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《英国医生杂志》
Low fat diet works better with extra vegetables and whole grains
Avoiding fat, particularly saturated fat, is one way of improving your plasma lipid profile. A low fat diet works even better if it includes plenty of fruit, vegetables, and whole grains. A randomised trial in 120 healthy Americans found that a traditional low fat diet lasting four weeks reduced participants' serum concentration of total cholesterol by 0.24 mmol/l. Participants who ate the same diet with added extras reduced their serum concentration of total cholesterol by 0.46 mmol/l (P = 0.01). At the end of the four weeks, the group given extra fruit, vegetables, and whole grains had significantly lower serum concentrations of total cholesterol (0.22 (95% CI 0.05 to 0.39) mmol/l lower) and low density lipoprotein cholesterol (0.18 (0.04 to 0.32) mmol/l lower) (figure).
Credit: ANNALS OF INTERNAL MEDICINE
The trial diets were carefully matched to contain identical amounts of fat, saturated fat, protein, carbohydrate, and cholesterol, and the participants were carefully chosen: they were all healthy, aged between 30 and 65, and had a body mass index less than 31 kg/m2 and serum concentrations of low density lipoprotein cholesterol between 3.3 and 4.8 mmol/l (moderately hypercholesterolaemic).
The researchers say the added impact of their "low fat plus" diet on serum lipid concentrations is probably due to the extra soy, fibre, garlic, and plant sterols in the diet, which was modelled on the latest revision of the American Heart Association's dietary guidelines.
Annals of Internal Medicine 2005;142: 725-33
Routine episiotomies should be abandoned
Despite 50 years of research it's still impossible to draw up a list of evidence based indications for episiotomy, say researchers from the United States. But one thing is fairly clear—episiotomies should not be done simply to prevent perineal injury in the mother. A thoughtful and systematic review of the best research available (only 26 studies in total) found no evidence that routine episiotomy helps women avoid serious perineal tears, no evidence that it reduces postpartum pain, and no evidence that it prevents incontinence or sexual problems later on. Trials consistently reported that women treated according to protocols restricting episiotomy were significantly more likely to end up with an intact perineum than women treated according to more liberal protocols (33.9% v 24.3% in the strongest trial).
What these authors did find, as others have before, was a large gap between research and practice that stubbornly refuses to close. At least one million women in the United States have an episiotomy each year. There's no convincing evidence that it does them any good, and the authors say we should now make a concerted effort stop doing episiotomies. They urge obstetricians and midwives to reduce their episiotomy rates more or less immediately to no more than 15% of spontaneous vaginal births, a goal they say is easily attainable with a minimum of professional effort.
JAMA 2005;293: 2141-8
Home visits by nurses don't protect children from recurrent abuse or neglect
Home visits by nurses can help prevent child abuse and neglect before it starts—but they probably can't stop it from happening again in families where a child has already been abused, according to a randomised trial. The study, which was from Canada, included 160 families with a history of physical abuse (excluding sexual abuse) involving a child still living at home. The families were given standard care by their local child protection agency, or standard care plus an intensive programme of visits by specially trained nurses. After three years, a blinded review of agency records showed no difference between the groups in the incidence of recurrent abuse (33% v 43%, intervention v control) or neglect (47% v 51%). Worse, a review of hospital records showed a significantly higher incidence of abuse among families who had had the visits (24% v 11%).
The authors were disappointed by these results, which underline just how difficult it can be to stop abuse once it has started. Their study was carefully done, well blinded, and big enough to find even a moderate benefit from nurse visits. The authors conclude that their visits programme adds nothing to standard, less intensive input from a child protection agency. Recurrent child abuse remains a common problem with no proved solutions.
