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THE LANCET

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September 25, 1997: 1.

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Value of natriuretic peptides in assessment of patients with possible new heart failure in primary care

Martin R Cowie, Allan D Struthers, David A Wood, Andrew JS Coats, Simon G Thompson, Philip A Poole-Wilson, George C Sutton

Summary

Background The reliability of a clinical diagnosis of heart failure in primary care is poor. Concentrations of natriuretic peptides are high in heart failure. This population-based study examined the predictive value of natriuretic peptides in patients with a new primary-care diagnosis of heart failure.

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Methods Concentrations of plasma atrial (ANP and Nterminal ANP) and B-type (BNP) natriuretic peptides were measured by radioimmunoassay 122 consecutive patients referred to a rapid-access heart-failure clinic with a new primary-care diagnosis of heart failure. On the basis of clinical assessment, chest radiography. and transthoracic echocardiography. a panel of three cardiologists decided that 35 (29%) patients met the case definition for new heart failure. ANP and NT-ANP results were available for 117 patients (34 with heart failure) and BNP results for 106 (29 with heart failure).

Findings Geometric mean concentrations of natriuretic peptides were much higher in patients with heart failure than in those with other diagnoses (29-2 vs 12-4 pmol/L for ANP: 63.9 vs 13-9 pmol/L for BNP: 1187 vs 410-6 pmol/L for NT-ANP: all p<0.001). At cut-off values chosen to give negative predictive values for heart failure of 98% (ANP 18-1 pmol/L. NT-ANP 537-6 pmol/L. BNP >22-2 pmol/L), the sensitivity, specificity, and positive predictive value for ANP were 97%, 72%, and 55%; for NT-ANP 97%. 66%, and 54%; and for BNP 97%, 84%, and 70%. Addition of ANP or NT-ANP concentration or both did not improve

Cardiac Medicine, Imperial College School of Medicine, National Heart and Lung Institute, London SW3 6LY, UK (M R Cowie MRCP, DA Wood FRCP, A JS Coats FRCP, P A Poole-Wilson FRCP); Department of Clinical Pharmacology and Therapeutics, Ninewells Hospital and Medical School, Dundee (A D Struthers FRCP); Department of Medical Statistics and Evaluation, Royal Postgraduate Medical School, London (S G Thompson ose); and Hillingdon Hospital, Uxbridge, Middlesex (G C Sutton FRCP) Correspondence to: Dr Martin R Cowie

the predictive power of a logistic regression model containing BNP concentration alone.

Interpretation In patients with symptoms suspected by a general practitioner to be due to heart failure, plasma BNP concentration seems to be a useful indicator of which patients are likely to have heart failure and require further clinical assessment.

Lancet 1997; 350: 1347-51

Introduction

Heart failure is commonly misdiagnosed, and the validity of the diagnosis in primary care is poor. The symptoms are non-specific and the clinical signs, although reasonably specific, are not at all sensitive. Consequently, even experienced physicians disagree on the diagnosis in individual cases, especially when the heart failure is mild.'

Natriuretic peptides are released in response to increased intracardiac volume or pressure. They have a natriuretic and vasodilatatory effect and suppress the renin-angiotensin-aldosterone system.' A prohormone, stored in the atria, on release is cleaved into the active Cterminal atrial natriuretic peptide (ANP) and the inactive and less rapidly cleared N-terminal atrial natriuretic peptide (NT-ANP). B-type natriuretic peptide (BNP) is secreted mainly by the ventricle. The plasma concentration of these peptides is higher than normal in patients with heart failure and also, but to a lesser extent, in patients with symptomless cardiac impairment." Measurements of these peptides could therefore provide valuable information about underlying cardiac function.' Previous work has focused on their role in detecting symptomless left-ventricular dysfunction after myocardial infarction," but little attention has been paid to the role of the natriuretic peptides in assessment of whether a patient's symptoms are due to heart failure at the time of first presentation to primary care. Measurement of natriuretic peptides might indicate whether referral for further cardiological assessment is necessary.

