Volume 29 - Number 11 - Thursday, February 27, 1997

Dangerous drug mixes

by Amy DiNolo

Studies conducted at McGill are helping to improve the quality of health care for senior citizens all over Quebec. It's research that may prevent illness and injury among the elderly and save the cash-strapped provincial health care system millions of dollars.

A multidiscipli-nary team called USAGE (The Quebec Research Group on Medication Use in the Elderly) has recently released the results of its research to date and is now working towards putting some of these findings into practice.

Led by Dr. Robyn Tamblyn of McGill's Department of Epidemiology and Biostatistics, USAGE is comprised of scientists and doctors from all four Quebec medical schools (McGill, Laval, Sherbrooke and Université de Montréal) as well as from the University of Georgia in the U.S.

The team of experts also includes members of the local Direction de la santé publique, a legal adviser, a bioethicist and a writer.
Dr. Robyn Tamblyn


USAGE conducted a study on the prevalence of potentially inappropriate drug combinations (PDICs) in senior citizens. With over 24,000 approved drugs in Canada, and 33,000 known dangerous interactions, the possibility of a doctor prescribing two or more conflicting drugs is great.

"We were actually doing work on medical training, medical practice, and patient outcome," explains Tamblyn. "One area where we believed there would be considerable impact was medication use. We chose the elderly because they take more drugs and are more vulnerable to the risks of drugs."

They began by studying data from 1990 on elderly people living in Quebec who were taking at least one of a cardiovascular drug, a psychotropic drug or a non-steroidal anti-inflammatory (such as Aspirin).

The results were alarming: up to 20.3% of the seniors in the psychotropic group had been prescribed PDICs; the most common cause of this was different physicians working on the same patient, ignorant of the drugs the others were prescribing.

The study found that the likelihood of dangerous drug interactions, in addition to increasing proportionately with the number of doctors involved in a patient's case, grows as people age and is higher among women. It also showed that 50% of people 65 and over were prescribed medications they didn't need.

"A drug-related illness may have many causes," notes Dr. Réjean Laprise, coordinator of the group. "Sometimes the drugs may interact with others, and sometimes, a drug just isn't the right one for a particular illness."

He attributes the higher incidence of PDICs among seniors to multiple physicians, and a tendency among the elderly to go "doctor-shopping" to treat various maladies. The problem is further complicated by the fact that the average person knows the medication he or she takes by its colour and size rather than its chemical name.

"The fact that you're taking an antibiotic for pneumonia and it's a 'little white pill' doesn't help," says Tamblyn. "Doctors need to know the exact name and dosage."

Another problem is that of patient compliance with a physician's instructions. This is due to both understanding and motivation.

"Sometimes, the patient just doesn't understand the doctor's instructions," says Laprise.

He adds, "If better explanations are given and patients feel responsible for their own medication management, they're more likely to comply" with the doctor's orders.

The most common side effects of harmful interactions are illness, falls and fractures, which frequently lead to hospitalization. "Deaths are not as frequent as hospitalization, thank God," said Tamblyn.

But those hospitalizations cause needless suffering--and are a huge drain on health care resources. According to USAGE, each fractured hip costs the province a minimum of $25,000. In 1990 alone, the overprescribing of sedatives is estimated to have caused injuries requiring $20,000,000 in services.

Fortunately, USAGE has also been busy developing solutions to the problem. Because pharmacists are the ones actually dispensing the drugs, they can serve as a buffer between patients and inappropriate prescriptions. But, without access to medical histories, the amount of help they can offer is limited.

USAGE responded to this need by refining software originally developed at Université de Montréal that can alert physicians to any PDICs that may have been prescribed.

The program, distributed by a firm called Clinidata, will create links to prescription information on a patient--reported routinely by pharmacies to the Régie de l'assurance-maladie du Québec--and the doctor's own files, allowing a physician to be fully informed before making decisions about prescriptions.

"Not only would that be a time-saver for the physician, but it would prevent avoidable hospitalization of seniors due to drug interactions," says Tamblyn.

The first phase of the project was pulling together the necessary funds to test the program. "This involved going to every Tom, Dick and Harry grant agency," says Tamblyn. "But [grant] money usually generates more money."

USAGE eventually received enough to begin the testing. Some of the money was used to put computers into the offices of physicians participating in the project.

The 54 most common drug interactions have been given priority in the computer program, now being tested by 110 Montreal physicians and 16,000 of their patients, all of whom have consented to be part of the study. Once this phase of the study is completed, USAGE will begin working on applying the results to the population at large.

Amy DiNolo, a science student majoring in Environmental Geosciences, is a participant in the Reporter's Student Science Writing Internship Program. The program, based on an initiative at the University of Guelph, is sponsored by NSERC.

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