Lancet 2005 May 5; doi 10.1016/S0140-6736(05)66388-X
Vitamin D and calcium don't work as secondary prevention against fractures
Older people who have had one osteoporotic fracture are quite likely to have another, and vitamin D3 and calcium are often prescribed for secondary prevention. But these supplements, alone or in combination, did not prevent fractures in the latest and largest placebo controlled trial. Taking vitamin D (800 IU daily), calcium (1000 mg daily), or both did not protect participants from any osteoporotic fracture, including hip (figure), and did not improve quality of life or survival during a follow-up of at least two years.
Credit: LANCET
All 5292 participants were over 70, with a previous history of osteoporotic fracture after low energy trauma. During treatment, which lasted two to five years, 13% of the participants had a second fracture. Fracture rates among those taking calcium, vitamin D, both, or neither were 13.3%, 12.6%, 12.6%, and 13.4%, a negative result that is consistent with some but not all previous trials and that calls into question a widespread clinical practice.
This trial was big enough and lasted long enough to find any treatment benefit, at least for this population, who were fit and living at home and had good cognitive function. But it's not the final word: the researchers had problems with compliance, which fell to 63% after two years. They also failed to measure serum concentrations of vitamin D adequately. Supplements might still prevent fractures in more vulnerable older people, especially those with a poor diet and low serum concentration of vitamin D.
Lancet 2005 April 28; doi 10.1016/50140-6736(05)63013-9
Acupuncture is no better than sham acupuncture for adults with migraine
In a randomised trial in 302 adults with migraine, half (51%) of the participants got at least 50% better after 12 sessions of acupuncture, but so did half (53%) of the patients who had sham acupuncture instead. Both groups did significantly better than a third group that was left on a waiting list for 12 weeks. Other outcomes echoed these results: over two periods of four weeks before and after treatment, acupuncture and sham acupuncture reduced the number of days with headache by a mean of 2.2. Patients who stayed on the waiting list reported a reduction of only 0.8 days between the same two periods, a significant difference compared with the acupuncture groups (figure).
Credit: JAMA
These finding suggest that sham acupuncture works as well as the real thing, but also that both "treatments" work better than nothing. The authors aren't sure why sham acupuncture worked so well in this trial, which was done in Germany. It's possible that sham needling has some kind of physiological effect comparable to real needling, but it's also possible that sham acupuncture and real acupuncture are associated with a particularly powerful placebo effect in people with migraine (typically about 30% in drug trials).
JAMA 2005;293: 2118-25
Weight gain after stopping smoking substantially reduces the benefits
The health benefits of stopping smoking, including healthier lungs, are often offset by increasing body weight, a problem that seems to be worse for men. A recent study from Europe found that weight gain after quitting reduced the beneficial impact on lung function by 38% in men and 17% in women over about nine years.
The authors used data from a large population based survey of 6654 European men and women who had their lung function measured between 1991 and 1993, when they were aged 22 to 44, then again between 1998 and 2002. They were also weighed and answered detailed questions about smoking habit at each survey.
Overall, both men and women lost 0.8% of their lung function each year, a loss of 32 ml and 25 ml from the maximum FEV1 (forced expiratory volume in one second) each year. The decline was accelerated in smokers and slower in former smokers and those who had quit between surveys. The participants also gained weight over time, each extra kilogram reducing their FEV1 by another 11.5 ml for men and 3.7 ml for women. Those who quit between surveys put on the most weight. In this European population, gains from quitting (slower decline in lung function) outweighed the losses (faster decline due to weight gain) by 7.3 ml a year for men and 7.9 ml a year for women. These benefits are better than nothing, but substantially less than they would be if people giving up smoking were given more help to manage their weight.
Lancet 2005;365: 1629-35
Alendronate is not cost effective for postmenopausal women with osteopenia
We already know that antiresorptive drugs such as alendronate reduce fractures in postmenopausal women with osteoporosis (bone mineral density T score -2.5 or less) but the benefits of treating women with osteopenia (T score -1.5 to -2.4) are much less clear. A recent cost effectiveness analysis suggests that to treat postmenopausal women with T scores at the femoral neck between -1.5 and -2.4 and no other risk factors for fractures would cost between $70 000 and $332 000 for each life year gained. Even the lower figure is $20 000 more per life year gained than US society has been willing to pay.
