Scabies, thrombosis and RA

Too busy to read the journals? Dr Honor Merriman catches up on the latest research.

Diagnosis of scabies
CMAJ 3 June 2008; 178 (12) doi:10.1503/cmaj.061753

Scabies is traditionally diagnosed by clinical symptoms and signs, and confirmed by microscopic examination of burrow skin scrapings, suspended in mineral oil or saline.

But handling and processing scrapings rapidly and effectively in general practice is not always straightforward. Patients usually want an on-the-spot diagnosis so the treatment can be started straight away.

Dermoscopy is an alternative technique for diagnosing scabies. An illuminated magnifier, also known as an epiluminescent stereomicroscope (magnification x20-60) is required.

At this magnification the typical appearance of the mite's head and two pairs of forelegs resembling the triangular shape of a hang-glider can be seen. Dermoscopy for scabies is 91 per cent sensitive and 86 per cent specific.

Dermoscopy is a simple, accurate and rapid technique that is worth considering for the diagnosis of scabies.

Thrombosis after hip and knee replacement
CMAJ June 3 2008; 178 (12) doi:10.1503/cmaj.071388

It is already accepted that hip and knee replacement surgery is a risk factor for DVT and pulmonary embolism (venous thromboembolism). Most of these events occur after the patients are discharged from hospital.

This study looked at which patient types are at risk of this occurring and whether the use of thromboprophylaxis would reduce mortality in these patients.

In total, 2,059 patients (19 per cent) received thomboprophylaxis at discharge. The mean age of the patients was 75.4.

Patients discharged from university teaching hospitals were less likely than those discharged from community hospitals to receive thromboprophylaxis after discharge. Patients were more likely to receive thromboprophylaxis if they had hip (v. knee) replacement, osteoarthritis, heart failure, AF or hypertension.

In total, 2 per cent of the patients died in the three-month period after discharge. The risk of short-term mortality was lower among those who received thromboprophylaxis after discharge.

Occluded coronary arteries after heart attacks
Lancet 2008; 371: 1, 15-20

This recent Dutch randomised controlled trial showed that, of 1,060 patients followed up, only 3.6 per cent of those who had a clot-removal procedure died in the year after their MI, compared with 6.7 per cent who received the usual treatment - percutaneous coronary intervention (PCI) with a stent. Stents placed in coronary arteries within the first few hours of MI symptoms are effective, but can displace small fragments of the blood clot further down the artery.

The new technique is called thrombus aspiration, and the researchers concluded that 'compared with conventional PCI, thrombus aspiration before stenting of the infarcted artery seems to improve the one-year clinical outcome after PCI for ST-elevation MI.'

NHS Knowledge Service said of this study: 'No measurement of infarct size of the heart attack or the function of the heart muscle (left ventricular function) was done. This means that they were unable to suggest subgroups in which the procedure may be beneficial.'

Alcohol and RA
Ann Rheum Dis 5 June 2008; doi:10.1136/ard.2007.086314

Two recent case-control studies from Scandinavia asked for details of alcohol and smoking habits in patients with early rheumatoid arthritis (RA), compared with those with no detected disease.

Alcohol consumption was found to be significantly more common in the groups who did not have RA, and it was associated with a reduced risk of RA. Risk decreased as alcohol consumption increased. Data from the same study reported that smokers were more likely to have arthritis.

So, two potential health messages have emerged from this study, both of them useful. The exact mechanism by which drinking a moderate amount of alcohol exerts this potential protective effect is not yet fully understood, and there is no case for advising people who do not drink that starting would reduce arthritis risk.

Safety of ACE inhibitors in patients with heart failure
CMAJ 6 May 2008; 178 (10) doi:10.1503/cmaj.060068

This study of 43,316 patients with heart failure compared survival over three years in those treated with ramipril versus those treated with other ACE inhibitors. The researchers found a 10-15 per cent increase in mortality with captopril and enalapril compared with ramipril among patients with congestive heart failure.

This patient group had all been discharged from hospital at the start of the study so it is not quite clear whether the same conclusions could be drawn for patients diagnosed and treated in the community, but it seems to point to ramipril as the ACEi of choice in heart failure.

Red rice extract and MI
Am J Cardiol 11 Apr 2008; doi:10.1016/j.amjcard.2008.02.056

Red rice extract is used in Chinese cookery to produce a red colour used in Peking duck.In this study, Chinese patients who had previously had an MI were randomised to receive either rice extract or placebo. It was found that those receiving the rice extract has far fewer major cardiovascular events compared with patients in the placebo group.

This represented a reduction of 4.7 per cent in major events, or a relative reduction of 45 per cent of events compared with the placebo. The rice extract is known to contain lovastatin (an early statin), and although there may be other useful compounds these have not been identified.

  • Dr Merriman is a GP in Oxford and a member of our regular team of journal reviewers
The quick study
  •  Scabies can be diagnosed using a x20-60 magnification dermoscope.
  • Thromboprophylaxis reduced mortality in patients undergoing hip or knee replacement.
  •  Thrombus aspiration reduced mortality after MI, compared with usual treatment of PCI plus stent.
  • Alcohol consumption appears to reduce the risk of developing RA.
  • Ramipril reduced three-year mortality in patients with congestive heart failure, compared with captopril or enalopril.
  • Red rice extract has been found to reduce risk of subsequent cardiovascular events in patients post MI.

 

 

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