This study was conducted in three phases. The first phase spanned from 1998-2003 (PubMed ID:14706961; PubMed ID: 12915495) and the second phase spanned from 2003-2007 (PubMedID: 18401289; PubMed ID: 17698577). The final phase of the study spanned 2007-2011 and is the scope of this submission.