Patient-centered care is an important benchmark for quality of healthcare, and communication has been identified as a key to achieving patient-centered care [18
]. Communication between BC patients and their physicians in our study population might be particularly challenging, given the fact that the majority of the study population consisted of a less acculturated ethnic minority with language barriers known to have less self efficacy in patient-physician interactions compared to other populations [23
]. This is one of the first studies focusing on the role that patient-centered communication played in adjuvant hormone therapy adherence in a low-income population. This study is also particularly notable for its large Latina representation, allowing a close examination of an important patient outcome in the largest racial/ethnic minority group in the U.S.[37
], about which little is known.
Overall, self-reported use of TAM/AI at three years was relatively high (88%) in our study population and compares favorably to other recent studies. Partridge et al. reported adherence of 82% to 88% in the first year and 62% to 79% in year 3 in three commercially insured populations, and most of the women who were non-adherent were found to have discontinued therapy [38
]. Kahn et al, reported that at 4 years, 79% of women with early stage breast cancer were still taking hormonal therapy[39
], while Hershman et al. found that by 4.5 years, 68% of women with early stage breast cancer treated in the Kaiser Permanente of Northern California health system were continuing therapy[40
]. Hershman et al found that the estimated survival at 10 years was 81% for women who continued adjuvant hormonal therapy compared with 74% for those who discontinued [9
]. Extrapolating from these data, notwithstanding the more advanced disease in the BCCPT cohort, given their higher than expected adherence rate at three years, the women in our study may have better outcomes than might be otherwise expected.
The positive impact of patient-centered communication on adherence from our study is consistent with Kahn et al’s study showing patient-centered care as a positive predictor of patient adherence to ongoing tamoxifen use among women with BC in a general population [10
]. This result is also consistent with prior literature demonstrating improvement in patient outcomes such as better cancer care and reduced symptom burden with the use of patient-centered communication [20
]. This type of communication might be particularly needed to deliver care among a population with language barriers and less confidence in their ability to get their physicians to attend to their health concerns than other populations [41
]. Studies show that patients report difficulties in communicating with physicians such as the physician not listening to their concerns, caring about their problems, or providing enough information about their treatment[43
]. By showing respect to patients, spending enough time with patients, listening carefully to patients’ questions, and explaining things in a manner that the patient can understand, patient-centered communication may help address patients’ concerns and achieve better clinical outcomes. A recent study has shown that patients were less likely to have tamoxifen treatment interruptions if they were given chances to ask questions about treatment at diagnosis [46
Findings from the current study indicate that patients with higher perceived self-efficacy in interacting with physicians had greater odds of use of hormone at 3 years after BC diagnosis. This finding consistently supports the concept that self-efficacy in interacting with physicians is positively associated with many positive BC outcomes in vulnerable populations [26
]. Women with greater self-efficacy may be able to solicit and incorporate information that is personalized to their particular informational and psychosocial needs for decision-making about hormone therapy.
As expected, hormone therapy discontinuation rates were significantly greater among women those physicians documented side effects. Although TAM and AIs are generally well tolerated, associated adverse effects include vasomotor symptoms and gynecologic problems [47
]. Side effects have been reported as major reasons for hormone therapy non-adherence in many studies [10
]. Grunfeld et al showed that about one fifth of women discontinued tamoxifen therapy within the 3-year follow up because of side effects [14
]. However, patients are more likely to be adherent to the hormone therapy if they are well informed about the side effects before the treatment initiated, underscoring the need for effective patient-physician communication [10
Findings on the impact of comorbidities on hormone therapy adherence have been mixed. Some studies found that having one or more comorbidities was not a predictor of adherence [9
]; while other findings indicated that the presence of a comorbidity was predictive of continuous use of hormone therapy [4
]. In our study, women with at least one comorbidity were more likely to be adherent to the therapy than those without any comorbidities. Some researchers suggest that patients taking more than one prescription medication may have developed routines to promote adherence [8
]. Also, patients with comorbidities might have more contact with the healthcare system and receive more support for taking medications as prescribed.
Interestingly, less acculturated Latinas were significantly more likely than whites to remain on hormone therapy 3 years after the BC diagnosis. This finding is in contradistinction to research indicating that racial/ethnic minority BC patients tend to have poorer medication adherence rates than whites [49
]. Specific to hormone therapy, African Americans have been shown to have lower adherence rates [40
]. Less acculturated Latinas have been found to be particularly fearful of BC recurrence compared to whites[52
], and this may have driven adherence rates higher. Another possible explanation might be that healthcare providers may be more likely to spend time to discuss hormone treatment with patients or use culturally and linguistically competent approaches to communicate with patients when patients’ language and cultural differences are apparent. In addition, patient beliefs about the risk and benefits of hormone use have been shown to be predictive of adherence [11
]. Although we were unable to evaluate it in this study, there may be differences in these beliefs related to race/ethnicity. Further research is needed to explore the contributing factors to the ethnic variation in adherence found in this study.
Not surprising, health insurance status had a great impact on the continuity of therapy at 36 months after BC diagnosis. Having insurance, in general, is an important facilitator of access to healthcare. Our finding mirrors the previous literature findings on lack of insurance as a barrier for treatment adherence [53
]. Indeed, the relatively high rate of adjuvant hormone treatment adherence in our population might reflect in part the facilitated access to care for un-or underinsured women by virtue of enrollment into the BCCTP program. However, our study raises key questions regarding the degree of patient-centered communication that is needed to improve cancer treatment adherence even in a safety-net healthcare system. Healthcare providers should be aware of the power that patient-centered communication has in enhancing hormone therapy adherence among vulnerable populations.
Several limitations to this study should be noted. Because the sample was comprised of low-income, medically underserved women in a specific Medicaid BC treatment program in California, generalizability of the findings to other low-income populations may be limited. Also, generalizability to other Latina populations other than Mexican Americans may be limited due to their predominance in the California Latino population [55
]. Third, although we achieved a 61% response rate, the differences between responders and non-responders in terms of age and race/ethnicity might potentially have biased the observed results if non-responders were less likely to be adherent to hormone therapy. However, our response rate is comparable to other similar studies [56
], and recent studies revealed that even if differences exist between respondents and non-respondents, lower response rates do not necessarily bias results [58
]. Fourth, since adherence was measured by patient self-report, the high adherence rate may have been affected by social desirability response bias. However, a recent published paper on this study population reported that self-reporting of key treatment and prognostic information is relatively accurate among these low-income women with BC [60
Taken together, this study’s results suggest that adherence to hormone therapy among low-income, medically underserved women with BC could be enhanced by targeted interventions aimed at increasing patient-centered communication and by attention to side effects from the treatment. In addition, future research would be helpful in identifying the underlying cultural factors that contribute to ethnic variation in cancer treatment adherence.