Yoga recommended for Backache

Medscape Psychiatry Minute. 

by Dr. Peter Yellowlees. 

Clinicians frequently advise patients with chronic back pain to take up yoga as part of a multimodal approach to therapy. Although we know that yoga can improve physical function, does it also reduce pain? Now a team of investigators^[1] from the University of Duisburg-Essen in Germany has systematically reviewed and meta-analyzed the literature on the effectiveness of yoga for low back pain. Ten randomized controlled trials with a total of 967 chronic low back pain patients were included in the study. The investigators found strong evidence for short-term effectiveness, and moderate evidence for long-term effectiveness, of yoga for chronic low back pain. Of importance, yoga was not associated with any serious adverse events. It is safe to conclude that yoga can be recommended as an additional therapy to chronic low back pain patients. Perhaps we should also be using it more ourselves because of its positive global effect on health. This article is selected from Medscape Best Evidence.I'm Dr. Peter Yellowlees.

Abstract

Statins Linked to Cataracts in Large, Retrospective Study

Heartwire

Shelley Wood

Sep 20, 2013

SAN ANTONIO TX — Another large study is linking statin use to the development of cataracts

The latest, following on a Canadian analysis last year, is a propensity score-matched analysis of over 45 000 subjects in a military healthcare system, published this week in JAMA Ophthalmology .

As Dr Jessica Leuschen (Wilford Hall Ambulatory Surgery Center, San Antonio, TX) and colleagues point out, observational studies of statins have been conflicting, with some suggesting an increased risk of cataracts with statin usewhile others appear to show a beneficial effect of statins on cataract risk. At the recent European Society of Cardiology(ESC) 2013 Congress , Dr John B Kostis (Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ) presented the results of a random-effects meta-analysis, showing a 20% lower rate of cataracts with statin use compared with no statin use, with a more pronounced benefit seen when statins were started in younger patients.

The meta-analysis published today, however, found the opposite. It matched 6972 statin users with nonusers within the San Antonio Military Multi-Market Area health system using propensity scores based on variables that increased the likelihood of receiving statins and increased the risk of developing cataracts. Statin users had to have been on the drugs for more than 90 days; simvastatinwas prescribed in almost three-quarters of the patients.

They found that statin users in the propensity-matched analysis had a 9% increase in cataracts. In secondary analyses that looked at all patients with no comorbidities (based on the Charlson index) at baseline, the risk of developing cataracts was 29% higher in the statin users. Results were consistent regardless of whether patients had been taking statins for two, four, or six years, authors note.

The study is the first to use propensity matching to try to eliminate baseline confounding--making it a key contribution to the relatively recent research into this potential interaction. To heartwire , senior author Dr Ishak Mansi (VA North Texas Health Care System, Dallas) noted that there are a number of ways in which statins could be a marker for important confounders, including accessible healthcare and health insurance, as well as underlying risk factors such as smoking, diabetes, and older age--all of which are also risk factors for cataract.

That kind of confounding may have been a factor in the Kostis et al meta-analysis at ESC, Mansi commented, when asked about the divergent findings, adding that since the paper is not yet published, he hasn't had a chance to review its methodology.

"Without knowing the specifics of the paper . . . I can generally say the following: During the mid-1990s and early 2000s, there were many papers that associated statin use with improved outcomes of many diseases such as cataract, fracture, infection, dementia, etc; however, recently, it was realized that statin use was associated with 'healthy-user bias.' That is to say, individuals who are health-conscious are more likely to take statins, and better outcomes may be secondary for their health consciousness and not due to the statin itself. . . . Therefore, if this meta-analysis included large-volume studies that date back to this period of time, their results may be affected by these biases of these studies."

Cardiologists have had plenty of experience with seemingly contradictory studies, he added. "Historically, we have been through these controversies on several topics, such as the use of hormonal-replacement therapy, treatment of chronic systolic heart failures with antiarrhythmic drugs, etc. We will have to study and search for our best capabilities until we reach an answer.

"Statins are very effective medications; therefore, side effects are expected. Healthcare providers should make sure that there is justifiable indication to prescribe statins according to guidelines and that the potential benefits outweigh the potential risks of side effects for individual patients. These medications should not be prescribed lightly."

For the public, however, the message is slightly different. "For some patients, these medications have been a main tool in treatment of heart disease and should not be stopped because of a small higher risk of association with other diseases," Mansi said. All effective medications can be expected to have side effects, he continued. "It is much better to do your best to lower your own risk of cardiovascular disease (if feasible) by stopping smoking and keeping physically active than to take a pill to lower your risk of heart disease."

Vitamin B Supplements May Lower Stroke Risk

Medscape Medical News > Neurology

Pauline Anderson

Sep 18, 2013

Unlike other similar reports that failed to find a significant effect of vitamin B supplementation on stroke risk, an updated meta-analysis has shown that taking these vitamins to lower homocysteine levels significantly reduces the stroke rate.

