Opioid use in chronic noncancer pain: guidelines revisited

The treatment of chronic noncancer pain with opioids is controversial. This review aims to find answers to three questions patients and physicians might have: how much (pain relief can be expected), how long (will pain relief be sustained) and how bad (are side-effects)? To this end, we reviewed the second generation of clinical guidelines on this topic. These are based on a significantly higher number of randomized controlled trials than former ones and, therefore, allow evidence-based statements. Six guidelines have been launched recently to improve care and safety when treating chronic noncancer pain with opioids. The evidence base for long-term administration of opioids is weak, mostly due to methodological flaws in the available studies and because opioids have no superior effects compared with other analgesics. The maximum pain relief attributable to opioid or nonsteroidal anti-inflammatory drug administration for up to 3 months is 8-12 out of 100 units. It is doubtful that this is clinically important for patients with chronic noncancer pain. Even selected 'responders' from previous randomized controlled trials do not report noticeable pain relief. The small effect-size differences between the classes of analgesic drugs do not provide a basis for differential therapeutic decisions. Many guideline panels concentrate their recommendations solely on safety of opioid analgesics and patients are usually not informed about the (low) degree of pain relief to be expected. This makes adherence of patients unlikely. Beyond that, multimodal treatment of chronic noncancer pain should become the center of attention.