JAMA news releases are made available to the public after 3 pm US Central time on the first 4 Tuesdays of each month. The Archives Journals news releases are made available to the public after 3 pm Central time on Mondays. We also provide a list of previous news releases.
THIS WEEK'S CONTENT
JAMA NEWS RELEASES
(Embargoed for Release: 3 p.m. CT Tuesday, February 3, 2009)
JAMA NEWS RELEASES
Cardiac Imaging Method May Expose Patients to High Radiation Dose
Older Adults Who Experience Osteoporotic Fracture Have Increased Risk of Death For 5 - 10 Years
Dialysis Patients Residing at Higher Altitude Have Lower Rate of Death
JAMA REPORT (VIDEO SCRIPT)
VIDEO: Windows Media | Quicktime
STUDY FINDS HIGHER ALTITUDES COULD MEAN LOWER MORTALITY RATES FOR PATIENTS WITH END-STAGE RENAL DISEASE
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Embargoed for Release: 3:00 p.m. CT, Tuesday, February 3, 2009
Media Advisory: To contact Jörg Hausleiter, M.D., email hausleiter{at}dhm.mhn.de. To contact co-author Thomas C. Gerber, M.D., call Kevin Punsky at 904-953-0746 or email punsky.kevin{at}mayo.edu. To contact editorial author Andrew J. Einstein, M.D., Ph.D., call Alex Lyda at 212-305-0820 or email mal2133{at}columbia.edu.
Cardiac Imaging Method May Expose Patients to High Radiation Dose
CHICAGO—Use of the imaging technique known as cardiac computed tomography (CT) angiography (CCTA) has the potential to expose patients to high doses of radiation, and methods available to reduce radiation dose are not frequently used, according to a study in the February 4 issue of JAMA.
The 64-slice (able to scan 64 images per rotation) CCTA has emerged as a useful diagnostic imaging method for the assessment of coronary artery disease and has been proposed to be useful for evaluating patients in emergency departments with chest pain. "With the constantly increasing number of CCTA-capable scanners worldwide, the volume of CCTA scans performed is likely to show substantial further increase," the authors write. They add that the clinical usefulness of CCTA for the assessment of coronary artery disease has to be weighed against the radiation exposure of CCTA and the small but potential risk of cancer. Many clinicians may still be unfamiliar with the magnitude of radiation exposure that is received during CCTA in daily practice and with the factors that contribute to radiation dose, according to background information in the article.
Jörg Hausleiter, M.D., of the Deutsches Herzzentrum München, Klinik an der Technischen Universität München, Munich, Germany, and colleagues investigated the magnitude of radiation dose of CCTA in daily practice, factors contributing to radiation dose and the use of currently available strategies to reduce radiation dose. The trial, the Prospective Multicenter Study On Radiation Dose Estimates Of Cardiac CT Angiography In Daily Practice I (PROTECTION I), an international, multicenter study (21 university hospitals and 29 community hospitals) included 1,965 patients undergoing CCTA between February and December 2007. Analysis was used to identify independent predictors associated with radiation dose, which was measured as dose-length product (DLP; equals the average radiation dose over a specific investigated volume multiplied by the scan length), which best mirrors the radiation a patient is exposed to by the entire CT scan, according to the authors.
The researchers found that the median (midpoint) DLP of the patients in the study was 885 mGy x cm (a measurement of absorbed radiation), which corresponds to an estimated radiation dose of 600 chest x-rays. A high variability in DLP was observed between study sites (range of median DLPs per site, 331-2,146 mGy x cm).
Independent factors associated with radiation dose were patient weight (relative effect on DLP, 5 percent); absence of stable sinus rhythm (type of heart rhythm; 10 percent effect); scan length (a 1-cm increase in the scan length was associated with a 5 percent increase in DLP); the use of electrocardiographically controlled tube current modulation (resulting in a reduction of DLP of 25 percent, applied in 73 percent of patients); 100-kV (kilo volts) tube voltage (46 percent reduction of DLP, applied in 5 percent of patients); sequential scanning (78 percent reduction; applied in 6 percent of patients); experience in cardiac CT (1 percent reduction); number of CCTAs per month; and type of 64-slice CT system (for highest vs. lowest dose system, 97 percent effect).