These figures are estimates based on five years' treatment with alendronate, and calculated using effectiveness data from a well known placebo controlled trial. The researchers conclude that alendronate is not cost effective for the large and growing population of postmenopausal women with osteopenia alone. Treatment would become cost effective only if alendronate got substantially cheaper or if the benefits were greater or lasted longer than current trials indicate.
A linked editorial (p 796-7) says women with osteopenia who have a history of fractures, are of advanced age, or are taking high risk treatments such as coricosteroids may still be candidates for treatment. In other words, we should be treating women who are likely to have fractures, not simply treating T scores.
Annals of Internal Medicine 2005;142: 734-41
Exercise therapy relieves chronic back pain—but not much
Five years ago, a Cochrane review concluded that exercise therapy worked for people with chronic back pain, but probably not for people with acute back pain. A recent update reaches broadly the same conclusions. The latest review included 61 randomised trials in 6390 people. As before, many of the trials were methodologically poor and badly reported. Pooled results from trials of treatments for chronic back pain showed that compared with no treatment, exercise therapy reduced pain scores by a mean of 10.2 points on scale of 100 points (95% CI 1.31 to 19.09 points), or by 5.93 (2.21 to 9.65) points compared with other conservative treatments. Both improvements are small (figure). In patients with acute back pain, exercise therapy, other conservative treatments, and no treatment had similar effects.
Credit: ANNALS OF INTERNAL MEDICINE
In a further systematic review (p 776-85) of 43 randomised trials, two of the same authors found that the most successful components of exercise therapy for chronic back pain were good supervision, individually designed programmes, stretching and strengthening exercises, and extra conservative treatments such as manual therapy or non-steroidal anti-inflammatory drugs. They estimate that a programme including all these ingredients would decrease pain scores by 18.8 points out of 100, compared with no treatment, and by 13.0 points compared with other conservative treatments alone.
Avoiding fat, particularly saturated fat, is one way of improving your plasma lipid profile. A low fat diet works even better if it includes plenty of fruit, vegetables, and whole grains. A randomised trial in 120 healthy Americans found that a traditional low fat diet lasting four weeks reduced participants' serum concentration of total cholesterol by 0.24 mmol/l. Participants who ate the same diet with added extras reduced their serum concentration of total cholesterol by 0.46 mmol/l (P = 0.01). At the end of the four weeks, the group given extra fruit, vegetables, and whole grains had significantly lower serum concentrations of total cholesterol (0.22 (95% CI 0.05 to 0.39) mmol/l lower) and low density lipoprotein cholesterol (0.18 (0.04 to 0.32) mmol/l lower) (figure).
Credit: ANNALS OF INTERNAL MEDICINE
The trial diets were carefully matched to contain identical amounts of fat, saturated fat, protein, carbohydrate, and cholesterol, and the participants were carefully chosen: they were all healthy, aged between 30 and 65, and had a body mass index less than 31 kg/m2 and serum concentrations of low density lipoprotein cholesterol between 3.3 and 4.8 mmol/l (moderately hypercholesterolaemic).
The researchers say the added impact of their "low fat plus" diet on serum lipid concentrations is probably due to the extra soy, fibre, garlic, and plant sterols in the diet, which was modelled on the latest revision of the American Heart Association's dietary guidelines.
Annals of Internal Medicine 2005;142: 725-33
Routine episiotomies should be abandoned
Despite 50 years of research it's still impossible to draw up a list of evidence based indications for episiotomy, say researchers from the United States. But one thing is fairly clear—episiotomies should not be done simply to prevent perineal injury in the mother. A thoughtful and systematic review of the best research available (only 26 studies in total) found no evidence that routine episiotomy helps women avoid serious perineal tears, no evidence that it reduces postpartum pain, and no evidence that it prevents incontinence or sexual problems later on. Trials consistently reported that women treated according to protocols restricting episiotomy were significantly more likely to end up with an intact perineum than women treated according to more liberal protocols (33.9% v 24.3% in the strongest trial).
