Terrifying side- effects ignored
Canada failing to use tests to avert potentially deadly drug reaction
Nearly blind, covered in burn- like blisters and barely able to swallow, Sonia Whyte-Croasdaile lay in hospital for six agonizing weeks.
As she did, her face was transformed into a swollen, peeling mask, her weight plummeted, and the lining of her throat disintegrated.
“I had to be tube fed, suctioned all the time. And my body was literally just wasting away,” she says. “I would not wish it on my worst enemy.”
The nurse/ social worker was treated in a burn ward, but the affliction that brought her close to death — and four years later still produces debilitating after- effects — had nothing to do with external injury.
She had contracted a skin condition called toxic epidermal necrolysis ( TEN), usually triggered by allergic reactions to prescription drugs and, experts say, quite preventable for most people.
Yet the genetic tests that can reveal whether someone is susceptible to the disease, and have been available now for several years, are rarely administered in Canada.
That means people are often contracting the traumatic condition — and in some cases dying — for no good reason, says Dr. Neil Shear, head of a unique drug- safety clinic at Toronto’s Sunnybrook Health Sciences Centre and Whyte- Croasdaile’s dermatologist.
“This is a travesty,” he says. “It’s the kind of thing that when I started doing research in this 30 years ago, we prayed would exist: to be able to screen people, and not give drugs to the wrong people … Why there are blinders on about this, I do not understand.”
Shear advocates a concerted effort by federal and provincial regulators and the pharmaceutical industry to encourage routine genetic screening before patients are administered drugs that can trigger TEN. It has worked elsewhere. In April 2013, authorities in Singapore urged doctors to test patients for a key gene before prescribing the epilepsy drug carbamazepine. The country normally records 15 cases a year of TEN or the less severe Stevens- Johnson syndrome. In the screening program’s first seven months, there were none.
“We’ve got good science, we’ve got good ways of preventing something, but ( in Canada) we don’t have the cohesiveness or the focus,” says Shear.
As with so many other terrifying diseases, TEN’s early symptoms are similar to those of influenza, but what happens next is anything but flu- like. The skin starts to blister and peel, the painful lesions often spreading across the whole body, and invading the mouth and throat, as well as damaging mucous membranes.
The large, open sores are portals for infection, which can lead to sepsis, organ failure and death. Stevens- Johnson has less extensive symptoms, but can also be fatal.
They are rare conditions, yet amplified by the devastating impact on patients.
A study published last year identified 141 cases of TEN and 567 of Stevens- Johnson in Ontario over the 10 years ended March 2012. Of those, 127 died in hospital or within two months of being released.
That included 23 per cent of the TEN patients, though Sunnybrook has managed to reduce the death rate in recent years, Shear says.
At Edmonton’s University of Alberta Hospital, the burn unit sees between three to 10 cases a year of TEN. Its director, plastic surgeon Dr. Ted Tredget, recalls one summer a few years ago when he treated two patients back to back.
The good news is rapid advances in genomics have helped identify several DNA variations — chiefly involving “HLA” genes linked to the immune system — that can predispose people to the reaction if they take particular medications.
A “perfect storm” of genetics, drugs and health status seems to bring on the disease, says Bruce Carleton, head of the pharmaceutical outcomes program at British Columbia Children’s Hospital.
The list of suspect medicines is now dozens long, including common sulpha antibiotics. The genetic connections of some have been well studied and should prompt testing, says Shear.
Like other experts, he recommends anyone of Han Chinese, southeast Asian or South Asian background — about four million Canadians — be screened before getting carbamazepine for epilepsy.
Everyone should be tested before being put on the drug allopurinol, for gout and other diseases, Shear says.
Tests that have been available for the last half- dozen years — and cost about $ 100 to $ 200 each — could prevent as many as 70 per cent of cases, he believes.
Carleton is more cautious, but agrees more illness could be avoided with wider use of screening.
And yet, tests rarely are done, say Shear and Tredget.
“It’s not very well known, to be honest with you,” says the Alberta surgeon. “In our dermatology community, guys don’t screen for it and don’t recognize it.”
The Health Canada- approved product monograph for carbamazepine does suggest testing for Asian patients, though that message seems seldom heeded.
The label for allopurinol acknowledges there is a link between a specific HLA gene and TEN, but says the value of screening for the gene “has not been established.”
For those who do contract TEN, meanwhile, the ordeal continues well beyond the hospital door.
Whyte- Croasdaile, 47, had to grow new eyebrows, eyelashes and toenails, learn to walk again, and for a time eat only baby food. Damage to her mucous membranes means she still has no saliva, making eating a chore, while her dry eyes constantly feel gritty.
Despite extensive testing, it remains a mystery what caused her disease. But the resident of Milton, Ont., believes genetic screening should be embraced if it could prevent others from enduring the hell she did.
“It is such a devastating illness and the journey is so lonely, and you never really come back to the person you were.”
We’ve got good science … but ( in Canada) we don’t have the cohesiveness or the focus.
DR. NEIL SHEAR