7 million premature deaths annually linked to air pollution

25 March 2014 | Geneva - In new estimates released today, WHO reports that in 2012 around 7 million people died - one in eight of total global deaths – as a result of air pollution exposure. This finding more than doubles previous estimates and confirms that air pollution is now the world’s largest single environmental health risk. Reducing air pollution could save millions of lives.

New estimates

In particular, the new data reveal a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischaemic heart disease, as well as between air pollution and cancer. This is in addition to air pollution’s role in the development of respiratory diseases, including acute respiratory infections and chronic obstructive pulmonary diseases.

The new estimates are not only based on more knowledge about the diseases caused by air pollution, but also upon better assessment of human exposure to air pollutants through the use of improved measurements and technology. This has enabled scientists to make a more detailed analysis of health risks from a wider demographic spread that now includes rural as well as urban areas.

Regionally, low- and middle-income countries in the WHO South-East Asia and Western Pacific Regions had the largest air pollution-related burden in 2012, with a total of 3.3 million deaths linked to indoor air pollution and 2.6 million deaths related to outdoor air pollution.

“Cleaning up the air we breathe prevents non-communicable diseases as well as reduces disease risks among women and vulnerable groups, including children and the elderly...”

Dr Flavia Bustreo, WHO Assistant Director-General Family, Women and Children’s Health

“Cleaning up the air we breathe prevents noncommunicable diseases as well as reduces disease risks among women and vulnerable groups, including children and the elderly,” says Dr Flavia Bustreo, WHO Assistant Director-General Family, Women and Children’s Health. “Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves.”

Included in the assessment is a breakdown of deaths attributed to specific diseases, underlining that the vast majority of air pollution deaths are due to cardiovascular diseases as follows:

Outdoor air pollution-caused deaths – breakdown by disease:

• 40% – ischaemic heart disease;
• 40% – stroke;
• 11% – chronic obstructive pulmonary disease (COPD);
• 6% - lung cancer; and
• 3% – acute lower respiratory infections in children.

Indoor air pollution-caused deaths – breakdown by disease:

• 34% - stroke;
• 26% - ischaemic heart disease;
• 22% - COPD;
• 12% - acute lower respiratory infections in children; and
• 6% - lung cancer.

The new estimates are based on the latest WHO mortality data from 2012 as well as evidence of health risks from air pollution exposures. Estimates of people’s exposure to outdoor air pollution in different parts of the world were formulated through a new global data mapping. This incorporated satellite data, ground-level monitoring measurements and data on pollution emissions from key sources, as well as modelling of how pollution drifts in the air.

Risks factors are greater than expected

“The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes,” says Dr Maria Neira, Director of WHO’s Department for Public Health, Environmental and Social Determinants of Health. “Few risks have a greater impact on global health today than air pollution; the evidence signals the need for concerted action to clean up the air we all breathe.”

After analysing the risk factors and taking into account revisions in methodology, WHO estimates indoor air pollution was linked to 4.3 million deaths in 2012 in households cooking over coal, wood and biomass stoves. The new estimate is explained by better information about pollution exposures among the estimated 2.9 billion people living in homes using wood, coal or dung as their primary cooking fuel, as well as evidence about air pollution's role in the development of cardiovascular and respiratory diseases, and cancers.

In the case of outdoor air pollution, WHO estimates there were 3.7 million deaths in 2012 from urban and rural sources worldwide.

Many people are exposed to both indoor and outdoor air pollution. Due to this overlap, mortality attributed to the two sources cannot simply be added together, hence the total estimate of around 7 million deaths in 2012.

“Excessive air pollution is often a by-product of unsustainable policies in sectors such as transport, energy, waste management and industry. In most cases, healthier strategies will also be more economical in the long term due to health-care cost savings as well as climate gains,” says Dr Carlos Dora, WHO Coordinator for Public Health, Environmental and Social Determinants of Health. “WHO and health sectors have a unique role in translating scientific evidence on air pollution into policies that can deliver impact and improvements that will save lives.”

The release of today’s data is a significant step in advancing a WHO roadmap for preventing diseases related to air pollution. This involves the development of a WHO-hosted global platform on air quality and health to generate better data on air pollution-related diseases and strengthened support to countries and cities through guidance, information and evidence about health gains from key interventions.

Later this year, WHO will release indoor air quality guidelines on household fuel combustion, as well as country data on outdoor and indoor air pollution exposures and related mortality, plus an update of air quality measurements in 1600 cities from all regions of the world.

