Access and Utilization of New Antidepressant and Antipsychotic Medications. Chapter VI. Patterns of Antipsychotic and Antidepressant Utilization in Medicaid, 1995-1998

The truest measure of access to and utilization of pharmaceuticals is analysis of actual patterns of claims processed for individual drugs. Although analysis of these patterns across all health care payers is outside the scope of this research, this section analyzes trends in utilization of antidepressants and antipsychotics in Medicaid between 1995 and 1998.

In brief, this analysis found:

Antidepressants and antipsychotics account for a large proportion of Medicaid pharmaceutical prescriptions and reimbursements. The impact of newer antidepressants and antipsychotics on expenditures is out of proportion to the number of prescriptions for these agents.

• In 1998, antidepressants and antipsychotics accounted for 9% of Medicaid prescriptions but 19% of Medicaid drug expenditures.
• Although the total number of prescriptions reimbursed by Medicaid has remained relatively constant between 1995 and 1998, expenditures have increased by over 40%.
• The growth rate in both number of prescriptions for and cost of antidepressants and antipsychotics outpaces that observed in Medicaid pharmacy benefits as a whole by more than 2-fold.

The volume of Medicaid antidepressant and antipsychotic prescriptions grew dramatically between 1995 and 1998.

• Medicaid antipsychotic prescriptions increased nearly 20% between 1995 and 1998.
  • Antipsychotic prescriptions totaled 9.1 million in 1995.
  • Antipsychotic prescriptions totaled 11 million in 1998.
• Medicaid antidepressant prescriptions grew by over 40% between 1995 and 1998.
  • Antidepressant prescriptions totaled 13.6 million in 1995.
  • Antidepressant prescriptions totaled 19 million in 1998.

Total expenditures by Medicaid programs for antidepressants and antipsychotics grew dramatically between 1995 and 1998.

• Medicaid antipsychotic expenditures increased nearly 160% between 1995 and 1998.
  • Antipsychotic expenditures totaled $484 million in 1995.
  • Antipsychotic expenditures totaled $1.3 billion in 1998.
• Medicaid antidepressant expenditures grew by over 96% between 1995 and 1998.
  • Antidepressant expenditures totaled $592 million in 1995.
  • Antidepressant expenditures totaled $985 million in 1998.

New generation antipsychotics been accepted into common use within Medicaid programs.

• In 1998, 51% of the 11 million prescriptions for antipsychotics were for atypical antipsychotics. Three 2^nd generation atypicals were available in 1998.
  • In contrast, atypicals accounted for only 17.5% of 9.1 million Medicaid antipsychotic prescriptions in 1995. Only one 2^ndgeneration atypical was available in 1995 (risperidone).
    • The use of atypical antipsychotics in Medicaid has more than doubled since 1995.
    • Concomitantly, the use of typical antipsychotics in Medicaid has dropped by 25% since 1995.

New generation antipsychotics have not simply supplanted typical antipsychotics. Rather the total market for antipsychotics in Medicaid has grown since their introduction. Increased use of atypical antipsychotics has driven expenditures.

New generation antidepressants have been accepted into common use in Medicaid.

• In 1998, 62% of the 19 million Medicaid antidepressant prescriptions were for new-generation, branded antidepressants.
  • In contrast, new generation antidepressants accounted for from 44% of 13.6 million Medicaid antidepressant prescriptions in 1995.
    • The market share of new generation antidepressants has grown by approximately 50% since 1995.
    • Concomitantly, the market share of TCAs in Medicaid has decreased by nearly 50%.
• The selective serotonin reuptake inhibitors (SSRIs) comprised 46% of total antidepressant prescriptions in 1998.
  • Prescriptions for the three leading agents (fluoxetine, paroxetine, and sertraline) were nearly equal with approximately 3 million prescriptions each, or a 15-16% share each.
• Tricyclic antidepressants accounted for 27% of total prescriptions in 1998.

Increased Medicaid expenditures for antidepressants have been driven both by uptake of new generation, branded agents and increased prescription volume.

• Much of this increase can be attributed to the steady, yet significant rise of the three leading SSRI antidepressants (fluoxetine, sertraline, and paroxetine).
  • Together, spending for fluoxetine, sertraline and paroxetine comprised over 70% of all Medicaid spending on antidepressant drugs in 1998 ($711 million).
• TCAs accounted for only 5% of all Medicaid dollars reimbursed for antidepressants ($54 million).

New generation antidepressants have not simply supplanted tradition antidepressants. Rather the total market for antidepressants in Medicaid has grown since their introduction.

Utilization of new-generation antidepressants and antipsychotics varies among the states. Not all states have adopted new-generation agents as quickly as others.

New-generation antidepressants and antipsychotics have been accepted into common use by Medicaid programs at about the same rate and to the same extent as other innovator drugs.

