International field testing of the psychometric properties of an EORTC quality of life module for oral health: the EORTC QLQ-OH15

Purpose: This international EORTC validation study (phase IV) is aimed at testing the psychometric properties of a quality of life (QoL) module related to oral health problems in cancer patients. Methods: The phase III module comprised 17 items with four hypothesized multi-item scales and three single items. In phase IV, patients with mixed cancers, in different treatment phases from 10 countries completed the EORTC QLQ-C30, the QLQ-OH module, and a debriefing interview. The hypothesized structure was tested using combinations of classical test theory and item response theory, following EORTC guidelines. Test–retest assessments and responsiveness to change analysis (RCA) were performed after 2 weeks. Results: Five hundred seventy-two patients (median age 60.3, 54 % females) were analyzed. Completion took <10 min for 84 %, 40 % expressed satisfaction that these issues were addressed. Analyses suggested a revision of the phase III hypothesized scale structure. Two items were deleted based on a high degree of item misfit, together with negative patient feedback. The remaining 15 items formed one eight-item scale named OH-QoL score, a two-item information scale, a two-item scale regarding dentures, and three single items (sticky saliva/mouth soreness/sensitivity to food/drink). Face and convergent validity and internal consistency were confirmed. Test–retest reliability (n = 60) was demonstrated as was RCA for patients undergoing chemotherapy (n = 117; p = 0.06). The resulting QLQ-OH15 discriminated between clinically distinct patient groups, e.g., low performance status vs. higher (p < 000.1), and head-and-neck cancer versus other cancers (p < 0.03). Conclusion: The EORTC module QLQ-OH15 is a short, well-accepted assessment tool focusing on oral problems and QoL to improve clinical management. Trial Registration: ClinicalTrials.gov Identifier: NCT01724333.