What these authors did find, as others have before, was a large gap between research and practice that stubbornly refuses to close. At least one million women in the United States have an episiotomy each year. There's no convincing evidence that it does them any good, and the authors say we should now make a concerted effort stop doing episiotomies. They urge obstetricians and midwives to reduce their episiotomy rates more or less immediately to no more than 15% of spontaneous vaginal births, a goal they say is easily attainable with a minimum of professional effort.
JAMA 2005;293: 2141-8
Home visits by nurses don't protect children from recurrent abuse or neglect
Home visits by nurses can help prevent child abuse and neglect before it starts—but they probably can't stop it from happening again in families where a child has already been abused, according to a randomised trial. The study, which was from Canada, included 160 families with a history of physical abuse (excluding sexual abuse) involving a child still living at home. The families were given standard care by their local child protection agency, or standard care plus an intensive programme of visits by specially trained nurses. After three years, a blinded review of agency records showed no difference between the groups in the incidence of recurrent abuse (33% v 43%, intervention v control) or neglect (47% v 51%). Worse, a review of hospital records showed a significantly higher incidence of abuse among families who had had the visits (24% v 11%).
The authors were disappointed by these results, which underline just how difficult it can be to stop abuse once it has started. Their study was carefully done, well blinded, and big enough to find even a moderate benefit from nurse visits. The authors conclude that their visits programme adds nothing to standard, less intensive input from a child protection agency. Recurrent child abuse remains a common problem with no proved solutions.
Lancet 2005 May 5; doi 10.1016/S0140-6736(05)66388-X
Vitamin D and calcium don't work as secondary prevention against fractures
Older people who have had one osteoporotic fracture are quite likely to have another, and vitamin D3 and calcium are often prescribed for secondary prevention. But these supplements, alone or in combination, did not prevent fractures in the latest and largest placebo controlled trial. Taking vitamin D (800 IU daily), calcium (1000 mg daily), or both did not protect participants from any osteoporotic fracture, including hip (figure), and did not improve quality of life or survival during a follow-up of at least two years.
Credit: LANCET
All 5292 participants were over 70, with a previous history of osteoporotic fracture after low energy trauma. During treatment, which lasted two to five years, 13% of the participants had a second fracture. Fracture rates among those taking calcium, vitamin D, both, or neither were 13.3%, 12.6%, 12.6%, and 13.4%, a negative result that is consistent with some but not all previous trials and that calls into question a widespread clinical practice.
This trial was big enough and lasted long enough to find any treatment benefit, at least for this population, who were fit and living at home and had good cognitive function. But it's not the final word: the researchers had problems with compliance, which fell to 63% after two years. They also failed to measure serum concentrations of vitamin D adequately. Supplements might still prevent fractures in more vulnerable older people, especially those with a poor diet and low serum concentration of vitamin D.
Lancet 2005 April 28; doi 10.1016/50140-6736(05)63013-9
Acupuncture is no better than sham acupuncture for adults with migraine
In a randomised trial in 302 adults with migraine, half (51%) of the participants got at least 50% better after 12 sessions of acupuncture, but so did half (53%) of the patients who had sham acupuncture instead. Both groups did significantly better than a third group that was left on a waiting list for 12 weeks. Other outcomes echoed these results: over two periods of four weeks before and after treatment, acupuncture and sham acupuncture reduced the number of days with headache by a mean of 2.2. Patients who stayed on the waiting list reported a reduction of only 0.8 days between the same two periods, a significant difference compared with the acupuncture groups (figure).
Credit: JAMA
These finding suggest that sham acupuncture works as well as the real thing, but also that both "treatments" work better than nothing. The authors aren't sure why sham acupuncture worked so well in this trial, which was done in Germany. It's possible that sham needling has some kind of physiological effect comparable to real needling, but it's also possible that sham acupuncture and real acupuncture are associated with a particularly powerful placebo effect in people with migraine (typically about 30% in drug trials).
