Drug Hypersensitivity Quality of Life Questionnaire: validation procedures and first results of the Portuguese version

Background Hypersensitivity reactions to drugs are unpredictable and can be very complex and severe, even life threatening. Assess its impact on patient's health related quality of life (HRQoL) is crucial. The Drug Hypersensitivity Quality of Life Questionnaire (DrHy-Q) is the only validated disease-specific HRQoL questionnaire. We aimed to translate and cross-cultural validate the DrHy-Q to the Portuguese population. It was also our purpose to determine the impact of drug hypersensitivity on patients' HRQoL. Methods The translation and cross-cultural adaptation of the DrHy-Q to Portuguese was performed according to standards. Reliability of the DrHy-Q Portuguese version was assessed in terms of internal consistency and test-retest reliability. Structural validity, divergent validity (with a generic health related QoLQ-PGWBI) and discriminant validity were also evaluated. Forty patients accepted to participate in the validation phase. The Portuguese version of the DrHy-Q was applied to 260 consecutively adult patients, studied in our Department for suspected drug hypersensitivity. Results The Portuguese DrHy-Q showed adequate internal consistency (Cronbach's alpha = 0.938), good test-retest reliability [ICC = 0.713 (95% CI 0.488-0.850] and one-dimensional structure. No significant correlation was found between the DrHy-Q and the PGWBI total scores (r = - 0.010, p = 0.957). Two hundred of patients completed the study: 78.5% female; mean age = 44 +/- 15 years. Mean DrHy-Q score was 36.8 +/- 12.6. Two clinical factors significantly predict DrHy-Q total score: clinical manifestations and number of suspected drugs. Patients with anaphylaxis (beta = 11.005; 95% CI 5.523; 16.487), urticaria/angioedema (beta = 7.770; 95% CI 2.600; 12.940) and other manifestations (beta = 7.948; 95% CI 1.933; 13.962) are more likely to have higher DrHy-Q total score than patients with maculopapular exanthema. Patients with >= 2 suspected drugs are also more likely to have worse QoL (beta = 7.927; 95% CI 3.687; 12.166). Conclusion The Portuguese version of DrHy-Q revealed adequate validity and reliability, indicating that it is appropriate to assess the impact of drug hypersensitivity on patients' HRQoL, providing data for a better comprehension and management of our patients. Moreover, our results highlight that the severity of the drug hypersensitivity reaction and the number of suspected drugs have impact on patient's DrHy-QoL.