rh2+ Groups.

A novel trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM)-based organometallic complex, i.e., a dimeric POM containing two bridging Cp*Rh(2+) groups (Cp* = C5Me5) or [{α-P2W15Ti3O60(OH)2}2(Cp*Rh)2](16-) (D-1) with Ci symmetry, was synthesized in an analytically pure form by a 1:2 -molar ratio reaction of the organometallic precursor [Cp*RhCl2]2 with the separately prepared, monomeric trititanium(IV)-substituted Wells-Dawson POM, "[P2W15Ti3O59(OH)3](9-)" (M-1). The crystalline sample (NaK-D-1) of the water-soluble, mixed sodium/potassium salt of D-1 was obtained in the 14.7% yield, which has been characterized by complete elemental analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solution ((183)W, (31)P, (1)H and (13)C{(1)H}) NMR spectroscopy. Single-crystal X-ray structure analysis revealed that the two species of the protonated Wells-Dawson subunits, "[P2W15Ti3O60(OH)2](10-)" were bridged by the two Cp*Rh(2+) groups, resulting in the an overall Ci symmetry. The Cp*Rh(2+) groups were linked to the two terminal oxygen atoms of the titanium(IV) sites and one edge-sharing oxygen atom of the surface Ti-O-Ti bond. The (183)W NMR of D-1 dissolved in D2O showed that its solution structure was represented as a dimeric POM with a formula of [{α-P2W15Ti3O60(OH)3}2{Cp*Rh(OH)}2](16-) (D-2) with Ci (or S2) symmetry. A trititanium(IV)-substituted Wells-Dawson POM-supported organometallic complex has never been reported so far, and thus D-1 in the solid state and D-2 in solution are the first example of this type of complex.

Does removal of out-of-pocket costs for cervical and breast cancer screening work? A quasi-experimental study to evaluate the impact on attendance, attendance inequality and average cost per uptake of a Japanese government intervention.

Reducing out-of-pocket costs is known to improve mammography attendance, but an evidence gap remains concerning Pap smear testing. The Japanese government implemented a politically determined intervention to remove out-of-pocket costs for Pap smear tests and mammography attendance, costing US$148 million, in 2009. It targeted women when they reached the first year of a 5-year age group (i.e., 20, 25, 30 years) with the aim of reducing attendance inequality. Our objective is to evaluate the intervention in terms of uptake and average cost per uptake for cancer screening attendance and to assess socioeconomic inequalities in cancer screening attendance pre- and postintervention. A quasi-experimental study utilizing national repeated cross sections, observed pre- and postintervention, which compared intervention and comparison groups by the Difference-in-Differences method, was conducted. Outcome measures were uptake of cancer screening attendance resulting from the intervention with average cost per uptake and broad inequality indicators for cancer screening attendance according to socioeconomic inequality. In total, 34,043 age-eligible, noninstitutionalized women were analyzed. Uptake among the overall population was 13.9% point in the age- and income-adjusted model for Pap smear and 9.8% point for mammography, with an average cost of US$139 per uptake. The intervention increased inequality indicators in Pap smear attendance (more than +100%) but decreased inequality in mammography attendance (ranging from -12.9 to -74.1%) within the intervention group. In conclusion, removing out-of-pocket costs improves female cancer screening uptake in Japan but may not be cost-saving. Although cost removal reduces inequalities in attendance for mammography, it appears to increase inequalities in Pap smear attendance.

The rare urological entity of ureterosciatic hernia: A case report of successful treatment after repeated recurrence.

Ureterosciatic hernia is a rare urological entity. We report a case of successful laparoscopic surgery for a ureterosciatic hernia that recurred repeatedly after conservative treatment. A 73-year-old woman complained of left abdominal pain. Computed tomography (CT) showed a left ureterosciatic hernia. After placement of the ureteral stent, the ureterosciatic hernia improved. The ureteral stent was removed after ureteral migration became normal. Four years and 8 months later, left ureterosciatic hernia recurred. Same treatment was performed; however, it recurred again. Therefore, laparoscopic surgery using a mesh was performed. The patient had no recurrence 9 months postoperatively.

Effects of web-based learning for nurses on their care for pregnant women with hiesho (sensitivity of hands or feet to cold): A randomized controlled trial.

