Validity and reliability of the Swedish Occupational Fatigue Inventory (SOFI-20) among Iranian working population

Perceived work-related fatigue is an important issue since it may adversely impact workers’ performance. Additionally، workers’ fatigue is known as a main cause of occupational accidents in workplaces. Considering the consequences of perceived work-related fatigue، assessing fatigue at workplace is critical to work-related fatigue risk management. Therefore، this study assessed the validity and reliability of the Persian version of the Swedish Occupational Fatigue Inventory (SOFI-20) among Iranian employees. In this cross-sectional study، 501 employees of two petrochemical companies were selected by simple sampling method. The Persian version of SOFI-20 was developed using forward and backward translation processes and used to collect the required data. The validity and reliability of the translated inventory were examined by confirmatory factor analysis (CFA) and Cronbach’s alpha coefficient، respectively. Assuming that some items of the Persian version of the SOFI-20 were correlated، the confirmatory factor analysis was repeated to achieve better fitness. The results of CFA revealed an acceptable fit for the Persian version of SOFI-20. The total Cronbach’s Alpha coefficient for the SOFI-20 was 0. 95. Cronbach’s alpha coefficients for different dimensions of the SOFI-20 were found to range from 0. 690 to 0. 887. The validity and reliability of the Persian version of the SOFI-20 was acceptable for assessing the dimensions of work-related fatigue among Iranian employees.