Location of inflammation is irrelevant to severity for the most part. Mouth to the anus. You can have 4 inches of bowel so ulcerated it's eaten into your body cavity, and that's severe. you can have yards of bowel affected, yet be deemed mild because the inflammation is minor at best. You don't have to have malnourishment or "colitis" (which is colon specific, thus, again, subjective per patient for location) to be deemed mild or severe, it's an accumulative effect: BM's per day, pain, weight loss, fatigue, blood presence, etc... all add up to diversify your caliber of severity. On top of that, most mild cases never see Remicade treatment because they're treated with lesser drugs first (assuming bottom up approach is taken)...Asacol/Pentasa is a common mild medicine.