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July 13, 2009JAMA news releases are made available to the public after 3 pm US Central time on the first 4 Tuesdays of each month. The Archives of 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 CONTENTS
ARCHIVES OF INTERNAL MEDICINE NEWS RELEASES
(Embargoed Until: 3 P.M. (CT), Monday, July 13, 2009)
ARCHIVES OF NEUROLOGY NEWS RELEASES
(Embargoed Until: 3 P.M. (CT), Monday, July 13, 2009)
ARCHIVES OF OPHTHALMOLOGY NEWS RELEASES
(Embargoed Until: 3 P.M. (CT), Monday, July 13, 2009)
INFORMATION CONTAINED IN THESE NEWS RELEASES IS PROTECTED BY COPYRIGHT. JOURNAL ATTRIBUTION IS REQUIRED. JOURNALISTS CAN NOW ACCESS EMBARGOED JAMA/ARCHIVES STUDIES ON-LINE. Go to www.jamamedia.org for more information and to apply for access. Please Note: The FOR THE MEDIA website now has a search feature to enable media to find previous JAMA/Archives news releases on specific medical topics. This search feature link is located on the home page at www.jamamedia.org
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Study Estimates Radiation Dose, Cancer Risk from Coronary Artery Calcium Screening
CHICAGO—A study based on computer modeling of radiation risk suggests that widespread screening for the buildup of calcium in the arteries using computed tomography scans would lead to an estimated 42 additional radiation-induced cancer cases per 100,000 men and 62 cases per 100,000 women, according to a report in the July 13 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Coronary artery calcification is associated with coronary artery disease. "Computed tomography (CT) has been proposed as a tool for routine screening for coronary artery calcification in asymptomatic individuals as part of a comprehensive risk assessment," the authors write as background information in the article. Evidence suggests that this type of screening may detect the presence of calcium in the arteries of individuals who would be at low risk when assessed by traditional risk factors. "However, the potential risks of screening, including the risk of radiation-induced cancer, have to be considered along with the potential benefits." Kwang Pyo Kim, Ph.D., then of the National Cancer Institute, Bethesda, Md., and now of Kyung Hee University, Gyeonggi-do, Republic of Korea, and colleagues estimated the radiation doses delivered to adult patients undergoing CT screening for coronary artery calcification from a range of available protocols in the literature (there is not yet one agreed-upon standard). "Radiation risk models, derived using data from Japanese atomic bomb survivors and medically exposed cohorts, were used to estimate the excess lifetime risk of radiation-induced cancer," the authors write. Because of differences in scanner models and techniques, radiation dose from a single scan varied more than 10-fold, the authors note. Organs or tissues estimated to receive measurable radiation doses included the breast, lung, thyroid, esophagus, bone surface and adrenal glands. "The wide dose variation also resulted in wide variation in estimated radiation-induced cancer risk," they continue. "Assuming screening every five years from the age of 45 to 75 years for men and 55 to 75 years for women, the estimated excess lifetime cancer risk using the median dose of 2.3 millisieverts was 42 cases per 100,000 men (range, 14 to 200 cases) and 62 cases per 100,000 women (range, 21 to 300 cases)."
There are currently no estimates of the benefits of CT screening for coronary artery calcification, but when they become available, they could be compared with these estimates of radiation-induced cancer risk to design appropriate detection and prevention strategies. "Many technical factors influence radiation dose from coronary artery calcification measurement with multidetector CT," the authors write. "Careful optimization of these factors may reduce radiation exposure without detriment to the clinical purpose of the screening examination. Further efforts by professional societies are necessary to standardize protocols in order to decrease unnecessary radiation exposure and to minimize cancer risk."
