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STATISTICAL BRIEF #314:
Expenditures for the Top Five Therapeutic Classes of Outpatient Prescription Drugs, Medicare Beneficiaries, Age 65 and Older, 2008

February 2011

Anita Soni, PhD

Highlights

In 2008, the top five therapeutic classes ranked by total expense among Medicare beneficiaries, age 65 and older for prescription drugs were: metabolic agents, cardiovascular agents, central nervous system agents, gastrointestinal agents, and respiratory agents.
Among the Medicare population age 65 and older in 2008, expenditures for the top five therapeutic classes totaled $59.9 billion and represented almost 72 percent of annual expenditures for prescription drugs.
Prescription medicine expenses for metabolic agents accounted for more than one-fourth of total prescription drug expenses for the Medicare population age 65 and older in 2008.
More than three-fourths of the Medicare population age 65 and older with a prescribed drug expense in 2008 purchased a cardiovascular agent.
In 2008, of the top five therapeutic classes, gastrointestinal agents had the highest average expense per prescription, which was more than three times the average expense of the therapeutic class of cardiovascular agents which had the lowest average.

Introduction

This Statistical Brief provides descriptive statistics on expenditures for the top five therapeutic classes of outpatient prescription drugs, ranked by total expense in 2008 for Medicare beneficiaries age 65 and older in the U.S. civilian noninstitutionalized population. MEPS uses prescription drugs therapeutic classes as defined by the Multum Lexicon (see Definitions). In 2008, 18 broad therapeutic classifications were identified.

The estimates presented are derived from the Household and Pharmacy Components of the 2008 Medical Expenditure Panel Survey. Expenditures include payments for Medicare beneficiaries ages 65 and older, from all sources (e.g., out of pocket, private, and public insurance sources) for outpatient prescription drug purchases during 2008. Insulin and diabetic supplies and equipment are also included in MEPS prescribed medicines estimates. Over-the-counter medicines are excluded from these estimates as are prescription medicines administered in an inpatient setting or in a clinic or physician's office. All differences discussed in the text are statistically significant at the 0.05 level or better.

Findings

In 2008, the top five therapeutic classes (ranked by total expense) of prescribed drugs purchased by Medicare beneficiaries age 65 and older were metabolic agents, cardiovascular agents, central nervous system agents, gastrointestinal agents, and respiratory agents. These classes together totaled almost $60 (59.9) billion and accounted for almost 72 percent (71.9) of the $83.4 billion total prescription drug expenses by these adults (figure 1).

Metabolic agents had the highest total expenses ($23.6 billion) among the top five therapeutic classes for Medicare beneficiaries ages 65 and older (figure 2). This was almost five times the expenses for respiratory agents ($4.8 billion), the fifth highest therapeutic class. Expenditures on cardiovascular agents ($15.1 billion), the second highest class, were also notably higher than the other three classes. When expressed as percentages of all prescribed medicine expenses for Medicare beneficiaries, these classes ranged from 5.7 percent for respiratory agents to 28.3 percent for metabolic agents (figure 3).

Among Medicare beneficiaries age 65 and older with a prescribed drug expense, over three-quarters (77.5 percent) purchased cardiovascular agents, almost two-thirds (64.9 percent) purchased metabolic agents, and nearly half (47.9 percent) purchased central nervous system agents (figure 4). Smaller proportions of persons purchased gastrointestinal agents (27.6 percent) or respiratory agents (18.2 percent) (figure 4).

In terms of average expense per prescription, gastrointestinal agents had the highest average ($127) followed by respiratory agents ($111) (figure 5). Among the other three classes, the averages for central nervous system agents ($69) and cardiovascular agents ($41) were both lower than the metabolic agents ($103).

Data Source

The estimates shown in this Statistical Brief are based on data from the MEPS HC-121 2008 Full Year Consolidated File and HC-118A 2008 Prescribed Medicines File.

Definitions

Therapeutic classifications
Therapeutic class and subclass were assigned to MEPS prescribed medicines using Multum Lexicon variables from Cerner Multum, Inc. MEPS prescribed medicines files were linked to the Multum Lexicon database to obtain therapeutic class and subclass variables. The therapeutic class metabolic agents includes the subclasses of antihyperlipidemic agents and antidiabetic agents. The therapeutic class of cardiovascular agents includes calcium channel blockers and diuretics; and central nervous system agents include the analgesics, anticonvulsants, and antiparkinson agents. The therapeutic class of gastrointestinal agents includes the H2-receptor antagonists, antacids, antidiarrheals, and proton pump inhibitors; and the therapeutic class of respiratory agents includes decongestants, antihistamines, respiratory inhalant, and antiasthmatic products.

Cerner Multum occasionally makes changes to the Multum Lexicon therapeutic classification system. For example, antihyperlipidemic agents was its own therapeutic class in the 2003 and 2004 data, but was reclassified as a therapeutic subclass of the new therapeutic class metabolic agents in 2005. These types of changes effect comparisons of the types of estimates presented in this Brief across years.

About MEPS-HC

MEPS-HC is a nationally representative longitudinal survey that collects detailed information on health care utilization and expenditures, health insurance, and health status, as well as a wide variety of social, demographic, and economic characteristics for the U.S. civilian noninstitutionalized population. It is cosponsored by the Agency for Healthcare Research and Quality and the National Center for Health Statistics.

