People with bladder cancer who are also colour blind have a 52% higher mortality rate than people with bladder cancer and normal vision because they have difficulty recognising the first signs – red blood in urine.

Researchers from Standford Medicine in the United States said recognising blood in urine is often the impetus that leads people to a diagnosis of bladder cancer, but for those with colour blindness that first warning sign is more likely to go unnoticed.1 Catching the cancer at later stages leads to worse outcomes.

“I’m hopeful that this study raises some awareness, not only for patients with colour blindness, but for our colleagues who see these patients,” said Dr Ehsan Rahimy, senior author of the study, published in Nature Health.

Colour blindness affects about one in 12 men and one in 200 women. The most common forms make it difficult to distinguish red and green.

The Stanford Medicine team used a research platform called TriNetX, which aggregates real-time electronic health records, providing some 275 million deidentified patient records. This enabled them to curate a particular population of patients.

Among people diagnosed with bladder cancer, those who were colour blind had lower survival probability than a match control group with normal vision. Over 20 years, those who were colour blind had a 52% higher overall mortality risk. (The mortality risk includes deaths from all causes.)

Dr Rahimy said the study may be undercounting deaths among those with colour blindness and bladder cancer, because colour blindness is often undiagnosed.

Reference available at mivision.com.au.