Gambling disorder falls into the category of Substance-Related and Addictive Disorders in the DSM-5. Within this category, gambling disorders are included as Non-Substance-Related Disorders while disorders caused by drinking and drug use are considered as Substance-Related Disorders . According to the DSM-5, the lifetime prevalence rate of gambling disorder is about 0.4% - 1.0% and the past-year prevalence rate of the same disorder is about 0.2% - 0.3% in the general population . Meanwhile, a study conducted in Japan found that there were quite a number of disordered gamblers . Among various types of entertainment associated with gambling disorder in Japan, Pachinko and pachislot play the most important role. Both pachinko and pachislot are legally defined as games but not gambling ones. They are widely played across Japan, and pachinko/pachislot parlors are found in people’s areas of daily living such as downtown and shopping streets. The total sales revenue for pachinko and pachislot combined is 21.626 trillion yen, far exceeding the total sales revenue of legal Japanese gambling, including horse racing and the lottery, which is 5.888 trillion yen . While being hugely popular, pachinko/pachislot has been considered problematic particularly in terms of gambling disorder issues. In fact, most gambling disorder outpatients are pachinko/pachislot players  . Understanding of the characteristics of Japanese gambling disorder therefore will require insight into the characteristics of pachinko-pachislot playing disorder.
There have been only a few studies that examined Japanese gambling disorder with the focus on pachinko/pachislot. One possible reason for this is the use of scales administered primarily in Europe and the US in Japanese research on gambling disorder, prohibiting researchers from studying the disorder with the focus on pachinko/pachislot. To overcome this situation, Akiyama et al.   developed the Pachinko-pachislot Playing Disorder Scale (PPDS) in their series of research projects and specified the cut-off value in line with the DSM-5 criteria. Using the PPDS, we examined gambling disorder with the focus on pachinko/pachislot.
It should be noted that, like any entertainment that causes gambling disorders, playing pachinko/pachislot itself will not automatically result in gambling disorder. While exposure to pachinko/pachislot is naturally a prerequisite for Pachinko-pachislot Playing Disorder, there should be player characteristics that have stronger connections to the disorder. Therefore, we closely examined the PPDS responses from individuals who played pachinko/pachislot in the past year to discover how many of them were likely to develop the disorder and what kind of characteristics they had. In this paper, we report results and discussions obtained by reorganizing simple results found in a domestic report written in Japanese  in order to examine those issues.
The sample size was 9000 consisting of males and females from 18 to 79 years old living in Japan selected through two-stage stratified random sampling. There were 5173 questionnaire responses (57.5%) and 5060 (56.2%) were valid.
2.2. Survey Period
The survey was conducted from January 4 to February 17, 2017.
2.3. Items Asked in the Survey
2.3.1. Demographic Variables
“Gender” and “Age” of the respondents were obtained from the Basic Resident Register. Age was then divided into the three categories: “Under 20,” “20 to 64,” and “65 and over.” “Community size” of the respondents was obtained from the population statistics disclosed by municipalities listed in the Basic Resident Register and was divided into the four categories: “City designated by government ordinance or Tokyo’s 23 wards,” “City (population of 150,000 and more),” “City (population less than 150,000),” and “Town or village.”
As indicators of the socio economic status of the respondents, data on their “Annual household income” and “Amount of savings” was collected. Respondents who knew their annual household income or amount of savings used a 14-point scale ranging from “Less than 1 million yen” to “13 million yen or more” to answer. If they did not know their annual household income or amount of savings, they were asked to choose “Don’t know.” In the tabulation process, “Annual household income” was divided into five categories: “Don’t know” and four categories ranging from “Less than 3 million yen” to “8 million yen or more.” Similarly, “Amount of savings” was divided into the three categories: “Don’t know,” “Have no savings,” and “Have savings.” As an indicator of educational level, the respondents were asked about their highest educational attainment.
2.3.3. Divorce Experience
The respondents were asked whether or not they had divorce experience.