For more information about MEPS, call the MEPS information coordinator at AHRQ (301) 427-1656 or visit the MEPS Web site at http://www.meps.ahrq.gov/.

References

For a detailed description of the MEPS-HC survey design, sample design, and methods used to minimize sources of nonsampling error, see the following publications:

Cohen, J. Design and Methods of the Medical Expenditure Panel Survey Household Component. MEPS Methodology Report No. 1. AHCPR Pub. No. 97-0026. Rockville, MD: Agency for Health Care Policy and Research, 1997. http://www.meps.ahrq.gov/mepsweb/data_files/publications/mr1/mr1.shtml

Cohen, S. Sample Design of the 1996 Medical Expenditure Panel Survey Household Component. MEPS Methodology Report No. 2. AHCPR Pub. No. 97-0027. Rockville, MD: Agency for Health Care Policy and Research, 1997. http://www.meps.ahrq.gov/mepsweb/data_files/publications/mr2/mr2.shtml

Cohen, S. Design Strategies and Innovations in the Medical Expenditure Panel Survey. Medical Care, July 2003: 41(7) Supplement: III-5–III-12.

Ezzati-Rice, T.M., Rohde, F., Greenblatt, J. Sample Design of the Medical Expenditure Panel Survey Household Component,1998-2007. Methodology Report No. 22. March 2008. Agency for Healthcare Research and Quality, Rockville, MD. http://www.meps.ahrq.gov/mepsweb/data_files/publications/mr22/mr22.shtml

Suggested Citation

Soni, A. Expenditures for the Top Five Therapeutic Classes of Outpatient Prescription Drugs, Medicare Beneficiaries, Age 65 and Older, 2008. Statistical Brief #314. February 2011. Agency for Healthcare Research and Quality, Rockville, MD. http://www.meps.ahrq.gov/mepsweb/data_files/publications/st314/stat314.shtml

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AHRQ welcomes questions and comments from readers of this publication who are interested in obtaining more information about access, cost, use, financing, and quality of health care in the United States. We also invite you to tell us how you are using this Statistical Brief and other MEPS data and tools and to share suggestions on how MEPS products might be enhanced to further meet your needs. Please e-mail us at mepspd@ahrq.gov or send a letter to the address below:

Steven B. Cohen, PhD, Director
Center for Financing, Access, and Cost Trends
Agency for Healthcare Research and Quality
540 Gaither Road
Rockville, MD 20850

Figure data for accessible table follows the image

Total RX expenditures = $83.4 billion

	Top five	All other
Figure 1. Expenditures for top five therapeutic classifications of prescribed drugs relative to total prescription medication expenses, Medicare beneficiaries age 65 and older, 2008
Dollars in billions	59.9	23.5
Source: Center for Financing, Access, and Cost Trends, AHRQ, Household and Pharmacy Components of the Medical Expenditure Panel Survey, 2008

Therapeutic classifications	Dollars in billions
Figure 2. Total expenses for prescribed drugs by therapeutic classification (top five), Medicare beneficiaries age 65 and older, 2008
Metabolic agents	$23.6
Cardiovascular agents	$15.1
Central nervous system agents	$8.7
Gastrointestinal agents	$7.7
Respiratory agents	$4.8
Source: Center for Financing, Access, and Cost Trends, AHRQ, Household and Pharmacy Components of the Medical Expenditure Panel Survey, 2008

Therapeutic classifications	Percentage of total prescribed medication expenses
Figure 3. Expenditures for top five therapeutic classifications as percentages of total prescribed medication expenses, Medicare beneficiaries age 65 and older, 2008
Metabolic agents	28.3
Cardiovascular agents	18.2
Central nervous system agents	10.5
Gastrointestinal agents	9.2
Respiratory agents	5.7
Source: Center for Financing, Access, and Cost Trends, AHRQ, Household and Pharmacy Components of the Medical Expenditure Panel Survey, 2008

Therapeutic classifications	Percentage of population with prescribed medication expenses
Figure 4. Percentage with prescribed drug expenses by therapeutic classification (top five), Medicare beneficiaries age 65 and older with prescribed medication expenses, 2008
Metabolic agents	64.9
Cardiovascular agents	77.5
Central nervous system agents	47.9
Gastrointestinal agents	27.6
Respiratory agents	18.2
Source: Center for Financing, Access, and Cost Trends, AHRQ, Household and Pharmacy Components of the Medical Expenditure Panel Survey, 2008

Therapeutic classifications	Average expense per prescription in dollars
Figure 5. Average expense per prescription by therapeutic classification (top five), Medicare beneficiaries age 65 and older, 2008
Metabolic agents	$103
Cardiovascular agents	$41
Central nervous system agents	$69
Gastrointestinal agents	$127
Respiratory agents	$111
Source: Center for Financing, Access, and Cost Trends, AHRQ, Household and Pharmacy Components of the Medical Expenditure Panel Survey, 2008

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STATISTICAL BRIEF #314: Expenditures for the Top Five Therapeutic Classes of Outpatient Prescription Drugs, Medicare Beneficiaries, Age 65 and Older, 2008