Health-related quality of life of food allergic patients measured with generic and disease-specific questionnaires

Background: Health-related quality of life (HRQL) has never been measured with both generic and disease-specific questionnaires in the same group of food allergic patients. The aim of this study was to compare HRQL of food allergic patients as measured with generic and disease-specific questionnaires. Methods: Generic questionnaires (CHQ-CF87 and RAND-36) and disease-specific HRQL questionnaires (FAQLQ-CF, -TF and -AF) were completed by 79 children, 74 adolescents and 72 adults with food allergy. Floor and ceiling effects, percentage of agreement and multivariate stepwise regression analysis were used to compare the generic and disease-specific measurements. Results: The Food Allergy Quality of Life Questionnaires (FAQLQs) showed minimal floor or ceiling effects. The CHQ-CF87 and RAND-36 showed minimal floor effects, but remarkable ceiling effects (>73%) were found for the scales role functioning-emotional (RE), role functioning-behaviour (RB), role functioning-physical (RP) in children and adolescents and the scale RE (>79%) in adults. Additionally, we found low percentages of agreement between the generic and disease-specific questionnaires to identify the same food allergic patients with the best or worst HRQL. Only patients with the best disease-specific HRQL also tended to have the best generic HRQL. Finally, the explained variance in HRQL by patient characteristics was higher in the disease-specific questionnaires (30.7-62.8%) than in the generic scales (6.7-31.7%). Conclusion: Disease-specific HRQL questionnaires may be more suitable to measure clinically important impairments in HRQL or HRQL differences over time in food allergic patients. However, generic HRQL questionnaires are indispensable for the comparison between different diseases and are thus complementary.