Background: the present study aimed to translate the cystic fibrosis questionnaire for adolescents and adults (CFQ-R 14+) into Persian, and assess its validity and reliability.
Methods: In total, 35 patients with cystic fibrosis (CF) completed the Persian version of CFQ-R 14+, and Forced Expiratory Volume in one second (FEV1) and body mass index (BMI) were measured. In addition, the Pediatric Quality of Life inventory (PedsQL) was completed by the subjects. The validity of the CFQ-R 14+ was assessed using the face validity, Content Validity Ratio (CVR), and Content Validity Index (CVI), along with concurrent and know-group validities for checking its construct validity. The scale’s reliability was also estimated by test-retest and Cronbach's alpha coefficients.
Results: After forward-backward translation, the values of the total CVR and CVI and their sub-items were higher than 0.8 and 0.49 respectively. Most of the scales had strong internal consistency (Cronbach's Alpha≥0.70), and the test-retest correlations were within the range of 0.72-0.95, considered significant for all the scales. Moreover, strong correlations were observed between the total CFQ-R and PedsQL 4.0 (r=0.9; P<0.001), as well as moderate-to-strong incomparable domains (r=0.4-0.8). A significant correlation was denoted between the total CFQ-R scale and FEV1 (r=0.42; P=0.01), while a reverse correlation was observed between the total CFQ-R scale and age group discrimination (r=-0.35; P=0.03).
Conclusion: According to the results, the Persian version of the CFQ-R 14+ is a reliable and valid instrument for measuring the health-related quality of life among Iranian adolescent and adult patients with CF.