These results should be considered in light of five sets of potential limitations. First, people who were homeless or institutionalized were excluded from the NCS-R; however, this is a small percentage of the total population. Second, not all DSM-IV disorders were assessed in the NCS-R; therefore, some people who may have met criteria for a disorder were classified as not having one. Third, the CIDI diagnoses of impulse-control disorders have not yet been validated. Fourth, the validity of the self-reports of treatment use in the NCS-R is unknown. Although the NCS-R did exclude a small percentage of respondents (<1%) who would not agree that they would think carefully and answer honestly in response to survey questions, it is still possible that respondents overestimated [42
] or underestimated [44
] service use. However, note that the Healthcare for Communities Survey found similar rates of service utilization for people with mental disorders[2
]. Finally, it is unknown whether patients in the GM + SMH group saw providers from different sectors serially or concurrently within the previous year.
In spite of these potential limitations, these results shed light on important differences in the clinical characteristics of patients who are treated in particular health care sectors. It appears that cases receiving GM-only treatments are less likely to have severe mental disorders than those receiving SMH-only treatments. Some of the earlier investigations have also found that patients seeking help from general medical physicians tend to have a less serious profile of disorders than those treated in other sectors [12
]. In some mild cases, the less intensive care delivered in GM settings (vs SMH) [2
] may be appropriate. On the other hand, other investigators have not found substantial differences in severity or impairment between primary care and specialty samples[11
]. Reasons for differences between older results and the current study are uncertain, but could be due to changing patterns of care. The current results do indicate that in absolute terms there continue to be many patients with serious disorders who are treated in the GM sector alone (i.e., 15% of these patients have a severe mental illness). It is essential that these patients receive high quality treatments.
As expected, cases treated in both the GM + SMH settings do indeed have more severe forms of psychiatric illness than those seen in either SMH or GM alone. Similarly, Lesage et al.[19
] also reported that individuals receiving joint care exhibited more severe role impairment. This may be partially due to an association between the number of visits and the severity of mental illness [2
]. That is, by definition, in order to receive treatment in two sectors, one must have a minimum of two mental health visits, whereas only one visit is required to receive treatment in a single sector. However, because two visits in two separate sectors may take a much greater effort on the part of the patient than two visits to the same sector, it is unlikely that this completely accounts for the greater severity of mental illness in this group.
A limitation of the NCS-R data is that we do not know to what extent people receiving care in both settings were receiving concurrent care from two providers, versus to what extent the care was serial. That is, the GM + SMH group may include a) patients that GM practitioners referred to a SMH provider, who then assumed responsibility for mental health care or b) patients who dropped out of SMH treatment and then presented to their GM for mental health treatment. To the extent that the GM + SMH group does represent people receiving truly combined treatment, these findings provide some grounds for encouragement, given the data from clinical trials suggesting that combined modality treatments are particularly effective for severe mental illnesses [26
]. The scenario in which GM practitioners refer these more severely ill patients to SMH providers is also encouraging: these may be the patients who are appropriately treated by a specialist. Of more concern is the scenario in which severely ill patients drop out of SMH treatment. [46
]Further investigation of who receives GM + SMH care and exactly what this care consists of is warranted.
Consistent with some of the previous research[18
] is the fact that patients receiving GM treatment (whether alone or with SMH treatment) were more medically ill. Exact reasons for this are unclear but may include the possibility that patients with complex medical problems find it more comfortable or convenient to also have their mental health needs met by their GM provider. Regardless, the fact that primary care physicians must manage all of a patient’s health needs, including the considerable general medical comorbidity that afflicts primary care populations, almost certainly exacerbates “competing demands” on physicians’ limited time and resources and may lead to less intensive and adequate treatment of mental disorders[23
]. More surprising is the fact that SMH providers also see many people with general medical conditions, with over 60% of SMH cases having two or more chronic physical conditions. Although general medical disorders are not necessarily their responsibility, SMH providers clearly have the potential to have an impact on their patients’ general medical treatments and overall health outcomes (e.g., through interventions to improve adherence, increase exercise, or improve diet).
Our results suggest that there are some demographic differences amongst the three sectors. If certain groups, such as the elderly, comprise a larger proportion of the GM sector (relative to the other two sectors), and are less likely to accept mental health treatment [47
], this may also contribute to the decreased adequacy of GM treatment. However, women also comprise a larger proportion of the GM sector, and women may be more accepting of mental health diagnoses than men [49
]. Therefore, it is unlikely that demographic differences between sectors would explain the differing degrees of adequacy of treatment. On the other hand, the demographic differences between sectors do reinforce the need to either ensure that the different sectors provide adequate treatment or decrease barriers to access (especially to combined GM + SMH treatment).
Given that primary care physicians do treat a substantial number of people with moderate-severe mental illness, it is important to improve the quality of GM treatments. Several promising models of outreach and enhanced treatment that incorporate SMH providers in primary care practices have already proven to be effective. A recent study shows that, when primary care physicians and psychiatrists use protocol-driven, measurement-based care to pharmacologically treat depression, they achieve similar outcomes [50
]. A series of studies have also demonstrated improved outcomes in primary care settings with the use of a non-physician depression care manager, who is supervised by a SMH provider, and who follows depressed patients closely, helps the patient and physician to develop a treatment plan, monitors treatment adherence and response, and may offer brief psychotherapy [51
]. There is evidence to suggest that these types of interventions are not only effective but also cost-effective [54
Likewise, the fact that the majority of patients in both GM and SMH treatments have multiple chronic physical conditions also presents enormous opportunities to improve the general health outcomes of patients with mental disorders. As an example, research has found that a collaborative primary care-based depression treatment program improves depression outcomes amongst patients who have diabetes [55
]. However, despite the fact that depression is associated with poorer diabetes outcomes, this treatment program did not result in improved diabetes management. These authors suggest that an integrated disease management intervention that focuses on diabetes-related self-care as well as depression may be needed in order to effect changes in diabetes outcomes as well. In general, the high degree of comorbidity between physical and mental health problems suggests that there is a need for development and testing of integrated disease management interventions that treat common comorbid mental and physical health problems [56
]. These programs may be useful in both SMH and GM settings.