Mother-Daughter Preference Conflicts and Willingness to Pay for HPV Vaccines

Presenter: F. Reed Johnson, RTI International

Abstract

Human papillomavirus (HPV) is the most common sexually transmitted disease. Nearly 80% of all people get HPV during their lifetime. While most cases are harmless and never detected, about 10% of people contract genital warts and 1% of women develop cervical cancer, which is caused almost exclusively by HPV. To date, the U.S. Food and Drug Administration (FDA) has approved one HPV vaccine for females ages 9-26 that protects against 4 different strains of HPV. Another vaccine HPV protecting against 2 different strains is currently undergoing FDA review. Consumer-direct advertising and an Advisory Committee on Immunization Practice (ACIP) recommendation of routine vaccination for girls age 11-12 has raised substantial public awareness in the U.S. However, perceptions are mixed and inoculation levels remain low (25% or less), especially among younger adolescents.

The HPV vaccine may be controversial for several reasons, including: (1) the link between HPV and sexual activity; (2) the young age of routine recommendation; (3) limited vaccine safety and follow-up data; (4) substantial expense (retail $360 for 3 doses); and (5) the low incidence and fatality rate of cervical cancer. Vaccination decisions for adolescent vaccines, including HPV, involve household decision making, presumably incorporating both parent and daughter preferences. How potential conflicts between parent and daughter vaccine preferences are resolved may be an additional factor influencing uptake levels.

We developed a conjoint analysis (CA) survey of adolescent girls (age 13-17) and their mothers to understand their preferences and willingness to pay for HPV vaccination. CA methods are particularly valuable here because most of the population has not had the vaccine, and because multiple vaccines are likely be available soon in the U.S., each with somewhat different features.

We collected preference data from 307 mother-daughter pairs in the Knowledge Networks nationally representative online panel. Key attributes were price, duration, effectiveness against cervical cancer, and effectiveness against genital warts. Mother-daughter pairs completed individual surveys in a three-part format: background health history and attitudes, sociodemographics, and 8 choice tasks on personal preferences for hypothetical vaccines. When mothers picked either the less-expensive vaccine or "no vaccine" in a choice task, a follow-up question asked whether they would purchase the more expensive vaccine if their daughter preferred it.

We estimated dyad discordance as a function of vaccine attributes and sociodemographics. Mothers and daughters both reported significant, positive willingness to pay (WTP) values for HPV vaccination, but this was driven by different features for each group: daughters had a higher WTP and placed greater value on genital wart protection than mothers. On average, mothers were willing to pay over $200 to avoid conflict with her daughter and switch to their daughters’ preferred alternative, after controlling for vaccine characteristics.