NHLBI Communications Office
NHLBI-Funded Emphysema Study Finds Certain Patients
at High Risk for Death Following Lung Surgery
Emphysema patients who have severe lung obstruction with either limited
ability to exchange gas when breathing or damage that is evenly distributed
throughout their lungs receive little benefit from lung volume reduction surgery
(LVRS) and are at high risk of death from the procedure, according to early
results from the National Emphysema Treatment Trial (NETT). NETT is a five-year,
multicenter, randomized study to evaluate the role of LVRS in the treatment
of severe emphysema.
This is the first time that researchers have identified scientifically based
selection criteria for patients seeking LVRS as a potential treatment for
advanced emphysema. As a result of the findings, patients with these high-risk
characteristics are no longer being enrolled in NETT; however, the study will
continue to recruit other eligible patients until its scheduled completion
"This is exactly the kind of insight we hope to gain from NETT,"
said Dr. Claude Lenfant, director of the National Heart, Lung, and Blood Institute
(NHLBI), the primary sponsor of the study. "Identifying which patients
should not undergo this surgery is a key goal of this study. We expect the
final results of NETT will guide us further in determining if and when this
procedure should be used to treat emphysema."
The findings will be posted on the New England Journal of Medicine
(NEJM) Web site (www.nejm.org) on
August 14. Because of the importance of the results, NEJM editors agreed
to expedite their review of the findings and to publish them on their Internet
site prior to printing the investigators' report within the next few months.
The largest study of its kind, NETT compares the safety and effectiveness
of LVRS with medical treatment in patients with advanced emphysema. The study
also aims to define better who benefits from LVRS and who is at excessive
risk of complications or death from the procedure. More than 1,000 participants
at 17 clinical sites have enrolled in NETT since 1997.
In emphysema, the fine architecture of the lung is destroyed, leading to
large holes in the lung, obstruction of the airways, trapping of air, and
difficulty exchanging oxygen. Current medical treatments include supportive
measures such as medications, exercise rehabilitation, and nutritional supplementation.
LVRS is an unproven modality to ease symptoms associated with advanced emphysema
and to improve overall lung function. The procedure is believed by some to
improve the ability to move air in and out of the lungs by surgically removing
as much as one-third of each lung, targeting the most damaged regions with
the expectation that the remaining lung will have better air exchange. NETT
was developed in response to concerns from both the medical community and
from the Center for Medicare and Medicaid Services (formerly the Health Care
Financing Administration) about the risks and benefits of LVRS compared to
medical treatment for advanced emphysema.
During its quarterly review of the study data in May 2001, the NETT Data
and Safety Monitoring Board (DSMB) found that a subgroup of participants undergoing
the procedure had a 30-day post-surgery death rate considered unacceptable
based on the study's safety monitoring guidelines. The DSMB is a designated
group of experts who are unaffiliated with NETT and who are responsible for
overseeing participants' safety and outcomes data; in addition, the NETT DSMB
is charged with identifying subgroups of patients who may benefit from or
be at high risk of dying from LVRS.
Based on its analysis, the DSMB recommended that the study protocol be revised
to no longer enroll patients that meet specific criteria. NHLBI and the NETT
investigators agreed with the DSMB recommendation and modified the patient
eligibility criteria immediately. Within the following weeks, NHLBI notified
the leading pulmonary professional societies and the NETT investigators notified
the participants and their families.
As a result of this decision, NETT is no longer enrolling patients with severe
obstruction in the lung as measured by a forced expiratory volume in one second
less than or equal to 20 percent of predicted, plus one of the following characteristics:
severe loss of lung surface area as measured by a diffusing capacity of less
than 20 percent predicted or homogeneous damage to the lung, that is, disease
is evenly distributed throughout the lung, rather than being confined to certain
Of the 1,033 current participants, 140 (14 percent) met the above high-risk
criteria, 69 of whom underwent surgery as part of the trial. These patients
had a 16 percent 30-day mortality rate. In contrast, no deaths were reported
in the medical treatment group 30 days following the start of medical treatment.
Furthermore, compared to similar participants who received only medical treatment,
high-risk participants who survived the surgery were found to have only slightly
improved functional outcomes and quality-of-life scores six months after enrolling
in the study.
In addition to NHLBI, NETT is supported by the Center for Medicare and Medicaid
Services, which supports clinical services for the study, and the Agency for
Healthcare Research and Quality.
Emphysema is a disabling condition that affects approximately 2 million Americans,
most of them over age 50. Typically caused by cigarettes, the disabling and
deadly condition costs more than $2.5 billion in annual health care expenses
and kills more than 16,000 people in the U.S. each year.
NHLBI is part of the National Institutes of Health in Bethesda, Maryland.
To arrange an interview with Dr. Gail Weinmann, NHLBI project officer, please
call the NHLBI Communications Office at (301) 496-4236.NHLBI press releases,
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