Of course, but they divided the patients into two groups: Mild/moderate and severe clinical phenotypes. It's not optimal, but it is far from subdividing into 20

Of course, but they divided the patients into two groups: Mild/moderate and severe clinical phenotypes. It's not optimal, but it is far from subdividing into 20 classes or making up arbitrary classifiers until you got the number you were looking for. The clinical phenotypes were already established prior to the analysis.