U.S. Population Reference Values for the Myelofibrosis Symptom Assessment Form
Authors: Morlock Robert , Martins Bayer Andréa , Morlock Amy , Wroclawska Monika , Gwaltney Chad 
Published: December 2024

Background
The patient experience with myelofibrosis (MF) symptoms differs throughout the disease continuum, worsening as the disease progresses. The Myelofibrosis Symptom Assessment Form v4.0 (MFSAF) is frequently used in clinical trials to assess MF symptom severity. Limited information is available on the extent to which symptoms seen in MF occur in the general population.
Aim
To estimate U.S. general population reference values for the MFSAF to allow a comparison of symptom severity in patients with MF relative to a representative population.
Methods
A cross-sectional online survey was conducted July 4-6, 2024, with US adults aged ≥18 years recruited using a sampling framework similar to the demographic composition representative of the U.S. adult population. Respondents were assessed for health conditions and health-related quality of life (HRQoL) using measures including the Patient-Reported Outcomes Measurement Information System (PROMIS)-Global Health assessment and the MFSAF v4.0. The MFSAF includes 7 items that measure the burden of MF symptoms including fatigue, night sweats, pruritus, abdominal discomfort, pain under left ribs, early satiety, and bone pain at their worst on a 0 (absent) to 10 (worst imaginable) scale over the past 7 days or 24 hours. The 24-hour recall period version was used in this survey. Total MFSAF scores can range from 0-70, with higher scores indicating worse symptom severity. U.S. Normative reference values were estimated for the MFSAF overall and stratified by age, sex, region and morbidity as assessed by the Charlson Comorbidity Index (CCI). An Analysis of Covariance (ANCOVA) was performed to compare the mean MFSAF scores across groups, while controlling for age, sex and comorbidities.
Results
Of the 1,118 respondents completing the assessment, 50.1% (n=560) were women and 49.9% (n=558) were men; no respondents had MF. The average age of respondents was 50.3 years (SD 17.03). The overall average MFSAF total symptom score (TSS) was 13.58 (95% CI: 12.98-14.18). Average item scores were as follows: fatigue 3.62 (95% CI: 3.47-3.77); night sweats 1.88 (95% CI: 1.75-2.02); pruritus 1.66 (95% CI: 1.54-1.79); abdominal discomfort 2.08 (95% CI: 1.94-2.22); pain under left ribs 1.0 (95% CI: 0.89-1.11); early satiety 2.01 (95% CI: 1.87-2.15); bone pain 1.33 (95% CI: 1.21-1.45). Women reported a higher MFSAF TSS relative to men (mean difference 3.13 [95% CI: 1.92-4.34]) and higher individual item scores for fatigue (mean difference 0.92 [95% CI: 0.62-1.22]); night sweats (mean difference 0.87 [95% CI: 0.59-1.14]); abdominal discomfort (mean difference 0.82 [95% CI: 0.54-1.10]); and bone pain (mean difference 0.24 [95% CI: 0.10-0.48]).There were no differences in MFSAF scores by region. The MFSAF TSS was highest among respondents aged 35 to 44 years (14.48 [SD 11.86]) and lowest for those 65+ years (11.54 [SD 10.01]). The MFSAF TSS was lowest for those with a CCI of 0 and highest for those with a CCI score of 3 or more. For all MFSAF items, PROMIS physical and mental health scores were lower for those endorsing any MFSAF item with a score of 1 or more vs. those not experiencing the MFSAF concept.
Conclusion
The availability of reference values for the MFSAF v4.0 TSS enables researchers to compare MFSAF scores from patients with myelofibrosis with the general U.S. adult population and allow for a better interpretation of those scores. Summarizing the proportion of treated patients obtaining a score at or below normalized MFSAF scores may be an important outcome for use in clinical practice and within clinical trials.