The research team looked at how doctors record their patient notes and found that those relating to black patients were more likely to include notations or language that suggested they were not believed by medical staff. Crucially, the notes in a person's medical records often form the basis of later treatment decisions and options.

“The bias reflected in those medical records may in turn affect care from future clinicians,” said study lead author Mary Catherine Beach, a professor in the university’s Schools of Medicine and Public Health.

The study, published in the most recent issue of the Journal of General Internal Medicine, looked at more than 9,000 notes written by 165 doctors for some 3,300 patients in the US.The researchers first noticed discrepancies when it came to notes on patients who suffered from sickle cell disease – a condition that is more prevalent in black people – with doctors and nurses signaling disbelief in recording reports of pain.

They then expanded their search and worked with a computer scientist and a linguist to identify common hallmarks of bias. The medical records they reviewed were found to contain quotation marks around patients’ own descriptions of their experiences or contained specific words such as “claims” or “insists” that indicated doubt, and some ‘evidentials’ reporting patient symptoms as hearsay.

“We found all three of these forms of language more often in the records of black patients than white patients,” noted researcher Somnath Saha.

Notes written about black patients were also more likely to contain at least one quote, at least one judgment word and more evidential sentences.

When it came to the differences in notes on male and female patients, the researchers found no significant difference in terms of judgement or evidentials. Women’s records, however, had higher odds of containing at least one quote.