"...the study demonstrates that radiation exposure can be reduced substantially by uniformly applying the currently available strategies for dose reduction, but these strategies are used infrequently," the authors write. "...an improved education of physicians and technicians performing CCTA on these dose-saving strategies might be considered to keep the radiation dose 'as low as reasonably achievable' in every patient undergoing CCTA."
"As CCTA is being used more frequently worldwide for diagnosing coronary artery disease, all strategies for reducing radiation exposure will finally reduce the patient's lifetime cancer risks. Although the associated risk is small (estimated lifetime attributable risk of death from cancer after an abdominal CT scan is 0.02 percent) relative to the diagnostic information for most CT studies, this risk needs to be realized especially when repeated CT scans are being performed."
(JAMA. 2009;301[5]:500-507. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
Editorial: Radiation Protection of Patients Undergoing Cardiac Computed Tomographic Angiography
In an accompanying editorial, Andrew J. Einstein, M.D., Ph.D., of the Columbia University College of Physicians and Surgeons, New York, writes that there are a number of implications from this study for patient care.
"First, the study results reinforce the observation that cardiac CT angiography (CTA) is still a potentially high-dose procedure, and like all procedures involving the use of ionizing radiation, a patient-specific benefit-risk analysis should always be performed to justify the imaging study. Second, the findings suggest that dose-reduction methods can be used in the majority of patients, which should serve as a wake-up call to cardiac CT laboratories that do not routinely use these methods. ...Third, PROTECTION I reveals a degree of variability in radiation dose between sites that had not been previously appreciated, but which offers the potential to decrease radiation burden from cardiac CTA while maintaining diagnostic image quality by instituting quality improvement programs to close the gap. Fourth, the lack of clinically significant association between procedure volume and dose suggests that despite the general association between case volumes and quality of care, even many high-volume centers can benefit from such quality improvement programs."
"The international system of radiological protection stands on three principles: justification, optimization, and diagnostic reference levels. PROTECTION I provides valuable information pertaining to each of these in the context of cardiac CTA, and as such makes an important addition to the evidence base."
(JAMA. 2009;301[5]:545-547. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Please see the article for additional information, including financial disclosures, funding and support, etc.
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Embargoed for Release: 3:00 p.m. CT, Tuesday, February 3, 2009
Media Advisory: To contact corresponding author Jacqueline R. Center, M.B.B.S., Ph.D., email j.center{at}garvan.org.au.
Older Adults Who Experience Osteoporotic Fracture Have Increased Risk of Death For 5 - 10 Years
CHICAGO—Women and men age 60 years or older who have a low-trauma osteoporotic fracture have an increased risk of death for the following 5 to 10 years, compared to the general population, and those who experience another fracture increase their risk of death further for an additional 5 years, according to a study in the February 4 issue of JAMA.
Osteoporotic fractures represent a growing public health problem in both developed and developing countries, with a projected increasing incidence as the population ages. There are limited data on the long-term risk of death following osteoporotic fracture or a subsequent fracture, according to background information in the article.
Dana Bliuc, M.Med., of the Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, Australia, and colleagues examined the long-term risk of death (up to 18 years) following all types of osteoporotic fractures in women and men in different age groups and the association of subsequent fracture with mortality risk. The study included women and men age 60 years and older from Dubbo, Australia (in 1989, this consisted of 2,245 women and 1,760 men) who sustained a fracture between April 1989 and May 2007. In women, there were 952 low-trauma fractures followed by 461 deaths, and in men, 343 fractures were followed by 197 deaths.
In comparison to the general population, increased mortality risk was observed across all age groups following hip, vertebral, and major fractures for 5 years post-fracture except for minor fractures, where an increased risk of death was only apparent in those age 75 years or older. After five years, the mortality risk decreased, with hip fracture–associated mortality remaining elevated for up to 10 years. After 10 years, mortality rates were not different from that of an appropriately age-matched population.
