Breast cancer screening disparities among urban immigrants: a population-based study in Ontario, Canada

Tables 4 and 5 display overall and across the age groups screening rates by immigration groups and other socio-demographic and health-related characteristics. Sixty-four percent of women 50–69 were appropriately screened. Overall, screening rates were lower for identified immigrants (57 %) and RR (57 %) compared to 66 % among LTR (Table 4). There were higher appropriate screening rates among older women (67 %) compared to younger women (62 %) (Table 5). Furthermore, breast cancer screening rates increased with increasing neighborhood income, greater utilization of health services, and higher number of co-morbidities, having a periodic health exam, having a primary care physician, patient enrolment models particularly Family Health Teams (FHT), Family Health Organizations (FHO) and Family Health Networks (FHN), having a female physician, and having a Canadian-trained physician (Tables 4 and 5). FHO and FHN are blended capitation models and FHT is a team-based model with physicians reimbursed through blended capitation or blended salary.

In our multivariate analyses, we found significant differences in appropriate screening by immigrant group. The screening rate for new immigrants (i.e. ≤5 years in Canada) was 50 % as opposed to 52 % for recent immigrants (6–10 years) and 60 % for established immigrants (11 years and more) (data not shown). The older new immigrants had the lowest screening rates (46 %) while the younger established immigrants had the highest (60 %) (data not shown). Table 6 and Fig. 1a, b, c show ARRs for appropriate screening rates for overall participants and by age group and socio-demographic, immigration and health related characteristics. Immigrants had significantly lower rates compared to LTR (ARR 0.87, 95 % CI 0.85–0.88) for new immigrants, (ARR 0.90, 95 % CI 0.89–0.91) for recent immigrants, (ARR 0.96, 95 % CI 0.96–0.97) for established immigrants), and this was most pronounced among the older age group. The income gradient was similar for both age groups, with women living in the lowest income neighborhoods being approximately 10 % less likely to be appropriately screened than their high income counterparts (ARR 0.91, 95 % CI 0.91–0.91). Screening rates increased with increasing health care use. Patient enrolment models were associated with an increased likelihood of being screened; those not enrolled were 22 % less likely to be screened compared to those who were enrolled in FHO (ARR 0.78, 95 % CI 0.77–0.79). Having a periodic health exam increased the likelihood of being appropriately screened by 60 % (ARR 1.60, 95 % CI 1.59–1.61).

Considering the national target participation rate of 70 %, our study showed that overall breast cancer screening rates in Ontario are still suboptimal with less than two-thirds of eligible women being appropriately screened. However, rates of appropriate screening were significantly lower among immigrant women than for long term residents and varied by their length of stay in Canada. Older immigrant women aged 60–69 years had significantly lower rates than younger immigrant women aged 50–59 years. Higher rates of screening were associated with being enrolled in a primary care PEM, having higher use of health services and co-morbidities, and having a periodic health exam. Factors that were associated with lower rates of screening included living in low- income neighborhoods, having a male physician, and having an internationally-trained physician.

Our finding of lower rates of screening mammography among immigrant women supports the screening disparities reported in other studies [4‐6, 13‐16] but also shows an increase in screening use with increasing length of residence in Canada. The effect of acculturation particularly among those living in Canada more than 10 years seem to be playing a role in promoting screening practices. Cultural beliefs and values (such as culturally-based fatalistic beliefs, viewing cancer as taboo and stigmatic, belief that cancer can be caused just by thinking or talking about it) in conjunction with factors such as linguistic and economic challenges after migration, and limited knowledge of available health care services in the host country are common barriers to access and use of screening services by immigrant women [5, 9, 10, 22‐28]. The notion of prevention and early detection has been reported to be quite alien to non-European immigrants, particularly those from developing countries. The emphasis on treatment of symptoms and anomalies in the home countries may hinder immigrant women to seek medical care while asymptomatic post migration [5, 10, 27‐30]. These insights can be used to guide the design and implementation of culturally and linguistically appropriate breast cancer screening education and programs to address their pre-existing beliefs about breast cancer and screening.

