A total of 9,706 women enrolled in the HSS project were included in our analyses. Women who were positive for human immunodeficiency virus and women without valid HPV test results were excluded. Among the cohort, 291 women were classified as AI/AN, which represented 3% of the overall group (). NHW women comprised 40%, African Americans 26%, Hispanic women 22%, and Asian or Pacific Islander (API) 11% of the group.
Prevalence of HR-HPV by demographic characteristics and cytology results among AI/AN women compared with the entire HSS study, 2003–2005
Of 291 AI/AN women, 61 (21%) self-identified as AI/AN alone, 136 (47%) self-identified as AI/AN and Hispanic, 51 (18%) self-identified as AI/AN and white, 14 (5%) self-identified as AI/AN and African American, and 29 (10%) self-identified as AI/AN and other (API/Hawaiian or multiracial). Among AI/AN women alone, the crude HR-HPV prevalence was 41% (95% CI 29, 53) compared with 27% (95% CI 18, 37) among AI/AN women with an additional race and 43% (95% CI 19, 46) for AI/AN women combined with two or more races (data not shown).
Among the AI/AN women, the age range was 14–65 years, with more than half of the women (54%) in their 20s at the time of testing. About half of the women were from family planning clinics (51%), with 35% tested in STD clinics, and the remainder in primary care clinics (14%). Geographically, 59% were seen in the Seattle clinics, 26% in the Denver clinics, 8% in the Boston clinics, and the rest in the other cities ().
The overall crude prevalence of HR-HPV infection was 32.7% (95% CI 27.5, 38.4) in AI/AN women compared with 24.9% (95% CI 24.0, 25.8) in women of other racial/ethnic minority groups. Prevalence was highest among the 39 adolescents (aged 14–19 years), with 48.7% testing positive for HR-HPV. The prevalence of HR-HPV by clinic type was highest among AI/AN women attending STD clinics (42.6%) compared with family planning (31.8%) and primary care (11.9%) clinics. These findings are consistent with the overall group of women enrolled in HSS ().
To assess the relative effects of race/ethnicity on HR-HPV, HPV 16 and 18, and abnormal Pap smear test results, we calculated age- and clinic-adjusted prevalence estimates and indirectly standardized to the total number of women entered in the study from all cities. Adjusted prevalence for HR-HPV in AI/AN women was 29.1% (95% CI 23.9, 34.3), which was similar in NHW women (25.8%, 95% CI 24.4, 27.2). Prevalence rates in African American and multiracial women were similar to AI/AN as well. Hispanic and API women had a statistically significant lower rate of HR-HPV, although the absolute difference in prevalence was small ().
Prevalence of HR-HPV and abnormal Pap smear test results by race/ethnicity, adjusted by age and clinic type among women in the HSS study, 2003–2005
Among AI/AN women, 234 (83%) had a normal Pap smear test result compared with 8,480 (86%) in the non-AI/AN group (). The crude prevalence of HR-HPV in women with normal Pap smear test results was higher in AI/AN vs. non-AI/AN women (25.2% vs. 19.1%, p=0.02) but not statistically significant after adjusting for age and clinic type. Among women with an abnormal Pap smear test result, there was no difference in the crude or adjusted prevalence of HR-HPV DNA detected in cervical swab specimens among the AI/AN and non-AI/AN groups.
For the HR-HPV types targeted by the prophylactic HPV vaccine (i.e., HPV 16 and 18), adjusted prevalence estimates were not significantly different for AI/AN (6.7%, 95% CI 3.9, 9.6) and NHW (8.8%, 95% CI 7.9, 9.7) women. The rates in Hispanic, African American, and API women were also similar. Prevalence was higher at a statistically significant level for non-AI/AN multiracial women (14.9%, 95% CI 8.0, 21.7) (). Among those positive for HR-HPV, the crude estimate of HPV 16 and 18 among AI/AN women was 23% (23/95) and was similar to prevalence in non-AI/AN women (30% [720/1,625], p=0.12 for comparison) (data not shown).
Comparing racial/ethnic groups, age- and clinic-adjusted prevalence estimates of abnormal Pap smear test results (≥ASC-US), AI/AN women were no more likely to have an abnormal Pap smear test result than NHW women (16.0% vs. 14.9%) (). Similarly, no significant differences were found between AI/AN and Hispanic or multiracial women, although AI/AN women were more likely to have an abnormal Pap smear test result compared with African American and API women.
The crude prevalence of specific HR-HPV types for the AI/AN group was compared with non-AI/AN women (). HPV 16 was the most prevalent (5.5%) followed in descending order by 52, 39, 59, 66, 53, 56, 45, 73, 31, 18, 58, 51,70, 67, 68, 33, 35, 82, 26, and 69. HPV IS39 was not found in the AI/AN population. While the descending order for the non-AI/AN group varied from the AI/AN group, the trend for these types was quite similar, with HPV 16 being the most prevalent and HPV 82, 26, and 69 being the least prevalent for both groups. We did not control for the presence of multiple HR-HPV DNA types in these analyses; however, the crude prevalence estimates of multiple infections were similar between AI/AN women (37.0% [36/95]) and non-AI/AN women (38.8% [909/1,436]) (p=0.86).
Prevalence of type-specific HR-HPV DNA among women in the HSS Study, 2003–2005a