1. Kaiser Permanente Division of Research, Oakland, California (M.E.R., J.H., A.M.)
2. The Permanente Medical Group Walnut Creek, Walnut Creek, California (R.P.)
3. The Permanente Medical Group and Kaiser Permanente Division of Research, Oakland, California (D.W.B.)
4. The Permanente Medical Group Vallejo, Vallejo, California (I.B.)
5. The Permanente Medical Group Santa Clara, Santa Clara, California (C.W.)