As stated in Method section, a positive SII (including the CI) means the trend that people with a low education drink or smoke more than those with a high education. A negative SII (including the CI) means the opposite. As Harper S et al. reported, low education is not always associated with harmful behaviors.  By subdividing the characteristics of drinkers, we discovered which groups have positive or negative educational disparity indices.
First, we assumed that the desirable situation for developed countries is that positive estimates of educational disparities are observed in harmful behaviors. From this point of view, there is no problem in smoking in the latest year, because positive estimates of SII are always observed among any genders. The same thing can be said for drinking behaviors among young. However, middle-aged and elderly groups do not have positive estimate of SII in current drinking. Especially, women have negative one, which means the trend that people with a high education do current drinking more than those with a high education. We do not think education in the past had any effect of driving them to drinking. As Table 1 shows, the estimates of educational disparity indices become smaller among the older groups. We assumed the role of education at that time was so small among them that other factors easily drove them to drinking.
Second, we focused on the difference of educational disparity by gender. Among middle-aged and elderly men, there was no statistical educational disparity in current drinking in the latest year. On the other hand, among middle-aged and elderly women, a negative estimate of SII was observed in current drinking. It is difficult to do correct estimation for the difference by gender, but it may reflect gender disparity in the past. For example, in Japan around 1970, many women became family workers, so the number of female employees was small.  At that time, young female employees were often forced to entertain middle-aged men of important position in restaurant, bar and so on. This may be one of the interpretations of our study. Young female employees and middle-aged men, who were relatively high-educated, had many chances of drinking, and those women may keep current drinking. This hypothesis can explain the reason why the estimate of SII is moving in the positive direction among the middle-aged and elderly men, while the estimate of SII is negative and stable among the middle-aged and elderly women. Middle-aged men at that time are on their way to decreasing acutely, and the number of women, who were high-educated and often forced to drink, is decreasing slowly, but many still alive. It also matches the difficulty of stopping drinking from early initiation. 
Asians should not underestimate the risks associated with alcohol, because it is known that around half of Asians are likely to accumulate acetaldehyde through a genetic problem and to have complications.  Japan is the most tolerant of drinking on a global level.  Therefore, specific plans to change people’s awareness of risks associated with alcohol are required, especially for elderly.
Finally, there are some limitations in this study. First, as noted by the Centers for Disease Control and Prevention in the US, recent common definitions of binge drinking differ for men and women from the perspective of health risks.  For example, this is generally five standard drinks for men and four standard drinks for women in 2 hours. However, the definition of binge drinking used by Health Japan 21 is the same for both men and women, and the questions in the national survey reflected this definition. Therefore, we could not extract binge drinkers using the more common definition. Second, this is a cross-sectional study, and we cannot infer the direction of causality. Third, CSLC is a self-reported data, so it lacks precision about consumption of drinking.