Development of the Diaphragmatic Paralysis Questionnaire: a simple tool for patient relevant outcome

OBJECTIVES Measurement tools of health-related quality of life (HRQL) that are specific for the underlying disorder are inevitably needed to assess HRQL changes following specific treatment strategies. The aim of the current study was to develop a questionnaire assessing HRQL in patients with unilateral diaphragmatic paresis. METHODS Firstly, topics of health impairments covering physical, psychological, social and functional aspects were predefined by a physician expert panel to ensure face validity. Secondly, all predefined topics were rated by a patient group with unilateral diaphragmatic paresis (untreated: n = 11; postoperative: n = 9) using a 5-point Likert scale ranging from ‘not relevant at all’ (−2) to ‘absolutely relevant’ (+2) to guarantee content validity. Thirdly, only relevant topics (0 to +2) were used for item development, while non-relevant items (<0) were not subject for item development. RESULTS In total, 20 patients rated a total of 43 topics covering a broad spectrum of health impairment. 21 were considered as relevant for item development. Items are answered on a 5-point Likert scale ranging from ‘completely untrue’ (−2) to ‘always true’ (+2). The Diaphragmatic Paralysis Questionnaire (DPQ) Summary Score ranges from 0 (worst HRQL) to 100 (best HRQL). Finally, the German DPQ was professionally translated and transculturally adapted into English, Italian, Dutch, French, Greek and Spanish, using translation/back-translation procedures. CONCLUSIONS The DPQ is the first diseases-specific HRQL measure developed for patients with diaphragmatic paresis. In addition, the DPQ is available in 7 languages free of charge for non-profit purposes. Clinical trial registration German clinical trials register: DRKS00017056