Measurement properties of selected patient-reported outcome measures for use in randomised controlled trials in patients with systemic lupus erythematosus: a systematic review

OBJECTIVE: The heterogeneous multisystem manifestations of SLE include fatigue, pain, depression, sleep disturbance and cognitive dysfunction, and underscore the importance of a multidimensional approach when assessing health-related quality of life. The US Food and Drug Administration has emphasised the importance of patient-reported outcomes (PROs) for approval of new medications and Outcome Measures in Rheumatology has mandated demonstration of appropriate measurement properties of selected PRO instruments. METHODS: Published information regarding psychometric properties of the Medical Outcomes Survey Short Form 36 (SF-36), Lupus Quality of Life Questionnaire (LupusQoL) and Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT-F), and their suitability as end points in randomised controlled trials (RCTs) and longitudinal observational studies (LOS) were assessed. A search of English-language literature using MEDLINE and EMBASE identified studies related to development and validation of these instruments. Evidence addressed content validity, reliability (internal consistency and test-retest reliability), construct validity (convergent and divergent) and longitudinal responsiveness, including thresholds of meaning and discrimination. RESULTS: All instruments demonstrated strong internal consistency, reliability and appropriate face/content validity, indicating items within each instrument that measure the intended concept. SF-36 and LupusQoL demonstrated test-retest reliability; although not published with FACIT-F in SLE supported by evidence from other rheumatic diseases. All instruments demonstrated convergent validity with other comparable PROs and responsivity to treatment. CONCLUSION: The measurement properties of PRO instruments with published data from RCTs including: SF-36, LupusQoL and FACIT-F indicate their value as secondary end points to support labelling claims in RCTs and LOS evaluating the efficacy of SLE treatments.