Do we need to drink 8 glasses of water a day?

A Scottish GP, Margaret McCarthney, wrote a feature article in the BMJ last week that the common recommendation to drink 6 to 8 glasses of water a day is "debunked nonsense", as a result, hundreds of comments, some agreeing, many disagreeing, were sent to the BMJ and other media.

The GP argued that there is no high quality evidence to support the recommendation and that too much water can lead to hyponatremia and other problems. She said that the "Hydration for Health" initiative, sponsored by Danone, maker of bottled water Volvic and Evian, has vested interests to re-inforce the myth. Dr McCarthney argued that reports that drinking more water can improve concentration and mental performance in kids have lacked evidence and that Hydration for Health has oversold the benefits of drinking more water without clear evidence to support it. "We should just say no", she said.

An expert noted that there is well established literature on the negative effects of dehydration on mental skills in adults and children. Another said that the author failed to mention an important US report(2004) that reviewed all studies.

Dr McCartheny argued that her article was to examine the evidence of the benefits that Danone claimed via "Hydration for Health" and was not a systematic review on the subject and she did not imply that it is dangerous for children to drink 6-8 glasses of water a day.

Source: Waterlogged? BMJ 2011; 343:d4280 doi: 10.1136/bmj.d4280 (Published 12 July 2011) , full text via Athens

Provenge therapy for advanced prostate cancer

Prostate cancer is one of the most common malignancy in North American males causing more than 30,000 deaths each year, up to 30% experience recurrence.

Chemotherapy and hormonal therapy are the usual treatment available to these patients, but many patients have progressed to castrate-resistant prostate cancer (CRPC) and chemotherapy has significant side effects.

A new study was published online in the journal Maturitas in May about a novel therapeutic cancer vaccine, Sipuleucel-T, or Provenge, produced by Dendreon Ltd, for the treatment of CRPC after randomized trials showed significant survival advantage compared to controls.

In April 2010, the US FDA approved the vaccine therapy for advanced prostate cancer that has failed to respond to hormone therapy. The therapy involves taking the patient's own immune cells, externally activated against prostate cancer antigen PAP and infuse back into the patient. The patient's own immune system will then create T-cells to attack these cells.


Provenge does not cure prostate cancer but trials show that it extends survival by 4 months or years for some patients. Phase I and Phase II trials show that the vaccine is safe but some patients suffer side effects such as fatigue, headache, back pain, joint pain etc. It is advised that patients should discuss the risks and benefits with their physicians.

Source: "Vaccine therapy with sipuleucel-T (Provenge) for prostate cancer". Maturitas 2011 Aug;69(4):296-303. Epub 2011 May 31

sitting for long periods doubles risk of blood clots in the lungs

According to a new study published by the BMJ, women who sit for long period of time everyday are 2 to 3 times more likely to develop blood clot in their lungs than more active women. The study is the first to prove that a sedentary lifestyle increases the risk of developing a pulmonary embolism.

US researchers followed almost 70,000 female nurses for 18 years and collected information about their lifestyle through biennial questionnaires. They found that the risk of pulmonary embolism was more than twice higher in women who spent more than 41 hrs a week (outside work) sitting comapred with those who spent less than 10 hrs a week. The study also showed that physical inactivity correlated with heart disease and hypertension.

The authors concluded that physical inactivity is associated with pulmonary embolism in women and suggest that the incidence of pulmonary embolism could be redudced by discouraging physical inactivity among the general public.

Source: Physical inactivity and idiopathic pulmonary embolism in women: prospective study. BMJ 2011; 343:d3867 (Published 4 July 2011) Open access

Risk of irregular heart rhythm from NSAIDs is low

The use of NSAIDs, commonly known as painkillers, including ibuprofen are already known to be associated with cardiovascular risk but a new study, published in the BMJ, showed for the first time a link between the drugs and atrial fibrillation or flutter (AF) also known as irregular heart rhythm.

Danish researchers examined the records of more than 32,000 patients who had a first diagnosis of AF between 1999 and 2009 and compared each to 10 randomly selected control patients.They found that patients starting treatment with non-aspirin NSAIDs had 40-70% increased risk of AF compared to non-users. New users of cox-2 inhibitors, the newer forms of the drugs, were associated with a 70% increased risk.