JAMA 2005;293: 2118-25
Weight gain after stopping smoking substantially reduces the benefits
The health benefits of stopping smoking, including healthier lungs, are often offset by increasing body weight, a problem that seems to be worse for men. A recent study from Europe found that weight gain after quitting reduced the beneficial impact on lung function by 38% in men and 17% in women over about nine years.
The authors used data from a large population based survey of 6654 European men and women who had their lung function measured between 1991 and 1993, when they were aged 22 to 44, then again between 1998 and 2002. They were also weighed and answered detailed questions about smoking habit at each survey.
Overall, both men and women lost 0.8% of their lung function each year, a loss of 32 ml and 25 ml from the maximum FEV1 (forced expiratory volume in one second) each year. The decline was accelerated in smokers and slower in former smokers and those who had quit between surveys. The participants also gained weight over time, each extra kilogram reducing their FEV1 by another 11.5 ml for men and 3.7 ml for women. Those who quit between surveys put on the most weight. In this European population, gains from quitting (slower decline in lung function) outweighed the losses (faster decline due to weight gain) by 7.3 ml a year for men and 7.9 ml a year for women. These benefits are better than nothing, but substantially less than they would be if people giving up smoking were given more help to manage their weight.
Lancet 2005;365: 1629-35
Alendronate is not cost effective for postmenopausal women with osteopenia
We already know that antiresorptive drugs such as alendronate reduce fractures in postmenopausal women with osteoporosis (bone mineral density T score -2.5 or less) but the benefits of treating women with osteopenia (T score -1.5 to -2.4) are much less clear. A recent cost effectiveness analysis suggests that to treat postmenopausal women with T scores at the femoral neck between -1.5 and -2.4 and no other risk factors for fractures would cost between $70 000 and $332 000 for each life year gained. Even the lower figure is $20 000 more per life year gained than US society has been willing to pay.
These figures are estimates based on five years' treatment with alendronate, and calculated using effectiveness data from a well known placebo controlled trial. The researchers conclude that alendronate is not cost effective for the large and growing population of postmenopausal women with osteopenia alone. Treatment would become cost effective only if alendronate got substantially cheaper or if the benefits were greater or lasted longer than current trials indicate.
A linked editorial (p 796-7) says women with osteopenia who have a history of fractures, are of advanced age, or are taking high risk treatments such as coricosteroids may still be candidates for treatment. In other words, we should be treating women who are likely to have fractures, not simply treating T scores.
Annals of Internal Medicine 2005;142: 734-41
Exercise therapy relieves chronic back pain—but not much
Five years ago, a Cochrane review concluded that exercise therapy worked for people with chronic back pain, but probably not for people with acute back pain. A recent update reaches broadly the same conclusions. The latest review included 61 randomised trials in 6390 people. As before, many of the trials were methodologically poor and badly reported. Pooled results from trials of treatments for chronic back pain showed that compared with no treatment, exercise therapy reduced pain scores by a mean of 10.2 points on scale of 100 points (95% CI 1.31 to 19.09 points), or by 5.93 (2.21 to 9.65) points compared with other conservative treatments. Both improvements are small (figure). In patients with acute back pain, exercise therapy, other conservative treatments, and no treatment had similar effects.
Credit: ANNALS OF INTERNAL MEDICINE
In a further systematic review (p 776-85) of 43 randomised trials, two of the same authors found that the most successful components of exercise therapy for chronic back pain were good supervision, individually designed programmes, stretching and strengthening exercises, and extra conservative treatments such as manual therapy or non-steroidal anti-inflammatory drugs. They estimate that a programme including all these ingredients would decrease pain scores by 18.8 points out of 100, compared with no treatment, and by 13.0 points compared with other conservative treatments alone.