Abstract
BACKGROUND: A new lymphoedema-specific Patient Reported Outcome Measure (LYMPROM©) was developed to help patients easily report the impact of their lymphoedema and enable lymphoedema therapists to understand what matters most to patients. AIMS: This paper describes the validation of LYMPROM© for adults with lymphoedema. METHODS: A multi-phased iterative review was undertaken to investigate the reliability and validity of LYMPROM©. Face and content validity were reviewed by surveying patient representatives and healthcare professionals, along with the validity of LYMPROM© Cymraeg, a Welsh translation. Following COSMIN guidelines, validation study phases used anonymised routinely collected data to examine internal consistency, structural validity, construct validity (compared with the EQ5D-5L), measurement error, test-retest reliability and responsiveness. RESULTS: LYMPROM© demonstrated validity (content and construct) and reliability (test-retest, internal consistency). All items were regarded as relevant, comprehensive and clear, with item content validity index (CVI) between 0.83 to 1.00, and average overall assessment of 0.94. Robust development of LYMPROM© Cymraeg ensured appropriate translation into Welsh. LYMPROM© item scores, with means and medians generally in the lower half of the scale, were positively correlated, as were three (Physical health, Social health and Emotional health) domain scores (domain correlations: 0.595 to 0.812). LYMPROM© total and domain scores showed moderate negative correlations (-0.577 to -0.435) with EQ5D-5L measures. LYMPROM© total and domain scores showed good test-retest (within two weeks) properties, with little or no change in mean or median scores, and strong positive correlations between test and retest scores (Total: 0.919; Physical health domain: 0.922; Social health domain: 0.889; Emotional health domain: 0.820). LYMPROM© showed good responsiveness, with strong, positive correlations between total and domain initial and repeat (between four weeks and seven months later) scores, with a slight reduction in scores (-3.8 to -2.0 units) and some indication of relationships between reduction and time interval (Total: p = 0.025; Physical health domain: 0.034; Social health domain: 0.181; Emotional health domain: 0.009). CONCLUSION: Evidence shows that LYMPROM© offers a reliable and valid tool for use in clinical practice. Scores on three domains allow a more granular assessment of the patient's view of their condition; these scores and the total LYMPROM© score exhibit moderate correlations with more generic EQ5D-5L measures. Further research will explore relationships between patient-level characteristics and LYMPROM© responses, and extend initial work on its cross-cultural validity.