Methods are provided for diagnosing the risk of a cardiovascular event in a patient. In some embodiments, the method includes measuring the level of proprotein convertase subtilisin kexin type 9 (PCSK9) in a sample obtained from a patient and comparing the measured level of PCSK9 to a control. Also provided are methods of selecting a therapy for a patient prior to administration of the therapy. In some embodiments, the method includes measuring a PCSK9 blood concentration in a sample from a patient to determine the presence or absence of a PCSK9 blood concentration indicative of responsiveness to an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Further provided are methods for assessing the efficacy of a therapy being administered to a patient. In certain embodiments, the method includes detecting a change in a PCSK9 blood concentration in a sample from a patient, wherein a change in detected levels is indicative of whether the therapy is efficacious.
