What's the death rate of stevens johnson syndrome here in the u.S.?

Depends on BSA. The death rate from steven's johnson syndrome (sjs) is dependent on the extent of skin sloughing. When body surface area (bsa) sloughing is less than 10%, the mortality rate is approximately 1-5%. However, with more extensive  sloughing (30% bsa)  the death rate is 25-35%, or higher.