Background: Seropositivity to human papillomavirus (HPV)16 and 18 antibodies is used as a measure of cumulative HPV exposure and as a stratifier of HPV exposure for vaccine efficacy analyses. Overall performance of these assays, as a measure of HPV exposure, has not been evaluated.
Methods: Using data from the enrollment phase of the HPV16/18 vaccine trial in Costa Rica, we evaluated the performance of the polyclonal enzyme-linked immunosorbent assay (ELISA) HPV16 and 18 serological assays as a measure of HPV exposure. Biologic (e.g., HPV infection at the cervix) and behavioral characteristics (e.g., lifetime number of sexual partners) with known associations with current and past HPV infection were used to define cases and controls (HPV exposed vs. not exposed). Prevaccination serum was measured for antibodies against HPV16 and 18 by ELISA; cervical samples were tested for HPV DNA using PCR SPF10/LiPA25. ELISA results were analyzed using receiver–operator characteristic curves; performance was evaluated at the manufacturer set cut point (HPV16 = 8, HPV18 = 7) and at cut points chosen to optimize sensitivity and specificity (HPV16 = 34, HPV18 = 60).
Results: Defining cases as type-specific HPV DNA positive with high-grade abnormal cytology (i.e., combined molecular and microscopic markers of infection), HPV16-ELISA gave sensitivity that was lower at the optimal cut point than the manufacturer cut point (62.2 compared with 75.7, respectively; P = 0.44). However, specificity was higher (85.3 compared with 70.4, respectively; P < 0.0001). Similarly, HPV18-ELISA gave sensitivity that was lower at the optimal cut point than the manufacturer cut point (34.5 compared with 51.7, respectively; P = 0.40), with higher specificities (94.9 compared with 72.6, respectively; P < 0.0001).
Conclusions: Modifying cut points did not improve the low sensitivity. The low sensitivity of this assay does not support its use for risk stratification or clinical settings.
From the *Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD; †Proyecto Epidemiológico Guanacaste, Fundación INCIENSA, Liberia, Costa Rica; ‡Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD; §Division of Cancer Prevention, National Cancer Institute, Bethesda, MD; ¶GlaxoSmithKline Biologicals, Rixensart, Belgium; and ∥DDL Diagnostic Laboratory, Voorburg, The Netherlands
The authors thanks to the women of Guanacaste and Puntarenas, Costa Rica, who consented for participating in this effort. They also acknowledge the tremendous effort and dedication of the staff in Costa Rica involved in this project, including Bernardo Blanco and his team (census), Ricardo Cerdas and Ana Hernández (blood processing), José Miguel González, Osman López, Johnny Matamoros, Manuel Sánchez, Rafael Thompson, and Jorge Umaña (field activity coordinators), Su Yen Araya, Hazel Alvarez, Hayleen Campos, Muriel Grijalba, Ana Cristina Monge, Ana Peraza, Diana Robles, María Fernanda Sáenz, Dorita Vargas, and Jessica Vindas (clinic coordinators), Paola Alvarez, Dinia Angulo, Ana Live Arias, Betzaida Barrantes, Andrea Bolaños, Diego Bonilla, Marianela Bonilla, Mary José Calvo, Loretto Carvajal, Jessenia Chinchilla, Blanca Cruz, Marianela Herrera, Andrea Interiano, Fabiola Jiménez, Erick Lagos, Viviana Loría, Andrea Messeguer, Rebeca Ocampo, Ana Cristina Ocampo, Silvia Padilla, Angie Ramírez, Daniela Romero, Byron Romero, Yessenia Ruiz, Daniela Ruiz, Genie Saborío, Sofía Soto, Malena Salas, Adriana Torrez, Natalia Ugalde, Adriana Vallejos, Yesenia Vásquez, Maricela Villegas (clinicians), Marta Alvarado, Ana Cristina Arroyo, Gloriana Barrientos, Diana Díaz, Marlen Jara, Maureen Matarrita, María Ester Molina, Elida Ordóñez, Adriana Ramírez, Gina Sánchez, and Sihara Villegas (nurses), Arianne Castrillo and Vivian López (education and outreach effort coordinators), Karla Coronado (appointment coordinator), Ricardo Alfaro (quality control coordinator), Yenory Estrada (pharmacist) Charles Sánchez and Livia Romero (document center coordinators), Cristian Montero (quality assurance, regulatory) and Carlos Avila and Eric Alpízar (IT coordinators). Special recognition is also extended to Sofía Elizondo, Executive Director of Fundación INCIENSA and her staff for their administrative support. In the United States, they thank the team from Information Management Services (IMS) responsible for the development and maintenance of the data system used in the trial and who served as the data management center for this effort. They thank for the invaluable contributions made by Julie Buckland and Laurie Rich. They also thank for the contributions made by individuals at Westat, Inc., who provided project development and/or monitoring support, including Maribel Gomez, Kirk Midkiff, Isabel Trejos and Susan Truitt, and the assistance provided by Carla Chorley, Troy Moore, Kathi Shea, Mindy Collins, and Heather Siefers in the establishment of a specimen and vaccine repository for the trial and in their continued assistance with the handling and shipment of specimens. From GSK Biologicals,they thank Gary Dubin, Anne Schuind, Kelechi Lawrence, Darrick Fu, and Bruce Innis for their contribution to discussions regarding trial conduct and Francis Dessy and Catherine Bougelet for HPV-16/18 antibody testing. They thank members of the Data and Safety Monitoring Board charged with protecting the safety and interest of participants in their trial (Steve Self, Chair, Adriana Benavides, Luis Diego Calzada, Ruth Karron, Ritu Nayar, and Nancy Roach) and members of the external Scientific HPV Working Group who have contributed to the success of their efforts over the years (Joanna Cain, Chair, Diane Davey, Francisco Fuster, Ann Gershon, Elizabeth Holly, Silvia Lara, Wasima Rida, Henriette Raventós, Luis Rosero-Bixby, and Sarah Thomas).
