Chronic Knee pain from osteoarthritis and what to do about it - Topical ibuprophen.

About 1 in 3 adults over the age of 50 have chronic pains in the knees. Most are caused by osteoarthritis, essentially a wearing out of the joint, most likely due to age, prior injuries, obesity or other overuse (work or weight bearing), and in part to one’s genes. If you want to know if you have osteoarthritis a good source is the US National Institutes of Health. They have a patient friendly guide that is free. (Handout on Health Osteoarthritis) Figure is in the handout and shows the main joints that are affected by osteoarthritis.

Most people with more severe forms of pain, especially pain that limits walking, will try anti-inflammatory drugs like aspirin or ibuprofen. These drugs, collectively called NSAIDs (non-steroidal anti-inflammatory drugs), however, can cause side effects, the most serious of which is bleeding in the stomach. Minor side effects are also reported such as indigestion (gastritis or abdominal pains) and a few others such as increases in blood pressure or decreases in kidney function. They should be used with care in patients with pre-existing hypertension, heart, kidney or liver disease and in patients with known gastric bleeding and or taking drugs that might make bleeding easier (anti-coagulants, steroids).

Recently topical ibuprofen has become available.

This study is an RCT of 282 patients selected from general practices in the UK. They represent about 1% of the patients in these practices who were identified as possibly having osteoarthritis. Of these, 85% completed the study.

Primary Outcome Measure: Knee pain at 12 months in the topical and oral groups.

Result: There was no difference between the two groups in pain severity, joint stiffness or mobility.


Interpretation of study:

Topical and oral ibuprofen provided equivalent relief for osteoarthritis of the knees. The study was not designed to show that topical ibuprofen was less likely than oral ibuprophen to cause side effects, especially gastrointestinal bleeding, nor that other side effects were less or more frequent.

The study was not blinded at the patient level: subjectivity may have played a part in this result. Given the low statistical power obtained in this carefully planned study it is difficult to imagine that any other study could do much better. The we may never know the answer to the study question - are topical NSAIDs as good and safer and better tolerated than oral NSAIDs? It is likely however that oral ibuprophen would provide a larger effective dose, resulting in better pain relief and a higher incidence of side effects.

Implications:

For the patient

The rational patient could try topical ibuprofen and expect to find equivalent symptom relief to his or her oral pill: And judge for themselves if this occurred and was worth the additional cost of the topical drug.

The authors say that symptom relief generally did not change over the study, suggesting, perhaps that neither route of administration works - that a placebo or simple acetaminophen (Tylenol, Paracetamol), or no drug treatment might do just as well, and have with fewer side effects.

For Society

Given the higher costs (currently) of topical Ibuprofen, the equivalence of oral and topical ibuprophen for symptom relief and the paucity of data on serious adverse effects, health insurance plans should consider topical ibuprophen to be cost-ineffective compared to oral generic products and therefore not covered. Database studies of large numbers of users might be used to detect rate differences in serious adverse events and if this were so, then the topical agents might be cost-effective.

References:

Underwood M, Ashby D, Cross P et al. Advice to use topical or oral ibuprofen for chronic knee pain in older people: randomized controlled trial and patient preference study. BMJ 2008:336:138-42 doi:10.1136/bmj.39399.656331.25