For more information, contact

Mr Tarik Jasarevic
Mobile: +41 79 367 6214
Telephone: +41 22 791 5099
E-mail: jasarevict@who.int

Glenn Thomas
Telephone: +41 22 791 3983
Mobile: +41 79 509 0677
E-mail: thomasg@who.int

Nada Osseiran
Communications Officer, Department of Public Health, Environmental and Social Determinants of Health
Telephone: +41 22 791 4475
Mobile: +4179 445 1624
E-mail: osseirann@who.int

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Pain medication will be used in the removal of the prostate has been linked to cancer

Use the anesthetic management of patients with prostate cancer, to surgical methods and control pain, prostate gland cancer affecting their long-term cancers result when removing, guided by a Mayo Clinic study has found. Suppress the ability of the immune system to fight cancer cells after opioid, usually specified when, after painkillers. To radical prostate removal except before in research reduce opioids patients need surgery after the spinal or epidural associated complement and painkillers combined with General anesthesia, found this lower risk of cancer recurrence is suggested. Survey results will be published online in the British Journal of anaesthesia.

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The mutations breast cancer has been linked to treatment-resistant.

University of Michigan comprehensive cancer type of mutation to develop anti estrogen therapy in patients with Breast Cancer Center researchers has been confirmed. Mutations explain why patients in therapy often become to resistance is one reason.

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HPV linked to growing number of young adults with oropharyngeal cancer

Sep. 24, 2013 — The human papillomavirus (HPV) may be to blame for the alarming increase of young adults with oropharyngeal cancer, according to researchers from Henry Ford Hospital in Detroit.

The study reveals an overall 60 percent increase from 1973 and 2009 in cancers of the base of tongue, tonsils, soft palate and pharynx in people younger than age 45.

Among Caucasians, there was a 113 percent increase, while among African-Americans the rate of these cancers declined by 52 percent during that period of time.

But compared to Caucasians and other races, the five-year survival rate remains worse for African Americans.

“The growing incidence in oropharyngeal cancer has been largely attributed to the sexual revolution of the 1960s and 1970s, which led to an increased transmission of high-risk HPV,” says study lead author Farzan Siddiqui, M.D., Ph.D., director of the Head & Neck Radiation Therapy Program in the Department of Radiation Oncology at Henry Ford Hospital.

“We were interested in looking at people born during that time period and incidence of oropharyngeal cancer. Not only were we surprised to find a substantial increase in young adults with cancer of the tonsils and base of tongue, but also a wide deviation among Caucasians and African Americans with this cancer.”

The study – which examined the trends in cancers of the base of tongue, tonsils, soft palate and pharynx among people 45 years-old and younger – was presented at the 55th Annual Meeting of the American Society for Radiation Oncology (ASTRO) in Atlanta.

The American Cancer Society estimates about 36,000 people in the U.S. will get oral cavity and oropharyngeal cancers in 2013; an estimated 6,850 people will die of these cancers. Oropharyngeal cancers are more than twice as common in men as in women, and about equally common in African Americans and Caucasians.

Recent medical research has shown that HPV exposure and infection increases the risk of oropharyngeal squamous cell cancer independently of tobacco and alcohol use, two other important risk factors for the disease, according to the National Cancer Institute.

The incidence of oropharyngeal cancer has been growing in recent years due to increasing rates of HPV infection. This has been largely attributed to changes in sexual practices. Studies have shown, however, patients with HPV related head and neck cancer do have a better prognosis and survival.

For the Henry Ford study, Dr. Siddiqui and his colleagues used the SEER (Surveillance Epidemiology and End Results) database to gather information about adults younger than age 45 who had been diagnosed with invasive squamous cell oropharyngeal cancer between1973 and 2009.

Since SEER does not record HPV information, the researchers used tumor grade as a surrogate indicator of HPV infection.

Among the study group of more than 1,600 patients, 90 percent were ages 36-44 and the majority (73 percent) was Caucasian.

During the 36-year period, the majority of patients (50-65 percent) underwent surgical resection for their tumors. Patients who had both surgery and radiation therapy had the highest five-year survival rate.

“These patients have a favorable prognosis and are likely to live longer while dealing with treatment related side-effects that may impact their quality of life,” notes Dr. Siddiqui.

The five-year survival for the study group was 54 percent. There was no difference in survival based on gender. African Americans, however, had significantly poor survival compared to other races.