Editor's Note: Co-author Dr. Einstein is supported in part by a National Institutes of Health K12 Institutional Career Development Award. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. Editorial: Results Shed Light on Risks and Benefits
"The critical appraisal of any medical test or strategy requires careful assessment of its potential risks, benefits and costs," write Raymond J. Gibbons, M.D., and Thomas C. Gerber, M.D., Ph.D., of Mayo Clinic, Rochester, Minn., in an accompanying editorial. "Accurate definition of the risks, benefits and costs of the use of coronary artery calcium scanning with computed tomography in asymptomatic individuals remains an elusive goal," they write. "In this issue of the Archives, Kim et al contribute to our knowledge about potential risks by reporting estimated radiation doses and excess lifetime risks of radiation-induced cancer from coronary artery calcium scanning for a variety of CT scanners and scanning protocols that have been described in the literature."
"For patients in whom coronary artery calcium scoring is considered, health care providers should ideally discuss the potential risks and benefits of the procedure," they conclude. "This discussion should include the small radiation (and potential cancer) risk described by Kim et al."
Editor's Note: Dr. Gerber was supported in part by a grant from the National Institutes of Health. Please see the article for additional information, including author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org.
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Condoms Associated With Moderate Protection Against Herpes Simplex Virus 2
CHICAGO—Condom use is associated with a reduced risk of contracting herpes simplex virus 2, according to a report based on pooled analysis of data from previous studies in the July 13 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Herpes simplex virus 2 (HSV-2) typically causes genital herpes, a chronic, life-long, viral infection. Although studies indicate that consistent condom use reduces the spread of HIV and other sexually transmitted diseases such as chlamydia and gonorrhea, the effectiveness of preventing the transmission of HSV-2 through condom use is less certain, according to background information in the article. Emily T. Martin, M.P.H., Ph.D., of Children's Hospital Research Institute and the University of Washington, Seattle, and colleagues analyzed data from six HSV-2 studies to assess the effectiveness of condom use in preventing the virus. The studies included three candidate HSV-2 vaccine studies, an HSV-2 drug study, an observational sexually transmitted infection (STI) incidence study and a behavioral STI intervention study. These yielded results from 5,384 HSV-2-negative individuals (average age 29) at baseline for a combined total of 2,040,894 follow-up days. More than 66 percent of those who took part in the six studies were male, 60.4 percent were white, 94.1 percent were heterosexual and most reported no prior STIs. A total of 415 of the individuals acquired HSV-2 during follow-up. "Consistent condom users [used 100 percent of the time] had a 30 percent lower risk of HSV-2 acquisition compared with those who never used condoms," the authors write. "Risk of HSV-2 acquisition decreased by 7 percent for every additional 25 percent of the time that condoms were used during anal or vaginal sex." The risk of acquiring the virus increased significantly with increasing frequency of unprotected sex acts. There were no significant differences found in condom effectiveness between men and women.
"Based on findings of this large analysis using all available prospective data, condom use should continue to be recommended to both men and women for reducing the risk of HSV-2 acquisition," the authors conclude. "Although the magnitude of the protective effect was not as large as has been observed with other STIs, a 30 percent reduction in HSV-2 incidence can have a substantial benefit for individuals as well as a public health impact at the population level."
Editor's Note: Funding for this project was provided by grants from the National Institutes of Health, National Institute of Allergy and Infectious Diseases. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org.
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Active Commuters Have Fewer Heart Disease Risk Factors
CHICAGO—Men and women who walk or ride a bike to work appear more fit, and men are less likely to be overweight or obese and have healthier triglyceride levels, blood pressure and insulin levels, according to a report in the July 13 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. For most adults, 60 minutes of brisk walking per day is sufficient to meet physical activity guidelines for avoiding weight gain, according to background information in the article. "One potentially effective means of increasing physical activity is through alternative, non-leisure forms of physical activity such as active commuting (walking or biking to work)," the authors write. However, little previous research has been conduced on the cardiovascular and overall health benefits of such lifestyle exercise. Penny Gordon-Larsen, Ph.D., of the School of Public Health, University of North Carolina at Chapel Hill, and colleagues studied 2,364 adults in the Coronary Artery Risk Development in Young Adults (CARDIA) study who worked outside the home. At examinations conducted between 2005 and 2006, participants reported the length of their commute in minutes and miles, including details on the percentage of the trip taken by car, public transportation, walking or bicycling. The participants' height, weight and other health variables, including blood pressure and fitness levels as assessed by a treadmill test, also were collected. In addition, they wore an accelerometer to measure their levels of physical activity during at least four days of the study period. A total of 16.7 percent of the participants used any means of active commuting to reach their workplace. "Active commuting was positively associated with fitness in men and women and inversely associated with body mass index, obesity, triglyceride levels, blood pressure and insulin level in men," the authors write. The results add to existing evidence that walking or biking to work is beneficial, they note. "Public support for policies that encourage active commuting has been shown, particularly for individuals with experience using active commuting and with positive attitudes toward walking and biking," the authors write. "Furthermore, increasing active commuting will have the dual benefits of increasing population health and in reduction of greenhouse gas emissions. Environmental supports for commuting, such as physical environment and sociocultural factors, have been shown to promote active forms of commuting."
