Individuals, averages, and evidence based medicine

In asking “Does this work for you?”1 Christakis finds the heart of evidence based medicine—“the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.”2 The individual approach can also reconcile clinical trial results with the demands of clinical practice: “managers and trialists may be happy for treatments to work on average; patients expect their doctors to do better than that.”3

That not all patients achieve great benefit and need an individualised approach has been shown in treating depression4 and is particularly true for pain.

In acute pain, patients either have very good or very poor pain relief with non-steroidal anti-inflammatory drugs. In neuropathic pain fewer than half of patients commonly achieve adequate pain relief with any treatment. In migraine the proportion of patients achieving rapid and prolonged pain relief (adjusted for the placebo response) is only about 25%. With TNF-antagonists in rheumatoid arthritis the proportion achieving a beneficial outcome after 12 months is 60% for ACR20, 40% for ACR50, and 20% for ACR70. In osteoarthritis the 80-20 rule applies, 80% of patients getting 20% pain relief, and 20% getting 80% pain relief; about half get half pain relief, a very good outcome.

Various solutions would make clinical trials more useful—for example, better reporting of conventional trial designs and use of enriched enrolment randomised withdrawal designs, especially when the proportion of patients experiencing benefit is low.5 Clinical effectiveness trials comparing different treatments and reporting a level of response that makes sound clinical sense would have immediate clinical impact, would underpin clinical decision making and guideline development, and may offer more relevant approaches to health economic assessment.

The individual patient approach is even more important in clinical practice, especially when few if any interventions produce high rates of good response. In difficult conditions such as neuropathic pain many interventions are needed to be able to achieve a good result for the patient we are treating. Restrictive formularies don’t help.