Correlation, causation, and Presidential pronouncements on health

The historical track record of major U.S. Presidential pronouncements on health is as abysmal as one might expect given their prior occupations (27 lawyers, zero physicians or medical researchers). In 1971, Richard Nixon famously declared a "war on cancer"; 54 years later, not only is cancer still very much with us, but the Trump administration is now waving the white flag and pulling back on research investments. In 2000, Bill Clinton announced the completion of the Human Genome Project, forecasting that sequencing the human genome would lead to all kinds of breakthroughs in preventing and treating genetic diseases. A quarter-century later, notable progress has been made on many conditions, but genomic insights have yet to transform medicine as initially promised. In 2016, Barack Obama launched the Cancer Moonshot as part of the 21st Century Cures Act, and after his Vice President, Joe Biden, ascended to the Presidency in 2021, he re-committed the U.S. to accelerating progress toward cancer cures. The jury is still out on this one, but the current Health and Human Services Secretary's blanket opposition to mRNA vaccines (including those for cancer) has stacked the deck against it.

So when President Donald Trump made a "major announcement" on autism at the White House earlier this week, the former real estate developer and reality TV show host was following in the ignominious footsteps of his predecessors who, to put it bluntly, should have stayed in their lane. Taking his cue from Robert F. Kennedy, Jr., who for years led a nonprofit organization that opposes routine childhood vaccinations, Trump blamed infant shots and acetaminophen (Tylenol) in pregnancy for the increased prevalence of autism diagnoses in the U.S. and around the world. Dismissing the pain and discomfort that often accompanies being pregnant, he implored women to "tough it out" rather than take a pain reliever that is considered by every major medical organization to be safe in pregnancy. (And yes, there absolutely are downsides to avoiding Tylenol, given the clearly established harms of alternatives for pain and fever.)

I wanted to simply dismiss what Trump said, but after two days of seeing patients and responses on my social media, it's clear that many people are taking him and RFK Jr. quite seriously. To explain why they (and perhaps you) shouldn't be concerned about your child's vaccines or taking Tylenol when needed, join the first-year medical student class in evidence-based medicine that I taught at Georgetown for many years. The question we would examine in our first meeting was: does radiation from cell phone use cause brain tumors? (TL;DR - although there isn't any way to prove without a doubt that cell phones don't cause cancer, most of the evidence suggests that the answer is no.)

But think like a researcher for a moment. How would you study this question? You could do what's called a case-control study and compare the cell phone use of persons with brain tumors to persons without them. (This type of study would have been easier to do in the days before cell phones were ubiquitous; I didn't purchase my first cell phone until 2002.) In addition to asking about ownership, you could ask people to recall how long they spent talking on the phone on average, and which side of their head they pressed it to their ear. (Again, easier to do in the days before hands-free earbuds.) But there's a big problem with this type of study: recall bias. Human beings have a tendency to come up with plausible explanations when bad things happen, and a brain tumor certainly qualifies as a bad thing. Just as a recently administered MMR vaccine is a convenient explanation for the subsequent diagnosis of autism, a cell phone is a convenient explanation for cancer.

So let's say you perform a better type of study, a cohort study where you compare two groups by a more objective measure of cell phone exposure: cell phone subscriptions and number of minutes used each month. Obviously this design poses complications as family and business cell phone plans may not reliably identify who was actually using the phone, even setting aside issues of privacy and phone companies allowing researchers to access granular data. But if you find an association between increased cell phone use and risk for brain tumors, you can feel more confident that it's a true correlation. Similarly, some studies have shown associations between Tylenol use and neurodevelopmental disorders, though others have not.

But it's a huge leap from showing correlation to proving causation. The latter requires systematically eliminating confounding factors that may affect both the exposure and the outcome. For example, perhaps the true correlation is that women carrying pregnancies with children who are genetically predisposed to develop autism are more likely to experience fever-causing infections or musculoskeletal pain. Naturally, they will be more likely to seek fever or pain relief from acetaminophen, making it appear - incorrectly - that exposure to acetaminophen caused the outcome. We do not know if this is happening, as the FDA made clear in its news release.