Additional research is needed to elucidate other potential benefits of active commuting, as well as unraveling the association between walking or biking to work and other health-promoting behaviors, they conclude.
Editor's Note: The CARDIA study is supported by National Heart, Lung, and Blood Institute grants. Analysis is supported by National Cancer Institute and National Institute of Child Health and Human Development grants. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org.
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Smoking Associated With More Rapid Progression of Multiple Sclerosis
CHICAGO—Patients with multiple sclerosis who smoke appear to experience a more rapid progression of their disease, according to a report in the July issue of Archives of Neurology, one of the JAMA/Archives journals. Cigarette smokers are at higher risk of developing multiple sclerosis (MS), according to background information in the article. However, the effect of smoking on the progression of MS remains uncertain. Brian C. Healy, Ph.D., of Brigham and Women's Hospital, Harvard Medical School and Massachusetts General Hospital, Boston, and colleagues studied 1,465 patients with MS who visited a referral center between February 2006 and August 2007. Participants had an average age of 42 and had MS for an average of 9.4 years. Their progression was assessed by clinical characteristics as well as by magnetic resonance imaging (MRI) over an average of 3.29 years. A total of 780 (53.2 percent) of the patients had never smoked, 428 (29.2 percent) had smoked in the past and 257 (17.5 percent) were current smokers. During follow-up, seven never-smokers began smoking and 57 current smokers quit. Current smokers had significantly more severe disease at the beginning of the study in terms of scores on disability scales and also in the analysis of MRI factors. Current smokers were also more likely to have primary progressive MS, characterized by a steady decline, rather than relapsing-remitting MS (involving alternating periods of attacks and symptom-free periods). A group of 891 patients was assessed over time to evaluate the rate of conversion from relapsing-remitting MS to secondary progressive MS (steady decline that develops after a period of relapsing-remitting symptoms). During an average of 3.34 years, 72 patients (20 of 154 smokers, 20 of 237 ex-smokers, and 32 of 500 never-smokers) experienced this progression. "The conversion from relapsing-remitting MS to secondary progressive MS occurred faster in current smokers compared with never-smokers but was similar in ex-smokers and never-smokers," the authors write. An adverse effect of smoking on the progression of MS would be consistent with previous research, the authors note. Components of cigarette smoke are known to have toxic effects on brain and neural tissue; for example, cyanides, which have been associated with the destruction of nerve cells' myelin coating (a characteristic feature of MS) in animals. "Other chemicals in smoke (e.g., nicotine) can compromise the blood-brain barrier or have immunomodulatory effects," the authors write. "Cigarette smoke increases the frequency and duration of respiratory infections, which have been linked to risk of MS and to the occurrence of MS relapses."
"In conclusion, the results of this large and in part prospective investigation support the hypothesis that cigarette smoking has an adverse effect on progression of MS as measured by clinical and MRI outcomes," they conclude. "Although causality remains to be proved, these findings suggest that patients with MS who quit smoking may not only reduce their risk of smoking-related diseases but also delay the progression of MS."
