The development and psychometric evaluation of an interprofessional identity measure: Extended Professional Identity Scale (EPIS).

The purpose of this study was to develop and evaluate an interprofessional identity measurement instrument based on Extended Professional Identity Theory (EPIT). The latter states that interprofessional identity is a social identity superordinate to a professional identity consisting of three interrelated interprofessional identity characteristics: belonging, commitment and beliefs. Scale development was based on five stages: 1) construct clarification, 2) item pool generation, 3) review of initial item pool, 4) shortening scale length (EFA to determine top four highest factor loadings per subscale; 97 dental and dental hygiene students), and 5) cross-validation and construct validity confirmation (CFA; 152 students and 48 teachers from six curricula). Explained variance of the EPIS was 65%. Internal consistency of the subscales was 0.79, 0.81 and 0.80 respectively and 0.89 of the overall scale. CFA confirmed three-dimensionality as theorized by EPIT. Several goodness-of-fit indexes showed positive results: CFI = 0.968 > 0.90, RMSEA = 0.039 < 0.05, and SRMR = 0.056 ≤ 0.08. The factor loadings of the CFA ranged from 0.58 to 0.80 and factors were interrelated. The Extended Professional Identity Scale (EPIS) is a 12-item measurement instrument with high explained variance, high internal consistency and high construct validity with strong evidence for three-dimensionality.