by Kevin Schofield
This weekend, we have two readings lined up, both about how longstanding and conventional medical practices change from time to time in the face of new information.
First, we have an updated recommendation from the American Medical Association (AMA) on the use of low-dose aspirin to reduce the risk of certain cardiovascular disease outcomes, including heart attacks and strokes, as well as colorectal cancer. Prescribing low-dose aspirin has grown in popularity throughout the 2000s since evidence was published showing it reduced the risk of these diseases, and in 2016 the AMA issued a recommendation that doctors prescribe to their high-risk patients aged 50 and over. cardiovascular diseases.
As with many drugs, aspirin has advantages and disadvantages, and deciding whether a patient should take it is a delicate balancing act. We know a lot about its basic function: it inhibits the function of platelets, the component of blood that causes it to clot. Blood clotting is helpful and important when it quickly stops bleeding from a cut or wound. However, it is dangerous and harmful when it creates clots inside blood vessels which can pass through our body and ultimately block a vein or artery. This can lead to deep vein thrombosis (DVT) in a leg, a heart attack if it occurs in one of the major coronary arteries, or a blockage that prevents blood from reaching part of the brain (called a “stroke”). ischemic”). As we age and our arteries harden and narrow or become clogged with plaque, the risk of blocked blood clots increases, and aspirin has been shown to reduce the risk of such clots.
On the other hand, as we age, we also become more susceptible to weakened blood vessels. We need our blood to clot in order to protect us from a hemorrhagic stroke (a broken blood vessel in our brain) or an uncontrolled bleeding ulcer, both of which can be life threatening. Aspirin not only increases these risks by preventing clotting, but has also been shown to inhibit the mucus in our digestive system which provides additional protection against ulcers.
The AMA’s recommendations for low-dose aspirin are based on a calculation of benefits and risks. Specifically, it calculates how long people are likely to live based on reducing their risk of heart attack or ischemic stroke, and how long they are likely to live based on increasing their risk of hemorrhagic stroke or bleeding from the digestive tract. If it is a net positive, AMA recommends it; if it is neutral or negative, it advises against it. But that means understanding the different risks that different age groups face, as well as assessing an individual’s risk of cardiovascular disease.
What the researchers found, based on the latest studies, is that people between the ages of 40 and 59 who are at higher risk for cardiovascular disease derive a small net benefit from daily low-dose aspirin; people aged 60 to 69 saw variable (but generally negative) benefits depending on the severity of their cardiovascular disease risk; and for people 70 and older, low doses of aspirin were a net negative. Based on this finding, the new AMA recommendation is that a daily regimen of low-dose aspirin is only recommended for people between the ages of 50 and 69 with an increased risk of cardiovascular disease and a low risk of bleeding. This is a significant step back from the old orientation.
An interesting parallel discussion in the report concerns how the medical community assesses whether a person is at high risk for conditions such as cardiovascular disease. Some parts are formula-based and directly data-based, based on age and family history. But other parts are based on statistical analyzes of large populations. For example, studies have shown that black people tend to have a higher incidence of cardiovascular disease; this is often attributed to assumptions about diet and exercise that are supported by demographic studies. Accordingly, the standard assessment for assessing cardiovascular risk assigns a higher risk to all black people. But lately, these kinds of demographic factors have been questioned more openly. The authors of this report have chosen to include the following discussion on this issue:
Risk prediction equations generally show a higher risk for black people than for white people. The USPSTF recognizes that race is a social construct and an imperfect indicator of the social determinants of health and the effects of structural racism. Calibration concerns exist, with many external validation studies showing overestimation in large populations (men and women of all racial and ethnic groups). Limited evidence also suggests underreporting in disadvantaged communities which could lead to underuse of preventive therapies. Clinicians need to recognize that 10-year forecasts [cardiovascular disease] events using pooled cohort equations are estimates.
This underscores that these kinds of radical race-based disease risk assessments fail both ways: they may overestimate the risk for many people, for example by assuming that all blacks are at higher risk for cardiovascular disease; but they may also underestimate the risk for individuals, for example by assuming that anyone of Asian descent is less at risk, as demographic studies show that traditional Asian diets tend to be heart-healthy. As a result, a black person might be mistakenly prescribed low-dose aspirin unnecessarily, and an Asian person might be denied the same prescription even though they might personally benefit from it.
Altogether, this demonstrates how important it is for us to share with healthcare professionals the specifics of our own health situation so that the right decisions can be made for us individually.
Use of aspirin to prevent cardiovascular disease
The second report is about how doctors treat appendicitis. For decades, the conventional wisdom has been that the one and only proper treatment for appendicitis is an appendectomy: surgically removing one’s appendix. As far as we know, the appendix, true to its name, serves no important purpose in our body and can be removed without impairing any necessary bodily functions. And while an infected and inflamed appendix is painful, the one that bursts afterwards is life-threatening. But invasive surgery to remove an appendix also comes with risks, including surgical complications, infections, postoperative recovery, and the risks that come with the use of general anesthesia.
Over the past few years, and especially from around 2014, some medical professionals have begun to challenge conventional wisdom by first treating appendicitis with antibiotics in cases that seem less severe (and the less imminent risk of appendix bursting). More recently, the health profession has accumulated enough case data to be able to compare the results of antibiotic treatment versus appendectomy. They found that the vast majority of cases treated with antibiotics are resolved successfully and only a small fraction of them ultimately require appendectomy.
It is important to remember, however, that science must be reproducible: a single research study is insufficient to cause the medical community to revise its practices. This report replicates previous studies comparing the two treatments for appendicitis and comes to the same conclusion: antibiotics are, in most cases, effective.
What makes this particular study different is that it tackles a common weakness of this type of research: the way study participants were selected. Some studies randomly assign patients to one of two forms of treatment; others ask patients to choose whether they want conventional or experimental treatment. If patients are randomly assigned, there are both ethical concerns and broader issues of removing patients’ control over their own health care; studies show that patients do better when they are actively involved in making decisions about their own health care. But allowing patients to choose treatment creates the possibility of “selection bias”, in which certain types of patients (e.g. risk takers, those with more years of education or those with higher socioeconomic status) may be more likely to choose the investigational treatment. processing, which may skew the results.
But in this study, the researchers did both: they had one cohort where the patients chose the form of treatment themselves, and another cohort where the treatment was randomly chosen for each patient. And they found that there were no differences in outcomes between the two cohorts. This is strong evidence that the findings are generalizable to a large patient population, and it sets an important example for future studies – including for other types of treatments – of how this type of research should be done. . But in the short term, we can see how it would make us more comfortable when a doctor decides to treat appendicitis with a course of antibiotics rather than rushing to the operating room, and that gives us another example of how the medical profession improves its own practices to ensure that the subjects of its studies are representative of broad populations and free from bias. They’re not quite there yet – far too many research studies still rely on easily accessible, non-representative patient populations – but the problem is more widely recognized today, and we can see visible progress in studies like this one.
Self-selection vs randomized allocation of appendicitis treatment
Kevin Schofield is a freelance writer and the founder of Seattle City Council Overview, a website providing independent information and analysis about the Seattle City Council and City Hall. He also co-hosts the “Seattle News, Views and Brews” podcast with Brian Callanan, and appears occasionally on Converge Media and KUOW’s Week in Review.
📸 Featured Image: Emerald Team graphic.
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