AIM: Hiesho is a condition characterized by having a cold sensation in the hands or feet (i.e., sensitivity of the hands or feet to cold). This condition is common among Japanese women and is an important health problem. In this study, we aimed to evaluate a hiesho intervention program for nurses called "Preventing Hiesho: Intervention Program for Educating Nurses" in terms of its effectiveness in improving the knowledge and perceptions of nurses about the importance of hiesho care. METHODS: A total of 130 nurses from Japanese hospitals and clinics providing prenatal care participated in our randomized controlled trial. Sixty-eight nurses participated in the "Preventing Hiesho: Intervention Program for Educating Nurses" for 2 weeks (intervention group). Sixty-two nurses received a pamphlet on hiesho care (control group). The responses of the participants to the questionnaire survey were collected by postal mail. An intention-to-treat analysis of the results was conducted. RESULTS: One week after the implementation of the web-based learning program, the scores of knowledge and perceptions of the importance of administering hiesho care were significantly higher in the intervention group than in the control group. CONCLUSIONS: A 2-week web-based learning program for educating nurses on preventing hiesho significantly improved their knowledge and perceptions of the importance of hiesho care.

Real-Time Survey of Vaccine Safety of the mRNA-1273 SARS-CoV-2 Vaccine in Workplace Vaccination at Keio University.

The mRNA-1273 Moderna COVID-19 vaccine was introduced to combat the COVID-19 global pandemic in 2020. Although the safety of the vaccine has been investigated worldwide, real-world safety data is scarce in Japan. An online, real-time survey of adverse events following immunization (AEFIs) with mRNA-1273 was conducted in the setting of a workplace vaccination program at the School of Pharmacy, Keio University from 26 June 2021, to 11 June 2022. Participants were requested to take four surveys during a seven-day follow-up period after each of the first, second, and third booster doses. The maximum number of responses, from 301 respondents, was obtained on day 0 (vaccination date) for the first dose. 98% of respondents reported local and systemic AEFIs for the second dose on day 1. No noticeable difference in local reactions was seen among the three doses. Females reported more AEFIs than males, and the young group (18-29 years) reported a higher rate than the middle age group (≥30 years) after the first dose. Age and gender differences in rates decreased at the second and third doses. This survey confirmed that the safety profile of mRNA-1273 in a real-world setting was similar to that derived from the clinical trials, and that the agent was well-tolerated.

Neural correlates of foreign-language learning in childhood: a 3-year longitudinal ERP study.

A foreign language (a language not spoken in one's community) is difficult to master completely. Early introduction of foreign-language (FL) education during childhood is becoming a standard in many countries. However, the neural process of child FL learning still remains largely unknown. We longitudinally followed 322 school-age children with diverse FL proficiency for three consecutive years, and acquired children's ERP responses to FL words that were semantically congruous or incongruous with the preceding picture context. As FL proficiency increased, various ERP components previously reported in mother-tongue (L1) acquisition (such as a broad negativity, an N400, and a late positive component) appeared sequentially, critically in an identical order to L1 acquisition. This finding was supported not only by cross-sectional analyses of children at different proficiency levels but also by longitudinal analyses of the same children over time. Our data are consistent with the hypothesis that FL learning in childhood reproduces identical developmental stages in an identical order to L1 acquisition, suggesting that the nature of the child's brain itself may determine the normal course of FL learning. Future research should test the generalizability of the results in other aspects of language such as syntax.

[New trends in research on personality traits: contributions to economics and epidemiology].

Research has shown that personality traits have strong predictive validity for economic variables (e.g., income, work attainment) and epidemiological variables (e.g., longevity, physical health), as well as for psychological variables such as problem behaviors, and mental disorders. Importantly, personality traits are predictive even after controlling for socioeconomic status and cognitive abilities. The authors believe that current personality research in Japan almost completely overlooks this perspective. In this article, the authors review these new trends in personality psychological research. They propose a model for research involving A (accurate assessments), B (big samples), C (controlling for covariates and confounders), D (developmental trajectories), and E (economic and epidemiological variables). They outline three future directions to embody personality psychology for prediction, prevention, public wealth, and population health.

Effectiveness of influenza vaccination for children in Japan: Four-year observational study using a large-scale claims database.

