Study shows that conversions from FACIT-F to PROMIS Fatigue are feasible and applicable for RA clinical trials.The Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-F), developed for use in cancer patients, has been validated for measuring fatigue in RA, and is often the tool used in European clinical trials; with 10 out of its 13 items being relevant for patients with RA. The Patient-Reported Outcomes Measurement Information System (PROMIS), developed and calibrated in the United ...