The reliability and validity of Reward Probability Index-Chinese version applied among individuals with opioid dependence

Objective To evaluate the reliability and validity of the Reward Probability Index-Chinese version (C-RPI) among individuals with opioid dependence. Methods A total of 160 individuals with opioid dependence were recruited from the methadone maintenance treatment(MMT) programs in Wuhan.The C-RPI was used in the investigation, and items/exploratory factors and confirmatory factors were adopted to analyze with IBM SPSS 22.0 and AMOS 24.0, respectively. Results The correlation between each item and the total score of the scale was 0.325-0.657 (all P<0.01) and the item discrimination of the scale was good.Exploratory factor analysis extracted two factors, including reward probability and environmental suppressors, and a load of each item on its factor ranged from 0.519 to 0.744.The fitting indexes of confirmatory factor analysis were as follows: χ2/df=1.623, RMR=0.030, RMSEA=0.063, IFI=0.902, TLI=0.885, CFI =0.900.The internal consistency coefficient (Cronbach's α) of the C-RPI was 0.800; and there was no ceiling/floor effect on each dimension and total scale. Conclusion The classification of dimensions for the C-RPI is reasonable, and the scale has good reliability and validity to measure the ability to obtain environmental rewards for individuals with opioid dependence. Key words: Reward probability index (RPI); Reliability; Validity; Opioid dependence