Investigation of the validity and reliability of the Turkish version of the communication outcome after stroke scale (COAST) and carer communication outcome after stroke scale ( CARER COAST)

Current assessment approaches in aphasia recommend functional approaches as well as impairment-based assessments. In this context, self- assessment scales that evaluate the functional communication skills and quality of life of aphasic individuals are of critical importance. Additionally, taking the opinions of caregivers is necessary for conducting a holistic evaluation. To this end, our work (Communication Outcomes after Stroke Scale -COAST) and (Carer Communication Outcomes after Stroke Scale -Carer COAST) aimed to examine the validity and reliability of these scales in Turkish. One hundred and one aphasic individuals and caregivers were included in the study. In our study, construct, content and criterion validity; internal consistency and test-retest reliability were examined. SAQOL-39-TR scale was used for criterion validity. Cronbach's Alpha values for COAST-Turkish (COAST-TR) and CARER COAST-Turkish (COAST-TR-BV) were found to be 0.898, 0.883, and the values for test-retest reliability were found to be 0.948, 0.949. The average item-total correlations for COAST-TR and COAST-TR-BV were found to be sufficient as 0.594, 0.566. A moderate positive correlation was found between COAST-TR and SAQOL-39-TR. Additionally, moderate and high correlations were found between the scores obtained from the COAST -TR and COAST-TR-BV scales. Furthermore, there were statistically significant differences between groups in the individual and caregiver scales between different aphasia severity groups and fluent/non-fluent groups. Moreover, COAST-TR and COAST-TR-BV scales were proven to be valid and reliable in Turkish.