A popular treatment for high blood pressure that affects a large proportion of the elderly is, according to Dr. Anderson a common trigger of the prescribing cascade.
He cited a Canadian study of 41,000 older adults with high blood pressure who were prescribed drugs called calcium channel blockers. Within a year of starting treatment, almost one in ten people was given a diuretic to treat the swelling of their legs caused by the first drug. Many have been inappropriately prescribed what is known as a loop diuretic, which Dr. Anderson can cause dehydration, kidney problems, drowsiness, and falls.
Type 2 diabetes is another common condition in which drugs to treat drug-induced side effects are often not properly prescribed, said Lisa M. McCarthy, doctor of pharmacy at the University of Toronto who led the Canadian study. Recognizing a side effect as such can be hindered if the effect does not occur weeks or even months after starting a drug. While patients taking opioids for pain can easily spot constipation as a result, Dr. McCarthy suggests that patients taking metformin for diabetes over time may develop diarrhea and potentially treat themselves with Lomotil, which in turn can cause dizziness and confusion.
Dr. Paula Rochon, a geriatrician at Women's College Hospital in Ontario, said that patients who take a drug called a cholinesterase inhibitor to treat early dementia can develop urinary incontinence, which is then treated with another drug that clears the confusion Patient can worsen.
To make matters worse, some people use a large number of drugs. "Older adults often take a lot of drugs, two-fifths five or more," wrote Dr. Anderson in JAMA Internal Medicine. In cases of polypharmacy, as it is called, it can be difficult to determine which of the medications a person is taking is causing the current symptom.
Dr. Rochon emphasized that a prescribing cascade can happen to anyone. She said, "Everyone needs to consider the possibility every time a drug is prescribed."
Before accepting a prescription, she recommended that patients or their caregivers ask the doctor a series of questions, starting with "Do I have a symptom that could be a side effect of a medicine I was taking?" Follow-up questions should include:
Is this new drug being used to treat a side effect?
Is there a safer drug than what I am taking?