Editor's Note: This study was supported by the Partners Multiple Sclerosis Center and by a grant from the National Institute of Neurological Disorders and Stroke, National Institutes of Health Molecular Epidemiology of Epstein-Barr Virus and Multiple Sclerosis (Dr. Ascherio). Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org. EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Higher Education Level, Greater Disability Associated With Treatment Timing in Parkinson's Disease
CHICAGO—Individuals who have higher levels of education and who are more impaired by Parkinson's disease appear to require treatment for their symptoms earlier than do other patients, according to a report posted online today that will appear in the September print issue of Archives of Neurology, one of the JAMA/Archives journals. "Parkinson's disease is a chronic progressive neurodegenerative disease that leads to significant morbidity, disability and increased likelihood of institutionalization," the authors write as background information in the article. "In view of the potential for short-term and long-term drug complications, symptomatic treatment is customarily delayed in Parkinson's disease until the severity of motor symptoms results in functional impairment. Therefore, the initiation of symptomatic treatment is considered an early indicator of disease progression in Parkinson's disease and is used as an important benchmark in clinical trials." Sotirios A. Parashos, M.D., Ph.D., of the Struthers Parkinson's Center, Golden Valley, Minn., and colleagues in the NET-PD Investigators group analyzed data from 413 patients with early, untreated Parkinson's disease who participated in two double-blind trials of experimental drugs. "Site investigators used their clinical judgment to determine when participants had reached a level of dysfunction sufficient to require symptomatic therapy in any one of three areas: ambulation [walking], activities of daily living or occupational status," the authors write. After 12 months, the researchers assessed all the treatment groups to identify which patients had started taking medication for their symptoms-including levodopa or dopamine agonists, treatments that regulate the amount of the neurotransmitter dopamine. At this time, 200 of the 413 participants (48.5 percent) had started symptomatic treatment. Those who had higher levels of impairment and disability at the beginning of the study, as measured by several Parkinson's disease scales, were more likely to progress quickly. Higher education levels were also independently associated with an earlier need for symptomatic treatment. "A possible explanation is that higher education may be associated with greater occupational demands and an increased need for symptomatic control," the authors write. "However, one might expect that occupations placing higher demands on physical abilities (usually associated with lower education levels) would be associated with a more pressing need for symptomatic control. An alternate possibility is that patients with higher education are likely to be better advocates for their health care needs and play a more active role in medical decision-making."
"Emotional, psychiatric and quality of life factors at baseline played a smaller role in determining need for symptomatic treatment and did not enter the final model when baseline impairment, disability and education were taken into account," they conclude. "The impact of the patient's education level on clinical management is an unexpected finding and merits further investigation."
Editor's Note: This study was supported by the National Institute of Neurological Disorders and Stroke, National Institutes of Health. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org.
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Certain Type of Implanted Lenses May Be a Treatment Option for Some Patients With Nearsightedness
CHICAGO—Implantable lenses made of a collagen-like substance appear to provide stable correction of moderate to high nearsightedness (myopia) over four years of follow-up, according to a report in the July issue of Archives of Ophthalmology, one of the JAMA/Archives journals. "Laser-assisted in-situ keratomileusis (LASIK) has gained widespread popularity as a safe and effective surgical method for the correction of myopia, but patients with high [severe] myopia or thin corneas face some restrictions in avoiding the risk of developing keratectasia [a weakening of the cornea]," the authors write as background information in the article. An implantable lens consisting of a biocompatible collagen copolymer was developed to overcome these disadvantages, and has been reportedly effective in correcting moderate to severe vision problems. The implantation procedure is largely reversible and the lens is interchangeable, unlike LASIK. However, complications such as the formation of cataracts, loss of cells lining the eye and glaucoma have been reported and are expected to increase with time. To assess the long-term clinical outcomes of the lens implantation, Kazutaka Kamiya, M.D., Ph.D., of the University of Kitasato School of Medicine, Kanagawa, Japan, and colleagues evaluated 56 eyes of 34 patients who underwent implantation of the collagen copolymer lens. Routine post-operative examinations were conducted one, three and six months and one, two and four years later. At four years after surgery, 44 of the eyes (79 percent) were within 0.5 diopter (unit of measuring lens power) of the targeted correction and 52 (93 percent) were within one diopter. The authors suggest that collagen polymer lens implantation "results were good in all measures of safety, efficacy, predictability and stability for the correction of high myopia throughout the four-year follow-up," they write. "To our knowledge, this is the longest study to assess the refractive outcomes and adverse events" of the collagen copolymer lens implantation for myopia.
