Depression as a Risk Factor for Underuse of Mammography

Depression is an important women’s health issue. Both the prevalence rates and incidence rates of major depression are higher among women than among men.^1–3 Women are also more likely than men to report each of the depressive symptoms, such as changes in appetite and sleep.⁴ These findings on sex differences have been demonstrated not only in the United States but also around the world.^5,6 Although a number of theories have been proposed to explain the gender differences in rates of depression, why women are more prone to depression is incompletely understood. There is evidence that these sex differences are not simply related to reporting differences in sadness or other symptoms, after controlling for the level of depression.⁷

The high prevalence and incidence of depression in women have significant implications for the overall health of women. Depression has been found to be associated with poor health status outcomes and poor health-related quality of life.⁸ Depression has been linked to increased morbidity from chronic medical illnesses, such as coronary heart disease (CHD) and diabetes. For example, depression following a myocardial infarction (MI) is associated with poor cardiac outcomes,^9,10 and a history of depression in persons with diabetes is associated with the development of diabetic complications.¹¹ Although the mechanisms by which depression complicates medical illness have yet to be elucidated, many authors have found evidence that depression has adverse physiological manifestations and, therefore, is an independent risk factor for a variety of diseases.^9,12,13 Other authors have suggested that depression is linked to poor adherence to treatment recommendations. Noncompliance or nonadherence to treatment recommendations has been found to be associated with depression in a variety of diseases, including angina, end-stage renal disease, cancer, and diabetes, and in different medical settings, including both generalist and specialty care.^11,14–18

In this issue of the Journal of Women’s Health, Pirraglia et al.¹⁹ present an examination of depression as a barrier to breast and cervical cancer screening. The authors report that women with a high depressive burden were significantly less likely to report use of mammography in the year following assessment. No significant relationship was found for depressive burden and subsequent Pap screening.¹⁹ Many authors have argued that breast cancer screening is the best way we have of reducing mortality from breast cancer,^20,21 and although there has been some recent controversy,²² the United States Preventive Services Task Force (USPSTF) found fair evidence that mammography screening reduces mortality. The USPSTF found that the evidence was strongest for women aged 50–69 but stated that many studies indicated a possible mortality benefit for women undergoing mammography at ages 40–49.²³ Reducing breast cancer mortality is part of the Healthy People 2010 cancer focus area goals for the nation.²⁴ Efforts to improve the use of screening mammography will help to fulfill the overall goals of Healthy People 2010 of increasing the quality and length of healthy life and eliminating health disparities.

The findings of Pirraglia et al.¹⁹ suggest that patients with depressive symptoms are less likely to adhere to the preventive health recommendation for breast cancer screening and are in line with some other studies. Two previous investigations reported an association between depression and diminished attendance at breast cancer screening clinics,^25,26 and one previous investigation reported that lower level of depression was predictive of subsequent adoption of mammography.²⁷ In contrast, other authors have not found an association between depression and mammography use in psychiatric service settings^28–30 or in primary care.³¹

Interestingly, Pirraglia et al.¹⁹ found a relationship between depression and mammography screening but not between depression and Pap screening. Several other studies have reported that mammography use and Pap tests were highly related.^32,33 In fact, one study suggested that performing a Pap smear appeared to serve as a prompt for physicians to order a mammogram.³⁴ The findings from the present study examining the Study of Women’s Health Across the Nation (SWAN) cohort indicate the possibility that depressed women might see their healthcare provider for cervical cancer screening but need extra assistance to follow up with mammography screening. These findings highlight the importance of depression screening at the time that gynecological examinations are performed in primary care settings.

The examination of depression symptom burden and screening for breast and cervical cancers by Pirraglia et al.¹⁹ used data from the SWAN study, a large cohort study. SWAN data spanned 4 years and involved 3302 community-dwelling women age 42–52 at the beginning of the follow-up period. The large sample size, the inclusion of women of color, and the prospective design were all strengths. Women with high depressive burden (Center for Epidemiological Studies Depression score [CES-D] ≥ 21) had an adjusted odds ratio (OR) of reporting having had mammography of 0.84, compared with women with a low depressive burden (CES-D < 16). The authors adjusted for age, ethnicity, smoking status, education and income, insurance status, high medical use, study site, and family history of breast cancer. Depression symptom burden was not found to be significantly related to cervical cancer screening.

The findings from the SWAN cohort provide prospective evidence that depression may be a possible risk factor for underuse of mammography. Other authors have shown that higher family income, ≥12 years of education, having health insurance coverage, having a usual source of care, and living in an urban area are associated with use of mammography.^35–38 Some studies have also suggested that use of mammography may differ depending on ethnicity.^36,39,40 Data from the U.S. Department of Health and Human Services from 2000 show that 72% of non-Hispanic white women, 68% of non-Hispanic black or African American women, and 61% of Latina or Hispanic women reported having a mammogram in the past 2 years.⁴¹ Previous studies have only begun to explore the factors related to underuse of mammography, but the evidence is growing that depression may be one of such factors.

The barriers to mammography use are complex. Future research is needed to both confirm the factors that have been shown to be associated with underuse of mammography and also explore whether other factors might be related to mammography use. Precisely identifying barriers to mammography is necessary to design and maximize effective interventions.

Evidence suggests, however, that assessing depression should be considered when developing breast cancer screening programs. Through assessment of depression, a subgroup of vulnerable women could be identified and specifically targeted in screening programs. Offering breast cancer screening programs to women with depression will not be without challenges. Most people with depression never seek treatment in either primary care or mental health settings.⁴² The challenge is to develop ways to recognize vulnerable women who have poor access to medical care or who may not make optimal use of the medical system. Doing so will require that we continue to study how to integrate medical care and care for depression.