• Newer antipsychotics appear to be proportionally more expensive than other new generation pharmaceuticals such as oral antidiabetics.
• Newer antidepressants appear to be roughly equivalent in cost to these other classes.

• A. Methodology

  • Quarterly, state level data on prescription drug utilization are available from the Health Care Financing Administration(now known as Centers for Medicare and Medicaid Services(CMS)) (HCFA(now known as CMS)). These data are reported at the National Drug Code (NDC) level. These data include all pharmaceuticals reimbursed through State Medicaid pharmacy programs. However, these data exclude prescriptions dispensed to Medicaid recipients enrolled in managed care plans where pharmacy benefits are included in the capitation arrangement. Therefore these data will miss drug utilization within those plans. As most Medicaid Managed Care plans are limited to the AFDC or TANF populations, therefore, one would expect that this deficiency would affect the analysis of antidepressant utilization more than it would antipsychotic utilization.

    While these data are representative of the US Medicaid population, state-level analyses are difficult in some States due to missing data. Arizona and Tennessee fail to report Medicaid drug utilization data at all while Texas has not reported since the second quarter of 1995, and Colorado has not reported since the fourth quarter of 1996. Connecticut reported no data for 1998. Other States with questionable data include Indiana, Kansas, and Wyoming (1995 and 1996 data appear to be off by a factor of 10).

    A total of 19 States report data for all 16 quarters of 1995-1998. Data imputation was accomplished for 13 other States using a linear or exponential growth interpolation model in Microsoft Excel. Missing data were imputed for States missing up to three quarters of data over the 1995-1997 period. Imputation of missing data allows analysis of data from 44 States and the District of Columbia (i.e., "45 States"). Data from Connecticut is included for years 1995-1997, but not 1998. Based on information from HCFA(now known as CMS) form 2082 (1998), these 46 States accounted for over 80% of Medicaid recipients in 1998. Only Arizona, Tennessee, Texas, Colorado, Kansas, and Indiana are excluded because of missing or suspect data.

    Because the Medicaid data do not report diagnosis or dosage associated with each prescription, we were unable to analyze use of antidepressants and antipsychotics as a function of disease treated. Rather, we summarize all Medicaid use of these agents regardless of diagnosis. It should be emphasized that these data, therefore, include the use of antidepressants and antipsychotics for the treatment of illnesses other than schizophrenia or major depressive disorder. For antipsychotics, these illnesses may include behavioral disturbances in various forms of dementia as well as treatment-refractory depression and bi-polar illness. Antidepressants may be used to treat Obsessive-Compulsive Disorder, Attention Deficit Disorder, Generalized Anxiety Disorder, Bulimia, chronic pain, and sleeplessness to name a few.

    In the following discussion, the word "prescription" should be understood to refer to, on average, a month's supply of medication. Using this definition requires claims data for clozapine to be divided by a factor of 4.3 to achieve comparability to prescriptions for other agents (this method accounts for Federal supply limitations of 7 days).

    The monetary figures quoted for drug expenditures are net of rebate (i.e., the rebate amount returned to the State Medicaid agencies, as required by OBRA 1990, has been factored out of the expenditure data). As a result, Medicaid reimbursements represent a lower bound estimate of actual costs.

• B. Trends in Medicaid Pharmaceutical Coverage

  • Total prescriptions in Medicaid were relatively flat between 1995 and 1998. Medicaid programs reimbursed 327 million prescriptions in 1995 and 331 million prescriptions in 1998. During the same period, antipsychotic prescriptions increased by nearly 20% while antidepressant prescriptions increased by just over 40%.

    However, prescription expenditures increased by 43% between 1995 and 1998. Medicaid programs paid almost $8.9 billion for prescription drugs in 1995 and $12.8 billion in 1998. During the same period, expenditures on antipsychotics increased by approximately 160%, while prescriptions for antidepressants increased by 96%.

    In 1998, the 11 million Medicaid antipsychotic prescriptions accounted for only 3% of all Medicaid prescriptions. However, the $1.3 billion spent for these pharmaceuticals represented nearly 11% of total expenditures. Similarly, the 19 million antidepressant prescriptions accounted for nearly 6% of total prescriptions, while the $985 million spent for these agents approached 8% of expenditures. Therefore, although antidepressants and antipsychotics account for nearly 9% of total Medicaid prescriptions in 1998, their impact to total pharmaceutical costs is nearly twice as large as their market share.

• C. Utilization of Antipsychotics in Medicaid, 1995-1998

  • The American Hospital Formulary lists nearly twenty different agents that are classified as antipsychotics. Most of these belong to the general class of phenothiazine derivatives. For the purposes of this analysis, antipsychotic medications were grouped into 8 general categories as indicated in Exhibit VI-1 below.

