Health
In an analysis of nearly 100 studies that included approximately three million adults, relative to normal weight, overall obesity (combining all grades) and higher levels of obesity were both associated with a significantly higher all-cause risk of death, while overweight was associated with significantly lower all-cause mortality, according to a study in the Jan. 2 issue of JAMA.
“Estimates of the relative mortality risks associated with normal weight, overweight, and obesity may help to inform decision making in the clinical setting,” according to background information in the article.
Katherine M. Flegal, Ph.D., of the National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Md., and colleagues conducted a study to compile and summarize published analyses of body mass index (BMI) and all-cause mortality that provide hazard ratios for standard BMI categories.
For the review and meta-analysis, the researchers identified 97 studies that met inclusion criteria, which provided a combined sample size of more than 2.88 million individuals and more than 270,000 deaths.
Regions of origin of participants included the United States or Canada, Europe, Australia, China or Taiwan, Japan, Brazil, Israel, India and Mexico.
All-cause mortality hazard ratios for overweight, obesity, grade 1 obesity, and grades 2 and 3 obesity were calculated relative to normal weight.
The researchers found that the summary hazard ratios indicated a 6 percent lower risk of death for overweight; a 18 percent higher risk of death for obesity (all grades); a 5 percent lower risk of death for grade 1 obesity; and a 29 percent increased risk of death for grades 2 and 3 obesity.
The authors note that the finding that grade 1 obesity was not associated with higher mortality suggests that that the excess mortality in obesity may predominantly be due to elevated mortality at higher BMI levels.
The researchers add that their findings are consistent with observations of lower mortality among overweight and moderately obese patients. “Possible explanations have included earlier presentation of heavier patients, greater likelihood of receiving optimal medical treatment, cardioprotective metabolic effects of increased body fat, and benefits of higher metabolic reserves.”
The use of predefined standard BMI groupings can facilitate between-study comparisons, the authors conclude.
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A new study finds that certain changes in blood vessels in the eye’s retina can be an early warning that a person is at increased risk for glaucoma, an eye disease that slowly robs people of their peripheral vision.
Using diagnostic photos and other data from the Australian Blue Mountains Eye Study, the researchers showed that patients who had abnormally narrow retinal arteries when the study began were also those who were most likely to have glaucoma at its 10-year end point.
If confirmed by future research, this finding could give ophthalmologists a new way to identify and treat those who are most vulnerable to vision loss from glaucoma.
The study was recently published online by Ophthalmology, the journal of the American Academy of Ophthalmology.
Open-angle glaucoma (OAG), the most common form of the disease, affects nearly three million people in the U.S and 60 million worldwide.
Vision loss occurs when glaucoma damages the optic nerve, the part of the eye that transmits images from the retina to the brain.
Unfortunately, because glaucoma does not have symptoms, many people don’t know they have the disease until a good portion of their sight has been lost. Early detection is critical to treating glaucoma in time to preserve vision.
The findings of the new study, led by Paul Mitchell, M.D., PhD, of the Centre for Vision Research, University of Sydney, supports the concept that abnormal narrowing of retinal blood vessels is an important factor in the earliest stages of OAG.
Tracking nearly 2,500 participants, the study found that the OAG risk at the 10-year mark was about four times higher in patients whose retinal arteries had been narrowest when the study began, compared with those who had had the widest arteries.
None of the participants had a diagnosis of OAG at the study’s outset. Compared with the study group as a whole, the patients who were diagnosed with OAG by the 10-year mark were older, had had higher blood pressure or higher intraocular pressure at the study’s baseline, and were more likely to be female.
Elevated intraocular pressure, or pressure within the eye, is often found in patients with OAG. Study results were adjusted for age, family history of glaucoma, smoking, diabetes, hypertension, and other relevant factors.
“Our results suggest that a computer-based imaging tool designed to detect narrowing of the retinal artery caliber, or diameter, could effectively identify those who are most at risk for open-angle glaucoma,” said Dr. Mitchell. “Such a tool would also need to account for blood pressure and other factors that can contribute to blood vessel changes. Early detection would allow ophthalmologists to treat patients before optic nerve damage occurs and would give us the best chance of protecting their vision.”
A symptomless eye disease like glaucoma highlights the importance of regular eye exams. The American Academy of Ophthalmology recommends that everyone have a complete eye exam by an ophthalmologist at age 40 and stick to the follow-up exam schedule advised by their doctor.
This January during Glaucoma Awareness Month, the Academy encourages people to learn more about the disease known as “the sneak thief of sight.”
People who have a family history of glaucoma, or who are African-American or Hispanic, may be at higher risk.
For more information on glaucoma, its risk factors and treatment options, visit www.geteyesmart.org .
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