In the meantime, I am not going to change how I counsel patients about vaccines in childhood or Tylenol in pregnancy. These medications have clear benefits (preventing serious diseases and relieving fever and pain in pregnancy), and the burden of proof rests on proponents of hypothetical negative effects, including Trump and RFK Jr. Finally, I think it's unconscionable for the President to put a "I took Tylenol in pregnancy so maybe I gave my baby autism" guilt trip on mothers without ironclad proof of either correlation or causation.

Are cash benefits for families associated with positive childhood experiences?

In the U.S., state and federal governments employ vast bureaucracies that aim to ensure that only the "deserving" receive public assistance in the form of subsidized health care, food, and housing. 2025 has seen a near-complete reversal of the pandemic policy of keeping people on Medicaid by default; now, states will be required to not only confirm Medicaid eligibility every 6 months, but to verify that certain "able bodied" beneficiaries are enrolled in job training or working at least 80 hours per month. Never mind that Medicaid is only a health care benefit - you can't use it to pay the rent or feed your family - or that work requirements have been unequivocal failures in states that have tried implementing them in the past. The point of this cruel policy isn't to increase employment; it's to save money by removing people from health insurance rolls even if they are working.

What are the effects of financial insecurity on child health? A systematic review in AJPM Focus found that "financial strain was associated with poorer health and well-being and more behavior challenges among children of all ages, poorer academic performance among school-age children, and more depressive symptoms among adolescents." Adverse childhood experiences (ACEs) such as child neglect, abuse, and exposure to violence affect at least one in four American children and are associated with unhealthy behaviors and chronic diseases in adults. As one might expect, these experiences occur more often in neighborhoods with built-in disadvantages such as high concentrations of poverty, pollution, limited green-space, and poor access to healthy food sources. A medical approach to this problem would be to screen patients for ACEs and provide some sort of intervention to counteract the negative effects of childhood trauma. It's unclear if such an approach actually helps, though, and even if it does, the public health professional in me thinks there must be better ways to prevent ACEs in the first place.

A recent cross-sectional study in 4 states (Kansas, Montana, South Carolina, and Wisconsin) turned the concept of ACEs on its head and instead asked more than 20,000 adults if they had experienced one or more of the following positive childhood experiences (PCEs):

1. Adult made you feel safe and protected

2. Felt you belonged in high school

3. Felt supported by friends

4. At least 2 adults took an interest in you

5. Felt your family stood by you

6. Enjoyed community traditions

7. Felt able to talk to your family

Adults who reported higher numbers of PCEs were more likely to have attended postsecondary school, had greater household incomes, were less likely to smoke, and had fewer chronic medical conditions than those reporting lower numbers. So how can our society reduce exposure to ACEs and increase exposure to PCEs? An analysis in the Milbank Quarterly illustrated that state policies that improve economic security are associated with better mental health outcomes in children and adults. More bureaucracies, then? Hardly. Arguably the most effective social policy implemented during the pandemic was the temporary 2021 expansion of the Child Tax Credit, which effectively provided "a near universal, unconditional child cash benefit," reducing child poverty to historically low levels.

Closer to home, since 2022 Philadelphia has experimented with providing no-strings attached cash assistance to low-income families rather than making them wait for inadequate public housing or limited numbers of vouchers to become available. Families (households had to have at least one child under the age of 16) fortunate enough to receive monthly payments ranging from $15 to $2057 (with a median of $1000) have generally applied them toward rent. Not only were households who received cash less likely to be evicted or become homeless, they also had fewer concerns about the quality of their housing.