2.3.4. Experience of Playing Other Gambling Games
Regarding nine types of official gambling games, such as horse racing and the lottery, the respondents were asked how frequently they had played them in the past 12 months. Again, a 4-point scale was used. In the tabulation process, respondents who experienced at least one of the nine gambling games were categorized as “Have experience” and those who had no experience with any of the gambling games were categorized as “No experience.”
2.3.5. Pachinko-Pachislot Playing Disorder Scale (PPDS)
The PPDS was developed based on items in gambling disorder scales such as the SOGS, DSM-IV, NODS, PGSI, and G-SAS     . It consists of 27 items in 12 categories to measure the three factors of the disorder: motivation, behavior, and consequence (See Table 1). It is designed to ask individuals
Table 1. Average and standard deviation for each PPDS item.
who played pachinko/pachislot in the last 12 months about their behavior and experience associated with gambling disorder in that period. Among 27 items, 26 were in the form of a 4-point scale ranging from “Disagree” to “Agree” or from “Never” to “Often.” The remaining item was about borrowing money and was presented in the form of a multiple answer question. The respondents were asked to select all places from which they borrowed money. Responses on the 4-point scales were converted into 1 to 4 points, with “Disagree” and “Never” being 1 point. Responses on the multiple answer question on borrowing money were converted into 0 to 7 points. The score was 0 if the respondents selected “Never borrowed,” but otherwise the number of places from which the respondents borrowed money became the points for that question. The sum of the 4-point scale points and the points for the question on borrowing money were used in the analysis as the Pachinko-pachislot Playing Disorder Scale score (PPDS score). The obtained PPDS score ranged from 26 to 111.
A request for survey participation was sent by mail to 9000 individuals chosen by two-stage stratified random sampling. More specifically, postcards requesting survey participation were first sent to them and a package of survey materials followed. The questionnaire was collected either manually by investigators, via mail, or through a web-based form. Those who submitted responses received a 1000 yen-worth reward either directly or via mail.
3. Result and Discussion
3.1. Data Used in Analysis
Using the cut-off value proposed by Akiyama et al.  , respondents whose PPDS score was 61 or higher were categorized as “pachinko/pachislot players suspected to have a gambling disorder” (Disorder Group). Their responses were compared with those of respondents who played pachinko/pachislot in the past year and had a PPDS score of 60 or lower (Non-Disorder Group). Among all who submitted survey responses (5060), 582 played pachinko/pachislot in the past year. Among these 582 individuals, 24 submitted invalid PPDS responses and thus were excluded from analysis. As a result, data obtained from 558 PPDS respondents were analyzed.
3.2. Disorder Score Distribution
Table 1 shows the average and standard deviation of the score for each PPDS item, sub-scale score, and total score. Among the 558 PPDS respondents, 3.8% (21 individuals) had a “suspected gambling disorder.” These 21 individuals accounted for 0.4% of all 5,060 respondents (95% confidence interval: 0.2% - 0.6%). The DSM-5 (APA, 2013) reports that the past-year prevalence rate of gambling disorder is about 0.2% - 0.3% in the general population, and our study resulted in approximately the same appearance ratio.
3.3. Experience of Playing Other Gambling Games
There were no significant differences in the past-year gambling experience (excluding pachinko/pachislot) between those who had gambling disorder and those who did not. Engagement in non-pachinko/pachislot gambling games did not indicate any possibility of resulting in higher likeliness of developing Pachinko-pachislot Playing Disorder (χ2(1) = 1.04, n.s., V = .04; see Table 2).
3.4. Differences Attributable to Demographic Variables and SES
Table 2 shows the frequency and breakdown of responses to the demographic and SES items by the Disorder and Non-Disorder Groups.
Table 2. Demographic variables and experience of other types of gambling games.
