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This report is from AHRQ's Data Points Publication Series.
Within the Medicare population, the majority of beneficiaries who have a psychiatric diagnosis also have one or more medical diagnoses. Use of multiple medications is common in this population. In particular, the number of unique medications and number of unique medication groups is greatest for those with both medical and psychiatric diagnoses. This pattern is seen at all Part D benefit phases.
Psychiatric diagnoses are common among Medicare beneficiaries. Complicating the management of these conditions is the high rate of concurrent psychiatric and medical conditions. In 2010, 14% of Medicare fee-for-service (FFS) beneficiaries had depression. More than 65% of these beneficiaries with depression also had three or more chronic physical conditions. This pattern of dual psychiatric-medical comorbidity is seen with schizophrenia, bipolar disorder, depression, and anxiety and is associated with higher levels of morbidity and health care use, as well as poorer outcomes for chronic medical conditions.
The group of Medicare beneficiaries with psychiatric-medical comorbidity is likely to increase in size as more people age into Medicare program eligibility, particularly those with chronic psychiatric and medical disorders that require lifetime care. Care for chronic physical and psychiatric conditions often includes the use of multiple prescription drugs, which increases the potential for complex drug interactions. Multiple medications and use of psychotropic drugs increases the possibility of adverse drug events.
Expenditures for medication coverage under Medicare Part D are substantial. Concurrent with the implementation of the Medicare Part D program between 2005 and 2006, Medicare expenditures for outpatient prescription drugs increased from $5.9 billion to $44.3 billion, a sevenfold increase. Also between 2005 and 2006, the percentage of Medicare beneficiaries who received at least one Medicare payment for an outpatient prescription drug purchase increased from 21% to 68%. In 2008, the Congressional Budget Office estimated that Medicare Part D expenditures would grow to more than $54.3 billion in 2009 and to $138 billion by 2018.
Medication use and access has increased under Part D. A major focus of Part D benefits is increased drug coverage for low-income individuals. By 2008, more than one-third of Medicare beneficiaries enrolled in prescription drug plan (PDP) or Medicare Advantage prescription drug plans (MA-PD plans) received low-income subsidy assistance. Part D is required to cover nearly all antipsychotic and antidepressant medications to protect against the risk associated with interruptions in these medications. However, access to psychiatric medications may be lower among dual Medicare-Medicaid eligibles, leading to greater rates of psychiatric-related emergency department use. In addition, the existence of a Part D coverage gap before reaching the catastrophic coverage phase can decrease use of essential medications, including antidepressants. The population of Medicare beneficiaries with both medical and psychiatric conditions likely experiences complexity in treatment regimens. It is unclear how medication is being used within this population. Given this uncertainty, baseline data are needed regarding the medication use of Medicare beneficiaries.
This report examines medication utilization for beneficiaries with psychiatric, medical, or both types of diagnoses. In this report, we examine the numbers of Medicare beneficiaries diagnosed with psychiatric and medical conditions; their comparative patterns of medication receipt (number of unique medications, medication groups, receipt of generics, and number of prescribers); and the ways in which medication receipt varies as beneficiaries move through Part D coverage phases over the course of a year.
Within the Medicare population, the majority of beneficiaries who have a psychiatric diagnosis also have one or more medical diagnoses. While the beneficiaries who suffer from psychiatric or combined psychiatric-medical conditions are a minority of all Medicare beneficiaries, they still represent a large population with high rates of unique drug and drug group use and catastrophic coverage use. The joint occurrence of medical and psychiatric diagnoses places these beneficiaries at risk for poorer health outcomes and increases the risk of problems related to polypharmacy. This group accounts for 6 million beneficiaries in the Medicare Parts A and B FFS population, and is important to consider in future research and decisionmaking regarding best practices in medication and health care management.