Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by warfarin sensitivity ?
    ### Response:
    The prevalence of warfarin sensitivity is unknown. However, it appears to be more common in people who are older, those with lower body weights, and individuals of Asian ancestry.  Of the approximately 2 million people in the U.S. who are prescribed warfarin annually, 35,000 to 45,000 individuals go to hospital emergency rooms with warfarin-related adverse drug events.
    