The Italian version of the Outpatient Physical Therapy Improvement in Movement Assessment Log: cross-cultural adaptation and psychometric properties

Instruments to measure movement abilities from a patient's perspective are generally unavailable across diverse cultures and languages. The aim of this study was to translate, culturally adapt, and validate the Italian version of the Outpatient Physical Therapy Improvement in Movement Assessment Log (OPTIMAL) confidence scale. This study was an observational multicenter study. The Italian version of the OPTIMAL confidence scale (OPTIMAL-I) was developed following forward-backward translation and pretesting with a small group of patients. Reliability was measured by internal consistency (Cronbach α), and a factor analysis was carried out to explore the internal structure. Convergent validity was measured by comparing the OPTIMAL-I with the Italian version of the Activities-specific Balance Confidence (ABC-I). The process for obtaining the OPTIMAL-I required 3 months and it was administered to 290 outpatients in two different rehabilitation clinics. OPTIMAL-I showed high acceptability, high internal consistency (Cronbach's α=0.963), and high test-retest stability (intraclass correlation coefficient=0.92, P=0.001). Convergent validity with ABC-I was also high (r=0.56-0.86; P<0.001). Using factor analysis, we found evidence for a four-factor structure related to 'confidence with high-loads lower-extremity mobility', 'confidence with low-loads lower-extremity mobility', 'confidence with upper-extremity mobility', and 'confidence with trunk mobility' that explained 78.83% of the total variance. The OPTIMAL-I showed good psychometric properties and its use can be recommended for measuring confidence in Italian patients receiving physical therapy services. Future studies should focus on divergent validity and construct validity.