Anti-inflammatory stroke risk

THE risk of stroke associated with the over-the-counter painkiller diclofenac is similar to that of rofecoxib, which was withdrawn in 2004 due to its cardiovascular risk profile, new Australian research shows.

The retrospective cohort study of 162 065 Australian veterans with an average age of 76 years , published in the MJA, looked at hospitalisation for both ischaemic and haemorrhagic strokes in the year before and the year after initiation of non-steroidal anti-inflammatory drug (NSAID) use. It found that initiating diclofenac was associated with a 1.75 times increased risk of stroke while rofecoxib (Vioxx) had a 1.80 times increased risk. (1)

Overall, veterans had a 1.88 times increased risk of hospitalisation for stroke in the 12 months after being dispensed a NSAID. This equated to an increased absolute risk of 13.4 strokes per 1000 people each year.

Professor Geoffrey Donnan, director of the Florey Neuroscience Institutes, said the new research added to “mounting evidence that there’s something going on with these drugs”.

Professor Donnan, who is also a neurologist at Austin Hospital, Melbourne, said the increasing evidence about the risks of NSAIDs suggested that the worldwide withdrawal of Vioxx in 2004 was perhaps unwarranted.

“As it turns out, it seems to be a class effect so it probably was a bit hasty”, he said.

However, Professor Donnan said that it was important not to overreact to the MJA research because NSAIDs were “incredibly helpful” for some patients, and there were not many alternatives.

“Patients have to weigh it up — do you want to live a life of pain, or accept a small increased risk of vascular events?” Professor Donnan said he believed many patients would choose the pain relief option.

The researchers pointed out that the baseline absolute risk of stroke was low, at 7.1 strokes per 1000 people a year.

“Nevertheless, small increases in risk may be particularly important for older people, who commonly have comorbidities that are associated with increased risk of stroke”, they wrote.

“Individual assessment of cardiovascular risk, careful deliberation of the balance between risk and benefits and appropriate supervision is required when initiating NSAID therapy.”

Professor Les Cleland, director of rheumatology at Royal Adelaide Hospital, said the research was important, particularly because Australians used a lot of NSAIDs.

He said there was a need for greater awareness about the risks of NSAIDs among many clinicians and the public.

However, he disagreed that there were no other options for anti-inflammatory analgesia. His clinic uses high-dose fish oil (15 mL/day) and paracetamol in preference to NSAIDs among rheumatoid arthritis patients.

“Biochemical research has shown that long-term fish oil plus paracetamol achieves a similar COX-inhibitory effect as NSAIDs, with the advantage that fish oil reduces vascular risk rather than increases it”, he said.

Professor Cleland also called for diclofenac to be made prescription only, or even withdrawn.

“It seems totally anomalous that diclofenac is available as an over-the-counter preparation. The OTC availability carries an implication of safety which is not justified”, he said.

An accompanying editorial in the MJA, by neurologist Dr David Blacker, said the research showed that NSAIDs needed to be used with caution in patients with hypertension and other stroke risks. (2)

However, he said it was important to keep in mind that the research findings do not apply to younger, healthier populations.

- Sophie McNamara

1. MJA 2011; 195: 525-529
2. MJA 2011; 195: 488

Posted 7 November 2011