Across major drug classes used to treat SMI, most psychiatric medications were prescribed by PCPs. In rural areas, PCPs prescribed over 75% of the medications in four of the six drug classes examined, including hypnotics and psychotherapeutics, which are specialized psychiatric medications. Providers with behavioral health expertise provided more psychiatric medications in urban areas, at 40% for antipsychotics but less than 25% for other psychiatric medications. In rural areas, percentages from BHSs were significantly smaller, at 30% for antipsychotics and under 16% for other psychiatric medications. The remaining medications were provided by providers with other specialties, including physicians in general surgery, neurology, rheumatology, and psychologists and dentists.
The American Academy of Family Physicians (AAFP) states in their position paper on mental health care services that “family physicians are well-prepared to provide many mental health services” . Our findings demonstrate that primary care physicians are indeed playing a large role in this area of care, prescribing more than half of all psychiatric medications. Primary care APRNs were also substantially involved in prescribing psychiatric medications to Medicare beneficiaries with SMI, especially in rural areas, where they provided up to 13% of medications, including twice as many medications for antianxiety, antidepressants and hypnotics compared to urban areas. In rural areas, primary care APRNs prescribed 2-4 times as many medications across psychiatric drug classes than behavioral health specialty physicians.
The extensive involvement of primary care physicians and APRNs in managing psychiatric medications for patients with SMI in rural areas may, in part, reflect a lack of access to behavioral health specialists. Prior research found that primary care providers who practiced in counties with fewer psychiatrists were significantly more likely to report that they could not find outpatient mental health services for their patients . Our analysis did not identify if the PCPs sought to obtain specialist behavioral health services and cannot determine the extent to which the prescribing patterns observed by PCPs in some areas may have been driven by poor access to behavioral health specialists.
With large projected increases in the numbers of older adults with SMI in the coming years, the roles of primary care providers in the delivery of care for this population are likely to grow. Previous research has indicated that PCPs often feel underprepared to provide services for patients with complex behavioral health needs [27, 28]. Difficult medication schedules , multiple comorbidities, longer visit times, frequent follow-up care , and communication challenges  can make providing care for individuals with SMI especially demanding. For this reason, payment mechanisms that adequately reimburse primary care physicians and APRNs for the care of people with SMI should be instituted.
Our findings revealed that the role of psychiatric mental health APRNs in the prescribing of medications for older adults with SMI was limited compared to their colleagues in primary care. This provides a workforce opportunity to invest in the growth of psychiatric mental health nurse practitioners (PMHNP) who are trained to provide care to individuals with a wide variety of mental illnesses . A recent study examining billing trends in Medicare Part D of psychiatrist and PMHNPs found that between 2013 and 2019 the number of counties with only a psychiatrist billing for Part D services decreased from 277 to 178 and the number of counties with only a PMHNPs increased from 81 to 156. Yet, 857 rural counties had neither a psychiatrist nor PMHNPs prescribing medications . While the growth in numbers of PMHNPs prescribing medications in rural areas is promising, our results suggest that in comparison to primary care APRNs, PMHNPs provide a small proportion of medications to Medicare beneficiaries with SMI.
To optimally utilize the psychiatric mental health nurse practitioner workforce towards meeting population mental health needs, studies are needed that guide primary care practices in how best to integrate these specialized clinicians . Furthermore, research is needed that evaluates quality measures of behavioral health prescribing and other primary care outcomes with different clinician compositions as part of the primary care team. State scope of practice regulations for APRNs that require physician oversight for practice and prescribing even for experienced APRNs may be a barrier to accessing mental health care. Alexander and Schnell found that when APRNs can prescribe independently, counties that are underserved for mental health care resources have greater use of antidepressants and antipsychotics relative to when APRNs must have physician oversight . They also found better patient-reported mental health outcomes in states where APRNs can prescribe independently.
Our study had a number of limitations, including potentially outdated taxonomy information as providers may delay updating their board certification, potential misattribution of prescriptions due to Medicare rules that allow some APRN services to be billed by a physician , and that our analysis was descriptive and, thus, did not control for beneficiary, or any other characteristics. Further, our analysis identified SMI as diagnoses from bipolar disorder, major depression, schizophrenia, or psychosis. Other definitions of SMI could have resulted in different results. Finally, this analysis is based on Medicare claims data and findings might not be generalizable to other populations.
In summary, our results highlight the extensive roles of PCPs, including APRNs, in managing medications for older Medicare beneficiaries with SMI. Providing educational opportunities that prepare for the management of these complex patients and clinical support mechanisms seems warranted. Furthermore, as the demand for primary care clinicians with behavioral health expertise is continuing to grow, strategies aimed at growing the psychiatric mental health nurse practitioner workforce could be one avenue to increase access to BHSs, particularly in rural areas where APRNs are essential to accessing health care services.