Low-Dose Warfarin Prevents Clot Recurrence

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  • most appropriate approach to reduc-

    ing the risk of using dietary supple-

    ment products containing ephedrine

    alkaloids.

    The National Advisory Council for

    the National Center for

    Complementary and Alternative

    Medicine, part of the National

    Institutes of Health (NIH), was sched-

    uled to meet on March 17 to assess the

    evidence on ephedras safety and effec-

    tiveness in order to develop a research

    agenda on ephedra. FDA will give that

    committee an opportunity to com-

    ment on the notice, should the com-

    mittee find it appropriate to do so.

    Health care practitioners are being

    urged to submit written comments to

    the FDA or report any known adverse

    events related to ephedra use to

    www.fda.gov/medwatch.

    Sleeping PatternImportant in Reducing SIDS

    Infants accustomed to sleeping ontheir backs who are then placed to

    sleep on their stomachs or sides are at

    an increased risk for SIDSgreater

    than the increased SIDS risk of infants

    always placed on their stomachs or

    sides, according to a newly released

    study.

    The study, conducted by Kaiser

    Permanente in Northern and Southern

    California and supported by the

    National Institute of Child Health and

    Human Development (NICHD) and

    the National Institute on Deafness and

    Other Communications Disorders,

    appears in American Journal of

    Epidemiology.

    The study also shows that infants

    sleeping on their sides are at an

    increased risk of SIDS. The researchers

    think that a large part of the risk may

    be due to the instability of the side

    sleeping position and the tendency for

    infants sleeping in this position to turn

    onto their stomachs.

    The study, which was conducted in

    11 counties in Northern and Southern

    California, is the first to examine the

    relationship between infant sleeping

    position and SIDS in a racially diverse

    U.S. population. The incidence of

    SIDS has declined over 50 percent

    since 1992, when the American

    Academy of Pediatrics recommended

    that infants be placed on their backs to

    sleep. Before the current study, evi-

    dence of the link between stomach

    sleeping and SIDS risk was based

    largely on overseas studies, where pop-

    ulations and cultural practices are dif-

    ferent from those in the U.S.

    The researchers also collected infor-

    mation about bedding materials, type

    of mattress, room- or bed-sharing,

    room temperature, exposure to passive

    smoking and infant sickness. The

    researchers found that infants last

    placed on their sides for sleep were

    twice more likely to die of SIDS than

    infants last placed on their backs. In

    addition, the risk of SIDS was signifi-

    cantly increased if infants turned from

    their sides to their stomachs during

    sleep. While the reason isnt clear, the

    researchers think that the instability of

    the side position makes it more likely

    for babies who are placed to sleep in

    this position to roll over onto their

    stomachs.

    A pattern also emerged when the

    researchers looked specifically at the

    position in which an infant was last

    placed to sleep, compared to their

    usual sleeping position. If an infant

    who was usually placed to sleep in the

    low-risk positionon the backwas

    then placed to sleep in a high-risk

    position (the stomach or side), his or

    her SIDS risk was seven to eight times

    greater than that of an infant who was

    always placed to sleep on his or her

    back. The message here is every night

    and nap time count, said study co-

    author Dr. Marian Willinger of

    NICHD. Parents and caregivers

    should place their babies on their

    backs every time they go to sleep.

    Consistency is the key.

    One of the strengths of this study is

    that the researchers interviewed a

    raciallyand culturally diverse group

    of mothersWhite, African American,

    Hispanic, and Asian/Pacific Islander,

    although the small sample size limited

    the researchers ability to examine risk

    within each racial group. This study

    provides results from the first study of

    infant sleeping position in relation to

    SIDS risk to be collected entirely after

    the NICHDs Back to Sleep cam-

    paign is launched to inform the public

    about the importance of sleep position

    in preventing SIDS.

