According to WebMD, psoriasis does not generally lead to death. However, one study noted that men with severe psoriasis tended to die 3.5 years before those without the condition, and women with severe psoriasis tended to die 4.4 years before those without it.
According to the National Psoriasis Foundation, psoriasis is generally categorized by how much of the body is covered with the skin disease. Severe psoriasis is defined by covering more than 10 percent of the body. Some psoriasis is classified as severe if it adversely affects a person's life because of its placement on the body. In contrast, mild psoriasis is defined as covering less than 3 percent of the body.