BACKGROUND: To date, few large-scale comparative effectiveness studies of influenza vaccination have been conducted in Japan, since marketing authorization for influenza vaccines in Japan has been granted based only on the results of seroconversion and safety in small-sized populations in clinical trial phases not on the vaccine effectiveness. We evaluated the clinical effectiveness of influenza vaccination for children aged 1-15 years in Japan throughout four influenza seasons from 2010 to 2014 in the real world setting. METHODS: We conducted a cohort study using a large-scale claims database for employee health care insurance plans covering more than 3 million people, including enrollees and their dependents. Vaccination status was identified using plan records for the influenza vaccination subsidies. The effectiveness of influenza vaccination in preventing influenza and its complications was evaluated. To control confounding related to influenza vaccination, odds ratios (OR) were calculated by applying a doubly robust method using the propensity score for vaccination. RESULTS: Total study population throughout the four consecutive influenza seasons was over 116,000. Vaccination rate was higher in younger children and in the recent influenza seasons. Throughout the four seasons, the estimated ORs for influenza onset were statistically significant and ranged from 0.797 to 0.894 after doubly robust adjustment. On age stratification, significant ORs were observed in younger children. Additionally, ORs for influenza complication outcomes, such as pneumonia, hospitalization with influenza and respiratory tract diseases, were significantly reduced, except for hospitalization with influenza in the 2010/2011 and 2012/2013 seasons. CONCLUSIONS: We confirmed the clinical effectiveness of influenza vaccination in children aged 1-15 years from the 2010/2011 to 2013/2014 influenza seasons. Influenza vaccine significantly prevented the onset of influenza and was effective in reducing its secondary complications.

Disgust-specific impairment of facial expression recognition in Parkinson's disease.

There is contradictory evidence regarding whether the impairments of the recognition of emotional facial expressions in Parkinson's disease are specific to certain emotions such as disgust and fear. Generally, neurological case reports on emotion-specific impairments have been suspected of being confounded with the factor of task difficulty. Using a refined assessment method in which the difficulty factors were controlled by means of mixed facial expressions and item response theory, we attempted to clarify whether Parkinson's disease disproportionately impaired the recognition of specific emotions. We studied 14 patients with Parkinson's disease and 39 healthy controls who were matched in terms of gender, age, years of education and intelligence quotient. Whereas the refined method revealed that the patients with Parkinson's disease displayed significantly lower scores in disgust recognition alone, conventional methods failed to detect this impairment. In addition, control measures including face recognition abilities did not statistically explain the impairment observed in the patients. The results indicate that Parkinson's disease can indeed selectively impair the recognition of facial expressions of disgust; this provides concrete evidence for emotion-specific impairments that sufficiently withstands criticisms regarding the difficulty artefacts. Furthermore, the results support the proposed role of the basal ganglia-insula system in disgust recognition. This study effectively demonstrates the benefits of refining neuropsychological assessment by taking advantage of the modern psychometric theory.

Decline or improvement? Age-related differences in facial expression recognition.

We examined age-related differences in facial expression recognition in association with potentially interfering variables such as general cognitive ability (verbal and visuospatial abilities), face recognition ability, and the experiences of positive and negative emotions. Participants comprised 34 older (aged 62-81 years) and 34 younger (aged 18-25 years) healthy Japanese adults. The results showed not only age-related decline in sadness recognition but also age-related improvement in disgust recognition. Among other variables, visuospatial ability was moderately related to facial expression recognition in general, and the experience of negative emotions was related to sadness recognition. Consequently, age-related decline in sadness recognition was statistically explained by age-related decrease in the experience of negative emotions. On the other hand, age-related improvement in disgust recognition was not explained by the interfering variables, and it reflected a higher tendency in the younger participants to mistake disgust for anger. Possible mechanisms are discussed in terms of neurobiological and socio-environmental factors.

Researchers' choice of the number and range of levels in experiments affects the resultant variance-accounted-for effect size.

In psychology, the reporting of variance-accounted-for effect size indices has been recommended and widely accepted through the movement away from null hypothesis significance testing. However, most researchers have paid insufficient attention to the fact that effect sizes depend on the choice of the number of levels and their ranges in experiments. Moreover, the functional form of how and how much this choice affects the resultant effect size has not thus far been studied. We show that the relationship between the population effect size and number and range of levels is given as an explicit function under reasonable assumptions. Counterintuitively, it is found that researchers may affect the resultant effect size to be either double or half simply by suitably choosing the number of levels and their ranges. Through a simulation study, we confirm that this relation also applies to sample effect size indices in much the same way. Therefore, the variance-accounted-for effect size would be substantially affected by the basic research design such as the number of levels. Simple cross-study comparisons and a meta-analysis of variance-accounted-for effect sizes would generally be irrational unless differences in research designs are explicitly considered.

An Out-of-Pocket Cost Removal Intervention on Fecal Occult Blood Test Attendance.