“The predominance of oropharyngeal cancer in this age group suggests either non-sexual modes of HPV transfer at a younger age or a shortened latency period between infection and development of cancer,” says Dr. Siddiqui.

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Commonly prescribed statin linked to memory impairment, study in rats suggests

Sep. 25, 2013 — New research that looked at whether two commonly prescribed statin medicines, used to lower low-density lipoprotein (LDL) or 'bad cholesterol' levels in the blood, can adversely affect cognitive function has found that one of the drugs tested caused memory impairment in rats.

Between six and seven million people in the UK1 take statins daily and the findings follow anecdotal evidence of people reporting that they feel that their newly prescribed statin is affecting their memory. Last year, the US Food and Drug Administration (FDA) insisted that all manufacturers list in their side effects that statins might affect cognitive function.

The study, led by scientists at the University of Bristol and published in the journal PLOS ONE, tested pravastatin and atorvostatin (two commonly prescribed statins) in rat learning and memory models. The findings show that while no adverse cognitive effects were observed in rat performance for simple learning and memory tasks for atorvostatin, pravastatin impaired their performance.

Rats were treated daily with pravastatin (brand name -- pravachol) or atorvostatin (brand name -- Lipitor) for 18 days. The rodents were tested in a simple learning task before, during and after treatment, where they had to learn where to find a food reward. On the last day of treatment and following one week withdrawal, the rats were also tested in a task which measures their ability to recognise a previously encountered object (recognition memory).

The study's findings showed that pravastatin tended to impair learning over the last few days of treatment although this effect was fully reversed once treatment ceased. However, in the novel object discrimination task, pravastatin impaired object recognition memory. While no effects were observed for atorvostatin in either task.

The results suggest that chronic treatment with pravastatin impairs working and recognition memory in rodents. The reversibility of the effects on stopping treatment is similar to what has been observed in patients, but the lack of effect of atorvostatin suggests that some types of statin may be more likely to cause cognitive impairment than others.

Neil Marrion, Professor of Neuroscience at Bristol's School of Physiology and Pharmacology and the study's lead author, said: "This finding is novel and likely reflects both the anecdotal reports and FDA advice. What is most interesting is that it is not a feature of all statins. However, in order to better understand the relationship between statin treatment and cognitive function, further studies are needed."

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Unstable chromosomes linked to less favorable response to radiation therapy and surgery in prostate cancer patients

Sep. 25, 2013 — Detailed evaluation of a prostate cancer tumor biopsy may predict treatment outcomes for image-guided radiation therapy (IGRT) or surgery for prostate cancer, according to research presented today at the American Society for Radiation Oncology's (ASTRO's) 55th Annual Meeting. The study results indicate that patients who have abnormal levels of breaks at common fragile sites (CFSs), sites within the chromosomes that are sensitive to DNA damage, are more likely to have their cancer to return -- treatment failure. These CFS break abnormalities are usually associated with instability of the cell's DNA, a phenomenon that is particularly associated with cancer.

In this study, researchers assessed the outcomes of 280 prostate cancer (Cap) patients, and reviewed the DNA "fingerprints" of each patient's tumor (using the patient's initial diagnostic core biopsy) to determine if gene copy number alterations (CNAs), or breaks in CFSs, were related to a less positive response to treatment. Two groups were analyzed: 126 localized intermediate risk CaP patients who had received image-guided radiation therapy (IGRT) treatments, with a mean dose of 74.6 Gy; and 154 localized intermediate and high risk CaP patients who had undergone radical prostatectomy (RP), which is the surgical removal of the entire prostate gland.

Utilizing an array comparative genomic hybridization (aCGH), DNA from frozen needle biopsies of the RT patients was analyzed for 13 previously characterized CFSs: FRA2G, FRA3B, FRA4F, FRA6E, FRA6F, FRA7E, FRA7G, FRA7H, FRA7I, FRA7K, FRA8C, FRA9E, FRA16D. The effect of having at least one CNA in any CFS was assessed using the Kaplan-Meier method and Cox proportional hazard models.

The data revealed a pattern in which the patients who failed treatment had abnormal levels of CNAs at CFSs. In the IGRT group, CNAs in CFSs occurred frequently, with 80 of the patients (64 percent) having a CNA in one or more CFS locations (median was 1, and the range was 0 -- 10).

