Cultural adaption and multicenter validation of the German version of the LYMPH Q Upper Extremity Module

OBJECTIVE: Upper extremity lymphedema (UEL) is a burdensome disease with significant impact on quality of life underscoring the importance of quality of life measurements in this patient population. Only recently, the LYMPH Q Upper Extremity Module, a new patient-reported outcome measurement (PROM), has been developed. The aim of the study was to translate the LYMPH Q Upper Extremity Module from English to German and perform a comprehensive validation. METHODS: Translation was performed in accordance with the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) best-practice guidelines. To validate the German LYMPH Q, a multicenter study was conducted. Internal consistency was determined by Cronbach's alpha. Reliability was assessed by the intra-class correlation coefficient (ICC). To analyse construct validity, a Pearson correlation coefficient between the LYMPH Q, quickDASH and SF-36 was calculated. Responsiveness was assessed by comparing the pre- and postoperative LYMPH Q scores in five patients receiving lymphatic reconstructive surgery. RESULTS: Validation was performed in a cohort of 65 patients. Internal consistency of the different domains was good to excellent (α: 0.87-0.97). ICC ranged from 0.74 to 0.92. The domains of the LYMPH Q correlated significantly with the corresponding domains of the SF-36 and quick DASH. Construct validity was good with eight of ten hypotheses confirmed. Significant improvements of function (46.4 ± 13.3 vs. 77.8 ± 11.5; p= 0.03), symptoms (42.0 ± 10.7 vs. 70.6 ± 11.6; p= 0.02) and psychological well-being (40.4 ± 14.6 vs. 78.0 ± 17.3; p= 0.03) were observed after lymphatic reconstructive surgery. CONCLUSION: The German version of The LYMPH Q Upper Extremity Module is conceptually equivalent to the original English version. It is a reliable and valid PROM to assess physical and psychological impairments in patients with UEL.