national trends in the prescribing of anti-hypertensive medications

Stanford PreventionResearch Center

STANFORDSCHOOL OF MEDICINE

National Trends in the Prescribing of Anti-Hypertensive Medications

Jun Ma, MD, PhDResearch Associate

Mentor: Randall Stafford, MD, PhDProgram on Prevention Outcomes and Practices



Background

Practice guidelines aim to guide physician practice according to the best available evidence

Process of translating national guidelines and clinical evidence into public health benefit is complex

Past studies suggest that guidelines are not necessarily being followed



Background

Diffusion of information from latest guidelines and clinical trial findings is suboptimal

Despite the promise of new findings, adoption patterns may not always serve patients:Use of medications lacking evidence of benefitFailure to use drugs with the strongest evidence

Suggestion that sizable increase in drug costs has not provided a public health benefit



Antihypertensive Prescribing :Magnitude of the Problem

Elevated blood pressure is a major risk factor for heart diseases and stroke – leading causes of death in the U.S.

About 50 million Americans have elevated blood pressure with continued increases expected

Antihypertensive medications cost $15 billion annually (10% of drug costs)



Objective

Examine the impact of JNC guidelines on antihypertensive prescribing by physicians in private practice and hospital outpatient clinics



Guidelines for HTN TreatmentJoint National Commission (JNC) on Prevention, Detection,

Evaluation and Treatment of High Blood Pressure

JNC V recommendations (1993)Diuretics and β-blockers should be used as

preferred first-line medications

JNC VI recommendations (1997) Diuretics and/or β-blockers should be used

as first-line agents unless specific comorbidities compel selection of other drugs



Data Sources

U.S. ambulatory care surveys 1993-2002 by National Center for Health StatisticsNational Ambulatory Medical Care Survey

(NAMCS)Nationally representative sample of patient visits to

office-based physicians

National Hospital Ambulatory Medical Care Survey (NHAMCS)Nationally representative sample of patient visits to

hospital outpatient departments (OPDs)



Data Sources

Multistage probability sampling proceduresNAMCS: PSUPhysiciansPatient VisitsNHAMCS: PSUHospitalsOPDsVisits

Annual participation ratesNAMCS: 63-73% of selected physiciansNHAMCS: 94-98% of selected hospitals

Physician/staff-recorded information on standard patient encounter forms



Study Sample

Hypertensive visits: patient visits having a principal diagnosis of essential HTNSample size: 645-1059(namcs)/809-1110(nhamcs)

National estimates: 23-49M/18-37M

Antihypertensive drug visits: hypertensive visits in which at least 1 antihypertensive drug was mentioned% of hypertensive visits: 65-80%



Antihypertensive Medication Classes

Diuretics: thiazides vs. other diureticsBeta/Alpha-Beta BlockersCalcium AntagonistsACE InhibitorsAngiotensin Receptor Blockers (ARBs) Alpha BlockersCentral-Acting Alpha-AgonistsDirect Vasodilators



Trends in Antihypertensive Prescribing, NAMCS

0

10

20

30

40

50

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002%

of

Ant

ihyp

erte

nsiv

e D

rug

Vis

its

Diuretic Beta Blocker CCB ACE Inhibitor ARB

JNC V JNC VI



Trends in Antihypertensive Prescribing, NHAMCS

0

10

20

30

40

50

60

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002%

of

Ant

ihyp

erte

nsiv

e D

rug

Vis

its

Diuretic Beta Blocker CCB ACE Inhibitor ARB

JNC V JNC VI



Trends in Prescribing of Diuretics, NAMCS

0

10

20

30

40

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002% o

f A

ntih

yper

tens

ive

Dru

g V

isits

Thiazide Diuretic Other Diuretic

JNC V JNC VI



Trends in Prescribing of Diuretics, NHAMCS

0

10

20

30

40

50

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002% o

f A

ntih

yper

tens

ive

Dru

g V

isits

Thiazide Diuretic Other Diuretic

JNC V JNC VI



Differences in Prescribing of Diuretics, NAMCS and NHAMCS

Diuretics

Sex (ref: Female)

Male 0.65 (0.55 0.77)

Race (ref: White)

African American 1.53 (1.23 1.91)

Age (ref: 20-44 y)

45-59

60-74

75+

1.42 (1.05 1.91)

1.47 (1.12 1.93)

1.73 (1.23 2.43)

Time (ref: ‘93-’97)

’98-’02 1.07 (0.89 1.29)



Differences in Prescribing of -Blockers, NAMCS and NHAMCS

-Blocker

Sex (ref: Female)

Male 0.89 (0.74 1.07)

Race (ref: White)

African American 0.74 (0.57 0.95)

Age (ref: 20-44 y)

45-59

60-74

75+

1.01 (0.74 1.39)

0.88 (0.64 1.20)

0.86 (0.57 1.30)

Time (ref: ‘93-’97)

’98-’02 1.24 (1.01 1.51)



Guidelines for HTN TreatmentJoint National Commission (JNC) on Prevention, Detection,

Evaluation and Treatment of High Blood Pressure

JNC VII recommendations (2003)Thiazide diuretics should be initial choice either

alone or in combination with drugs of other classes

ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) (Dec 2002)Thiazide diuretics are at least as effective as the

more expensive ACE inhibitors and CCBs in lowering blood pressure as well as cardiovascular events



IMS Health Data

National Disease and Therapeutic IndexNationally-based random sample of patient

visits to office-based physicians

Physician-reported data on new and continuing medications for each diagnosis per patient visit

Annual sample size for HTN averaged 20,000



Most Recent Trends in Antihypertensive Prescribing

0

10

20

30

40

2001 2002 2003 2004

% o

f H

yper

tens

ive

Pat

ient

Vis

its

Thiazide Diuretic Other Diuretic CCB ACEI

ALLHAT JNC VII



Summary of Results

Changes in antihypertensive prescribing are generally consistent with JNC recommendations and clinical evidenceIncreased prescribing of thiazide diureticsIncreased prescribing of -blockersDeclined prescribing of CCBs and more

recently of ACE inhibitors



Summary of Results

Thiazides remain under prescribed despite most favorable cost-effectiveness

Immediate upswing in thiazides following the ALLHAT publication in December 2002 did not sustain Impact of clinical evidence alone can be

short-lived Efforts needed to encourage widespread

adoption of evidence-based medicine



Summary of Results

CCBs and ACE inhibitors remain the most frequently prescribed antihypertensive drug classes

Increasing popularity of ARBsMore recent market entry and associated

intense advertising



Limitations

Visit-based data may not reflect proportions of use in general population

Lack of data necessary to assess treatment appropriateness at individual level

Lack of data on patient compliance and outcomes



Implications

Need to foster more timely and complete dissemination of evidence-based guidelines

Need to address physician adherence barriersLack of awareness or familiarity with guidelinesLack of agreement with recommendationsAttractiveness of new therapies and pressure to

use the latest therapy



Implications

Need to shift focus from reducing blood pressure (single risk factor) to prevention of CVD (absolute risk)

Need to assess the impact of evidence in the context of other factors that can influence prescribing practices

national trends in the prescribing of anti-hypertensive medications

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