MEDICAL MATTERS: Medical error continues to be a highly topical issue. While I was on leave, two additional reports on the topic were published: one by the British Medical Journal (BMJ), and the other by the Canadian Institute for Health Information, writes Dr Muiris Houston.
Healthcare in Canada 2004 found one in nine Canadians received the wrong medication or wrong dose of a drug from a doctor. In addition, one in 152 deaths in Canada are associated with preventable errors for patients in acute care hospitals.
The BMJ report focused on adverse drug reactions (ADRs). The authors followed up almost 19,000 patients admitted to two Liverpool hospitals and assessed the reason for admission. More than 1,200 people (6.5 per cent) were admitted as a direct result of the side effect of medication. Their average length of stay was eight days.
Crucially, the authors found that most adverse reactions were avoidable. "Many ADRs were predictable from the known pharmacology of the drugs and many represented known interactions and are therefore likely to be preventable," they concluded.
So what kind of drugs caused the most difficulty? Interestingly and contrary to what one might have expected, it was the older drugs that continued to be most commonly implicated: aspirin and other non-steroidal anti-inflammatory drugs; diuretics (water tablets); the blood thinning drug warfarin; heart drugs, including beta blockers, ACE inhibitors and digoxin; and steroids.
Of the most common side effect, bleeding from the stomach and/or intestines stood out. Now all doctors have horror stories of how a patient with arthritis who appears to have settled well on an anti-inflammatory drug, is suddenly found to have a blood count well below normal. The explanation is simple; they have been bleeding quietly and unobtrusively for months from their gastrointestinal system as a direct side effect of the medication.
But what the BMJ study drew attention to were the number of drug interactions leading to this problem. Examples include the interaction between aspirin and warfarin, and aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) causing bleeding and peptic ulcers.
Overall, NSAIDs (including aspirin) caused 30 per cent of all adverse drug reactions. Water tablets (diuretics) - commonly used for blood pressure and heart failure - caused 27 per cent of adverse drug reaction. Again, the problem of drug interactions between two different types of diuretics and between ACE inhibitors and diuretics led to kidney failure.
Antidepressants caused 7 per cent of unwanted side effects resulting in confusion and low blood pressure.
The authors of this important study warn that more needs to be done to avoid adverse reactions. "It is incumbent on prescribers to determine the need for a particular drug in a patient and to use this drug at the lowest dose necessary to achieve benefit," they say, adding that many ADRs may be preventable through simple improvements in prescribing.
With the average GP prescribing around 15,000 items a year, the challenge to get it all right is immense. Yet, clearly, doctors will have to do better, especially on the drug interaction front. Computerised prescribing systems should lessen the risks.
Rather than have to carry information in their heads, doctors who prescribe electronically can avail of systems that flash warning signals when they attempt to misprescribe. Patients have a role to play also. If your doctor decides to add a new drug to your prescription, ask him to check that it won't interact with the other drugs you are taking. Always check your prescription before you leave the surgery.
Your community pharmacist has long been the "goalkeeper" in the prescribing process. Quick to notice wrong dosages, pharmacists increasingly advise on alternatives for patients and the prescribing doctor. In hospitals, their presence on ward rounds has been shown to reduce the incidence of prescribing error.
Both the Canadian and the British findings reinforce how important an area of healthcare this is. No one wants the cure to be worse than the disease, especially if it reaches a point where hospitalisation results from the treatment of a separate problem.
The results also add to the concern following a recent decision by the British Department of Health to offer the statin group of cholesterol-lowering drugs on an over-the-counter basis. The potential for drug interactions alone from this decision is significant.
"The young physician starts life with 20 drugs for each disease; the old physician ends life with one drug for 20 diseases." Sir William Osler's wise words become even more relevant the more modern medicine advances.
Dr Muiris Houston is pleased to hear from readers at mhouston@irish-times.ie but regrets he cannot answer individual queries.