WILMINGTON, N.C.--(BUSINESS WIRE)--Pharmaceutical Product Development, LLC (PPD) today announced it has been ranked one of the world’s best contract research organizations (CROs) in sustaining strong relationships with investigative sites to promote efficiency, quality and patient safety in clinical research. Research sites gave PPD excellent ratings on a series of key success indicators in the CenterWatch 2015 Global Site Survey, published today in CenterWatch Monthly. The survey measured the