    Low-Dose WarfarinPrevents Clot Recurrence

    Astudy of long-term, low-dosewarfarin to prevent the recur-rence of the blood clotting disorders

    deep vein thrombosis (DVT) and pul-

    monary embolism (PE) resulted in

    such a high degree of benefit to the

    patientswithout significant adverse

    106 AWHONN Lifelines Volume 7 Issue 2

  • effectsthat the National Heart,

    Lung, and Blood Institute (NHLBI)

    of the National Institutes of Health,

    in Bethesda, MD, stopped the study

    early.

    The multicenter Prevention of

    Recurrent Venous Thromboembolism

    (PREVENT) trial found a 64 percent

    reduction in episodes of DVT and pul-

    monary embolism in study partici-

    pants taking low-dose warfarin com-

    pared to those taking a placebo.

    Furthermore, there was no evidence of

    significant risks such as major hemor-

    rhage or other potential side effects of

    warfarin, which is an anticoagulanta

    drug that prevents blood clotting.

    At the time the study was terminat-

    ed, patients had been followed for up

    to about four years, with an average of

    about two years. All study participants

    had experienced a previous episode of

    either DVT or PE placing them at

    greater risk of a recurrence.

    PREVENT is the first study to eval-

    uate the use of low-dose warfarin for

    the long-term prevention of venous

    thromboembolism (VTE), a term that

    includes both DVT and pulmonary

    embolism. The study is published in

    the April 10, 2003, issue of The New

    England Journal of Medicine. Due to its

    importance, the journal posted the

    article online on February 24.

    The trial, which began in 1998, was

    scheduled to run until 2005. However,

    at a regularly scheduled meeting of the

    studys independent Data and Safety

    Monitoring Board (DSMB) held

    December 4, 2002, the interim findings

    were reviewed, and based on the

    strong benefit of low-dose warfarin,

    the DSMB recommended halting the

    study. The recommendation was

    approved by the NHLBI.

    The current standard treatment for

    DVT and pulmonary embolism not

    associated with surgery or another

    specific cause is 5 to 10 days of intra-

    venous or subcutaneous heparin fol-

    lowed by three to six months of full-

    April | May 2003 AWHONN Lifelines 107

    Levels of a type of adult stemcell in the bloodstream mayindicate a persons risk of develop-

    ing cardiovascular disease, according

    to a study supported by the NHLBI.

    The study looked at the blood

    level of endothelial progenitor cells,

    which are made in the bone marrow

    and may help the body repair dam-

    age to blood vessels. Scientists from

    NHLBI and Emory University

    Hospital in Atlanta, GA, found that

    cardiovascular disease risk was high-

    er in persons with fewer endothelial

    progenitor cells. The cells of those at

    higher risk also aged faster than

    those at lower risk, as determined by

    the Framingham Heart Study risk

    factor score, a standard measure-

    ment of cardiovascular risk.

    Additionally, the study found that

    blood vessels were much less likely

    to dilate and relax appropriately in

    persons with low levels of the cells.

    Results of the study, which

    involved 45 healthy men aged 21

    and older, some of whom had stan-

    dard cardiovascular risk factors,

    appeared in the February 13, 2003,

    issue of The New England Journal of

    Medicine.

    Researchers wrote that they

    believe that these endothelial pro-

    genitor cells patch damaged sites in

    blood vessel walls. When the cells

    start to run out, cardiovascular dis-

    ease worsens. We dont yet know

    what causes their depletion but it

    may be related to the fact that the

    risk of cardiovascular disease

    increases as people age. For instance,

    the cells may be used up repairing

    damage done by other risk factors

    or those risk factors could directly

    affect the survival of the endothelial

    cells themselves. They noted that

    some day it may be possible to test a

    persons risk of cardiovascular dis-

    ease by taking a blood sample and

    measuring these cells. If the level is

    too low, an injection of endothelial

    cells might boost the bodys ability

    to repair itself and prevent more

    blood vessel damage.

