chronic pain, yet again

in the flurry of recent articles on opioid prescribing for chronic pain, the annals of intl med came out with a systematic review and assessment of the 13 identified guidelines, evaluating them using 2 tools: AGREE II (appraisal of guidelines for research and evaluation II) and AMSTAR (a measurement tool to assess systematic reviews). for article, see chronic pain opioids annals 2013 in chronic pain folder in dropbox, or Nuckols, TK. Opioid prescribing: a systematic review and critical appraisal of guidelines for chronic pain -- online version 11/12/2013 annals of internal medicine for the articles. they basically found that the only 2 guidelines which received high ratings were the Am Pain Society one (chr pain guidelines am pain society jpain 2010 in chronic pain folder in dropbox, or doi:10.1016/j.jpain.2008.10.008) and the Canadian National Opioid Use Guideline Group one. overall, they were quite impressed at the level of agreement in the differing guidelines. major points:

--these guideline evaluators assessed many aspects of the formulation of the guidelines, including input from providers /patients, how evidence was selected, strengths/limitations of the evidence, how recommendations formulated, external reviews prior to publication, implementation recommendations, measures to ensure editorial independence...

--a recent workers' comp study (2012) found that 8-30% of pts with noncancer pain were on opioids, with average daily doses from 13-128 mg morphine equivalents

--nearly half of fatal overdoses were assoc with concommitant use of sedative-hypnotics, esp benzos. and esp an issue in the elderly

--leading risk factor for overdose or misuse of opioids is personal or family hx of substance abuse or psych issues

--there was general agreement that we should use extreme caution if doses greater than 90-200 mg of morphine equivalents per day. 5 guidelines published before 2012 felt that doses >200 mg morphine equiv conferred high risk, and observational studies found that the risk increased dramatically with doses over 100-200 mg.  in washington state, they began requiring workers' comp cases get a pain management referral if pt receiving more than 120 mg/d.  no data on pain control (unfortunately) but assoc signif decrease in opioid overdoses.

--if you are considering changing opioids because you are prescribing really high dose and want to see if other opioid is more effective, you should reduce the morphine equivalent dose by 25-50% (to avoid too much opioid in what may be a more potent drug for the patient)

--be careful with methadone (long QTc, respiratory suppression due to long half-life -- half-life typically 15-60 hrs, can be as high as 120 hrs) and follow more closely than other long-acting drugs (check drug-drug interactions, care with other drugs which prolong QTc).  also be careful with fentanyl patches "including limiting use to opioid-tolerant patients and being aware that unpredictable absorption can occur with fever, exercise or exposure to heat"

--important to use opioid risk assessment tools (eg appendix 4 or 5 in the am pain society paper), written treatment agreements, urine drug testing (guidelines differ a bit on frequency, but most suggest at baseline, and random thereafter, esp if risk is high).