The lead author concluded that the overall increased risk was still low and patients taking these medicine should not stop them but should discuss the potential risks with doctor. One-off doses or short courses of over-the-counter-strength ibuprofen are still considered safe.

In an accompanying editorial, the author said doctors should be cautious when precribing NSAIDs to older people because of the higher risk of AF.

Critics say that this was a population-based case control study with many strengths, but the lack of data on the amount of NSAIDs taken by the patients, confounders, lifestyle factors etc. could have affected the results.

Source: Schmidt M, Christiansen CF, Mehnert F, et al. Non-steroidal anti-inflammatory drug use and risk of atrial fibrillation or flutter: population based case-control study. BMJ 2011; 343:d3450 ( open access)

Editorial : Gurwitz JH. NSAIDs and atrial fibrillation. BMJ 2011, 343: d2495 (open access)

Anticholinergic medication may put elderly at risk

According to a new study, a group of researchers in the UK and US re-analysed data collected between 1991 and 1993 as part of a large ongoing MRC study into the decline of mental functioning in people over 65 to determine whether the use of anticholinergic drugs increases the cognitive impairment risk and death in older people.

Anticholinergic drugs block the chemical acetylcholine which is vital in the transmission of electrical impulses between nerve cells, also have an effect on concentration, memory and causes confusion. Drugs with anticholinergic effects are commonly used in many areas of medicine, eg, eye drops Timolol Maleate, warfarin for blood thinning, the painkiller Codeine, allergy tablets Piriton, incontinence drug Ditropan, the antidepressant Seroxat and the sleeping pill Nytol.


Researchers examined more than 80 drugs having anticholinergic effects and classified them with score into 3 groups : severe, moderate and mild based on potential harm. Drugs with a severe risk include Piriton, Nytol and Ditropan.


Researchers found that nearly half of the elderly patients in the study took 1 or more of these drugs, 4% were taking drugs with definite anticholinergic properties. The results showed that 20% of those taking drugs with a total score of 4 or more died by the end of the two-year study, compared with only 7% of those taking no anticholinergic drugs. Those taking several of the drugs had a 4% worse score in key tests to check the function of their brain. They concluded that the use of anticholinergic drugs increases the risk of cognitive impairment and mortality.


Critics say that the data were collected 20 years ago and may not reflect the current prescribing practice. Although the use of anticholinergic drugs was associated with increased death, it may have been influenced by some underlying conditions. It is important that people should not stop taking prescribed anticholinergic medication before speaking to their GP.


Source: Anticholinergic Medication Use and Cognitive Impairment in the Older Population: The Medical Research Council Cognitive Function and Ageing Study. Journal of the American Geriatrics Society. Article first published online: 24 JUN 2011 (full text via Athens)

More calcium does not reduce fracture risk

It is already known that calcium along with vitamin D are important in keeping bones healthy. In the US, the guideline for calcium intake was 1000 mg a day for women under the age of 50, 1200 mg for older women with the upper intake level of 2000 mg because of kidney stones and other risks caused by high calcium intake. In the UK, the recommended Ca intake for adults is 700 mg a day.

Several recent studies linked calcium supplements to increased risk for cardiovascular events and kidney stones in women. A new study published in the BMJ looked at the relationship between calcium and risk for fractures and overall bone health involving more than 61,000 Swedish women, followed up for 19 years.

The study found that women with the lowest Ca intake, below 750 mg, had a higher risk of fractures or develoing osteoporosis, but increasing intake of Ca did not reduce the risk of fracture further. Women who had the highest Ca, 1100+ mg seemed more at risk of broken hip. It concluded that moderate levels of calcium intake were best for bone health and more was not better.

The large size of the study with better precision is regarded a strength of the study, but critics say researchers used a questionnaire covering diet and lifestyle to find out how much calcium women were getting from food may result in recall bias. Experts suggest women should get enough calcium from a balanced diet, eg half pint of milk, green vegetables and nuts.


Source: "Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study". BMJ 2011; 342:d1473 (Published 24 May 2011) Open access