Enhancing patient-reported outcome measures for drug hypersensitivity: a validated 6-item Quality-of-Life Questionnaire for Patients with Drug Hypersensitivity (DrHy-Q6)

BACKGROUND Drug hypersensitivity reactions (DHR) can significantly impair patients’ health-related quality of life (HRQoL). However, tools for HRQoL assessment for patients with DHR are time-consuming and remain underutilized. OBJECTIVE To develop and validate an optimized version of the Drug Hypersensitivity Quality of Life Questionnaire (DrHy-Q) designed for everyday clinical use. METHODS Item response theory (IRT), a statistical framework for psychometric measurement, was used to evaluate the 15 questions from the original DrHy-Q for their respective item difficulty, discrimination, and information using prospective data from 243 patients with histories of suspected/confirmed DHR before allergy workup. Accordingly, the best-performing items were identified to develop a 6-item optimized version (DrHy-Q6), which was subsequently validated with another prospective cohort of 156 patients. RESULTS All 15 items of the original DrHy-Q demonstrated satisfactory parameters in IRT analysis, including very high discrimination (>1.7), appropriate difficulty (in between -1.5 and 1.5) and good information (a high and broad peak in the information curve). Six items with top-ranked IRT parameters were identified to construct an optimized version, which we named the DrHy-Q6. The DrHy-Q6 demonstrated a 1-factor structure with an improved fit compared to the original DrHy-Q (comparative fit index = 0.985, Tucker–Lewis’s index = 0.974), excellent convergent validity (Unadjusted Pearson correlation with the full version = 0.955; adjusted = 0.894, p<0.001), reliability (Cronbach’s α and McDonald’s ω = 0.93), divergent validity (Pearson correlation with all Short Form 12-item Healthy Survey Version 2 [SF-12v2] subscales < 0.60, p<0.001) and discriminant validity (significantly higher scores with multiple DHR labels [42.45 ± 27.26 vs. 32.93 ± 26.66], p=0.013). CONCLUSIONS From an IRT perspective, the DrHy-Q and all its constituent items are psychometrically valid for HRQoL assessment. We propose an optimized 6-item version (DrHy-Q6) as an abbreviated alternative for assessing HRQoL in patients with DHR, especially for routine use in clinical practice. Patients and physicians may benefit from its streamlined length and simpler scoring algorithm.