I attended a conference recently where a presenter half-facetiously, half-seriously, summed up all of the risk factors for developing a chronic health condition as "Don't Be Poor." Our historic societal response to poverty has been to create difficult-to-navigate welfare programs with ever-changing eligibility requirements that help poor people with health care and food and housing but basically force them to stay poor to keep receiving benefits. What if we cut through the red tape and just gave them cash instead? Would fewer ACEs and more PCEs occur, leading to better health for everyone in the long run? It's not the kind of research that the National Institutes for Health will fund any time soon - they're too busy trying to prove that vaccines cause autism - but it's definitely a question worth studying.

Courage and consequences at the CDC

In a recent presentation to preventive medicine residents at Johns Hopkins, I reflected on the painful circumstances that led to my resignation from the Agency for Healthcare Research and Quality (AHRQ) in November 2010. In short, political decision-makers well above my pay grade attempted to protect Democratic congressional majorities from blowback from an anticipated recommendation against prostate cancer screening by forcing the U.S. Preventive Services Task Force to cancel a scheduled meeting. Until this year, when Health and Human Services Secretary Robert F. Kennedy, Jr. cancelled the USPSTF's July meeting and expressed his intent to replace the entire panel, it was arguably the worst example in the Task Force's history of politics trumping science. (This time is worse - a LOT worse.)

Last week, the HHS Secretary fired recently confirmed Centers for Disease Control and Prevention (CDC) Director Susan Monarez over her unwillingness to “to rubber stamp [vaccine] recommendations that flew in the face of science.” In protest, three senior CDC officials simultaneously resigned. On his Inside Medicine Substack, Dr. Jeremy Faust posted the full text of the e-mails that Dr. Deb Houry, Dr. Demetre Daskalakis, and Dr. Daniel Jernigan sent to their colleagues announcing their respective resignations. Without question, these three doctors were far more critical to the day-to-day work of the CDC and HHS than I ever was or might have been at AHRQ. But their collective departure, like mine nearly 15 years ago, raises an important question: when a public servant who is also a health care professional witnesses the federal government taking immoral or profoundly troubling actions, is it more courageous to step down (and draw attention to how these actions endanger health) or to remain in place and continue to resist from the inside, hoping that eventually new leadership will restore the primacy of science and evidence-based medicine?

My red line was that the delay - which ended up being 17 months long - in ratifying the USPSTF's "D" recommendation against PSA-based prostate cancer screening would ultimately injure hundreds of thousands of patients who accepted screening without being aware of the Task Force's determination that it was more likely to cause them harm than good. My primary professional identity was and remains that of a family physician, and inherent in this identity is an obligation to provide patients with the best understanding of the science to help them make health decisions. Being told that I had to set this obligation aside because it might damage the electoral prospects of a Presidential administration and his political party was, in my view, unconscionable.

On the other hand, I admire my colleagues at AHRQ who chose to stay and sustain the USPSTF from the inside. A few still work there; others, unfortunately, were given pink slips by Elon Musk's Office of Government Efficiency when his group of twenty-something contractors couldn't figure out what the agency did that was important enough to warrant employing a few hundred scientists. No doubt the Task Force would have been much worse off if every member of its support staff had walked out with me on my last day and switched to careers in academic medicine. Leaving an impossible situation can be courageous, but staying on is, too. I salute Dr. Monarez and her departed senior leaders at CDC for their principled public resistance, but I also support the many staff who have remained despite RFK Jr.'s horrific interference with the agency's mission to protect the public's health.

Do pharmaceutical conflicts of interest compromise the AAP guideline on childhood obesity?

In January 2023, the American Academy of Pediatrics (AAP) published a clinical practice guideline on the evaluation and treatment of obesity in children and adolescents. Dr. Kathryn McKenna and I noted in an editorial in American Family Physician that the recommendation to consider prescribing weight loss drugs in adolescents 12 years and older was based primarily on short-term studies: “only 5 out of 27 randomized controlled trials [available to the AAP] included results beyond six months.” Although the percentage of US adolescents with obesity who were prescribed drugs rose modestly between 2018 and 2023, a recent study found that prescribing increased immediately after the guideline’s publication and every month thereafter through the end of 2024.

