Caesareans, genetics and vitamins

Too busy to read the journals? Let Dr Bryan Palmer guide you through the latest research.

OBESITY AND CAESAREAN SECTION
Obesity Reviews 2007; 8: 385-94

Despite numerous studies reporting an increased risk of caesarean delivery among overweight or obese compared with normal weight women, the magnitude of the association remains uncertain. Researchers from Atlanta, in the US, conducted a meta-analysis of the current literature, which included 33 studies.

The unadjusted odd ratios of a caesarean delivery were 1.46 (95 per cent confidence interval: 1.34-1.60), 2.05 (95 per cent CI: 1.86-2.27) and 2.89 (95 per cent CI: 2.28-3.79) among overweight, obese and severely obese women. This adds to all the other antenatal and postnatal problems seen in overweight mothers.

OUT-OF-BODY EXPERIENCES
Science 2007; 317: 1,048

Being a fan of Ghostbusters as a child led me to look up courses on the paranormal as well as medicine to read at university. This paper caught my attention as it combines both!

Are 'out-of-body experiences' just mumbo jumbo or scientific fact? People who are awake and see their body from a location outside their physical body are said to have an out-of-body experience.

This is usually reported by people with a disturbance of brain function, for example after strokes, partial epileptic seizures and drug misuse. This effect has been reproduced in healthy people by manipulating the perceptual processes of visual perspective (through goggles connected to two video cameras) in conjunction with multiple sensory stimulation of the body.

On reflection, parapsychology isn't that dissimilar to medicine. Both are sciences, both have mad people to look after and in both you have to humour people.

PHARMACOGENETICS
Am J Psychiatry 2007; 164: 1,181-8

Pharmacogenetics is a growing subject, which tries to explain how genetics can affect an individual's response to medicines.

New results from the STAR*D trial of antidepressants have shown that patients with a particular combination of two genetic variants were 23 per cent more likely to respond to an SSRI that those without them. One of the genes controlled a glutamate receptor, glutamate being closely implicated in depression.

CALCIUM AND VITAMIN D IN OSTEOPOROSIS
Lancet2007;370: 657-66

Although it is widely assumed that calcium and vitamin D are essential components in osteoporosis management, the evidence that they really make any difference is conflicting. Where I work in Australia, the Medicare system has been so unimpressed that calcium and vitamin D are no longer available on prescription and patients have to buy them if their doctor recommends. This meta-analysis pulls together data from 29 randomised controlled trials with a total of more than 63,000 participants to try to get an answer.

They concluded that calcium alone, or the combination of calcium and vitamin D, reduces fracture risk and increases bone mineral density. But, the effect is pretty small.

The accompanying commentary points out that over 60 patients must be treated for more than three years to prevent a single fracture. This study confirms the Australian federal government's position is correct.

Dr Palmer is a former Hampshire GP currently working in Australia, and a member of our team who reviews the journals

THE QUICK STUDY

Obese women are more likely to need a caesarean section than their normal-weight counterparts.

Out-of-body experiences can be reproduced in volunteers by manipulating visual perspective with special goggles.

Antidepressants may work better in those with particular genetic characteristics for the glutamate receptor.

Calcium and vitamin D, although effective in osteoporosis, the effect is modest and the NNT to prevent fracture is high.

RESEARCH OF THE WEEK

ANTIBIOTIC PRESCRIBING
BMJ2007; 335: 429-31

As antibiotics become less effective due to multi-resistance, we are more likely to be encouraged against prescribing them.

Further weight for reducing prescribing comes from this observational study of 119 children in the UK. The authors used throat swabs at entry, two weeks and 12 weeks to measure resistance to ampicillin.

The results suggested that prescribing amoxicillin to a child doubles the risk of recovering a beta-lactamase encoding resistance element from that child's throat two weeks later. The risk falls back to the level seen before treatment within 12 weeks.

Although this change is transient it is probably enough to promote resistance within the general population.

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