Novel patient-reported outcome instrument, FATIGUE-PRO, can help improve the measurement and management of fatigue in patients with systemic lupus erythematosus (SLE), according to study results published in Rheumatology.

Researchers developed FATIGUE-PRO using a 3-step mixed-methods psychometric approach. Draft items were generated and reviewed using interview data, followed by an evaluation and refinement using mixed-methods data from a phase 2 clinical study in SLE (Clinicaltrials.gov Identifier: NCT02804763) and a final evaluation using Rasch Measurement Theory (RMT) and complementary Classical Test Theory (CTT) analysis.

The first draft included 55 items generated from interviews with 39 patients. The mixed-methods approach produced the final 31 items divided across 3 scales of fatigue: physical fatigue (9 items), mental and cognitive fatigue (11 items), and susceptibility to fatigue (11 items). In the final evaluation, quantitative data from 106 patients as well as qualitative data from 43 patients showed that the scales’ content was comprehensive and targeted. The RMT analysis item thresholds covered 89% of the sample measurements for physical fatigue, 83% for mental fatigue, and 86% for susceptibility to fatigue. The internal consistency reliability of the 3 scales was high (RMT: 0.92-0.94 and CTT: 0.95-0.96) and assessments against other patient-reported outcome instruments supported construct validity.


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The study was limited by the large percentage of clinical trial patients in the development who may not be representative of the wider population of SLE patients. In addition, the tool was developed using qualitative data from only English-speaking patients and quantitative data from only English- and Spanish-speaking patients from a limited number of countries. Another limitation was the lack of associations between fatigue and disease activity.

Researchers concluded, “Overall, the FATIGUE-PRO addresses an unmet need for an instrument that encapsulates the conceptually complex and multifaceted nature of fatigue in SLE while achieving good psychometric performance.” They added, “The FATIGUE-PRO has primarily been developed for use in clinical trials, with the intention to develop an electronic assessment system to better facilitate future use in clinical practice.”

Disclosure: This study was supported by UCB Pharma. Please see the original reference for a full list of authors’ disclosures.

Reference

Morel T, Cano S, Bartlett SJ, et al. The FATIGUE-PRO: A new patient-reported outcome instrument to quantify fatigue in patients affected by systemic lupus erythematosus. Rheumatology. Published online December 13, 2021. doi:10.1093/rheumatology/keab920