Criteria commonly used to decide whether those at risk for stroke should have preventative surgery or drug therapy may underestimate the risk in women and overestimate it for men. The criteria to open clogged carotid arteries in the neck-- a risk factor for stroke--say that those with blockages of 70 percent or more may benefit from surgery. Lisa Tartaglino, M.D., associate professor of radiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, argues that the 70 percent criteria doesn't take into account that women's carotid arteries are smaller, permitting less blood flow. Such criteria may need to be changed to account for these differences.