Folate (vitamin B₉) and vitamin B₁₂ are important regulators of homocysteine metabolism. In several jurisdictions, cereals are fortified with folate. Folic acid is a supplemental form of folate.

Several biological factors may affect whether vitamin B supplements will affect stroke risk, the study showed.

"Based on our results, the ability of vitamin B to reduce stroke risk may be influenced by a number of other factors, such as the body's absorption rate, the amount of folic acid or vitamin B₁₂ concentration in the blood, and whether a person has kidney disease or high blood pressure," said Yuming Xu, MD, Department of Neurology, The First Affiliated Hospital of Zhengzhou University, China, in a press release.

The study is published online September 18 in Neurology.

Updated Analysis

Researchers searched for randomized controlled trials published before August 2012 that compared vitamin B supplementation with placebo, very-low-dose B vitamins, or usual care; had a minimum follow-up of 6 months; and included stroke events as a study endpoint.

Since 2010, several important meta-analyses have been published on the effects of therapy to lower homocysteine levels with B vitamin supplementation on vascular disease risk. The new meta-analysis included studies that were omitted from previous reports and adopted stricter inclusion criteria (it excluded several studies because of small samples, zero rates of outcome events, ill-defined endpoints events, and inappropriate control group design).

The updated analysis included 14 trials, all double-blind, with a mean age ranging from 52 to 68.9 years, and involving a total of 54,913 participants. Study follow-up ranged from 24 months to 87 months. One study, the Atherosclerosis and Folic Acid Supplementation Trial (ASFAST), had just folic acid as the intervention, while the rest adopted combined intervention with B vitamins.

In these 14 reports, there were 2471 stroke events. The researchers noted a reduction in overall stroke events resulting from lowered homocysteine levels following B vitamin supplementation (risk ratio, 0.93; 95% confidence interval, 0.86 - 1.00; P = .04).

However, several strictly designed trials reported increased stroke events even with B vitamin supplementation.

In a subgroup analysis, the researchers found no significant differences between intervention and control groups regarding primary or secondary stroke prevention, stroke type (hemorrhagic, ischemic), or stroke severity.

Results were also not significant in a subgroup analysis for changes of stroke risks in response to various doses of folic acid supplementation or various baseline blood homocysteine concentrations. Previous studies had shown that 0.4 or 0.8 mg of folic acid is beneficial for lowering homocysteine levels and improving vascular endothelial function.

The researchers did find a benefit in the subgroup with 3 or more years of follow-up.

Subgroups of patients with chronic kidney disease were included in 5 of the 14 studies and 1 subanalysis. Some trials reported decreased glomerular filtration rate with B vitamin supplements.

As for analyses specific to vitamin B₁₂, the report did not find significant benefit for reduction of stroke events in subgroups according to intervention dose, reduction of homocysteine level, or baseline blood vitamin B₁₂ concentration. An analysis of populations with folate fortification of cereal products also failed to obtain significant results regarding B₁₂ dose. Other research had reported that 1 mg of B₁₂ is beneficial.

Vitamin B₁₂ Deficiency

The authors explored the issue of pre-existing metabolic B₁₂ deficiency. A subanalysis of the Vitamin Intervention for Stroke Prevention (VISP) trial that excluded participants with low baseline B₁₂concentrations due to malabsorption and high B₁₂ levels following B₁₂ injection found beneficial results of B vitamin supplementation for reduction of stroke risk. The current analysis showed a beneficial trend although not a significant benefit in the group with baseline median B₁₂ concentrations of 322 to 400 pmol/L.

"Our clinical implication is that metabolic B₁₂ deficiency should be more thoroughly followed and treated, so that such deficiencies are found and treated appropriately with B vitamin intervention," the authors write. "In future, we should consider adoption of specific administration routes rather than a single oral route, e.g. oral route in populations with inadequate dietary intake or injection route in populations with B₁₂ malabsorption to obtain effective intervention results."

As for baseline blood pressure levels, the meta-analysis identified a benefit of B vitamins in study participants with baseline high blood pressure. Hyperhomocysteinemia is known to promote hypertension. In China, guidelines for hypertension recommend reducing homocysteine levels to manage blood pressure.

The analysis did not find a significant increase in cancer incidence.

Asked to comment, Ralph L. Sacco, MD, professor and Olemberg Chair of Neurology, executive director, McKnight Brain Institute, and chief of neurology, Jackson Memorial Miller School of Medicine, University of Miami, Florida, said he found the meta-analysis interesting but that the reduction in stroke events among those treated with vitamin B is only slight, albeit significant.

"The effects are quite small and greatest among those with elevated Hcy [homocysteine] over 20 and among subjects who do not have a diet with folate supplementation," Dr. Sacco told Medscape Medical News.

The addition of some new studies since the last meta-analysis explains the different findings, said Dr. Sacco, adding that the change is not sufficient to alter current guidelines.

