Compositions are disclosed comprising an effective amount of nitrated fibrinogen and a pharmaceutically acceptable carrier for detecting a patient's risk for coronary artery disease. The compositions can be used to determine the presence of nitrated fibrinogen which is linked with coronary artery disease. Also disclosed is a method for determining the presence or risk for coronary artery disease or risk for increased propensity for an adverse thrombotic event in a patient. The method comprises obtaining a sample of blood or fraction thereof from a patient; determining by immunoassay the amount of nitrated fibrinogen in the sample based on binding of the nitrated fibrinogen to an antibody that specifically recognizes SEQ ID NO: 2 and/or SEQ ID NO: 3; and comparing the amount of the antibody-bound nitrated fibrinogen in the sample with the amount of nitrated fibrinogen in a sample from a normal individual, such that a greater amount of nitrated fibrinogen in the patient sample than in the normal individual indicates that the patient has or is at greater risk of coronary artery disease or risk of increased propensity for an adverse thrombotic event. Kits for performing the method which include the composition and aforementioned antibody or antibodies are also provided.