Prior studies have reported that immigrants, particularly newcomers, are disproportionately included in low income neighborhoods [15, 30, 31]. People with low incomes may have competing priorities and not be able to make time for preventive care. Lobb and colleagues [32] identified several factors that could sway immigrants’ access to screening services in those neighborhoods, like fear of losing wages since screening services are offered during working hours, belief that payment was required for the tests, transportation, and need for interpretation.

The role of primary care providers in encouraging preventive services has been highlighted in several studies [33‐36]. We found that frequent contact with the health care system and having physical check-ups significantly increased screening. Having more contact with the health care system provides ample opportunities for healthcare providers to educate and inform women about the benefits of screening. We also found that lower rates of screening were associated with having internationally- trained physicians. Physicians’ inadequate knowledge of screening guidelines and lack of recommendations have been identified as key deterrents in screening participation and reinforcement of misperception that some groups are not at risk for cancer [31‐33]. Internationally- trained physicians may have a lack of awareness and familiarity with Canadian screening guidelines or may be contending with the imprints of previous training and practice which may have focused heavily on treatment of disease. Similar to results from other studies [37, 38], physician characteristics such as being female were associated with higher rates of screening. Differences in beliefs and practices of male and female physicians regarding the effectiveness, referral and follow up of screening, as well as patient preference for a female provider have been identified to contribute to the higher rates of mammography screening [37, 38]. Finally, the type of physician enrollment model was associated with use of screening. As expected and shown in prior studies [39, 40], rates were higher for those PEMs (e.g. FHO, FHTs and FHNs) where there are financial incentives to provide preventive care, and lowest for physicians not enrolled in any model. This may suggests that patients’ enrollment in PEMs should be encouraged in order to promote regular and timely uptake of screening by women in general and immigrants in particular.

Our study had several limitations. First, the use of administrative data limits the ability to address causation or account for some confounders such as religion and ethnicity that may affect women’s participation in screening. Second, those immigrant women who were not captured through CIC, but arrived between 1985 and 1993, would be included in the referent group. Moreover, the referent group also included immigrant women who arrived before 1985. However, the proportion of women this applies to, although unknown, should be relatively small and our results are likely not greatly affected. According to Canadian Census 2006, about 75 % of migrants to Ontario were from other countries and the remainder was from other Canadian provinces, some of whom were also immigrants [41]. If we had been able to isolate Canadian-born women, we then would expect to observe a larger disparity than reported here. Third, we used neighborhood income which is an ecological variable, as a proxy for women’s income, which may lead to ecological fallacy. However, the ecological-level variables are commonly used in the health equity studies and can provide conservative estimates of socioeconomic effects [42]. Finally, we used Poisson regression which is more commonly used for count variables as the dependent variable. This was done because our outcome (whether the woman had a breast cancer screening in the past 2 years) is quite common, so logistic regression, which gives odds ratios, would not give accurate estimates of rate ratios. It would give incorrectly large magnitudes for ratios. In cases where the outcome is common, Poisson regression can be used to calculate rate ratios as long as the follow-up time is the same for everyone, which in our case it was (i.e. in the past 2 years) [21, 40]. This approach will give a conservative confidence interval since Poisson errors are over-estimates of binominal errors, however because of our large sample size our confidence intervals remained relatively narrow. Despite these limitations, our study had many strengths. It is a large, population-based study with broad inclusion criteria which contained all women age 50–69 with health coverage in Ontario’s urban areas. The use of objective data instead of self-report is another advantage which overcomes biases inherent in self-report. We also stratified all the analyses by age group to determine if there were differences based on women’s age. Furthermore, the study looked at multiple individual and system related variables which permit us to identify high risk groups and tailor interventions and strategies for promoting breast cancer screening rates in underserved populations.