This study describes current screening rates and associated factors for a large number of American Indian and Alaska Native people surveyed in two regions of the US. Location (Alaska versus Southwestern US), educational status, income, and having one or more chronic medical conditions were consistently predictive of all three screening tests.
The overall prevalence of Pap test and mammography screening reported in the EARTH Study data were only slightly higher compared to rates reported by the Indian Health Services Government Performance Results Act (GPRA) Clinical Reporting System of medical encounter data collected from 1 July 2004 to 30 June 2005 for the Alaska and Southwest areas, and rates for colorectal cancer screening were similar [24
]. The differences in the screening prevalences between Alaska and the Southwest as measured by the IHS data were similar to those found in the EARTH Study.
The prevalence rates of cancer screening found in this study are lower than those reported by Coughlin using the 1992–1997 Behavioral Risk Factor Surveillance System (BRFSS) data [5
]. In addition, the EARTH Study findings for Alaska are lower than those reported by the Alaska BRFSS for 2002–2003 [25
]. The EARTH data are much closer to the IHS GPRA data than to the BRFSS data. Reasons for the discrepancies between EARTH and the BRFSS include: differences between statewide and regional data; differences in selection of study participants (the BRFSS only included people with telephones); and differences in how the questions were asked. The EARTH Study asked individuals how old they were at their last screening test (); the BRFSS asked survey respondents “how long has it been since you had your last test?” It has been suggested that there is a common tendency to underestimate the amount of time that has elapsed since a clinic visit [14
]. Therefore, asking how many years it has been since the last test may yield different results than asking how old one was at the last test.
Another difference between the EARTH Study and the BRFSS (and other studies of American Indian and Alaska Native populations) is that we did not use self-reported race, but required participants to state that they were eligible for Indian Health Services (IHS)-funded health care. Medical record review for Alaska EARTH Study participants found that it was a rare occurrence to find a participant who did not have a medical record in the IHS-funded tribally run system. However, we did not require participants to present documentation of their eligibility and it is possible that, given the areas in which we recruited participants, our definition may not represent a significant difference from self-reported race.
Residents of Alaska were more likely to receive age and sex-appropriate screening for cervical cancer, breast cancer and colorectal cancer than residents of the Southwest. Other studies have found similar discrepancies [5
]. The American Indian and Alaska Native mortality rates for cancer are higher in Alaska than in the Southwest. For all cancers, the 1996–2001 age-adjusted (to US 2000 population) mortality rate in Alaska was 253.7/100,000, and for the Southwest the rate was 131.6/100,000 [3
]. Because of the higher rates of death in Alaska from cancer, more concerted efforts are underway to get people screened; in time, it is hoped that these mortality rates will decrease. It is also possible that people value the importance of cancer screening differently in areas where cancer is seen as more of a threat to health.
All three screening practices were increased among those who had one or more chronic medical conditions. Other studies have found that a recent visit to a primary care provider or having had a recent routine check-up is a predictor of screening [5
]. Although the EARTH Study did not directly collect information on most recent visit or contact with the medical system, the relationship of screening to having a chronic medical condition provides indirect evidence that more frequent contact with the medical system leads to better screening outcomes.
The EARTH Study did not collect information on private or public health benefits other than Indian Health Service eligibility. A study among urban American Indian women found that those with private health insurance were more likely to report breast cancer screening, but a similar study conducted on a reservation did not find a relationship. [6
] We did ask participants where they usually went for medical care. Of 11,358 participants, only 4.1% were missing information on usual source of care. Of the remaining 10,891, the vast majority (99.6%) included at least one IHS or tribally run health facility as usual sources of health care.
For mammography and colorectal cancer screening, the prevalence of screening was higher among urban residents. Our finding that urban residents have higher rates of screening differs from some other studies of American Indian and Alaska Native populations which show that urban Indians who do not live near IHS facilities have difficulty gaining access to health care [6
]. When we analyzed the EARTH Study data by location, we found that the relationship between screening and urban/rural residence was most apparent for Alaska. In the Southwest, recruitment took place on the reservation, and few urban residents were enrolled. In Alaska, IHS-funded tribally run facilities are available to most beneficiaries. For residents of the remote rural villages of Alaska, PAP test screening is usually locally available, however, obtaining colonoscopy or mammography screening may involve one or more airplane rides for several hours to another area of the state, at considerable cost in terms of both time and money. In the Southwestern US, obtaining screening services can also be costly in terms of time and money, involving driving long distances.
In this study we found that individuals who spoke only English at home, compared to those who spoke their Native language, were more likely to have gotten a Pap test in the past three years, and also more likely to have received a colonoscopy/sigmoidoscopy. The relationship was not seen for mammography. Studies in other populations have found that those who speak a language different than English at home tend to have lower breast and cervical cancer screening prevalences, although similar findings have not been reported for American Indian and Alaska Native populations [7
]. Examining predictive factors specific to Alaska and to the Southwest revealed that the finding was most apparent in Alaska. It could be that language itself is not the risk factor, but rather a marker for access to services, despite efforts to control for other factors in the analyses. On the other hand, the finding could indicate that more culturally appropriate outreach efforts are needed to reach those less able to understand English. Factors potentially related to traditional lifestyle, including taking traditional medicine, consulting a traditional healer, participating in traditional events, identity with tribal tradition, and identity with non-Native culture were not related to screening prevalences. Other studies among American Indian and Alaska Native populations have also found these types of indicators not to be related to cancer screening. [7
Despite the fact that all study participants were eligible for IHS-funded health care, markers for socioeconomic status (education and income) predicted improved screening rates. Studies in many other populations have found educational status and/or income to be predictive of cancer screening [5
]. The finding has important implications for reaching American Indian and Alaska Native people to improve cancer screening. It may be that current outreach efforts are more successful among people of higher socioeconomic status, and that different efforts need to be developed for people of a lower socioeconomic status.
Marital status was related to Pap test, with those who were never married less likely to have received a Pap test in the past 3 years. Other studies have found that marital status is related to cancer screening [31
Having a family history of cancer may improve awareness of the disease, and increase both patient and provider efforts to obtain screening tests. We found that women with a family history of breast cancer were more likely to have received mammography, and that individuals with a family history of colorectal cancer were more likely to have had colonoscopy/sigmoidoscopy.
Former smokers were more likely to have had colonoscopy or sigmoidoscopy than current smokers or never smokers. It may be that individuals who can make the effort to stop using tobacco are more likely to make the effort to obtain a fairly difficult screening test. Current users of smokeless tobacco (snuff or chew) were less likely to receive mammography than former or never users. The relationships with tobacco use were most apparent in Alaska where tobacco use was much higher than in the Southwest.
In summary, this study investigated predictors of cancer screening in American Indian and Alaska Native people living in Alaska and in the Southwest United States. The screening prevalences varied between Alaska and the Southwest. Higher educational status, higher income and the presence of one or more chronic medical condition predicted each of the screening tests. Rural residents were less likely to have received age and sex appropriate cancer screening tests. Programs to improve screening among American Indian and Alaska Native people should include efforts designed to be sure to reach individuals of lower socioeconomic status, and who do not have regular contact with the medical care system. Special attention should be made to improve services to those who live in rural areas, and to those living in the Southwest US.