The results of this study highlight persistent suboptimal levels of treatment initiation for depression, as well as age and racial/ethnic disparities in the initiation of treatment, despite initiatives to enhance depression care in primary care. The study also highlights variations among health care systems in the initiation of treatment for depression, underscoring the importance of better understanding the effectiveness of depression care integration mechanisms and processes. Importantly, the study results reflect recent practice patterns among multiple health care systems, and are based on a significantly larger (n = 241,251) and more diverse patient population than those included in previous studies. The results are strengthened by the inclusion of important covariates (e.g., socioeconomic indicators, prior mental health service use) by leveraging uniform EHR data.

Depression Treatment Initiation in Primary Care

The observed proportion of patients initiating treatment for new episodes of depression diagnosed in primary care was low—36%. This finding is consistent with previous reports.28,29,30,–31 Reasons cited in previous studies for low levels of treatment initiation—stigma, patient resistance, insufficient training or discomfort of primary care providers, and access barriers, particularly for behavioral health services—likely contributed to the low levels of treatment initiation observed in this study.32, 33

Barriers to treatment initiation specific to primary care settings were also likely contributors. These include greater aversion to depression treatment among primary care patients than behavioral health patients, competing demands, time constraints, and different priorities for patients and providers.34, 35

Patient Characteristics, Treatment Initiation, and Treatment Choice

Race/Ethnicity

The results demonstrate significant, persistent differences in depression treatment initiation associated with race/ethnicity. The odds of Asians, non-Hispanic blacks, and Hispanics initiating treatment were at least 30% lower than those for NHWs, after controlling for all other variables. This finding is consistent with previous evidence of racial and ethnic disparities in depression treatment initiation.6, 7, 9, 36

This study also provides evidence of a preference among minority patients for psychotherapy over AD treatment.8,9,10,–11 Access to one’s preferred choice of depression treatment has been found to enhance treatment initiation, adherence, and outcomes.37, 38

Age

Persistent significant age-related differences were found in treatment initiation. The odds of patients aged 60 years and older starting treatment were half those of patients age 44 years and under. With a rapidly growing aging population, the importance of addressing the mental health needs of this group will increase. Previously reported depression treatment gaps for older patients are further supported by this study.39, 40 Lower treatment initiation among older patients has been attributed to a common misconception of depression as a natural part of the aging process, a generational culture of personal responsibility, attribution of depression to non-medical causes, and stigma.39, 41, 42 Resistance to AD treatment has also been identified in this population.43

Comorbid medical conditions among older patients may compete for the attention of primary care providers and potentially mask or overlap with depression symptoms.39 The results of this study show slightly higher odds of initiating treatment as comorbidities increase. Improved medical disease and depression outcomes have been reported with collaborative care approaches for patients with depression and common comorbidities, particularly diabetes and cardiovascular disease.18, 44,45,–46

Gender

Although depression is more common among women than men (8.2% vs. 4.6%),1 the study results revealed a slightly higher proportion of men initiating treatment. In addition, the odds of starting psychotherapy were 18% higher for men than for women. These gender-related differences in treatment initiation are a particularly important and positive finding, given that men account for more than three-quarters of suicides among middle-aged adults.47

Among those who started treatment, psychotherapy was initiated by 17%, and 83% started AD medications. This high proportion of AD use may reflect the large proportion of NHWs in the study population (47%), greater familiarity with AD among primary care providers, a desire to rapidly address a newly identified condition, and possibly access barriers to behavioral health specialty care.

Health Care System Factors

Large differences in treatment initiation were observed across the five participating health care systems, with aORs ranging from 0.66 to 1.03. While all sites had taken steps to enhance depression care, including the use of the PHQ-9 depression scale in some manner in primary care, the specific features and full scope of efforts to improve the quality of depression care in primary care varied across sites and within sites over time. For example, mechanisms for psychotherapy referral might have ranged from an instant consultation with a behavioral health specialist co-located in primary care at the time of the visit, to simply giving the patient a phone number. While it was not possible in this study to retrospectively reconstruct patient-level exposure to health care system initiatives to enhance depression care, the study results highlight the importance of doing so in the future. The proportion of new diagnoses with a concurrent PHQ-9 score (an important feature of care integration) ranged from 5% to 33% across sites (not shown). Higher treatment initiation among the screened group of patients could reflect a more focused approach to screening versus a general screening approach.

Limitations

Study limitations include the omission of any brief counseling provided by primary care physicians upon diagnosis. An important limitation is that we have little information about the reasons for failure to initiate treatment, or the relative contribution of patient, provider, and system factors. In addition, since depression is common in the study population, odds ratios may slightly overestimate the associations with predictive factors.48 Finally, while all study sites were using the PHQ-9, this study lacks detailed information about the specific conditions under which the tool was utilized, and particularly methods of care integration at the study sites during the study period.

Next Steps

Efforts to integrate behavioral health care within primary care settings have been under way and evolving across the United States for more than 15 years. The features of collaborative care models vary widely, but there is evidence that these models can be effective in improving depression management and outcomes19, 20, 49, 50 and that they are cost-effective.51,52,–53 There is also evidence that collaborative care models can be effective for particular patient groups, including younger54 and older populations51, 55,56,–57 and racial minorities.58,59,60,61,–62 Some models of care have been reported to reduce racial/ethnic disparities.63 While these models may not be universally effective,62, 64, 65 regulatory requirements and the desire to better meet patients' mental health care needs will lead to further implementation efforts.

The results of this study provide evidence that a substantial number of patients with diagnosed depression do not receive treatment, even in leading health care organizations. Ongoing efforts to address this problem, coupled with more thorough and sophisticated evaluation methods, will enhance our understanding of the mechanisms by which various models succeed in improving treatment engagement, incorporating patient preferences, improving adherence and outcomes, and reducing disparities.