When I reach for it
Every patient on an opioid, at each refill decision, and before adding a second opioid or a benzodiazepine.
Where it misleads
These factors add up a daily total. They are not for switching one drug to another: when rotating, cut the new dose by 25 to 50% for incomplete cross-tolerance. Methadone does not convert in a straight line, and buprenorphine is not counted this way.
How it is built
Daily MME = dose × doses a day × conversion factor, added across opioids. CDC 2022 factors: codeine 0.15, hydrocodone 1, hydromorphone 5, methadone 4.7, morphine 1, oxycodone 1.5, oxymorphone 3, tapentadol 0.4, tramadol 0.2, fentanyl patch 2.4 per mcg/hr.