Winnipeg researcher makes predicting kidney failure easy with simple equation

A Winnipeg researcher's work on an equation that could give patients and health-care professionals a better idea of the risk of kidney failure has been published in a prestigious peer-reviewed medical journal.

Dr. Navdeep Tangri hopes the publication of the study in the Journal of the American Medical Association on Tuesday will bring more widespread use of his equation, which he says reliably predicts kidney failure in patients regardless of location, gender, age and general health status.

The study published Tuesday looks at health information from roughly 700,000 kidney disease research patients from 30 countries across the world. It expands on work Tangri, a doctor and researcher at Seven Oaks General Hospital and one of the study authors, did earlier with Canadian health data.

Tangri, who is also an associate professor in the Faculty of Medicine at the University of Manitoba, first devised in 2011 an easy, reliable way to predict the likelihood that any patient with chronic kidney disease would later develop kidney failure.​

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His equation takes four variables — a patient's age and gender, their level of kidney function and the amount of protein found in their urine — and spits out answers about a patient's risk of kidney failure in the next two or five years.

Tangri said he developed it because he wanted to find a way to help provide stress relief for kidney disease patients.

"Too many times I sat as a doctor in the clinic and saw that the patient across from me, the biggest thing that was making them anxious was the fear of dialysis, and the doctor across from them was unable to give them any precise idea of what the patient's actual risk was," he said.

"The patients were very pessimistic or overly worried about their risk, [so] that if I could just tell them precisely what their risk is, it would result in significant relief and loss of anxiety."

Elegant equation

Tangri felt he did just that almost five years ago when he first published his equation.

But the beautiful simplicity of an equation doesn't ensure its success or widespread use. He and his collaborators recognized that if they couldn't make the equation easy for family doctors to use, it would never take off.

What 2016 and onwards is about is getting primary care doctors, family doctors across the continent and across the world, to use the equation.- Dr. Navdeep Tangri

They designed smartphone and computer apps, as well as an online calculator, to help encourage health-care professionals to use the equation. It's been in use in Manitoba and each province east to New Brunswick since 2011, but there have been critics and holdouts.

Data used in Tangri's first study was from Canadian research participants. He received pushback from peers in the international research community, who said the original study was limited in scope and might not apply to all kidney disease patients overseas.

Tangri believes he's put those criticisms to rest with the publication of the followup study.

"We showed the equation is highly accurate across the board," he said. 

Things that vary from place to place, such as environmental pressures and health challenges, didn't change how effective the equation was at predicting kidney failure in patients in the new study, he said.

"It really allows me to say to any physician, in almost any part of the world out there … that this equation is accurate and valid in their country for their patient," he said, adding it's accurate regardless of where patients live, their age and sex, environmental pressures or other chronic illnesses.

What is kidney disease?

About 3.1 million Canadian adults have kidney disease, which has to do with the way the body processes waste.

Blood is full of protein. The kidneys act as a "sieve," Tangri said, filtering waste and leaving good proteins in the blood.

When kidneys get damaged, a result of health issues such as diabetes or high blood pressure, "they become leaky," Tangri said. The greater the damage, the faster the progression of kidney disease, he added.

Options for patients experiencing kidney failure are limited to dialysis or a transplant.

Only about the sickest 10 to 20 per cent of kidney disease patients around the world see specialists for treatment. The other 80 to 90 per cent are seen by family doctors, Tangri said.

"What 2016 and onwards is about is getting primary care doctors, family doctors across the continent and across the world to use [the equation]," he said.

His hope is that the clout and exposure brought to his study by publication in JAMA, along with the relatively user-friendly nature of the apps and online tools, will influence more family doctors to use his equation to clarify what patients are up against.

"Now we have so much evidence that this is accurate in all stages of kidney disease, that it's really time to get the push into primary care."

More information about how the equation calculates kidney failure risk is available here.