Journals Watch: CT scans, TB and cannabinoids

Too busy to catch up on the latest research? Let Dr Honor Merriman update you on recent papers.

Risks of whole-body CT scans
BMJ 2008; 336: 14-5
A fashionable purchase these days is a whole-body CT scan. But the Committee on Medical Aspects of Radiation in the Environment has warned that private clinics should stop offering these tests since there is no evidence the benefits outweigh the risks.

The Committee estimates that 15 per cent of a person's radiation risk comes from medical sources. It says the risk of fatal cancer from the radiation dose from a single scan is one in 2,000 and if 100,000 people had a scan every five years between the ages of 40 and 70 an extra 240 deaths would result.

An additional risk is obvious in that scans can show lesions that later turn out to be harmless, but only after the person is exposed to the risks of unnecessary investigations. The only benefit of scans was in people at high risk of CHD, where the scans of the heart may show coronary artery calcification.

Better treatment for TB
CMAJ 2008; 178 (1). doi:10.1503/cmaj.071681

TB remains a huge health problem worldwide, killing 2 million people each year.

Many cases occur in countries where finding the money to pay for the treatment is a major challenge, so cheaper combination therapies are welcome.

Moxifloxacin has been used in trials instead of ethambutol as part of combination therapy (DOTS, or directly observed therapy short course, the standard therapy for TB). The results of the trials showed the new combination treatment was effective and inexpensive.

This is regarded as the most important breakthrough in TB treatment in the past 25 years because the cheapness of the treatment will allow more patients to be treated and the rapid onset of action means that patients get better quickly and infect fewer other people.

We regard TB as a third world disease but with UK incidence increasing we should regard advances as applicable to the UK.

Occupational therapy for patients with dementia
BMJ, doi:10.1136/bmj.39408.481898.BE

The sad downward spiral of dementia may lead clinicians to hold back from offering interventions beyond simple day-to-day support. Medication is unsuitable for many patients.

In this Danish study, occupational therapy was offered over a period of three months to those living in the community with mild-to-moderate dementia.

It took the form of training for patients in the use of devices to compensate for cognitive decline, and carers were given help with coping behaviours and supervision.

The study showed benefit for patients, with improved daily functioning, and for carers in improved mood and quality of life.

It also proved to be cost-effective. This form of healthcare would be of benefit to patients in the UK.

Traffic fumes can harm children's brains
Am J Epidemiol 2007; doi.1093/aje/kwm308
When lead was removed from petrol it was hoped that children would no longer be damaged by petrol fumes.

However, a US study has shown a reduction in IQ scores in children living in areas of Boston with above average levels of traffic pollution.

The tests included verbal reasoning and visual learning.

This effect was still shown after corrections were made for socio-economic factors.

The damage to children is thought to be due to particles in the fumes, which are able to penetrate the nose to enter the brain.

Teenage smokers and brain damage
J Neuroscience 2007; doi: 10.1523/jneurosci.2402-07.2007

It has been observed that teenagers who smoke suffer from auditory attention disorders. This results in an inability to concentrate on what is being said when other things are happening at the same time.

The main author comments 'the levels of disruption are significant enough that if you were struggling at school it could tip you towards school failure'.

The study examined how smoking affects the brain by using diffusion tensor imaging and showed changes in white matter in brain pathways that relay signals to the ear. Similar changes were found in young people whose mothers had smoked in pregnancy.

Cannabinoids for pain relief
BMJ; doi:10.1136/bmj.39429.619653.80

Chronic pain is a common problem managed in primary care and despite the many possible approaches available some patients cannot seem to be helped by any of them.

It is therefore good to read about research into different medications that might help.

Cannabinoids are now becoming therapeutic options and this study comparing nabilone (a synthetic cannabinoid licensed in the UK for the treatment of chemotherapy-induced nausea and vomiting) with dihydrocodeine looked at how effective each was in providing pain relief.

The study group were patients with chronic neuropathic pain, which is a difficult symptom to mange with few current options.

The two medications were found to produce similar effects on relieving pain albeit with fewer side-effects noted with dihydrocodeine.

Dr Merriman is a GP in Oxford and a member of our team who regularly reviews the journals

The quick study

Whole-body CT scans should be avoided in patients without symptoms because of the risks from radiation.

TB may be more cost-effectively treated with a combination therapy that uses moxifloxacin rather than ethambutol.

Dementia patients respond well to occupational therapy interventions that help them cope with cognitive decline.

Traffic fumes can reduce the IQ of children living in highly polluted areas.

Teenage smokers or those whose mothers smoked in pregnancy can cause auditory attention disorders which may adversely affect schooling.

Cannabinoids such as nabilone may eventually have a role in pain management.


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