"In addition, no vision-threatening complications occurred throughout the follow-up period," they conclude. The authors note that their findings suggest that collagen copolymer lens implantation "may be a good alternative for the treatment of moderate to high myopia. More prolonged careful observation for longer than four years is necessary to assess late-onset complications of this surgical technique."
Editor's Note: Co-author Dr. Shimizu reported having been a consultant to STAAR Surgical Company. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org.
EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, July 13, 2009
Medicare Expenditures Decrease for Glaucoma Surgery as Number of Procedures Increases
CHICAGO—The overall number of glaucoma surgical procedures appears to be increasing, but payments by Medicare for the procedures have been decreasing, according to a report in the July issue of Archives of Ophthalmology, one of the JAMA/Archives journals. Glaucoma is one of the leading causes of blindness worldwide and currently affects more than 2 million people in the United States, according to background information in the article. "Management and treatment of glaucoma can be costly, and it has been estimated that glaucoma is the primary reason for ophthalmologist visits in the United States," the authors write. One previous study estimated that annual Medicare payments for glaucoma exceeded $1.2 billion each year between 1991 and 2000. "An important driver of glaucoma treatment costs is surgery." Surgery is typically used to reduce intraocular pressure (pressure within the eye) when medications fail to do so. Jordana K. Schmier, M.A., of Exponent Inc., Alexandria, Va., and colleagues conducted an analysis of Medicare claims and payments for glaucoma surgery between 1997 and 2006. The most common surgical treatments for glaucoma include laser trabeculoplasty, in which a beam of light changes the drainage angle of the eye to relieve pressure; filtering surgery, in which surgeons use a surgical tool to create a drainage hole; shunt surgery, which involves placement of a small plastic tube with an attached pouch; and cyclodestructive procedures, used to reduce the production of eye fluid in severe cases of glaucoma. "Overall, there were decreases in both the number of glaucoma surgical procedures and the amount of annual payments from 1997 to 2001 but an increase in the number of procedures in the following years," the authors write. "Trends in claims and payments vary according to procedure. Average payments for trabeculectomies decreased over time, while annual payments for cyclophotocoagulation [a type of cyclodestructive procedure] and shunt-related procedures have increased." After an initial decline, the number of trabeculoplasties increased, coinciding with advances in technology and changes in the global period for reimbursement (the amount of time after a surgery during which additional billing is limited; in 2002, this period changed from 90 to 10 days for laser trabeculoplasty).
The analysis examines only direct medical fees paid to physicians, which may be less than half of total glaucoma-related expenditures, the authors note. "Regardless, Medicare payments remain an important component of the cost of glaucoma in the United States and the overall trend toward lower-cost surgical procedures (i.e., fewer trabeculectomies) despite the increased use of newer technologies (i.e., more glaucoma drainage devices) observed in this analysis may have a substantial impact on national glaucoma expenses," they conclude. "Further advances and the application of new technologies may help to moderate the cost of providing glaucoma care to all who require it."
Editor's Note: Funding for this research was provided by Alcon Research Ltd., Fort Worth, Texas. Ms. Schmier and co-author Mr. Lau received a grant from Alcon Research Ltd. to conduct this research. Co-author Mr. Covert is an employee of Alcon Research Ltd. Co-author Dr. Robin is a consultant to Alcon Research Ltd. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc. For more information, contact JAMA/Archives media relations at 312/464-JAMA (5262) or e-mail mediarelations{at}jama-archives.org. |
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