To be sure, the effects of nondrug interventions for obesity have been discouraging. A Cochrane review from 2020 found that combined dietary and physical activity interventions in adolescents 13 years and older did not lead to statistically significant changes to body mass index. Nonetheless, the US Preventive Services Task Force found insufficient evidence on the harms of long-term obesity medication use in children and decided to recommend only intensive behavioral interventions.

An analysis in the BMJ highlighted undisclosed financial conflicts of interest involving several authors of the AAP guideline and its accompanying technical report. Three guideline authors and one systematic review author received payments from pharmaceutical companies for consulting, travel, and other compensation between 2017 and 2023 ranging from $2,750 to $46,000; five other guideline authors received smaller amounts for meals and honoraria. From 2012 to 2024, 11 developers of glucagon-like peptide 1 (GLP-1) receptor agonist drugs made an estimated $1.9 to $2.6 million in corporate sponsorship payments to the AAP, including Novo Nordisk (semaglutide) and Eli Lilly (tirzepatide).

The AAP is hardly alone in permitting financial ties to drug companies. Other studies identified industry payments to the authors of the American Diabetes Association and the Infectious Diseases Society of America clinical practice guidelines, and 12 of 17 members of the 2023 board of directors and scientific committee of the Global Initiative for Asthma (GINA) received personal fees from AstraZeneca, which makes a brand-name inhaler used in the single maintenance and reliever therapy (SMART) treatment approach recommended by GINA guidelines.

Some would argue that the AAP guideline authors may have erred in not disclosing their pharmaceutical ties, but they would have likely come to the same conclusions about the effectiveness of GLP-1 receptor agonists and other weight loss drugs for adolescents. A counterpoint is that industry payments to individuals, regardless of amount, influence prescribing behavior and that those in a position to change the standard of care for children with obesity should refuse such payments. Finally, sound reasoning strongly supports that disclosing conflicts of interest is not enough to safeguard against bias in guidelines and other journal publications.

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This post first appeared on the AFP Community Blog.

Research supports moving away from race as a risk factor

In a 2021 American Family Physician editorial on the dangers of incorporating a patient’s race into medical decision-making, Dr. Bonzo Reddick observed, “Although we may hear about biologic or genetic differences between races, there is more variation within races than there is between them.” A recent landmark report from the National Institutes of Health’s All of Us Research Program compared self-identified race and ethnicity categories to continental and subcontinental genetic variation. Analyzing about 2 million common variants in the genomes of more than 230,000 unrelated participants, they found that “participants within self-identified race and ethnicity groups exhibit gradients of genetic variation rather than discrete clusters.”

Among White participants, 8% were found to have some South Asian ancestry, whereas smaller percentages had more than 50% African or Native American ancestry. Similarly, 1 in 100 self-identified Black participants had more than 50% European ancestry. The study also found notable regional differences in ancestry percentages among self-identified Black, Hispanic, and White participants. The researchers concluded that these gradients reflect “the historical impacts of US colonization, the transatlantic slave trade, and recent migrations” and “demonstrate that social constructs of race and ethnicity do not accurately reflect underlying genetic variation.”

Maternal race—specifically, Black race—is associated with increased risk for the development of preeclampsia. In its 2021 recommendation statement on aspirin to prevent preeclampsia and related morbidity and mortality, the US Preventive Services Task Force included Black race as a moderate risk factor, although it noted that it was a proxy for “environmental, social, and historical inequities, … not biological propensities.” However, a multicenter cohort study in JAMA Network Open found that Black race, similar to other moderate risks such as nulliparity, maternal age older than 35 years, and body mass index above 30, was not clearly associated with preeclampsia in the absence of a high risk factor (eg, chronic hypertension).

