To the editors.

TO THE EDITORS In the article by Marshall et al 1 there are several design flaws that tend to render the results far less useful than the authors conclude. The comparison of a scheduled narcotic for chronic pain with a similar medication for breakthrough pain only is not a clinically relevant comparison. Chronic pain should always be treated with a combination of chronic and immediate release (IR) medications. The question that should have been asked is whether a short half-life drug scheduled every 4 hours provided better relief than a scheduled drug every 6 hours or a sustained-release (SR) drug lasting 12 hours, each patient having the same opportunity for treatment of breakthrough pain. The oxycodone-acetaminophen group only took their medications on an as-needed basis, rather than on a set schedule, whereas patients in the oxycodone SR group received medication around the clock. Administration of medications on only an as-needed basis has been shown in other studies and clinical guidelines to clearly result in suboptimum outcomes because patients have the tendency to wait until they are in pain before taking the next dosage. 2,3 As-needed administration of drugs will frequently leave patients with the perception that the pain is not being well managed with the medication. In addition, the study by Marshall et al is biased in favor of the oxycodone SR group by allowing patients in this group 5 mg of oxycodone IR whenever requested. However, in the oxycodone-acetaminophen group, patient intake of drugs was limited in several ways. Because of the acetaminophen content, the doses per day were limited to less than the maximum; in fact some patients in the oxycodone-acetaminophen group could not even receive the full oxycodone IR every 4 to 6 hours because they were on other acetaminophen products (not a limiting factor in the oxycodone SR group). Moreover, the administration of 5 mg oxycodone in the oxycodone-acetaminophen group, unlike the administration in the oxycodone SR group, was available only at the discretion of the prescriber. The easier solution would have been to provide both groups with oxycodone IR as needed for breakthrough pain with no or low amounts of acetaminophen, thereby allowing patients whatever amount of oxycodone IR they needed. The measure of improvement was done using a scale that measured multiple variables through the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and the Health Utilities Index 3 (HUI3) scale; the latter contains …