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

Objective: Upper extremity lymphedema is a burdensome disease with significant effects on quality of life, underscoring the importance of quality of life measures for this patient population. Only recently, the LYMPH-Q Upper Extremity Module, a new patient-reported outcome measure, was developed. The aim of the present 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 best practice guidelines. To validate the German LYMPH-Q, a multicenter study was conducted. Internal consistency was determined using Cronbach's alpha. Reliability was assessed using the intraclass correlation coefficient. To analyze construct validity, the Pearson correlation coefficient between the LYMPH-Q, quickDASH (disabilities of the arm, shoulder, and hand), and short-form 36-item health survey was calculated. Responsiveness was assessed by comparing the pre- and postoperative LYMPH-Q scores in five patients who had undergone lymphatic reconstructive surgery. Results: Validation was performed using a cohort of 65 patients. The internal consistency of the different domains was good to excellent (alpha, 0.87-0.97). The intraclass correlation coefficient ranged from 0.74 to 0.92. The domains of the LYMPH-Q correlated significantly with the corresponding domains of the short-form 36-item health survey and quick-DASH. Construct validity was good, with 8 of 10 hypotheses confirmed. Significant improvements in function (46.4 +/- 13.3 vs 77.8 +/- 11.5; P= .03), symptoms (42.0 +/- 10.7 vs 70.6 +/- 11.6; P= .02), and psychological well-being (40.4 +/- 14.6 vs 78.0 +/- 17.3; P = .03) were observed after lymphatic reconstructive surgery. Conclusions: The German version of the LYMPH-Q Upper Extremity Module was shown to be conceptually equivalent to the original English version. It was shown to be a reliable and valid patient-reported outcome measure to assess the physical and psychological impairments in patients with upper extremity lymphedema.