Finally, a narrative article in the New England Journal of Medicine traced the historical debate over race-based hemoglobin thresholds that began in the 1970s, when epidemiologic analyses showed that on average, Black children’s serum hemoglobin levels were 0.5 g/dL lower than those of White children. Did this disparity reflect inherent biological differences between races or differences in nutrition? Should it support race-based definitions of normal hemoglobin levels? Although some analyses accounting for socioeconomic status and diet no longer found significant racial differences, conflicting guidance from the Institute of Medicine (now the National Academy of Medicine) and the Centers for Disease Control and Prevention persisted into the early 2000s. Today, the World Health Organization, American Academy of Pediatrics, and American College of Obstetricians and Gynecologists all recommend against using race-adjusted cutoffs for diagnosing anemia.

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This post first appeared on the AFP Community Blog.

RFK Jr. is wrong about the US Preventive Services Task Force

Responding to President Trump's criticism of a federal judge who ruled against his asylum policy during his first term, Supreme Court Chief Justice John Roberts released this statement: "We do not have Obama judges or Trump judges, Bush judges or Clinton judges. What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them." I am not qualified to comment on how closely federal and Supreme Court justices adhere to the partisan positions of the Presidents who appointed them. However, I was reminded of this statement when, over the weekend, the Wall Street Journal and multiple other news outlets reported that HHS Secretary Robert F. Kennedy, Jr. was planning to fire all the members of the U.S. Preventive Services Task Force (USPSTF) because he considers them "too woke."

I worked for the USPSTF during the Bush and Obama administrations. The transition was seamless; the work went on as before. In the November 2009 uproar caused by the unfortunate timing of the USPSTF's release of a new statement recommending that routine mammography begin at age 50 rather than 40, then-HHS Secretary Kathleen Sebelius clumsily tried to throw the Task Force under the bus by observing (correctly) that all of its members were appointed during the Bush administration - but this completely missed the point that members were selected for scientific expertise, not political ideology. In that respect, the USPSTF has been similar to the ACIP prior to RFK Jr.'s recently replacing all of the latter's members for nakedly political reasons.

"Woke" is such an overused pejorative in conservative political circles that it has lost all meaning, but it seems that the current HHS Secretary is responding to the Task Force's recent efforts to ensure that their recommendations are implemented equitably across people of all races and ethnicities, despite geographic and economic disparities in access to primary care and other resources critical for ensuring health. For example, it's well-documented that eligible Black patients are less likely than others to be offered or undergo lung cancer screening, and that interventions are needed to close this unacceptable gap. This is about as uncontroversial an idea in health care as there is, but apparently it is too much for RFK Jr. More likely, it's merely an excuse to replace the current highly qualified members with his handpicked ideologues. In the words of a former USPSTF member (and my friend and academic collaborator) Russ Harris, MD, MPH:

It may seem excessive [for the USPSTF] to spend so much time and energy on reviewing the evidence for health issues. After all, aren’t people supposed to “do your own research.” I wish it were that easy. What “doing your own research” usually leads to is finding a biased source on the internet or from an “influencer” on social media that is happy to give you their answer. That answer is certainly simple, but often wrong. Such answers are often based on self-interest, or on an ideological agenda, not on a careful review of the relevant evidence.

Recent letters to RFK Jr. from the American Medical Association and 104 health organizations (including 6 of which I am a current or former member) have rightly pointed out that federal policymakers and health insurance plans rely on the USPSTF recommendations to provide coverage of effective preventive services (those rated "A" or "B" with at least moderate certainty of moderate net benefit) such as certain cancer screenings, depression screenings, and preventive services for cardiovascular disease. To tell the truth, I'm less worried about my patients losing access to these services than I am that replacing the current Task Force would result in a flood of signoffs on services where the evidence is insufficient to know if they work (e.g., multicancer screening tests) or tests that sound great intuitively but have been proven to not work, such as screening for asymptomatic carotid artery stenosis, which causes more strokes than it prevents but is nonetheless performed by lots of for-profit companies. The USPSTF is a bulwark in protecting Americans against ineffective or potentially harmful preventive health care, and if RFK Jr. follows through on firing the members of the current panel, that protection will almost certainly cease to exist.