Classic test and generalizability theories are both useful for cross-cultural adaptation of an allergic rhinitis health-related quality of life questionnaire

BACKGROUND: An instrument to assess Allergic Rhinitis (AR) Health-Related Quality of Life (HRQL) in adult patients was developed in Spain. No validated instrument is currently cross-culturally adapted for use in daily practice to assess HRQL in AR patients in Colombia. PURPOSE: The aim of this study was to evaluate the measurement performance of an AR-HRQL specific questionnaire, ESPRINT-15 (Cuestionario ESPañol de Calidad de Vida en RINiTis), in Colombian adult patients with AR using the Classic Test Theory (CTT) and the Generalizability theory (G-theory) frameworks. METHODS: We conducted the cross-cultural adaptation in 2 stages. In stage 1, we evaluated comprehensibility, acceptability, and feasibility of ESPRINT-15 in healthy adults and adult patients with AR. In stage 2, we examined both reliability and validity of ESPRINT-15 scores using CTT and overall reliability applying the G-theory in adult patients with AR. RESULTS: For feasibility and acceptability, all items showed a higher than 95% level of understanding, and modifications in the original questionnaire were unnecessary. Reliability and validity using CTT showed a high internal consistency (Cronbach's alpha and Mc McDonald's omega = 0.95) and test-retest reliability (scores from 0.70 to 0.76). The overall reliability score using G-theory was 0.75, and G-coefficients scores associated with internal consistency and test-retest reliability measures were 0.96 and 0.61, respectively. Validity using exploratory factor analysis (EFA) identified 2 factors instead of the original ESPRINT-15 4 domains. However, confirmatory factor analysis (CFA) showed good fit regarding the original model. CONCLUSIONS: The proposed cross-cultural adaptation of ESPRINT-15 showed good reliability and validity measures. Additionally, it was easy to use and administer. ESPRINT-15 can be used clinically and for research in Colombian adults' patients with AR. CTT and the G-theory can be used in epidemiological studies to adapt AR-HRQL questionnaires cross-culturally in adult patients with AR.