In a qualitative study, Anna Cardellino, MPH, and colleagues investigated the content validity of the Myelofibrosis Symptom Assessment Form version 4.0 (MFSAF v4.0) in patients with myelofibrosis who had received JAK inhibitors. The MFSAF v4.0, a 7-item questionnaire, evaluates symptoms such as fatigue, night sweats, pruritus, abdominal discomfort, pain under left ribs, early satiety, and bone pain using an 11-point numeric rating scale. Interviews with 20 patients from the US and Europe (mean age 59.4 years, 50% male) revealed that fatigue and pain were the most frequently reported symptoms. Patients found the MFSAF v4.0 items relevant and understandable, with 90% affirming it represented their symptom experience. The study validated the numerical rating scale as an appropriate response scale, with patients indicating that a 2- to 4-point improvement would be meaningful.