Each patient's biochemical relapse-free rate (bRFR) was gauged, because if a patient relapses biochemically, his prostate specific antigen level has risen significantly and this is a reasonable indicator that the cancer has recurred. Thus, a high bRFR is desirable. On univariate analysis, patients with a CNA in at least one CFS showed a decreased 5-year bRFR (64 percent), compared with the bRFR of patients without genetic alteration in CFSs (90 percent; HR = 2.13, 95% CI: 1.17-3.86, p = 0.011). After adjusting for clinical factors in a multivariate model, a CNA in a CFS was determined to be a significant independent predictor of decreased response to radiation therapy and higher incidence of recurring cancer. (HR = 2.94, 95% CI: 1.51-5.75, P = 0.0016).

The results of the 154 patients in the RP group were compiled using the publically available Memorial Sloan-Kettering Cancer Center (MSKCC) aCGH database of patients. CNAs in CFSs were also frequent in the RP group, with 81 patients (53 percent) having a CNA in one or more location (median was 1, and the range was 0 -- 6). These results also correlated to decreased 5-year bRFR rates of 68 percent, compared to 82 percent for RP patients without genetic alterations in CFSs (HR = 1.79). Despite this strong trend, after adjusting for clinical factors in a multivariate model, a CNA in a CFS was not a statistically significant predictor of cancer recurrence (HR = 1.52, 95% CI: 0.77-3.02, P = 0.23).

"We thought that patients who have CFS breaks might be more sensitive to radiation therapy-induced DNA damage," said the lead author of the study, Robert G. Bristow, MD, PhD, a Professor within the radiation oncology and medical biophysics departments at the University of Toronto; and a Clinician-Scientist at the Princess Margaret Cancer Centre in Toronto. "We now think that the CFS breaks are a signal that the cancer cell has acquired numerous genetic changes that lead to more aggressive cancer cells that can spread early and outside the prostate gland. Our data suggest that the patients failing treatment are due to early metastatic (distant spread) disease. If we validate this study in similar, but larger groups of patients, we can develop a test based for CFS breaks; the results would allow us to place patients in one of two categories: those whose tumors do not have CFS breaks and who would likely do well with local treatment alone (e.g. radiotherapy or surgery); and, those patients whose tumors do have CFS breaks and would need a more complex treatment protocol, in addition to RT or surgery, to combat distant spread."

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Sanofi in $40 million settlement over obesity drug linked to suicidal thoughts

By Jonathan Stempel

NEW YORK (Reuters) - Sanofi SA has reached a $40 million settlement of a U.S. lawsuit accusing the French drugmaker of misleading investors about the safety of a weight loss pill that a U.S. regulatory panel linked to suicidal thoughts.

The all-cash settlement was disclosed in a court filing on Thursday, and requires approval by U.S. District Judge George Daniels in Manhattan.

It resolves claims that arose after a U.S. Food and Drug Administration advisory committee on June 13, 2007 urged that the agency reject Sanofi's drug rimonabant, known by the trade names Acomplia and Zimulti, on concern that using it could increase suicidal thinking and depression.

Sanofi is the world's fourth-largest pharmaceutical company as measured by prescription drug sales. European regulators had approved use of rimonabant prior to the FDA panel action, but sales were later suspended.

Plaintiffs led by the Hawaii Annuity Trust for Operating Engineers accused Sanofi of touting the drug as a possible "blockbuster" to treat obesity, with only mild side effects.

But they said Sanofi concealed clinical tests that showed a statistically significant increase in "suicidality" among people taking the drug.

The release of the advisory committee recommendation caused Sanofi's shares in Europe and American depository receipts in the United States to fall in price.

Thursday's settlement covers investors in Sanofi ADRs between February 24, 2006 and June 13, 2007, and equates to about 37 cents for each of Sanofi's roughly 108 million ADRs at the time.

It also resolves claims against Gerard Le Fur, the former chief executive, and Hanspeter Spek, an executive vice president of pharmaceutical operations, court papers show.

"The settlement, in light of all the risks, was exceedingly fair, and represented a high percentage of the total damages suffered by the class," said Tor Gronborg, a partner at Robbins Geller Rudman & Dowd who represents the plaintiffs, in an interview.

Sanofi did not immediately respond to requests for comment.

The plaintiffs' law firm plans to seek a fee of $11 million, or 27.5 percent of the settlement amount, court papers show.

The case is In re: Sanofi-Aventis Securities Litigation, U.S. District Court, Southern District of New York, No. 07-10279.

