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On the Pulse - 9th January 2009

On The Pulse

Tertius Lydgate

Friday, 09 January 2009

Out-patient management of upper GI bleeding
Bleeding of the upper gastrointestinal tract is a frequent reason for hospital admission, and measures that might shorten stay or avoid admission altogether are potential money-savers. Unfortunately, most existing triage scoring systems require endoscopy, which generally entails admission. A paper in the Lancet introduces a new scoring system that tries to avoid this problem: the Glasgow-Blatchford bleeding score. It successfully identifies many patients as suitable for out-patient management, apparently without adversely effecting outcomes. An accompanying Commentary is cautious and points out the need for further validation, but the data certainly look encouraging.

Google and flu
More and more people are turning to the internet for medical advice. So can analysis of the search terms they use and the websites they visit provide early warning of outbreaks of infectious disease? Google, in collaboration with the U.S. Centers for Disease Control and Prevention (CDC), has been exploring the possibility. A paper in Nature shows a close relationship between search engine query data for flu-related topics and CDC’s flu surveillance figures. The benefit is speed; it takes CDC a week or two to collect and process surveillance data, but Google’s web search logs can pick up an increase within 24 h. Google also provides an explanation of how it works.

Networks of the implausible
Those who remember the interesting study on the spread of happiness in social networks featured last month might also enjoy a companion piece in the BMJ, which illustrates the dangers of network analysis applied without sufficient regard for environmental confounders. The authors analyse subsamples of the US National Longitudinal Study of Adolescent Health for deliberately implausible network effects such as the spread of acne or headaches. None quite attains significance at the 5% level – a friend with acne increases your chance of acne problems by an odds ratio of 1.62, 95% CI 0.91 to 2.89 – but the point of the paper is that adequate controlling for confounders quickly reduces these illusory effects to near zero.

Parkinson’s disease and head injury
Apart from a few patients with genetically caused disease, the reason why some people develop Parkinson’s disease is unknown. Several case-control studies have suggested that previous head injury may be a factor. However, most were based on self-reporting, which raises the possibility that the findings could be the result of either recall bias or reverse causation. A large study from Denmark in the BMJ uses data from hospital records and finds that both these explanations are probably correct. Although people with Parkinson’s disease did have increased rates of hospital contact for head injury, the increase was confined to the 3 months before the diagnosis of Parkinson’s disease was made , which implies that any injury is a consequence of the evolving movement disorder, rather than its cause.

New anti-psychotics no better than predecessors 
A meta-analysis in the Lancet shows convincingly that the common notion of a ‘second generation’ or ‘atypical’ anti-psychotic is largely illusory. These drugs have no clear unifying characteristic, many are no better than their predecessors – although a handful show limited superiority – and the idea that they have fewer adverse effects is also very dubious. So how did this category arise? By listening to marketing people rather than doctors, argues an accompanying Comment, which goes on to explain how cunning trial design can produce flattering results for mediocre agents, if you choose your comparisons carefully.

Alexander Technique is economical in back pain
A few weeks ago, this column mentioned the encouraging results of a trial of Alexander Technique for the treatment of lower back pain. A follow-up paper from the same group in the BMJ examines the health economics of this approach, and perhaps unsurprisingly, also reports positively. An exercise prescription alone offered best value in purely financial terms (£2847 per QALY gain). But the combination of six lessons in Alexander Technique followed by exercise was far more effective in terms of pain-free days, and still cost only £5332 per QALY gain, where £20,000 is considered a standard threshold for cost-effectiveness. Seems quite a bargain.

Obesity and blood pressure
People who are overweight or obese are also likely to be hypertensive. But if they succeed in losing weight, their blood pressure will fall. A study in the NEJM reveals that part of the underlying mechanism involves melanocortin signalling within the central nervous system. It’s a complicated story, starting with leptin-sensitive neurones in the hypothalamus that express proopiomelanocortin (POMC). POMC is then cleaved to produce the melanocyte-stimulating hormones that in turn act on downstream neuronal pathways expressing melanocortin receptors. These pathways are important for control of both weight and blood pressure, and melanocortin receptor agonists may well turn out to be therapeutically useful in people who struggle to lose weight.

Two articles in PLoS Medicine, a systematic review and a perspective, remind us that over a million people in Western Europe and North America are homeless, and that this situation is associated with high prevalences of serious mental illness, drug use and alcohol dependence. Dr Lydgate hopes that accurate figures will provide ammunition for those arguing that we need to find more effective ways of delivering health care to this vulnerable group. And he’s sympathetic to the authors’ call for longitudinal studies to investigate the pathways into and out of homelessness.

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Tertius Lydgate

Originally from Northumberland, Tertius Lydgate studied medicine in Edinburgh, London and Paris. There he developed a special interest in communicable diseases and hoped to make great advances in treating and preventing them. But, after a promising start in a provincial centre of excellence in middle England, he was forced by circumstances (please, don't inquire) to abandon his high ideals. He now scrapes a living by pouring cold water on the over-enthusiastic at his private cryohydrotherapy clinic. Dreaming of the contributions he once hoped to make himself, he finds consolation in the latest medical journals and is happy to share his discoveries with his readers. He thinks that his creator, George Eliot, would have approved.
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