"When one examines the largest clinical trials individually, there is no significant effect of vitamin B supplementation for primary or secondary stroke prevention, so it's difficult to use a meta-analysis to change evidence-based guidelines. There may be some subgroups of patients who could benefit from vitamin B supplementation, but unfortunately the effects are small and limited."

Dr. Xu serves as an editorial board member for the Chinese Journal of Neurology and Life Science Journal and on the Scientific Advisory Board for the Chinese Medical Association and the Neural Immune Professional Committee of Hunan Province.

Airport X-Rays: How Worried Should We Be?

Medscape Internal Medicine > Medicine Matters

Sandra Adamson Fryhofer, MD

Sep 10, 2013

The topic: the safety of airport security scanners. Here is why it matters. Airport security is a must for public safety, but are the methods used to scan safe? Could the radiation emitted hurt us? What about privacy issues?

These questions and more were answered in a new report from the AMA Council on Science and Public Health.^[1]Exposure to ionizing radiation can damage DNA. Infants are more sensitive to cancer-causing effects of radiation than are adults. For fetuses, radiation exposure in the womb can increase the risk for birth defects. Cancer risk from radiation exposure decreases as we get older, but one should understand that not all scanners are the same.

The so-called backscatter models use low levels of ionizing radiation to create images. The newer millimeter wave models use radio waves instead, so there is no ionizing radiation. But even radiation exposure from the backscatter units is low intensity. Most exposure is to the skin and most of the rays are reflected back by the skin. Some radiation is absorbed by internal organs, but not that much.

The amount of radiation exposure from one backscatter x-ray security scan is very small: less than a tenth of a microsievert, which is less radiation exposure than you get from eating a banana. The radiation you get from a regular chest x-ray is 20 microsieverts. A mammogram is 400 microsieverts. A chest CT is 7000 microsieverts. The reality is that all of us are exposed to background radiation from the atmosphere. High altitudes from air travel increase radiation exposure due to cosmic rays. You get 700 times more radiation exposure from a transatlantic flight, 70 microsieverts, than you do from 1 backscatter scan.

Privacy issues are another matter. They are a concern. These scanners produce detailed images of your body -- very detailed images. Some might call them R-rated. This has been passengers' concern. It also has the attention of Congress, which is why Congress mandated special scanner software to make these images more generic and less embarrassing.

Note that the company that makes the backscatter machines could not meet the software deadline, so its contract was not renewed. This means that the backscatter scanners are now history, at least in airports. The Transportation Security Administration (TSA) was supposed to replace them all with millimeter wave machines as of June 2013.

For Medicine Matters, I'm Dr. Sandra Fryhofer.

Population-wide Sodium Guidance 'Makes No Sense' in Most Countries

Shelley Wood

Sep 04, 2013AMSTERDAM — A new analysis from the large internationalPURE trial should intensify the ongoing debate over the link between sodium and blood pressure. Presenting PURE SODIUM here at the European Society of Cardiology (ESC) 2013 Congress, Dr Andrew Mente (McMaster University, Hamilton, ON) and colleagues found that only certain subgroups will actually experience blood-pressure benefits from restricting their sodium consumption. As such, sweeping recommendations for daily sodium limits are likely pointless in many parts of the world.

 "A targeted approach would be more appropriate for populations that consume a moderate amount of sodium in the 3-to-5-g/day range, because there would be very little benefit or a modest benefit of getting them down to low levels," Mente told heartwire . "For people who consume high amounts of sodium, it's important to get them down to moderate levels, so . . . a population-based approach would be more effective: you'd get better bang for the buck."

In one of the most striking findings in their study of almost 100 000 subjects, Mente and colleagues found that none of the populations surveyed had a "usual intake" of sodium that fell at or below the 2.3 g/day recommended in most guidelines.

A Dash of Data

Looking first at sodium and potassium intake, authors report that sodium intake was lowest in Malay; ranged from 4200 to 4800 mg/day in North America, Europe, South Asia, Africa, and South America; and spiked to more than 5500 mg/day in China. Potassium intake was highest in North America, Europe, and the Middle East and lowest in South Asia and Malay. Higher potassium consumption leads to greater excretion of sodium in the urine.

Next Mente and colleagues looked at the proportion of study participants whose sodium consumption fell within the recommended guidelines. Here, just 3.1% of subjects had observed sodium-intake levels below 2.3 g/day and less than 1% had levels below the recommended 1.5 g/day. When "usual intake was calculated, zero percent of subjects consumed less than 2.3 g/day and less than 1.5 g/day."

In line with previous observations, PURE SODIUM investigators found a linear relationship between BP and sodium levels, with both rising in parallel with one another. Potassium showed the inverse.

But critically, when the group looked at systolic blood pressure changes in response to 1-g increases in sodium consumption, they found that response to sodium was important only in certain groups: hypertensive subjects, the elderly, and people consuming more than 5 g/day of sodium.