Painkillers, from the cheap over-the-counter variety through to expensive prescription drugs, are not much use for people suffering arthritis of the knee, according to a new study.
In fact, so-called non-steroidal anti-inflammatory drugs (NSAIDs) offer little more pain relief than sugar pills in the short-term. And, in the long-term, NSAIDs do more harm than good, the researchers concluded.
"As use of oral NSAIDs may incur serious adverse effects, they can only be recommended for limited use in arthritis of the knee," said Jan Magnus Bjordal, a research fellow at the Department of Public Health at the University of Bergen, Norway.
The study, published in today's edition of the British Medical Journal, challenges current practice because more than half of people with arthritis in the knee are prescribed a daily dose of NSAIDs.
NSAIDs are among the biggest selling drugs in the world. They include acetylsalicylic acid (Aspirin), ibuprofen (Advil, Motrin) and naproxene (Aleve), as well as cyclo-oxygenase-2 inhibitors such as rofecoxib (Vioxx) and celecoxib (Celebrex).
The research is another strike against cox-2 inhibitors, which were supposed to offer the same pain relief as traditional NSAIDs, but with fewer side effects.
Vioxx was recently withdrawn from the market after clinical trials revealed that it increased the risk of heart attack and stroke. There are now questions about the safety of Celebrex and valdecoxib (Bextra).
NSAIDs are not just pain relievers, they help reduce inflammation and lower fevers. They can also prevent blood from clotting. The main side effect is that they can increase gastrointestinal bleeding, exacerbate heart failure, and provoke dangerous interactions with other prescription drugs.
Cox-2 inhibitors became instant bestsellers because they promised pain relief and fewer gastrointestinal bleeds.
The new research is a meta-analysis, a compilation and analysis of previously published research. Norwegian scientists examined a total of 23 studies that included 10,845 patients. Each of the studies looked at various measures of pain.
Dr. Bjordal said that the analysis revealed that NSAIDs reduced knee pain by 17 to 22 per cent in the short-term.
He said that, practically speaking, that is insignificant because "patients have reported that pain has to be reduced by about 30 per cent to be considered meaningful."
Dr. Bjordal said that NSAIDs work well for reducing pain in acute conditions, such as a headache or injury, but they are not an effective means of controlling chronic pain, such as that which results from arthritis of the knee.
He noted that one in four patients who is prescribed NSAIDs for arthritic pain relief does not take the drug, another indication that these drugs are not that effective.
NSAIDs work by preventing an enzyme, cyclo-oxygenase, from doing its job -- and, in particular, they stop inflammation which is the source of much pain. (Cox has two forms in the body: Cox-1 protects the stomach lining from harsh acids and digestive chemicals and Cox-2 is produced when joints are injured or damaged.)
One in seven Canadians, about four million people, suffer from inflammatory joint disease, the most common form of which is osteoarthritis. Women are more than twice as likely to suffer from arthritis as men.
The No. 1 cause of long-term disability in Canada, arthritis costs the Canadian economy an estimated $9-billion a year.