Development and Validation of the Need-Based Quality of Life Scale (NBQoL) for Psychotropic Drug Abusers

Background and Purpose: Psychotropic drug abuse has adverse effects on almost all aspects of life which is a common concern worldwide. Psychotropic drug abusers (PDAs) expect to address multiple life issues in substance abuse treatment, not limited to abuse or health-related issues. Quality of life (QoL) is significantly associated with rehabilitation and is a helpful outcome indicator in assessing treatment effects. A measurement tool that is sensitive enough to detect treatment effects on QoL is thus considered beneficial to the rehabilitation outcomes for PDAs. This study developed and validated a QoL scale for PDAs that adopted the integrative model of QoL, combining the constructs of the relative importance and the satisfaction degree of basic needs. Since PDAs' perceptions of the relative importance of basic needs may constantly change during the treatment, the developed scale can evaluate the treatment effects on improving QoL more accurately by measuring these possible perception changes.

Methods: In the stage of item development, the inductive method (literature reviews) and deductive method (interviews with 25 PDAs) were used to generate the item pool. Expert judgment (interviews with 25 professionals) was used to test the content validity. 329 psychotropic drug abusers from 13 substance abuse treatment organizations were recruited using the snowball sampling method to develop and validate the scale. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to reduce items and confirm the scale structure. Internal consistency and split-half reliability were used to evaluate the scale’s reliability. Correlations (Pearson’s r) between the scores of the developed scale and WHOQOL-BREF assessed the concurrent validity. Convergent and discriminant validity were tested using the multitrait-multimethod (MTMM) matrix.

Results: Items with factor loadings under 0.60 were deleted from the scale by EFA, and six domains were identified that explained 69.9% of the total variance with factor loadings between 0.71 and 0.97. The results of CFA suggested good model fits of the 25-item scale with six items for relative importance and 19 items for satisfaction degree (df=171, CFI=0.958；TLI=0.948, RMSEA=0.054, SRMR=0.053, GFI=0.891, and NFI=0.884). The scale had good internal reliability (Cronbach’s alpha = 0.81–0.92) and split-half reliability (average=0.86). Pearson’s correlation test supported a significant correlation between the developed scale and WHOQOL-BFEF (r = 0.79) and demonstrated good concurrent validity of the developed scale. Correlation coefficients within/ between the items and the sub-scales were more than 0.60/ lower than 0.40, showing good convergent/ discriminant validity of the developed scale.

Conclusions and Implications: Our findings supported the good reliability and validity of the developed scale, which could effectively measure the QoL of PDAs. QoL results measured by the developed scale could indicate the improvement QoL of satisfaction degree for diverse needs by treatment and provide references for determining the personalized treatment priorities for PDAs. Future validation studies could be conducted among PDAs in settings other than substance abuse treatment organizations and regions with different languages to make the developed scale more universally applicable.