Diadexus, Inc. announced that it has signed an agreement with Sonic Healthcare USA to launch the company's PLAC Activity Test into Sonic's national network of laboratories. The PLAC Test for Lp-PLA2 Activity is the only FDA-cleared test used in conjunction with clinical evaluation and patient risk assessment as an aid in predicting the risk of coronary heart disease (CHD) in patients with no prior history of cardiovascular events, a population representing approximately 75% of CHD patients.