INTRODUCTION: To date, no comparative study has assessed the impact of a cost-removal intervention on fecal occult blood testing (FOBT). In 2012, the Japanese government introduced a nationwide project to remove out-of-pocket costs for FOBT. The study objective was to evaluate the differential impact of the intervention on FOBT attendance in the total population and various subgroups. METHODS: This study analyzed 309,103 people in national, repeated cross-sectional studies, observed pre- and post-intervention (2010 and 2013), using covariate-adjusted difference-in-differences estimates to compare intervention and no-intervention groups. The outcome measure was uptake of FOBT attendance resulting from the intervention. Stratified analyses were conducted according to sociodemographic and health-related characteristics. RESULTS: The intervention was associated with significantly positive uptake of FOBT in both genders, but the impact was greater in women than men: 6.7% (95% CI=5.2, 8.1) for women and 2.7% (95% CI=1.1, 4.3) for men in the covariate-adjusted models. Post-intervention, attendance increased in almost all subgroups in women. However, among men, some socially advantaged subgroups, such as high expenditure, high education, and public officers, showed no effect. Some subgroups such as current smokers and less than high school education were identified as hard-to-reach populations that may be less sensitive to the intervention, irrespective of gender. CONCLUSIONS: This is the first comparative study of cost-removal intervention for uptake of FOBT. The intervention may increase FOBT attendance. However, the size of the effect is not great, especially in men, and differential effects occurred across subgroups including gender and socioeconomic differences.

Measuring individual differences in sensitivities to basic emotions in faces.

The assessment of individual differences in facial expression recognition is normally required to address two major issues: (1) high agreement level (ceiling effect) and (2) differential difficulty levels across emotions. We propose a new assessment method designed to quantify individual differences in the recognition of the six basic emotions, 'sensitivities to basic emotions in faces.' We attempted to address the two major assessment issues by using morphing techniques and item response theory (IRT). We used morphing to create intermediate, mixed facial expression stimuli with various levels of recognition difficulty. Applying IRT enabled us to estimate the individual latent trait levels underlying the recognition of respective emotions (sensitivity scores), unbiased by stimulus properties that constitute difficulty. In a series of two experiments we demonstrated that the sensitivity scores successfully addressed the two major assessment issues and their concomitant individual variability. Intriguingly, correlational analyses of the sensitivity scores to different emotions produced orthogonality between happy and non-happy emotion recognition. To our knowledge, this is the first report of the independence of happiness recognition, unaffected by stimulus difficulty.

Awareness and use of electronic cigarettes and heat-not-burn tobacco products in Japan.

BACKGROUND AND AIMS: In addition to some electronic cigarettes (e-cigarettes), new heat-not-burn tobacco products Ploom and iQOS have recently begun to be sold by tobacco companies. These products are regulated differently in Japan, depending on whether the contents are liquid or tobacco leaf. Our objective was to estimate percentages of awareness and use of e-cigarettes and heat-not-burn tobacco products among the Japanese population, including minors. DESIGN AND SETTING: An internet survey (randomly sampled research agency panellists) with a propensity score adjustment for "being a respondent in an internet survey" using a nationally representative sample in Japan. PARTICIPANTS: A total of 8240 respondents aged 15-69 years in 2015 (4084 men and 4156 women). MEASUREMENTS: Adjusted percentages of awareness and use of e-cigarettes (nicotine or non-nicotine e-cigarettes) and heat-not-burn products among total participants; product types and percentages ever used among e-cigarettes ever users. FINDINGS: Of respondents in Japan, 48% [95% confidence interval (CI) = 47-49] were aware of e-cigarettes and heat-not-burn tobacco products, 6.6% (95% CI = 6.1-7.1) had ever used, 1.3% (95% CI = 1.0-1.5) had used in the last 30 days and 1.3% (95% CI = 1.1-1.6) had experience of > 50 sessions. Seventy-two per cent (95% CI = 69-76) of ever users used non-nicotine e-cigarettes, while 33% (95% CI = 30-37) of them used nicotine e-cigarettes, which has the majority share world-wide; 7.8% (95% CI = 5.5-10.0) and 8.4% (95% CI = 6.1-10.7) of them used the new devices, Ploom and iQOS, respectively, with a relatively higher percentage among the younger population. CONCLUSIONS: Approximately half the respondents in a Japanese internet survey were aware of e-cigarettes and heat-not-burn tobacco products, 6.6% had ever used. More than 70% of ever users used non-nicotine e-cigarettes, the sale of which is not legally prohibited, even to minors, in Japan, and 33% of them used nicotine e-cigarettes; 3.5% of never smoking men and 1.3% of never smoking women had ever used e-cigarettes. Corresponding figures for use in the last 30 days were 0.6% and 0.3%, predominantly non-nicotine e-cigarettes.