NT-ANP and BNP are more stable than ANP and therefore are more suitable for use in primary care. Both of these peptides seem to be more sensitive and specific

Q3.2 What level of reductions in greenhouse gas emissions and in the number of deaths associated with exposure to fine particles will result from EPA's recently promulgated fine particulate standard. begins to address this public health concern and should result in both some reductions in greenhouse gas emissions along with reducing the number of deaths associated with exposure to fine particles."

A3.2 EPA estimated that its new standard for fine particulates would save 15,000 premature deaths per year. EPA's standard setting rule does not address reductions in greenhouse gas emissions or the relationship between fine particulate and CO2 reductions.

Q3.3 Please document the figures provided in the response to question 3.2 above.

A3.3 An EPA fact sheet on the health and environmental effects of particulate matter is attached. Additional information on EPA's air quality regulations is available from EPA's Airlinks Web site (www.epa.gov/airlinks/) or from the Office of Air and Radiation in the Agency.

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HEALTH AND ENVIRONMENTAL EFFECTS OF PARTICULATE MATTER
Why are We Concerned About Particulate Matter?

. Particulate matter is the term used for a mixture of solid particles and liquid droplets found in the
air. Coarse particles (larger than 2.5 micrometers) come from a variety of sources including
windblown dust and grinding operations. Fine particles (less than 2.5 micrometers) often come
from fuel combustion, power plants, and diesel buses and trucks.

. These fine particles are so small that several thousand of them could fit on the period at the end of
this sentence.

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. They are of health concern because they easily reach the deepest recesses of the lungs.

Batteries of scientific studies have linked particulate matter, especially fine particles (alone or in
combination with other air pollutants), with a series of significant health problems, including:

• Premature death;

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Respiratory related hospital admissions and emergency room visits;
Aggravated asthma;

• Acute respiratory symptoms, including aggravated coughing and difficult or painful
breathing;

. Chronic bronchitis;

. Decreased lung function that can be experienced as shortness of breath; and

• Work and school absences.

Who is Most at Risk from Exposure to Fine Particles?

. The Elderly:

. Studies estimate that tens of thousands of elderly people die prematurely each year from
exposure to ambient levels of fine particles.

. Studies also indicate that exposure to fine particles is associated with thousands of hospital
admissions each year. Many of these hospital admissions are elderly people suffering from
lung or heart disease.

⚫ Individuals with Preexisting Heart or Lung Disease:

Breathing fine particles can also adversely affect individuals with heart disease,
emphysema, and chronic bronchitis by causing additional medical treatment. Inhaling fine
particulate matter has been attributed to increased hospital admissions, emergency room
visits and premature death among sensitive populations.

⚫ Children:

0 The average adult breathes 13,000 liters of air per day; children breathe 50 percent more air

Health and Environmental Effects of Particulate Matter

http://ttnwww.rtpnc.epa.gov/naaqsfin/pmhealth.htm

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per pound of body weight than adults.

• Because children's respiratory systems are still developing, they are more susceptible to
environmental threats than healthy adults.

Exposure to fine particles is associated with increased frequency of childhood illnesses,
which are of concern both in the short run, and for the future development of healthy lungs
in the affected children.

. Fine particles are also associated with increased respiratory symptoms and reduced lung
function in children, including symptoms such as aggravated coughing and difficulty or pain
in breathing. These can result in school absences and limitations in normal childhood
activities.

Asthmatics and Asthmatic Children:

. More and more people are being diagnosed with asthma every year. Fourteen Americans die
every day from asthma, a rate three times greater than just 20 years ago. Children make up
25 percent of the population, but comprise 40 percent of all asthma cases.

. Breathing fine particles, alone or in combination with other pollutants, can aggravate
asthma, causing greater use of medication and resulting in more medical treatment and
hospital visits.

How do Particulate Matter and Fine Particles Effect the Environment?