3.4.1. Demographic Variables
No significant gender difference was found between the Disorder and Non-Disorder Groups. In both groups, male pachinko/pachislot players accounted for more than the female counterparts (χ2(1) = 2.61, n.s., V = .07). No significant age differences were found between the two groups either. There were no particular age groups having high percentages of individuals with gambling disorder (χ2(2) = 0.68, n.s., V = .03). There was also no significant difference in distribution of areas of living (χ2(3) = 3.93, n.s., V = .08). Although some studies reported that the prevalence of gambling disorder was higher for men or younger age groups  , there were also study results showing the possibility of gender and age influencing the prevalence at different levels depending on how they interact with other variables. In the case of electronic gambling machines (EGMs), which are similar to pachinko/pachislot machines, no sexual difference was found in the prevalence when the frequency of play was controlled . In a previous gambling disorder study in Japan, Nishimura and Ishida  used data from individuals who called a telephone consulting agency to talk about their pachinko addiction to show that men scored significantly higher on the short form of the SOGS for addicted gamblers. When the same callers were divided into problem gamblers and non-problem gamblers using the cut-off value, however, there was no significant sexual difference. In pachinko/pachislot, gender strongly influences the rate of participation, but its influence on the level of disorder seems marginal.
Individuals with gambling disorder and those without showed no differences in the distributions of the two socio-economic status indicators, “Highest educational attainment” and “Annual household income”. (Highest education attainment: χ2(5) = 3.08, n.s., V = .08; Annual household income U = 2380.50, n.s., r = −.07). On the other hand, a significant difference was found in the distribution of “Amount of savings.” The Disorder Group had a higher percentage of individuals who reported they had no savings (χ2(2) = 23.98, p < .001, V = .21). SES, like gender, is considered to be a risk factor for gambling disorder. However, the influence of SES could change with other variables as reported in a previous study where its relationship with gambling disorder became apparent only after other risk factors such as race and marital history were controlled .
3.5. Divorce Experience
Table 2 shows the frequency distributions of “Divorce experience” for both the Disorder and Non-Disorder Groups. The Disorder Group had a higher percentage of individuals who responded that they had divorce experience (χ2(2) = 8.61, p < .01, V = .12). This agreed with previous studies that reported a higher divorce rate for problem gamblers than for non-problem gamblers  .
The relationship between problem gambling and negative emotions, such as depression, anxiety, and stress, has been pointed out in gambling disorder research. Some studies concluded that gambling was an escape-based coping strategy and was a maladaptive coping style  , and other studies suggested higher psychological stress resulted in a heightened desire to gamble . Both the present and previous studies showed a higher divorce rate for problem gamblers than non-problem gamblers   pointing out that a higher percentage of problem gamblers experienced negative life events than non-problem gamblers. Therefore, psychological stress caused by negative life events may make individuals rely more heavily on pachinko/pachislot as a method of releasing stress, resulting in higher likeliness of developing Pachinko-pachislot Playing Disorder.
The present study indicated that approximately 0.4% of the survey respondents had Pachinko-pachislot Playing Disorder. The study also showed that individuals with a suspected disorder were more likely than those without it to have been divorced, and have no savings. There were not enough levels of difference in gender, annual household income, or the highest education attainment between the two groups to consider them as characteristics of either group. Based on these findings, an important risk factor for Pachinko-pachislot Playing Disorder may be the personality that easily accepts pachinko/pachislot as a form of entertainment that provides enjoyment or allows an escape from uncomfortable situations rather than the social background of the individual. Note, however, the present study was a one-point correlational study. Examination of the influences or causal relationships of these variables will require detailed investigation through longitudinal studies involving surveys conducted twice or more.
All authors designed the study, had advises during the study and reviewed the completed manuscript. YH performed the statistical analysis and wrote the manuscript. HI monitored data collection. KA and AS performed the statistical analysis. All authors read and approved the final manuscript.
Kikunori Shinohara is on the board of trustees of Nichiyukyo (Japan Pachinko Pachi-Slot industry association).
Ethical Approval and Consent to Participate
This study was approved by the Ethical Review Board for Research in the Humanities at Ochanomizu University (Approval No. 2016-98).
This study is wholly funded by the Nikkoso Research Foundation for a Safe Society.
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