• D. Utilization of Antidepressants in Medicaid, 1995-1998

  • The American Hospital Formulary lists over 30 different agents that are classified as antidepressants. Most of these belong to the general class of tricyclic antidepressants. For the purposes of this analysis, antidepressant medications were grouped into 12 general categories as indicated in Exhibit VI-12 below.

    Exhibit VI-12. Antidepressant Classes

    Generic Name	Examples and Brand Names
    Citalopram	CelexaTM
    Fluoxetine	Prozac®
    Fluxvoxamine	Luvox®
    Paroxetine	Paxil®
    Sertraline	Zoloft®
    Tricyclic Antidepressants (Representative)	Amitriptyline (Elavil®) Desipramine (Norpramin®) Imipramine (Tofranil®) Nortriptyline (Pamelor®)
    Trazodone	Desyrel®
    Monoamine Oxidase Inhibitors (MAOIs)	Phenelzine (Nardil®) Tranylcypromine (Parnate®)
    Bupropion	Wellbutrin® Wellbutrin® SR Zyban®
    Mirtazapine	Remeron®
    Nefazadone	Serzone®
    Venlafaxine	Effexor®, Effexor® XR

• E. Comparison of Psychotherapeutic Utilization with Utilization of Other Drug Classes

  • A primary concern of this study has been to determine whether newer psychotherapeutics are subject to more stringent utilization controls than are other classes of pharmaceuticals. In this section, we compare the utilization of psychotherapeutics with the utilization of other classes of pharmaceuticals that have seen the introduction of newer agents in recent years.

    The new oral antidiabetic agents make constitute an excellent comparator group to psychotherapeutics for a number of reasons:

    • Diabetes represents a major cost center for health care payers, as does mental health;
    • Pharmacotherapy for diabetes and mental illness is always a long-term commitment;
    • New pharmacologic agents, representing new mechanisms of action, entered a therapeutic area dominated by generics; and
    • These new antidiabetic agents were introduced during the same time period as the atypical antipsychotics (1994-1997).

    The oral antidiabetics included in this analysis are described in Exhibit VI-22, below.

    Exhibit VI-22. Oral Antidiabetic Categories

    Generic Name	Examples and Brand Names	Launch Date
    Acarbose	Precose®	1995
    Glimepiride	Amaryl®	1995
    Glipizide (extended release)	Glucotrol® XL	1994
    Metformin	Glucophage®	1995
    Repaglinide	Prandin®	4th quarter 1997
    Troglitazone	Rezulin®	1st quarter 1997
    Generic Sulfonyl Ureas (Representative) Acetohexamide Chlorpropamide Glipizide Glyburide	Dymelor® Diabinese® Gluotrol® DiaBeta®, Micronase®	Prior to 1995

    Medicaid prescriptions for oral antidiabetic agents increased from 4.1 million in 1995 to 7.6 million in 1998, an increase of 82%. At the same time, expenditures for these agents increased nearly 3-fold, increasing from $114 million in 1995 to $311 million in 1998.

    Proportionally, the increase in spending for oral antidiabetics was far smaller than the increase observed for the psychotherapeutic classes. Exhibit VI-23 shows the ratio between the percentage increase in expenditures and the percentage increase in total prescriptions between 1995 and 1998 for the three classes, antipsychotics, antidepressants, and oral antidiabetics. The results show that the ratio between the increase in expenditures and the increase in prescriptions is 8.0 for antipsychotics. (It should be remembered that clozapine prescriptions were relatively flat during this time, and therefore the increase in cost is largely attributable to other new agents.) For antidepressants this ratio is 2.4, whereas for oral antidiabetics this ratio is 2.1. These data show that the cost (in terms of pharmaceutical expenditures) of converting to newer agents is far greater for antipsychotics than it is for either antidepressants or oral antidiabetics. However, the cost for converting to newer antidepressants is only marginally greater than that for oral antidiabetics.

    Exhibit VI-23. Comparison of Increase in Prescriptions and Expenditures for 3 Pharmaceutical Classes in Medicaid, 1995-1998

    Class	% Increase in Prescriptions	% Increase in Expenditures	Ratio
    Antipsychotics	20%	160%	8.0
    Antidepressants	40%	96%	2.4
    Oral Antidiabetics	82%	172%	2.1

    Source: HCFA(now known as CMS) Medicaid Drug Rebate Program Data, 1995-1998. 46 States reporting, 1995-1998, 45 States Reporting, 1998.

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    In spite of this difference in cost it appears that newer oral antidiabetics have replaced older agents only marginally faster than atypical antipsychotics have replaced traditional antipsychotics. In 1995, only 11% of all prescriptions for oral antidiabetics were for an agent other than a generic sulfonyl urea, by 1998, 55% of all prescriptions were for a newer agent. In contrast, whereas in 1995, only 16% of all antipsychotic prescriptions were for an atypical agent, in 1998, 51% of antipsychotic prescriptions were for an atypical antipsychotic.