"Nonhip, nonvertebral fractures, generally not considered in these types of studies, not only constituted almost 50 percent of the fractures studied, but also were associated with 29 percent of the premature mortality. Mortality risk decreased with time; however, the occurrence of a subsequent fracture was associated with a 3- to 4-fold increased mortality risk for a further 5 years," the authors write. "Given these findings, more attention should be given to nonhip, nonvertebral fractures..."
Predictors of death after any fragility fracture for both men and women included age, quadriceps weakness and subsequent fracture but not co-existing illnesses. Low bone mineral density and having smoked were also predictors for women and less physical activity for men.
"These data suggest fracture is a signal event that heralds an increased mortality risk: whether it is related to an underlying increased risk for both fracture and mortality, which may be the case for women, or whether it is related to some aspect of the fracture event itself, as appears to be the case for men, needs further exploration. Overall, this study highlights the premature mortality associated with all types of fractures, particularly that which occurs after subsequent fracture across the whole age spectrum of older men and women," the researchers conclude.
(JAMA. 2009;301[5]:513-521. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
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Embargoed for Release: 3:00 p.m. CT, Tuesday, February 3, 2009
Media Advisory: To contact Wolfgang C. Winkelmayer, M.D., Sc.D., call Holly Brown-Ayers at 617-534-1603 or email hbrown-ayers{at}partners.org.
Dialysis Patients Residing at Higher Altitude Have Lower Rate of Death
CHICAGO—Compared to dialysis patients living near sea level, dialysis patients living at an altitude higher than 4,000 feet have a 12-15 percent lower rate of death, according to a study in the February 4 issue of JAMA.
A recent study found that patients with end-stage renal (kidney) disease (ESRD) living at higher altitude achieved greater hemoglobin concentrations (a protein in red blood cells that primarily transports oxygen from the lungs to the rest of the body) while receiving lower doses of erythropoietin (a hormone that stimulates the production of red blood cells). Increased iron availability caused by activation of hypoxia-induced (oxygen deficiency) factors at higher altitude may explain this finding, according to background information in the article.
Wolfgang C. Winkelmayer, M.D., Sc.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues examined whether increased altitude would be associated with a reduced rate of death for patients initiating chronic dialysis. Using a comprehensive dialysis registry, the researchers identified 804,812 patients with ESRD who initiated dialysis between 1995 and 2004 and who met the study entry requirements. Most patients resided below an altitude of 250 ft. (40.5 percent) or between 250-1,999 ft. (54.4 percent). Only 1.9 percent of incident dialysis patients lived between 4,000 and 5,999 ft. and 0.4 percent higher than 6,000 ft. Patients were stratified by the average elevation of their residential zip code.
Compared with patients living at lower altitudes (less than 250 ft.), the rate of death was reduced for patients living from 250-1,999 ft. by 3 percent; from 2,000 through 3,999 ft. by 7 percent; from 4,000 to 5,999 ft. by 12 percent; and higher than 6,000 ft. by 15 percent.
Actuarial 5-year survival was 34.8 percent for patients living at or near sea level but was 42.7 percent among those living at an altitude higher than 6,000 ft.; patients in the highest elevation group experienced a 7.9 percent greater absolute or 22.7 percent greater relative 5-year survival. Median (midpoint) survival after initiation of dialysis was 3.1 years for those living lower than 250 ft. but was 4.0 years for those living at an altitude higher than 6,000 ft., for a difference in median survival of 0.9 years between these 2 groups.
While a decrease in age- and sex-standardized mortality at higher altitude was also observed in the general population, the magnitude of the risk reduction was half of that observed in the ESRD population.
"In conclusion, we found a graded reduction in mortality from any cause in ESRD patients residing at greater altitude, a finding that was not explained by differences in observed patient characteristics. The magnitude of this observation was markedly greater than the observed small reduction in mortality at higher altitude in the general population. We propose that hypoxia-inducible factors are persistent at high altitude in patients with ESRD and may confer protective effects," the authors write.
