RegiSCAR score is the sum of weighted clinical and laboratory criteria.

Criterion	Definition	Score
Fever	Temperature at least 38.5 degrees C	Present 0, absent or unknown -1
Lymphadenopathy	Enlarged lymph nodes more than 1 cm at two or more anatomical sites	Yes +1, no or unknown 0
Eosinophilia	Peripheral eosinophil count or percentage	Below 700 cells/microlitre or below 10 percent 0, 700-1499 cells/microlitre or 10-19.9 percent +1, at least 1500 cells/microlitre or at least 20 percent +2
Atypical lymphocytes	Present on peripheral blood film	Yes +1, no or unknown 0
Skin extent	Rash affecting more than 50 percent of body surface area	Yes +1, no or unknown 0
Rash typical of DRESS	At least two of facial oedema, infiltration, purpura beyond the legs or desquamation	Typical +1, not typical -1, unknown 0
Skin biopsy	Histology compatible with drug hypersensitivity	Compatible or not done 0, not compatible -1
Internal organ involvement	Objective internal-organ involvement attributed to DRESS	None 0, one organ +1, two or more organs +2
Prolonged course	Signs and symptoms persist for 15 days or longer	Yes 0, no or unknown -1
Alternative causes excluded	Reasonable exclusion of viral, autoimmune and neoplastic alternatives	Yes +1, no or insufficient testing 0

Total score ranges from -4 to +9. Scores below 2 are excluded, 2-3 possible, 4-5 probable and 6 or higher definite DRESS.

RegiSCAR Score for Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)