(Editing by Eric Walsh)

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Economic crisis 'linked to suicides'

18 September 2013 Last updated at 02:47 ET

The recent economic crisis could be to blame for an increase in suicide rates in Europe and America, say experts.

Their analysis in the British Medical Journal looked at data from 54 countries to assess the global impact of the financial problems triggered by the collapse of US credit and housing markets in 2008.

In the year after the crisis began, the male suicide rate rose by 3.3% overall.

This was largely in the countries where there were more reported job losses.

Unstable economy

The researchers from the universities of Oxford and Bristol in the UK, along with colleagues from Hong Kong University, used data from the World Health Organization mortality database, the Centers for Disease Control and Prevention and the International Monetary Fund's World Economic Outlook database.

In 2009, there was a 37% rise in unemployment and 3% falls in GDP per capita, reflecting the onset of the economic crisis in 2008.

At the same time, male suicide rates began to climb.

There were nearly 5,000 'extra' suicides above the expected level for that year.

These were mainly seen in the 27 European countries and 18 countries in the Americas studied.

In Europe, suicides increased among 15-24-year-old men, while in America the rise was seen in the 45-64 age group.

Yet the suicide rate for women did not change in Europe and only increased slightly in America.

The researchers say the link they found is likely to be causal - meaning the suicides were related to the emotional stress of being in a recession - but they cannot prove it.

It is possible other factors may be at play, but mental health charities say their own experience would back up the researchers' theory.

A Samaritans spokesperson said: "It is no surprise to us to be told that suicides rise during recessions.

"A snapshot survey of calls to our branches in 2008, just before the current recession began, showed that one in 10 callers talked about financial difficulties. That had risen to one in six at the end of last year. Clearly this is a factor that governments need to keep in mind when planning for economic downturns."

A spokeswoman for the charity Mind said they too had been receiving more calls to their helpline from people distressed about money worries and unemployment.

The national UK charity PAPYRUS (Prevention of Young Suicide) said while it could not say that there had been any recent rise in calls from young people to its national helpline specifically naming the economic crisis as a direct cause of feeling suicidal, difficulty in finding work, managing finances and student debt were "consistent themes" from those seeking help.

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Ability to move to a beat linked to brain's response to speech: Musical training may sharpen language processing

Sep. 17, 2013 — People who are better able to move to a beat show more consistent brain responses to speech than those with less rhythm, according to a study published in the September 18 issue of The Journal of Neuroscience. The findings suggest that musical training could possibly sharpen the brain's response to language.

Scientists have long known that moving to a steady beat requires synchronization between the parts of the brain responsible for hearing and movement. In the current study, Professor Nina Kraus, PhD, and colleagues at Northwestern University examined the relationship between the ability to keep a beat and the brain's response to sound.

More than 100 teenagers from the Chicago area participated in the Kraus Lab study, where they were instructed to listen and tap their finger along to a metronome. The teens' tapping accuracy was computed based on how closely their taps aligned in time with the "tic-toc" of the metronome. In a second test, the researchers used a technique called electroencephalography (EEG) to record brainwaves from a major brain hub for sound processing as the teens listened to the synthesized speech sound "da" repeated periodically over a 30-minute period. The researchers then calculated how similarly the nerve cells in this region responded each time the "da" sound was repeated.

"Across this population of adolescents, the more accurate they were at tapping along to the beat, the more consistent their brains' response to the 'da' syllable was," Kraus said. Because previous studies show a link between reading ability and beat-keeping ability as well as reading ability and the consistency of the brain's response to sound, Kraus explained that these new findings show that hearing is a common basis for these associations.

"Rhythm is inherently a part of music and language," Kraus said. "It may be that musical training, with an emphasis on rhythmic skills, exercises the auditory-system, leading to strong sound-to-meaning associations that are so essential in learning to read."

John Iversen, PhD, who studies how the brain processes music at the University of California, San Diego, and was not involved with this study, noted that the findings raise the possibility that musical training may have important impacts on the brain."This study adds another piece to the puzzle in the emerging story suggesting that musical rhythmic abilities are correlated with improved performance in non-music areas, particularly language," he said.

Kraus' group is now working on a multi-year study to evaluate the effects of musical training on beat synchronization, response consistency, and reading skills in a group of children engaging in musical training.

This research was funded by the National Science Foundation.

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Genes linked to being right- or left-handed identified

Sep. 12, 2013 — A genetic study has identified a biological process that influences whether we are right handed or left handed.

