Prevalence and Patterns of Medication Use Among Older Adults in the US: Findings from a National Population-based Study

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Prevalence and Patterns of Medication Use
Among Older Adults in the US Findings from a
National Population-based Study

• Dima Qato, PharmD, MPH
• G. Caleb Alexander MD, MS
• Rena M. Conti, PhD
• Michael Johnson, BA
• Phil Schumm, MA
• Stacy Tessler Lindau, MD, MAPP
• The University of Chicago, Chicago, Illinois

Academy Health Annual Research Meeting, June 2008
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Objectives

• Determine recent prevalence and patterns of
  medication use in the elderly
• Assess medication-related quality of care

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Background

• 92 of elderly have a prescription drug expense.
• 13 use Rxs concurrently with alternative
  medicines
• 21 use 5 or more Rx medications
• Elderly increased risk for Adverse Drug Events
  (ADE).
• ADE-related hospitalizations/ER visits most
  commonly due to GI bleeding
• Increase in Medicare spending on Rx drugs (2 in
  2005 to 18 in 2006)

Kaiser Family Foundation, 2007 Catlin, et al,
2008 Kaufman et al 2002 Gardiner et al 2006
Becker et al, 2007 Budnitz et al, 2007
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Limitations of available medication data sources

• Claims/administrative data
• Only patients with access to health care
• Only prescribed/dispensed medications
• Do not measure actual drug use (ingestion)
• Do not focus on elderly (aggregate adults 65 and
  older)
• Do not measure use of all types of medications.
• Outdated (do not account for new medications that
  enter market)

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Study Methods

• Data National, Social life, Health, and Aging
  Project (NSHAP)- Wave I (2005-2006)
• In-home interview of 3,005 community-residing
  adults ages 57-85
• Nationally-representative population-based
  probability sample minority over-sampling
  response rate75.5
• Weighted-estimates
• Universe Directly-observed Medication log
• medications currently used on a regular
  schedule, like every day or every week. Including
  prescription, OTC, vitamins, herbals and
  alternative medicines.
• Drug name matching rate97
• Micromedex Interaction software

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Prevalence of use Measures

• Prescription medication use use of at least one
  medication available only with a prescription.
• Over-the-counter use Use of non-prescription
  medication that is not a dietary supplement.
• Dietary supplement use use of a nutritional
  product or alternative medicine.

Patterns of use Measures

• Poly-pharmacy use of 5, 10 Rx
  medications
• Concurrent use use of a Rx medication
  concurrently with a non-Rx
• medication

• Quality of Care Measure
• Major medication interaction a drug-drug
  interaction of potentially
• Major severity as defined by Micromedex
  among users of the 20 most
• common Rx and OTC drugs and 20 most common CAM
  therapies.

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Rx and OTC Medications Commonly Used ( 5) by
Adults 65 and older (1999 vs.2005)
Slone (1998-1999) Slone (1998-1999)
1 Aspirin
2 Acetaminophen
3 Conjugated estrogens
4 Hydrochlorthiazide
5 Levothyroxine
6 Furosemide
7 Ibuprofen
8 Atenolol
9 Lisinopril
10 Digoxin
11 Warfarin
12 Triamterine
NSHAP (2005-2006) NSHAP (2005-2006) NSHAP (2005-2006) NSHAP (2005-2006)
1 Aspirin 13 Warfarin
2 Hydrochlorothiazide 14 Ezetimibe
3 Levothyroxine 15 Alendronate
4 Lisinopril 16 Lovastatin
5 Atorvastatin 17 Valsartan
6 Metoprolol 18 Omeprazole
7 Simvastatin
8 Atenolol
9 Amlodipine
10 Acetaminophen
11 Furosemide
12 Metformin
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Most commonly used ( 3) Dietary Supplements
Among Adults 65 and older (1999 vs.2005)
NSHAP(2005-2006) NSHAP(2005-2006)
1 Multivitamin/mineral
2 Calcium
3 Vitamin E
4 Vitamin C
5 Glucosamine
6 Vitamin B12
7 Folic Acid
8 Vitamin D
9 Chondroitin
10 Omega 3 Fatty Acids
11 Vitamin B6
12 Eye Vitamins
13 Magnesium
Slone (1998-1999) Slone (1998-1999)
1 Multivitamin/mineral
2 Vitamin E
3 Calcium
4 Vitamin C
5 Vitamin D
6 Magnesium
7 Glucosamine
8 Folic Acid
9 Ginkgo
10 Garlic
11 Zinc
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Medication Interaction Severity Definitions

• major life-threatening and/or require medical
  intervention to minimize or prevent serious
  adverse events.
• moderate may result in the exacerbation of the
  patients condition.
• minor the interaction would have limited
  clinical effects.

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Prevalence of Potentially Harmful Medication
Interactions
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Limitations

• Cross sectional data
• Comparability to previous studies
• Micromedex Interaction software
• Major Interactions reported only for commonly
  used medications.

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Conclusions

• Overall increase in the prevalence of medication
  use and number of commonly used medications among
  older adults
• Types of commonly used Rx, OTC, and dietary
  supplements varies over time
• Poly-pharmacy is common and increases with age
• Self-medication with NonRx is widespread across
  all older age groups
• Approximately 2.2 million (4) older adults in
  the U.S. are at risk for a harmful medication
  interaction
• Half are potentially at risk for GI bleeding

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Implications

• Up-to-date data on medication use among older
  adults increasingly important in the assessment
  of medication-related Quality of care
• National prescription data sources need to
  incorporate information on all types of
  medications
• Efforts to minimize harmful interactions should
  focus on common medications with the highest risk
  and the oldest age group
• Patient safety in older adults requires clinician
  awareness of current prescription medication and
  self-medication use patterns

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• Supported by
• The University of Chicago Program in
  Pharmaceutical Policy
• Chicago Core on Biomeasures in Population-Based
  Health and Aging Research, Center on Demography
  and Economics of Aging, NORC and the University
  of Chicago (P30 AG 012857)
• National Institute of Health and the National
  Institute on Aging, Office of Research on Women's
  Health Office of AIDS Research, and Office of
  Behavioral and Social Sciences Research
  (R01AG021487)
• Public use dataset available at
• http//www.icpsr.umich.edu/NACDA