Tag: 31/10/22

Categories : General InterestTags :

The Micromort: A Simple Way to Convey Mortality Risk

On By ModernMedia

When dealing with risks, the often-used metric of “deaths per 100 000 population” can be a bit unwieldy, especially when explaining risk to patients. During the COVID pandemic, this became something of a problem when trying to convey the risks of vaccination to the general public. Many felt that the risk of adverse effects outweighed the protection that the vaccination conferred against the coronavirus.

But there is a different, more approachable metric – in 1979, Ronald A. Howard introduced the ‘micromort’ – defined as one chance of death in a million. One in a million is about the same odds as flipping a coin 20 times a row and getting the same result.

Though its name is sure to make some people giggle, the micromort is commonly used in actuarial sciences and decision analyses to quantify the risk of death per unit of exposure to a risk factor or event (Howard, 1980). micromorts have the advantage of being easier to interpret and comprehend than abstract numerical figures, and have been used to convey risks associated with surgical operations and medical treatments.

For example, the mortality risk of general anaesthesia is 10 micromorts per procedure (ie, a 0.001% chance of dying), which is comparable to the mortality risk of an experienced skydiver takes when doing a parachute jump. Chronic cigarette smoking reduces adult life expectancy by 6.5 years on average; said differently, averaged over a lifetime, smoking reduces life expectancy by 7 micromorts per day (3.5 hours per day) (Shaw et al., 2000).

Simply being being alive carries a risk in itself: it is highest on the first day of lift at around 500 micromorts, drops rapidly in childhood and then increases steadily throughout adult life until the 90s, when each day is as risky as that person’s first day.

MicroMorts per day for average person in England and Wales—dashed line shows rate for first day of life. (Spiegelhalter, 2014)

Perhaps unsurprisingly, one UK estimate showed that travelling by motorbike carries the highest risk of death at 9.6km for each MicroMort. Travelling by car is far safer at 400km per MicroMort. But somewhat counterintuitively, walking is not much safer than travelling by motorbike: hitting the pavement results in one MicroMort per 27.2km walked. This can be partly explained by the greater amount of time spent walking and exposed to environmental hazards such as traffic, air pollution, crime and so on.

The concept of micromorts can also be applied to pregnancies and risks to the foetus. The risk per unit due to stillbirth is only about 19 or 3710 micromorts when drinking 5 units/week throughout pregnancy. For low risk women in the UK, planned first birth at home carries an additional 843 (-200 to 2620) micromorts compared with in hospital, and planned vaginal breech birth an additional 5870 (-4400 to 18 500), compared with planned caesarean. By contrast, the risk from the mother eating a serving of unpasteurised cheese, is negligible at 0.00026 micromorts (Hickson et al., 2020).

Categories : Obstetrics & GynaecologyTags :

Hopeful IVF Parents Should Skip the Drinks

On By ModernMedia
People clinking wine glasses
Photo by Jep Gambardella on Pexels

In a recent analysis published in Acta Obstetricia et Gynecologica Scandinavica, researchers found no link between women’s caffeine consumption and pregnancy or live birth rate after fertility treatments – but alcohol consumption was linked to decreased pregnancy rate after treatments with more than 84g of alcohol a week (approximately 7 standard drinks).

The link held true for their spouses as well: men’s alcohol consumption was associated with decreased live birth rate after fertility treatments in women when weekly consumption was greater than 84g.

The researchers searched the available literature and found a total of 7 studies on caffeine consumption and 9 studies on alcohol consumption were included, with a total of 26 922 women and/or their spouse who underwent fertility treatment.

Compared with those abstaining from alcohol, the chance of achieving a pregnancy after fertility treatment decreased by 7% for women who consumed 84g of alcohol per week, and the chance of partners achieving a live birth decreased by 9% for men who consumed 84g of alcohol per week.

“Couples should be aware that some modifiable lifestyle factors such as drinking habits may affect their fertility treatment outcomes. But how these factors impact the reproductive system still needs more research to elucidate,” said corresponding author Yufeng Li, MD, of Tongji Hospital, in China.

Source: Wiley

Categories : Regenerative MedicineTags :

Fixing Spinal Cord Injuries with Stem Cell Grafts and Rehabilitation

On By ModernMedia
Photo by Cottonbro on Pexels

In recent years, researchers have made strides in promoting tissue regeneration in spinal cord injuries (SCI) through implanted neural stem cells or grafts in animal models. Separate efforts have shown that intensive physical rehabilitation can improve function after SCI by promoting greater or new roles for undamaged cells and neural circuits.

