Women living below the poverty line are at greater risk for infection with potentially cancer-causing strains of human papillomavirus (HPV) than are better-off women, but among those living in poverty, there are few socioeconomic or demographic predictors of risk.1 Analyses of data from the 2003–2004 National Health and Nutrition Examination Survey indicate that among poor women, Mexican Americans are significantly less likely than whites to have a high-risk HPV infection, and unmarried women have higher odds of infection than married women. By contrast, for women living above the poverty line, the likelihood of infection is predicted by race, income, marital status and age.

The analyses were based on data from 14–59-year-old women in the nationally representative survey sample who agreed to have an HPV test in addition to completing the survey’s interview and health examination. Participants willing to have the test were taught to collect a vaginal fluid specimen for analysis; the 1,921 women who submitted specimens that were adequate for testing were included in the study. Researchers used chi-square and logistic regression analyses to explore the prevalence and predictors of HPV infection among women with varying socioeconomic and demographic characteristics.

On average, study participants were 36 years old; half were married. Most were white (69%) and had at least a high school education (78%); 18% had a household income that was below the poverty line for their household size. Sixteen percent of participants, representing more than 12 million U.S. women aged 14–59, tested positive for at least one high-risk type of HPV.

The prevalence of infection with any type of HPV that is linked to cervical cancer was significantly higher among women living in poverty than among those with an income at least three times the poverty threshold (23% vs. 12%). It also varied markedly by age (27–29% among women in their late teens and early 20s vs. 11–17% in other age-groups), race (21% among both black and multiracial women vs. 13–16% among other groups) and marital status (10% among married women vs. 21–23% among unmarried participants).

An initial multivariate analysis indicated that women aged 18–21, those aged 22–25 and those aged 30–39 had significantly higher odds of high-risk HPV infection than those aged 40 or older (odds ratios, 2.0, 3.1 and 1.8, respectively). The odds were higher among formerly married, never-married and cohabiting women than among their married peers (1.9–2.6), and were lower among Mexican Americans than among whites (0.6).

In univariate analyses, associations between the prevalence of high-risk HPV infection and race varied by poverty status. However, the data suggested that the differences may have been at least partly attributable to differences in marital status or income; therefore, the analysts calculated separate logistic regression models for poor and nonpoor women.

The stratified models yielded strikingly different results. For women living below the poverty line, only two characteristics were associated with the likelihood of having a high-risk HPV infection: Mexican Americans had lower odds of infection than whites (odds ratio, 0.4), and unmarried women had higher odds of infection than married women (3.3). Among women above the poverty line, however, several characteristics were significant predictors of infection. The likelihood of infection was higher for unmarried than for married women (2.0) and for women aged 18–25 than for those older than 40 (2.0–2.4); it was inversely associated with annual income (0.9). In addition, black women were more likely than whites to have a high-risk infection (1.4), but this difference largely reflected that nonpoor black women had a lower mean income and were less likely to be married than their white counterparts.

The researchers point out that measurement error and, in some subgroups of women, small numbers may have affected their findings. Furthermore, they note that not all women with HPV infections develop cervical cancer, and that they were unable to assess factors that may influence this outcome. Despite these limitations, they conclude that because few variables predict HPV infection in poor women, prevention interventions "must ensure that all low-income women have enhanced access to HPV vaccines as well as education and other preventive services." To achieve this goal, they recommend that girls be vaccinated "while they are still covered by benefits for low-income children" and that legislative and community efforts work toward ensuring the availability of low- or no-cost vaccines to low-income young adults.—D. Hollander

REFERENCE

1. Kahn JA et al., Sociodemographic factors associated with high-risk human papillomavirus infection, Obstetrics & Gynecology, 2007, 110(1):87–95.