Scientists at the Universities of Oxford, St Andrews, Bristol and the Max Plank Institute in Nijmegen, the Netherlands, found correlations between handedness and a network of genes involved in establishing left-right asymmetry in developing embryos.

'The genes are involved in the biological process through which an early embryo moves on from being a round ball of cells and becomes a growing organism with an established left and right side,' explained first author William Brandler, a PhD student in the MRC Functional Genomics Unit at Oxford University.

The researchers suggest that the genes may also help establish left-right differences in the brain, which in turn influences handedness.

They report their findings in the open-access journal PLOS Genetics.

Humans are the only species to show such a strong bias in handedness, with around 90% of people being right-handed. The cause of this bias remains largely a mystery.

The researchers, led by Dr Silvia Paracchini at the University of St Andrews, were interested in understanding which genes might have an influence on handedness, in order to gain an insight into the causes and evolution of handedness.

The team carried out a genome-wide association study to identify any common gene variants that might correlate with which hand people prefer using.

The most strongly associated, statistically significant variant with handedness is located in the gene PCSK6, which is involved in the early establishment of left and right in the growing embryo.

The researchers then made full use of knowledge from previous studies of what PCSK6 and similar genes do in mice to reveal more about the biological processes involved.

Disrupting PCSK6 in mice causes 'left-right asymmetry' defects, such as abnormal positioning of organs in the body. They might have a heart and stomach on the right and their liver on the left, for example.

The researchers found that variants in other genes known to cause left-right defects when disrupted in mice were more likely to be associated with relative hand skill than you would expect by chance.

While the team has identified a role for genes involved in establishing left from right in embryo development, William Brandler cautioned that these results do not completely explain the variation in handedness seen among humans. He said: 'As with all aspects of human behaviour, nature and nurture go hand-in-hand. The development of handedness derives from a mixture of genes, environment, and cultural pressure to conform to right-handedness.'

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Diabetes Drugs Avandia, Actos Linked to Vision Woes

AppId is over the quota
AppId is over the quota

MONDAY, June 11 (HealthDay News) -- British researchers report that thiazolidinediones, diabetes medications that are used to help control blood sugar levels, may cause eye problems in those who take them.

The drugs that fall into this group include Avandia and Actos, which have been tied to increased risk of heart attack in the case of Avandia and bladder cancer in the case of Actos. Now it is possible that these drugs may also cause diabetic macular edema, the study authors said.

"Patients who received a thiazolidinedione were at two- to three-fold increased risk of developing macular edema," said lead researcher Dr. Iskandar Idris, an associate professor in diabetes medicine at the University of Nottingham.

However, the risk of macular edema is very small, about 0.2 percent, so the increased relative risk translates into an absolute risk of less than 1 percent.

"More aggressive management of risk factors for macular edema should be implemented in patients who take thiazolidinedione. In addition, routine screening for visual acuity should be performed during routine diabetes review, especially for patients who take thiazolidinediones," he added.

The report was published in the June 11 online edition of the Archives of Internal Medicine.

For the study, Idris' team collected data on more than 100,000 people with type 2 diabetes included in the British Health Improvement Network database.

At the start of the study, none of these patients suffered from diabetic macular edema, the researchers noted.

After one year, 1.3 percent of patients taking thiazolidinedione developed diabetic macular edema, compared with 0.2 percent of those not taking these drugs, Idris' group found.

The association was seen whether patients were taking Actos (pioglitazone) or Avandia (rosiglitazone), they added.

Macular edema is a swelling of the part or the eye called the macula, which is responsible for sharp vision when looking straight ahead.

Swelling occurs when fluid leaks into the center of the macula, blurring vision. About 20 percent of people with diabetes have this problem, the researchers noted.

For people taking these drugs there are alternatives that effectively lower blood sugar, such as metformin and insulin.

Dr. Sonal Singh, an assistant professor of medicine at Johns Hopkins University School of Medicine, in Baltimore, and co-author of an accompanying journal editorial, said that "the major limitation of this study is the inability to completely separate out whether the effect of these drugs on macular edema is due to the drug or the underlying disease -- diabetes."

However, the study adds more weight to the concern that Avandia and Actos may cause fluid buildup behind the eyes, he said.

"Clinicians and patients need to balance the benefits of these drugs on lowering blood sugar against their risks," Singh said. "Despite this uncertainty, patients with diabetes should seek prompt referral to an eye doctor if patients experience visual symptoms while taking Avandia or Actos."

More information

For more on hypertension, visit the American Diabetes Association.

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