1. Department of Medicine, Intermountain Central Laboratory, Murray, Utah.
2. Central Laboratory, Intermountain Healthcare, Murray, Utah.
3. Statistical Data Center, Intermountain Healthcare Research, Salt Lake City, Utah.
4. Department of Medicine, McKee-Dee Hospital, Ogden, Utah.
5. Intermountain Healthcare, Salt Lake City, Utah.
6. Department of Clinical and Experimental Medicine, Policlinico Universitario di Messina, Messina, Italy.