Partisan Polarization Has Crept Into the Doctor’s Office

The recent government shutdown, which hinged on a partisan disagreement over extending Affordable Care Act tax credits for health insurance, illustrated just how politically polarized American healthcare policy has become.

Yet have partisan divisions trickled down to the doctor’s office? A new paper by Woojin Kim, an assistant professor of political economy at Stanford Graduate School of Business, suggests that they have.

When he was getting his PhD at the University of California, Berkeley, Kim studied how political polarization now characterizes the adoption of state-level policies, including health-related ones concerning Medicaid expansion and COVID regulations. “That led me to wonder whether these divisions had gone beyond policy and into how medicine is practiced,” he says. The question was particularly intriguing because medicine is widely regarded as a bastion of science where evidence transcends personal beliefs. “Unfortunately,” he says, “that’s not quite what I found.”

Looking at a representative sample of physicians who submitted claims for reimbursement to Medicare, the federal health insurance program for people age 65 and older, Kim tracked annual spending per patient from 1999 to 2019. He then identified the party affiliation of 28% of those physicians, around 309,000 doctors, by looking up their campaign contributions in a database of political donations.

Kim found that Republican and Democratic physicians initially billed Medicare similar amounts for the care they’d provided. From 2004 onward, however, their spending patterns began to diverge, and by 2019, Republican doctors were spending on average approximately 13%, or $70, more per patient annually than their Democratic colleagues. That might not sound like much, but it adds up to billions of dollars in spending on tests, treatments, and surgeries. Kim estimates that if Republican doctors had practiced more like their Democratic counterparts, public spending on Medicare would have been $6.2 billion lower in 2019 alone.

Spending by older cohorts of physicians did not change much over time. Instead, the bulk of the partisan spending gap was driven by younger cohorts of Republican physicians who began making political donations in the mid-2000s, and who tended to practice more aggressively than their Democratic counterparts. “It seems like what it means to be a Republican or Democratic physician has changed,” Kim says. But what drove that change, and was it connected to politics?

A Split in Beliefs

Kim identified a few possible explanations for this shift. First, Republican and Democratic doctors may specialize in different areas, live in different locations, or treat different patient groups. (For example, Republican doctors might see people who are sicker or demand more aggressive treatment.) Republican doctors may also seek to make more money and thus prescribe more tests or perform pricier procedures. Finally, Republican and Democratic doctors may have different beliefs about what care is appropriate and which treatments are warranted.

In the end, Kim found that doctors’ partisan spending gap mostly came down to a matter of belief. Looking at the data, he determined that if a group of Republican or Democratic doctors with the same specialties were to see patients in the same area for the same conditions, the Republicans would still be likely to spend more, especially on elective procedures where doctors have greater discretion. Patient composition made little impact, and Republican and Democratic physicians were equally likely to respond to financial incentives, such as administering more profitable drugs.

Surveys by other researchers have found that Republican and Democratic physicians express different beliefs and values. Republican doctors tend to place less emphasis on clinical guidelines and more on physician autonomy.

Poring over the Medicare claims data, Kim confirmed that Republican physicians provided more low-value treatments that provide little benefit to patients and that clinical guidelines recommend against, suggesting an alignment between their political affiliation, core values, and medical practice. In a striking example, Kim showed that recent cohorts of Republican physicians were significantly more likely than Democratic ones to prescribe chemotherapy for cancer patients in the final two weeks of life — a common indicator of overly aggressive treatment, since it is expensive, rough on patients, and ultimately provides little benefit in these cases.

The decision to provide such care, Kim says, depends on how a physician weighs the costs and benefits of treatment, and of quantity versus quality of life. “It comes down to your beliefs and values, which is where I think the difference lies,” he says.

Looking for a Cause

Precisely what prompted the divergence between Republican and Democratic physicians is not entirely clear, though the timing of the shift offers hints: The mid-2000s marked a period of intense polarization over healthcare policy, with Republican and Democratic politicians feuding over issues such as Medicaid expansion and the promotion of evidence-based medicine under the Affordable Care Act.

Yet Kim is wary of attributing the split to direct political influence. “It’s hard to make a causal argument,” he says, noting that younger cohorts of Republican and Democratic physicians have become more segregated in their medical school training, suggesting that the disparities in their beliefs and practice styles may be related to educational experiences. “I think that’s an obvious next question: How much does training explain these differences?” he says.

Whatever may be driving it, polarization among physicians has consequences for health policy. Doctors wield significant political power through their campaign contributions and lobbying efforts. “If they were unified about medical policies, you’d expect them to be a pretty authoritative force,” Kim says. But if the medical community is fragmented along partisan lines over the importance of evidence-based policies, politicians can claim that any arguments for or against them are simply a matter of partisan bias.

“We’ve seen the politicization of climate science for decades,” Kim says. “Now you can see the parallels with medicine as well.”