Int. J. Environ. Res. Public Health 2009, 6 3066 The inmates were less frequently admitted to treatment facilities, possibly because of their less frequent episodes of psychosis. The inmates also expressed their psychological problems not as depression or anxiety, but rather as uncontrollable violence, suicide attempts, and interpersonal relationship problems with their families and sexual partners. These results suggest that inmates expressed their psychological problems outwardly rather than viewed their psychological problems as an inner conflict. For inmates, the correct perceptions of their problems may be especially important for treatment [25]. Treatment programs should be implemented not only for patients but also for inmates. 4.2. Strengths and Limitations of the Study The present study provides basic statistical information about Japanese methamphetamine abusers in correctional settings measured by the ASI compared with abusers in treatment settings. Although Wada et al. [3] reported that most Japanese methamphetamine abusers belonged to correctional settings rather than treatment settings, characteristics of methamphetamine abusers in prisons have not been as well studied as those of abusers in hospital settings. The results of this study indicate many differences in the quantity and quality of methamphetamine abuse between inmates and patients. Additionally, the present study showed that the ASI could be an effective tool not only for patients but also for inmates to grasp the severity of their problems in multiple areas. The accumulation of data on incarcerated methamphetamine abusers in Japan might extend the use of the ASI as an interview tool. One possible limitation of the present study was the sampling procedure. The participants were not recruited randomly but were limited to inmates who gave informed consent and whose doctors recognized their ability to be interviewed. Therefore, the data of this study were not obtained from methamphetamine abusers in prison as a whole, but rather only from cooperative inmates with a relatively low severity of methamphetamine dependence. Additionally, Shizuoka prison especially treated offenders who were imprisoned for the first time, and offenders mainly came from Tokyo or Shizuoka prefectures. Consequently, the results of this study reflect only a portion of the methamphetamine abuse prisoner population. Inmates and patients were also recruited at different time-points, although the situation regarding methamphetamine use in Japan minimally changed from 2002 to 2007. Moreover, the large number of statistical tests performed in the present study might make some results significant by chance. Another limitation was the relatively low sample size. A subsequent study with more subjects from other correctional facilities and multivariate statistical analysis will be necessary to confirm our conclusions. In the future, the wide use of the ASI for methamphetamine abusers in correctional facilities will enable systematic collection of basic information from these subjects which may aid in more effective intervention. The ASI may be useful for selecting adequate treatment and re-education programs for inmates. Additionally, utilization of the ASI as a common tool among facilities that treat methamphetamine abusers, such as hospitals (or other treatment facilities), legal facilities (e.g., prisons or probation offices), and research institutes, may contribute to more effective treatment and research.