    NNeeww HHeeaarrtt DDiisseeaassee RRiisskk IInnddiiccaattoorr DDiissccoovveerreedd

  • dose warfarin. Therapy typically stops

    after the initial treatment period

    because long-term use of full-dose

    warfarin is associated with a substan-

    tial risk of major bleeding. After the

    initial therapy is completed, recurrent

    blood clots occur in 6 to 9 percent of

    patients each year. The new data

    demonstrate that these recurrent

    blood clots can be avoided using an

    inexpensive and safe therapy.

    If DVT is not treated, it can lead to

    pulmonary embolism in which the

    clots detach and travel through the

    bloodstream to the lungs, where they

    may enter a pulmonary artery. Large

    clots that completely block the pul-

    monary artery can be fatal. Symptoms

    of pulmonary embolism include sud-

    den shortness of breath, sharp chest

    pain, a cough with bloody sputum,

    excessive sweating, rapid pulse and

    lightheadedness. Acute DVT can also

    lead to complications like chronic

    venous insufficiency, which is charac-

    terized by pooling of blood, chronic

    leg swelling and increased pressure on

    the skin.

    There are a number of risk factors

    for DVT and pulmonary embolism,

    including long periods of inactivity,

    which decrease blood flow. People who

    are immobile after surgery or serious

    injuries and travelers on long trips are

    at increased risk of blood clots.

    In addition, the hormone estrogen

    found in birth control pills has been

    shown to increase the risk of blood

    clots. The results of the Womens

    Health Initiative study, reported last

    July, found significant increases in

    pulmonary embolism in healthy

    women taking combined estrogen and

    progestin.

    Genes Linked to Severe Lupus

    Agenetic signature may be thekey to understanding why someLupus sufferers have such severe

    symptoms, say a team of scientists

    supported by the National Institute of

    Arthritis and Musculoskeletal and

    Skin Diseases. This genetic signature

    is present in some patients with sys-

    temic lupus erythematosus (SLE) who

    develop such life-threatening compli-

    cations as blood disorders, central

    nervous system damage and kidney

    failure.

    Using DNA microarrayssmall sil-

    icon chips that contain tiny amounts

    of thousands of known genesto

    carry out a technique called gene

    expression profiling, researchers ana-

    lyzed thousands of genes in the

    peripheral blood cells of 48 lupus

    patients and 42 healthy controls.

    Surprisingly, 14 of the thousands of

    genes studied were linked to a subset

    of SLE patients with severe disease. In

    addition, 161 of the genes studied

    showed different expression patterns

    in SLE patients compared with healthy

    controls.

    The 14 genes, referred to collective-

    ly as the IFN (interferon) expression

    signature, are turned on by the activity

    of interferon, a complex family of pro-

    teins involved in the regulation of

    immune responses. The data,

    researchers say, provide strong support

    for developing new therapies to block

    IFN pathways in patients with severe

    lupus, and the pattern of gene expres-

    sion in blood cells may be useful in

    identifying patients most likely to ben-

    efit from these new therapies. Gene

    expression profiling in blood cells may

    also be useful in identifying disease

    pathways in other autoimmune and

    inflammatory disorders.

    SLE, or lupus, is a chronic, inflam-

    matory, autoimmune disease. Its

    symptoms range from unexplained

    fever, swollen joints and skin rashes to

    severe organ damage of the kidneys,

    lungs or central nervous system. Lupus

    is difficult to diagnose because its dif-

    ferent for every person who has it, and

    it affects women nine times more

    often than men.

    MRI for Diagnosing Heart Attacks

    Advanced magnetic resonanceimaging (MRI) technology candetect heart attack in emergency room

    patients with chest pain more accu-

    rately and faster than traditional meth-

    ods, according to a new study support-

    ed by the NHLBI.

    Published in the February 4 issue of

    Circulation: Journal of the American

    Heart Association, the findings suggest

    108 AWHONN Lifelines Volume 7 Issue 2

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