[1] UNIV BRITISH COLUMBIA,ST PAULS HOSP,DEPT HLTH CARE & EPIDEMIOL,VANCOUVER,BC,CANADA
[2] MUNICIPAL HLTH SERV,AMSTERDAM,NETHERLANDS
[3] UNIV CALIF SAN FRANCISCO,DEPT EPIDEMIOL & BIOSTAT,CTR AIDS PREVENT STUDIES,SAN FRANCISCO,CA 94143
[4] UNIV NEW S WALES,NATL CTR HIV EPIDEMIOL & CLIN RES,SYDNEY,NSW,AUSTRALIA
[5] UNIV CALIF SAN FRANCISCO,SAN FRANCISCO GEN HOSP,DEPT EPIDEMIOL & BIOSTAT,SAN FRANCISCO,CA