University of California San Diego researchers tested whether rehabilitation can pair with pro-regenerative therapies, such as stem cell grafting. They published their findings in in JCI Insight, 

The researchers induced a cervical lesion in rats that impaired the animals’ ability to grasp with its forelimbs. The animals were divided into four groups: animals who underwent the lesion alone; animals who received a subsequent grafting of neural stem cells designed to grow and connect with existing nerves; animals who received rehabilitation only; and animals who received both stem cell therapy and rehabilitation.

Rehabilitation therapy for some animals began one month after initial injury, a time point that approximates when most human patients are admitted to SCI rehabilitation centers. Rehabilitation consisted of daily activities that rewarded them with food pellets if they performed grasping skills.

The researchers found that rehabilitation enhanced regeneration of injured corticospinal axons at the lesion site in rats, and that a combination of rehabilitation and grafting produced significant recovery in forelimb grasping when both treatments occurred one month after injury.

“These new findings indicate that rehabilitation plays a critically important role in amplifying functional recovery when combined with a pro-regenerative therapy, such as a neural stem cell transplant,” said first author Paul Lu, PhD, associate adjunct professor of neuroscience at UC San Diego School of Medicine and research health science specialist at the Veterans Administration San Diego Healthcare System.

“Indeed, we found a surprisingly potent benefit of intensive physical rehabilitation when administered as a daily regimen that substantially exceeds what humans are now provided after SCI.”

Senior author Mark H. Tuszynski, MD, PhD, professor of neurosciences and director of the Translational Neuroscience Institute at UC San Diego School of Medicine, and colleagues have long worked to address the complex challenges of repairing SCIs and restoring function.

In 2020, for example, they reported on the observed benefits of neural stem cell grafts in mice and in 2019, described 3D-printed implantable scaffolding that would promote nerve cell growth.

“There is a great unmet need to improve regenerative therapies after SCI,” said Tuszynski. “We hope that our findings point the way to a new potential combination treatment consisting of neural stem cell grafts plus rehabilitation, a strategy that we hope to move to human clinical trials over the next two years.”

Source: University of California – San Diego

Categories : Cardiovascular DiseaseTags :

Intensive Blood Pressure Reduction after Ischaemic Stroke Increases Disability

On By ModernMedia
Credit: American Heart Association

The largest ever randomised controlled trial of intensive blood pressure lowering after thrombectomy in ischaemic stroke patients found that it led to deterioration in surrounding brain tissue and higher rates of disability, compared to less intensive treatment.

The results of the ENCHANTED2/MT trial were presented in a late-breaking session at the World Stroke Congress and simultaneously published in The Lancet. The trial was stopped early due to the significance of the findings.

Professor Craig Anderson, Director of Global Brain Health at The George Institute for Global Health, said the rapid emergence of this effect suggested the more aggressive approach was compromising the return of blood flow to the affected area.

“Our study provides a strong indication that this increasingly common treatment strategy should now be avoided in clinical practice,” he said.

Endovascular thrombectomy is an increasingly used non-surgical treatment for ischaemic stroke, in which x-ray guided microcatheters are inserted into the blood clot to dissolve it.

“A potential downside of this now widely used and effective treatment is that the rapid return of blood supply to an area that has been deprived of oxygen for a while can cause tissue damage known as reperfusion injury,” said Professor Anderson.

“This has resulted in a shift in medical practice towards more intensive lowering of blood pressure after clot removal to try and minimise this damage, but without evidence to support the benefits versus potential harms.”

To this end, researchers recruited 816 adults with acute ischaemic stroke who had elevated blood pressure after clot removal from 44 centres in China between July 2020 and March 2022. They had an average age of 67 and just over a third were female.

Of these, 407 were assigned to more-intensive (target < 120mmHg) and 409 to the less-intensive (target 140–180mmHg) systolic blood pressure control, with the target to be achieved within one hour of entering the study and sustained for 72 hours.

Researchers looked at how well the patients in both groups recovered according to a standard measure of disability, ranging from 0–1 for a good outcome without or with symptoms but no disability, scores of 2–5 reflecting increasing disability levels, and 6 being death.

Patients in the more-intensively treated group had significantly worse scores on the scale compared to those allocated to those treated less intensively.

Compared to the less-intensive group, they had more early brain tissue deterioration and major disability at 90 days but there were no significant differences in brain bleeds, mortality, or serious adverse events.

Patients who had their blood pressure more intensively controlled also rated their quality of life as significantly worse due to limitations on their physical abilities resulting from their stroke.

Prof Anderson said that after scouring the medical literature the research team had been unable to find strong enough evidence to recommend the ideal target for blood pressure control after blood clot removal in patients with acute ischaemic stroke.

“While our study has now shown intensive blood pressure control to a systolic target of less than 120mmHg to be harmful, the optimal level of control is yet to be defined,” he said.

Source: George Institute for Global Health