Supported by NCI (N01-CP-11005) with support from the NIH Office of Research on Women's Health and conducted in agreement with the Ministry of Health of Costa Rica. S.E.C. is supported in part by training grant NIH R25 CA098566.
W.Q. and L.-J.v.D. are employees of DDL Diagnostic Laboratory; C.B. is an employee of GSK Biologicals. None of the authors have any potential conflicts of interest to report.
The Costa Rican Vaccine Trial is a longstanding collaboration between investigators in Costa Rica and NCI. The NCI and Costa Rica investigators are responsible for the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation of the manuscript. Vaccine was provided for our trial by GSK Biologicals, under a Clinical Trials Agreement with NCI. GSK also provided support for aspects of the trial associated with regulatory submission needs of the company under FDA BB-IND 7920. Douglas Lowy and John Schiller are named inventors on US government owned HPV vaccine patents that are licensed to GSK and Merck, and so are entitled to limited royalties as specified by federal law. None of the other coauthors have any potential conflicts of interest to report.
Cervarix is a registered trade mark of the Glaxo Smith Kline Biologicals group of companies.
Gardasil is a registered trade mark of Merck and Co. Inc.
Names and Affiliations of investigators in the Costa Rica Vaccine Trial (CVT) group are as follows: Proyecto Epidemiológico Guanacaste, Fundación INCIENSA, San José, Costa Rica: Mario Alfaro (Cytopathologist); Manuel Barrantes (Field Supervisor); M. Concepción Bratti (co-Investigator); Fernando Cárdenas (General Field Supervisor); Bernal Cortés (Specimen and Repository Manager); Albert Espinoza (Head, Coding and Data Entry); Paula González (co-Investigator); Diego Guillén (Pathologist); Rolando Herrero (co-Principal Investigator); Silvia E. Jiménez (Trial Coordinator); Jorge Morales (Colposcopist); Lidia Ana Morera (Head Study Nurse); Elmer Pérez (Field Supervisor); Carolina Porras (co-Investigator); Ana Cecilia Rodríguez (co-Investigator); Libia Rivas (Clinician′s coordinator); Luis Villegas (Colposcopist).
University of Costa Rica, San José, Costa Rica: Ivannia Atmella (Microbiologist, Immunology Laboratory); José Bonilla (Head, HPV Immunology Laboratory); Enrique Freer (Director, HPV Diagnostics Laboratory); Alfonso García-Piñeres (Immunologist); Margarita Ramírez (Microbiologist, Immunology Laboratory); Sandra Silva (Head Microbiologist, HPV Diagnostics Laboratory).
United States National Cancer Institute, Bethesda, MD: Allan Hildesheim (co-Principal Investigator and NCI co-Project Officer); Aimee Kreimer (Investigator); Douglas R. Lowy (HPV Virologist); Nora Macklin (Trial Coordinator); Mark Schiffman (Medical Monitor & NCI co-Project Officer); John T. Schiller (HPV Virologist); Mark Sherman (QC Pathologist); Diane Solomon (Medical Monitor and QC Pathologist); Sholom Wacholder (Statistician).
SAIC, NCI-Frederick, Frederick, MD: Ligia Pinto (Head, HPV Immunology Laboratory); Troy Kemp (Scientist, HPV Immunology Laboratory).
Womens and Infants' Hospital, Providence, RI: Claire Eklund (QC Cytology); Martha Hutchinson (QC Cytology).
Georgetown University, Washington, DC: Mary Sidawy (Histopathologist)
DDL Diagnostic Laboratory, The Netherlands: Wim Quint (Virologist, HPV DNA Testing); Leen-Jan van Doorn (HPV DNA Testing).
Correspondence: Mahboobeh Safaeian, PhD, MPH, Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 6120 Executive Blvd, EPS, Room 7086, Rockville, MD 20852. E-mail: email@example.com.
Received for publication December 17, 2010, and accepted May 19, 2011.