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《英国医生杂志》
Aortic wall thickening could explain the link between low birth weight and heart disease
Credit: LANCET
When researchers measured the thickness of the aortic wall in 50 newborn babies, they found that the 25 smallest babies had thicker walled aortas than the 25 largest (maximum thickness 300 μm/kg v 199 μm/kg, P < 0.0001). Since the thickness of arterial walls is an early marker for atherosclerosis, the authors think they have found part of the mechanism behind the well known association between low birth weight and adult heart disease. All the babies were term singletons who were healthy after birth. Half of them had intrauterine growth restriction with a birth weight in the lowest 10th and the other half had normal or high birth weight (between the 50th to 90th centiles). The difference between the groups' maximum wall thickness was independent of maternal age, maternal smoking, and babies' sex.
Lancet 2005;365:7: 1484-6
A single computed tomogram can rule out pulmonary embolus
A single contrast enhanced computed tomogram of the chest can safely rule out pulmonary embolism in most patients, say a team of researchers from the US. In their meta-analysis, a single tomogram with normal appearances had a negative predictive value of 99.1% (95% CI 98.7% to 99.5%), which is comparable to the negative predictive value of pulmonary angiography (98.4%-100%) and substantially better than the negative predictive value of a ventilation perfusion scan (75.9%-88%).
The researchers analysed data from 15 studies and 3500 patients, evaluating chest computed tomography as a diagnostic test for pulmonary embolism. But instead of measuring the test's performance against a diagnostic standard (traditionally pulmonary angiography), they looked for venous thrombolic events in patients who had had a normal result, and assumed the original tomogram was wrong in patients who had a venous thrombolic event, including death, in the year after computed tomography. Using these criteria, the normal tomogram was right 99.1% of the time, so the authors conclude that it's probably safe to withhold anticoagulant treatment from low risk patients after a single computed tomogram showing no abnormality, saving patients from extra tests and reducing the healthcare bill. Their findings may not apply to patients with a high baseline risk of venous thrombosis.
JAMA 2005;293: 212-7
Workplace screening for haemochromatosis is easy and acceptable
Hereditary haemochromatosis is common, treatable, and caused by a single easy to find genetic mutation, but population screening remains controversial, partly because of worries about social stigma and genetic discrimination. So before starting their screening acceptability study, researchers from Australia did a deal with insurers guaranteeing that the industry would not discriminate against asymptomatic people who tested positive for the haemochromatosis mutation.
They screened 11 307 adults at work using samples taken with a simple brush against the cheek lining. Fifty one were homozygous for the haemochromatosis mutation (1 in 221). Forty six out of the 47 who were newly diagnosed agreed to further tests and treatment. Thirty had raised serum concentrations of transferrin and started regular venesection; four had liver abnormalities. No one who tried to find life insurance was refused or charged extra.
A battery of questionnaires before and after testing showed that screening had little, if any, impact on participants' mental state whether or not they had a positive result, and 98% of those surveyed said they were pleased they had had the test.
The authors conclude that screening for haemochromatosis is acceptable, feasible, and unlikely to cause serious anxiety among healthy adults screened at work. An ongoing economic analysis will soon report on the costs.
Lancet 2005 Apr 26 (www.thelancet.com) doi 10.1016/S0140-6736(05)63012-7
Implantable defibrillators are cost effective after a heart attack
We already know that implantable defibrillators can improve survival for selected patients. We also know they are expensive. At around $35 000 (￡18 000, 27 000) for each defibrillator, the annual cost of treatment in the US is already about $1bn. How much more would it cost to extend treatment to patients with heart failure after a heart attack, the most recent group of patients shown to benefit? A cost effectiveness analysis estimated that compared with drug treatment, patients with an ejection fraction less than 0.3 after a heart attack would get an extra 1.8 years of life from an implantable defibrillator, at a cost of $50 500 per life year gained. The authors think this is a reasonable price to pay.
Credit: ANNALS OF INTERNAL MEDICINE
In this analysis, which was based on a retrospective cohort of patients having cardiac catheterisation, the final figure depended heavily on the cost of defibrillators, their battery life, and the duration and magnitude of the benefit to patients.
Whether or not implantable defibrillators are cost effective in the long run, US cardiology services would struggle to meet the extra demand if treatment was extended to this large group of patients. About 34 000 Americans already receive an implantable defibrillator each year. These authors estimate that about 32 000 others would join the queue, nearly doubling the demand.
