Translation and validation of the Arabic version of generic medicines scale

Generic drugs are considered the best alternative for the originator brand drugs because they have the same quality, safety, and efficacy yet offered at considerbaly lower cost. Prior research has developed instrumentation to assess patients' perceptions of generic drugs; however, little has been done to translate these measures in other languages.

This study's aim was to translate and validate an Arabic version of the generic drug scale (GMS) in a Jordanian sample. This was a cross-sectional study.

The English version of the GMS was translated to an Arabic version using the standard "forward-backward" procedure of translation. The questionnaire was distributed to 225 patients. The translated version was then validated in a sample of patients. Face validity of the translated GMS was confirmed with pilot testing. Content validity of the translated GMS was evaluated by a number of pharmacists and academicians. Confirmatory factor analysis (CFA) was used to test a pre-specified relationship of observed measures.

The GMS consisted of two subscales: efficacy, and similarity of generic drugs to originator brand drugs. The efficacy subscale consisted of ten items while the similarity subscale consisted of six. The responses to the items were framed on five-point, Likert-type scales. The instrument demonstrated good internal consistency (Cronbach's alpha = 0.83). The range model fit was good for some fit indices. The RMSEA value was 0.08, which indicates good fit. Also, CMIN/DF indicated a good fit model with a value of 2.7, as well as GFI and CFI values of 0.95 and 0.91, respectively. NFI and CFI values were 0.92 and 0.93, respectively. Factor loadings were over 0.30 for all items, which means the scale has CFA validity indictors.

The Arabic version of GMS was proved to be a reliable and valid measure to investigate patients' belief regarding generic drugs as it showed acceptable, internal consistency reliability, face and content validity.