In a new study, researchers developed an estimate of clinically important change (CIC) in scores on a measure of fatigue in patients with paroxysmal nocturnal hemoglobinuria (PNH) being treated with eculizumab. Study findings were reported in the Journal of Patient-Reported Outcomes.

The fatigue measure used in this study was the functional assessment of chronic illness therapy-fatigue scale (FACIT-Fatigue). In their report, the researchers explained that although fatigue is common in patients with PNH, a CIC or clinically important difference (CID) had not previously been defined for use of the FACIT-Fatigue scale in evaluating patients with PNH.

The study involved adults with PNH included in the International PNH Registry who were receiving eculizumab therapy. FACIT-Fatigue scores were compared at baseline and at 6, 12, 24, and 36 (+3) months of follow-up.

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The researchers evaluated the CID and/or CIC in FACIT-Fatigue through a variety of analytical approaches. These included distribution-based estimates, using either one-half the standard deviation (0.5 x SD) or the standard error of the mean (SEM), and estimates incorporating certain clinical outcome variables.

There were 423 patients in the study, of whom 93% had reported fatigue at baseline. The mean age of patients at baseline was 45.9 years, and the mean FACIT-Fatigue score at baseline was 29.4.

Distribution-based values for the CID for FACIT-Fatigue were estimated to be 6.5 when calculated based on 0.5 x SD and 4.6 when calculated with the SEM. Following an assessment of internal consistency, the SEM-based approach was used to establish the referent CID.

In analyses using clinical outcome variables, the CID was estimated to be 8.4 based on Organisation for Research and Treatment of Cancer (EORTC) global health status (GHS)/quality of life (QoL) summary scores.

It was estimated to be 9.5 when evaluated using EORTC Fatigue Scale scores. FACIT-Fatigue mean scores appeared to show significant improvements beginning at 6 months. Statistically significant changes in FACIT-Fatigue scores with clinical outcome variables showed a range of 2.5 to 15.5.

Based on their analyses overall, the researchers concluded the study’s results supported using a value of 5 points as a CIC for FACIT-Fatigue in this study population. “Although a CIC of 5 may not be the minimal value, it is close to the range of CIDs reported in other diseases (3–5 points),” they wrote in their report.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of disclosures.


Cella D, Johansson P, Ueda Y, et al. Clinically important change for the FACIT‑Fatigue scale in paroxysmal nocturnal hemoglobinuria: a derivation from international PNH registry patient data. J Patient Rep Outcomes. 2023;7(1):63. doi:10.1186/s41687-023-00609-4