The risk for dying within 30 days after surgery is significantly higher among patients living in the lowest-income Ontario neighborhoods compared with those living in the highest-income neighborhoods, research suggested.

In a cohort study that examined more than a million patients, researchers found that those who lived in the lowest-income areas were at 52% increased odds of death compared with those who lived in the highest-income areas. The increased risk persisted after the researchers adjusted the data for potential confounding factors such as age, comorbidities, and type of surgery.

“Neighborhood incomes still played a major role in determining how people did after surgery. Even though we have universal healthcare, disparities still exist,” lead author Ashwin Sankar, MD, anesthesiologist at St. Michael’s Hospital, Unity Health Toronto, Toronto, told Medscape News Canada. “In the context of surgery, factors such as neighborhood income likely matter.”

The study was published on January 12 in JAMA Network Open.

What Is the Mechanism?

The results suggest the persistence of the association between social determinants of health and adverse postoperative outcomes that previously was observed in countries with universal healthcare, said Sankar.

“We have a universal healthcare system in Ontario, so all the medically necessary healthcare is essentially paid for. It’s a huge privilege, and because we have universal healthcare coverage, these disparities are less likely. But during the COVID-19 pandemic, we asked whether these types of disparities still matter. That’s what this study looked at,” he said.

The investigators assessed 30-day mortality in 1,036,759 patients (526,158 women) aged at least 18 years (median age, 66 years) who underwent scheduled inpatient surgical procedures between 2017 and 2023 in Ontario. Of these patients, 1780 (0.9%) from the lowest-income areas and 1307 (0.6%) from the highest-income areas died.

After adjusting the data for possible confounding factors, including age, sex, type and complexity of procedure, rural status, teaching hospital status, and comorbidities, the researchers found that patients from the lowest-income areas in Ontario had a 43% higher chance of dying within 30 days of surgery compared with those from the highest-income areas. The researchers also examined patients’ immigration and refugee status but found no association between these factors and mortality.

Future research must address the underlying mechanisms of this association, said Sankar. “Where are people from marginalized communities and low-income neighborhoods in the care continuum? Where do they need support? Is it possible that they have less frequent access to primary care, so they are presenting with other health issues that may not be well controlled? Are they presenting with disease or cancer that is more advanced than are people from the wealthier neighborhoods? Or is it something to do with recovery, where people from wealthier neighborhoods can take more time off work for recovery or present back to the emergency room with a complication sooner?”

Exploring these questions could reveal ways to “level the playing field, in terms of the outcomes after surgery,” Sankar said.

More Evidence Linking Wealth and Health

“This is another piece of evidence associating wealth and social determinants of health with poor health outcomes,” Jason Sutherland, PhD, UBC professor in health services and policy and director of the Centre for Health Services and Policy Research at the University of British Columbia in Vancouver, told Medscape News Canada.

“There’s a big body of evidence in Canada that associates one’s personal income and wealth with one’s ability to access prescribed drugs, for example. Poor people cannot fill all their prescribed drugs as often as those who are wealthier. For some Canadians, drugs are an uninsured benefit, so they skimp and maybe take a pill every 2 days vs every day,” Sutherland said.

The population of the current study is older and some participants may not be in good health because they cannot afford to take their drugs for chronic conditions, which makes them more susceptible to potential stressors like invasive surgery, he pointed out.

Housing and food insecurity also may foster the worse outcomes observed in lower-income areas. “If people can’t afford a diet that is rich in vegetables and fruits, there is a risk that their body is not in as good a shape and is not as robust as someone who is wealthier and has a more fulsome and better diet, and therefore better able to handle the stresses of surgery,” said Sutherland.

“It’s also possible that people who are wealthier are accessing noninsured health services more regularly. For instance, if you’re in the wealthiest income quintile and you know that you have orthopedic surgery coming up, you can afford to pay out of pocket for prehabilitation to get your body better able to handle the stresses of the surgery and recover more quickly. People who do not have those funds won’t be able to get physiotherapy or kinesiology services to get their body stronger for surgery,” Sutherland said.

Also, the association between lower income and higher levels of drinking, smoking, and poor diet is well documented. “If you have a low income, you’re probably more likely to be obese because you’re eating more processed foods and high-sugar foods that are cheaper, which places you at higher risk for surgery. This study cannot unpack that because it doesn’t have these clinical measures of personal and lifestyle risks, but nevertheless, the conclusion from this study is plausible,” he said.

This study was supported by a grant from the Canadian Institutes of Health Research, St. Michael’s Hospital Medical Services Association, and ICES, which is funded by the Ontario Ministry of Health and the Ministry of Long-Term Care. Sankar and Sutherland reported having no relevant financial relationships.