(JAMA. 2009;301[5]:508-512. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
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JAMA REPORTS
VIDEO:
Windows Media |
Quicktime
STUDY FINDS HIGHER ALTITUDES COULD MEAN LOWER MORTALITY RATES FOR PATIENTS WITH END-STAGE RENAL DISEASE
INTRO:
While the benefits of higher altitudes have been touted for elite athletes in training, new research has found that lower oxygen surroundings may also be beneficial for some people with health issues, specifically, those battling end-stage renal disease. Haley Weldon explains in this week's JAMA Report.
VIDEO:
B-ROLL
Dialysis patient
AUDIO:
THE OUTLOOK CAN SEEM BLEAK AND GENERALIZED FOR PEOPLE WITH END-STAGE RENAL DISEASE; THEIR KIDNEYS’ FUNCTION AT LESS THAN 10%; THEIR CONDITION IS IRREVERSIBLE; AND ALL THOSE UNABLE TO RECEIVE A KIDNEY TRANSPLANT MUST CONTINUOUSLY RELY ON DIALYSIS TO CLEAR THEIR BLOOD OF TOXINS.
VIDEO:
B-ROLL
Dr. Winkelmayer in his office
AUDIO:
BUT DR. WOLFGANG WINKELMAYER, OF BRIGHAM AND WOMEN’S HOSPITAL, AND HIS COLLEAGUES HYPOTHESIZED THAT ONE OBVIOUS DIFFERENCE IN THESE PATIENTS - THE VARYING ALTITUDES AT WHICH THEY LIVED - COULD HAVE AN EFFECT ON THEIR MORTALITY RATE.
VIDEO:
SOT/FULL
Super @ :28
Wolfgang C. Winkelmayer, M.D.
Brigham and Women’s Hospital
AUDIO:
Runs: :19
...the idea that we had developed from a previous study was that certain factors that respond to high altitude, to low oxygen exposure essentially, these factors that are activated under low oxygen circumstances may have beneficial effects.
VIDEO:
B-ROLL
Dialysis patient
AUDIO:
FOR THESE PATIENTS, ONE SUCH FACTOR THAT IS LOW-OXYGEN (OR “HYPOXIA”) INDUCED IS THE INCREASE IN THEIR FAILING KIDNEYS’ PRODUCTION OF AN IMPORTANT HORMONE, ERYTHROPOIETIN. (erythro-poy-eh-tin)
VIDEO:
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Wolfgang C. Winkelmayer, M.D.
Brigham and Women’s Hospital
AUDIO:
Runs: :19
Patients or individuals who move to higher altitudes experience hypoxia and the body in response turns on erythropoietin, which then in turns increases the formation of new red blood cells. If there are more red blood cells, there is more oxygen available for tissues to function.
VIDEO:
GFX/JAMA COVER
GFX/MAP OF UNITED STATES
ALTITUDE GROUP / DECREASE IN MORTALITY RATE
76 METERS ----
76-609 METERS 3%
610-1218 METERS 7%
1219-1828 METERS 12%
1828 METERS 15%
AUDIO:
THE STUDY, PUBLISHED THIS WEEK IN JAMA, THE JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, UTILIZED OVER 800,000 PATIENT FILES FROM THE UNITED STATES RENAL DATA SYSTEM. PATIENTS WERE CLASSIFIED INTO 5 ALTITUDE GROUPS BASED ON THEIR RESIDENTIAL ZIP CODES AND RESULTS CONFIRMED WHAT THE RESEARCHERS PREDICTED: MORTALITY RATES DECREASED AS ALTITUDES INCREASED.
VIDEO:
SOT/FULL
Wolfgang C. Winkelmayer, M.D.
Brigham and Women’s Hospital
AUDIO:
Runs : 16
Kidney disease patients who started dialysis at high altitudes, that is above 6000 feet above sea level, had a 15% lower mortality rate compared to very similar patients who started dialysis at or approximately at sea level.
VIDEO:
B-ROLL
Dialysis patient
AUDIO:
SO FOR PATIENTS WITH END-STAGE RENAL DISEASE, LIVING HIGHER UP MIGHT JUST MEAN LIVING LONGER. HALEY WELDON, THE JAMA REPORT.
