[Reliability and validity of the Japanese version of the DAST-20]

Assessing the degree of problems related to drug abuse is important in each treatment setting. The Drug Abuse Screening Test-20 (DAST-20) is a brief, simple 20-item instrument to measure the degree of problems related to drug use. The objective of the present study is to examine the reliability and validity of the Japanese version of the DAST-20.

We translated the DAST-20 into Japanese using back translation. The anonymous self-administered questionnaire was completed by 310 drug users at the Drug Addiction Rehabilitation Centers (DARC group, n = 113) and at HIV/AIDS regional hospitals (HIV group, n = 197) in Japan.

The average DAST-20 score was 7.6 (DARC group = 14.7, HIV group = 2.8). Each item score was highly correlated with the total score (r = 0.45-0.88). A high internal consistency (Cronbach's α = 0.95) was observed (men = 0.95, women = 0.84). Overall test-retest reliability was 0.86 (men = 0.85, women = 0.90). The total DAST-20 score was strongly positively correlated with the Severity of Dependence Scale-J score (r = 0.85), but moderately positively correlated with the Alcohol Use Disorders Identification Test score (r = 0.41). In addition, confirmatory factor analysis indicated an acceptable fit to the data (goodness-of-fit index [GFI] = 0.893, adjusted goodness-of-fit index [AGFI] = 0.854, comparative fit index [CFI] = 0.948, root mean square residual [RMR] = 0.008, root mean square error of approximation [RMSEA] = 0.073).

Our results clearly suggest that the Japanese version of the DAST-20 has sufficient internal consistency and acceptable levels of concurrent validity and construct validity.