⚫ The same fine particles linked to serious health effects are also a major cause of visibility
impairment in many parts of the U.S.

. In many parts of the U.S. the visual range has been reduced 70% from natural conditions. In the
east, the current range is only 14-24 miles vs. a natural visibility of 90 miles. In the west, the
current range is 33-90 miles vs. a natural visibility of 140 miles.

⚫ Fine particles can remain suspended in the air and travel long distances. For example, a puff of
exhaust from a diesel truck in Los Angeles can end up over the Grand Canyon, where one-third of
the haze comes from Southern California. Emissions from a Los Angeles oil refinery can form
particles that in a few days will effect visibility in the Rocky Mountain National Park. Twenty
percent of the problem on dirtiest days in that Park is attributed to Los Angeles-generated smog.

• Airborne particles can also cause soiling and damage to materials.

What Improvements Would Result from EPA's New Standards?

⚫ EPA's new standards will provide increased health protection from the following effects:

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. About 15,000 lives each year will be saved, especially among the elderly and those with
existing heart and lung diseases.

• Reduced risk of hospital admissions by thousands each year, and fewer emergency room
visits, especially in the elderly and those with existing heart and lung diseases.

• Reduced risk of symptoms associated with chronic bronchitis, tens of thousands fewer cases
each year.

• Reduced risk of respiratory symptoms in children, hundreds of thousands fewer incidences
each year of symptoms such as aggravated coughing and difficult or painful breathing.

• Reduced risk of aggravation of asthma, hundreds of thousands fewer incidences each year,
in children and adults with asthma.

• Reduced risks of susceptibility to childhood illnesses.

Improved visibility over broad regions in the east and urban areas:

. The Clean Air Act placed special emphasis on preserving visibility in certain national parks and wilderness areas. In response, EPA is developing a "regional haze" program intended to ensure all parts of the country make continued progress toward the national visibility goal of

Health and Environmental Effects of Particulate Matter

http://ttnwww.rtpnc.epa.gov/naaqsfin/pmhealth.htm

"no manmade impairment."

. New standards that EPA has promulgated, together with the "regional haze" program under
development, will protect against visibility impairment, soiling and material damage effects,
and will further reduce acid rain.

Background: What is Particulate Matter and What are "Fine" Particles?

. Particulate matter originates from a variety of sources, including diesel trucks, power plants, wood
stoves and industrial processes. The chemical and physical composition of these various particles
vary widely. While individual particles cannot be seen with the naked eye, collectively they can
appear as black soot, dust clouds, or grey hazes.

⚫ Those particles that are less than 2.5 micrometers in diameter are known as "fine" particles; those
larger than 2.5 micrometers are known as "coarse" particles. Fine particles result from fuel
combustion (from motor vehicles, power generation, industrial facilities), residential fireplaces
and wood stoves. Fine particles can be formed in the atmosphere from gases such as sulfur
dioxide, nitrogen oxides, and volatile organic compounds. Coarse particles are generally emitted
from sources such as vehicles traveling on unpaved roads, materials handling, and crushing and
grinding operations, and windblown dust.

⚫ EPA is also maintaining a national air quality standard focused on small particles less than 10
micrometers in diameter (known as "PM10") to protect against coarse particle effects. Ten
micrometers are about one-seventh the diameter of a human hair.

. Before 1987, EPA's standards regulated larger particles (so called "total suspended particulates"),
including those larger than 10 micrometers. By 1987, research had shown that the particles of
greatest health concern were those equal to or less than 10 micrometers that can penetrate into
sensitive regions of the respiratory tract. At that time EPA and states took action to monitor and
regulate particulate matter 10 micrometers and smaller.

. In the years since the previous standard was enacted, hundreds of significant new scientific studies have been published on the health effects of particulate matter. Recent health effects studies suggest those adverse public health effects, such as premature deaths and increased morbidity in children and other sensitive populations, have been associated with exposure to particle levels well below those allowed by the current standard.

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