Psychometric Results of a New Patient-Reported Outcome Measure for Uveal Melanoma Post-Brachytherapy Treatment: The PROM-UM

SIMPLE SUMMARY: Based on previous work, we designed a new questionnaire that asks patients to report how they feel after undergoing plaque radiation treatment for a certain type of eye cancer. This study aimed to test that the questionnaire measured what it was intended to measure. The questionnaire was given to 439 patients from three clinics in Canada and the United States of America. The results indicated that the questionnaire measures three domains: symptoms and their impact on the patient, the patient’s worry, and the patient’s discomfort. The questionnaire is easy to use and reliable. The questionnaire can help doctors manage patient care after the treatment. ABSTRACT: The objective of this study was to evaluate the psychometric properties of a new patient-reported outcome instrument intended for use with patients who have undergone brachytherapy for uveal melanoma (PROM-UM). Classical test theory and item response theory were used to evaluate the performance of individual items and domains. A convenience sample of 439 participants who had undergone brachytherapy for uveal melanoma from one of three North American ocular oncology treatment centers were included in this cross-sectional study. Exploratory factor analysis identified three domains which were labelled “Symptom Impairment”, “Worry”, and “Discomfort”. The acceptability of the instrument was supported by little missing data (range = 0.00–1.14%) and low maximum endorsement (range = 0.00–1.82%). Item-total (range = 0.68–0.85) and inter-item (range = 0.74–0.80) correlations indicated acceptable reliability. Discrimination and difficulty were assessed using item response theory. Items in all three domains indicated moderate to very high discrimination (range = 1.00–4.10). Two items in the Symptom Impairment domain were too difficult to measure. Response ranges in the other two domains demonstrated acceptable difficulty. These results from the study indicate that this new patient-reported outcome instrument can be used with patients treated with brachytherapy for uveal melanoma. Providers could use this instrument to help inform post-treatment management.