Improving the assessment of quality of life in the clinical care of myeloma patients: the development and validation of the Myeloma Patient Outcome Scale (MyPOS)

Thomas R Osborne, Christina Ramsenthaler, Stephen A Schey, Richard J Siegert, Polly M Edmonds, Irene J Higginson

Multiple myeloma is an incurable cancer with a rising incidence globally. Less toxic treatments are increasingly available, so patients are living longer and treatment decisions are increasingly guided by QOL concerns. There is no QOL assessment tool designed specifically for use in the clinical care of people with myeloma. This study aimed to develop and test the psychometric properties of a new myeloma-specific QOL questionnaire designed specifically for use in the clinical setting - the MyPOS. The MyPOS was developed using findings from a previously reported literature review and qualitative study. The prototype MyPOS was pretested using cognitive interviews in a purposive sample of myeloma patients and refined prior to field testing. The psychometric properties of the MyPOS were evaluated in a multi-centre, cross sectional survey of myeloma patients recruited from 14 hospital trusts across England. The prototype MyPOS contained 33 structured and open questions. These were refined using cognitive interviews with 12 patients, and the final MyPOS contained 30 items taken forward for field-testing. The cross-sectional survey recruited 380 patients for the MyPOS validation. Mean time to complete was 7 minutes 19 seconds with 0.58% missing MyPOS items overall. Internal consistency was high (α = 0.89). Factor analysis confirmed three subscales: Symptoms & Function; Emotional Response and Healthcare Support. MyPOS total scores were higher (worse QOL) in those with active disease compared to those in the stable or plateau phase (F = 11.89, p < 0.001) and were worse in those currently receiving chemotherapy (t = 3.42, p = 0.001). Scores in the Symptoms & Function subscale were higher (worse QOL) in those with worse ECOG performance status (F = 31.33, p < 0.001). Good convergent and discriminant validity were demonstrated. The MyPOS is the first myeloma-specific QOL questionnaire designed specifically for use in the clinical setting. The MyPOS is based on qualitative enquiry and the issues most important to patients. It is a brief, comprehensive and acceptable tool that is reliable and valid on psychometric testing. The MyPOS can now be used to support clinical decision making in the routine care of myeloma patients.