Credit: LANCET
When researchers measured the thickness of the aortic wall in 50 newborn babies, they found that the 25 smallest babies had thicker walled aortas than the 25 largest (maximum thickness 300 μm/kg v 199 μm/kg, P < 0.0001). Since the thickness of arterial walls is an early marker for atherosclerosis, the authors think they have found part of the mechanism behind the well known association between low birth weight and adult heart disease. All the babies were term singletons who were healthy after birth. Half of them had intrauterine growth restriction with a birth weight in the lowest 10th and the other half had normal or high birth weight (between the 50th to 90th centiles). The difference between the groups' maximum wall thickness was independent of maternal age, maternal smoking, and babies' sex.
Lancet 2005;365:7: 1484-6
A single computed tomogram can rule out pulmonary embolus
A single contrast enhanced computed tomogram of the chest can safely rule out pulmonary embolism in most patients, say a team of researchers from the US. In their meta-analysis, a single tomogram with normal appearances had a negative predictive value of 99.1% (95% CI 98.7% to 99.5%), which is comparable to the negative predictive value of pulmonary angiography (98.4%-100%) and substantially better than the negative predictive value of a ventilation perfusion scan (75.9%-88%).
The researchers analysed data from 15 studies and 3500 patients, evaluating chest computed tomography as a diagnostic test for pulmonary embolism. But instead of measuring the test's performance against a diagnostic standard (traditionally pulmonary angiography), they looked for venous thrombolic events in patients who had had a normal result, and assumed the original tomogram was wrong in patients who had a venous thrombolic event, including death, in the year after computed tomography. Using these criteria, the normal tomogram was right 99.1% of the time, so the authors conclude that it's probably safe to withhold anticoagulant treatment from low risk patients after a single computed tomogram showing no abnormality, saving patients from extra tests and reducing the healthcare bill. Their findings may not apply to patients with a high baseline risk of venous thrombosis.
JAMA 2005;293: 212-7
Workplace screening for haemochromatosis is easy and acceptable
Hereditary haemochromatosis is common, treatable, and caused by a single easy to find genetic mutation, but population screening remains controversial, partly because of worries about social stigma and genetic discrimination. So before starting their screening acceptability study, researchers from Australia did a deal with insurers guaranteeing that the industry would not discriminate against asymptomatic people who tested positive for the haemochromatosis mutation.
They screened 11 307 adults at work using samples taken with a simple brush against the cheek lining. Fifty one were homozygous for the haemochromatosis mutation (1 in 221). Forty six out of the 47 who were newly diagnosed agreed to further tests and treatment. Thirty had raised serum concentrations of transferrin and started regular venesection; four had liver abnormalities. No one who tried to find life insurance was refused or charged extra.
A battery of questionnaires before and after testing showed that screening had little, if any, impact on participants' mental state whether or not they had a positive result, and 98% of those surveyed said they were pleased they had had the test.
The authors conclude that screening for haemochromatosis is acceptable, feasible, and unlikely to cause serious anxiety among healthy adults screened at work. An ongoing economic analysis will soon report on the costs.
Lancet 2005 Apr 26 (www.thelancet.com) doi 10.1016/S0140-6736(05)63012-7
Implantable defibrillators are cost effective after a heart attack
We already know that implantable defibrillators can improve survival for selected patients. We also know they are expensive. At around $35 000 (￡18 000, 27 000) for each defibrillator, the annual cost of treatment in the US is already about $1bn. How much more would it cost to extend treatment to patients with heart failure after a heart attack, the most recent group of patients shown to benefit? A cost effectiveness analysis estimated that compared with drug treatment, patients with an ejection fraction less than 0.3 after a heart attack would get an extra 1.8 years of life from an implantable defibrillator, at a cost of $50 500 per life year gained. The authors think this is a reasonable price to pay.
Credit: ANNALS OF INTERNAL MEDICINE
In this analysis, which was based on a retrospective cohort of patients having cardiac catheterisation, the final figure depended heavily on the cost of defibrillators, their battery life, and the duration and magnitude of the benefit to patients.
Whether or not implantable defibrillators are cost effective in the long run, US cardiology services would struggle to meet the extra demand if treatment was extended to this large group of patients. About 34 000 Americans already receive an implantable defibrillator each year. These authors estimate that about 32 000 others would join the queue, nearly doubling the demand.