Global Rating of Change for Better or Worse-What Does It Mean When Patients Who Are Treated for Patellofemoral Pain Rate Their Change?

To investigate how a global rating of change (GROC) score corresponds to change in Knee injury and Osteoarthritis Outcome Score (KOOS) subscales in people with patellofemoral pain (PFP). Secondary analysis of data from 3 clinical trials. Four hundred ninety adolescents (10-18 years old) and adults (19-40 years old) with PFP completed KOOS (5 subscales, 0-100) at baseline and 3-month follow-up as well as GROC at 3-month follow-up. GROC category descriptors were mapped to 5 categories: worse, no change, a bit better, better, and much better. Gaussian approximation was then used to calculate the change in KOOS scores for each GROC category. Due to overlap between KOOS scores in "no change" and "a bit better," all analyses were performed on 4 categories. For all KOOS subscales, patients who reported being "worse" had negative KOOS scale change scores (≤ -2); patients reporting "no change" had KOOS scale change scores that ranged from -5 to 14; and patients feeling "better" or "much better" had positive KOOS scale change scores that ranged from 4 to 26 and ≥16, respectively. When patients with PFP reported feeling "worse," "better," or "much better," there was a small-to-substantial change across the different KOOS scales. This is in contrast to no difference between reporting "a bit better" or "no change" in KOOS. When patients say they feel a little better, clinicians should be less confident about whether change has truly occurred. .