Management of acute pain in methadone maintenance therapy in-patients

Methadone maintained treatment (MMT) patients may be given less opioid analgesia for acute pain than the general patient, due to requests for analgesia being misinterpreted as craving for drugs. Pain studies have showed that MMT patients have hyperalgesic responses and that cross-tolerance to opioids may be present, suggesting that they may need more analgesia than the non-MMT patient. This study compares the pain management of MMT patients and controls during an acute hospital stay. It is a retrospective study of MMT in-patients and controls matched for medical condition, age and gender, comparing the analgesia given and pain stated in hospital notes. Patients with a chronic pain condition were excluded. MMT patients and controls did not differ in relation to median morphine dose received or average number of pain reports per day, and only a small proportion of both groups engaged in drug-seeking behaviour. Behavioural problems were significantly more common among MMT patients (39% versus 5%, p < 0.001). The fact that the opioid doses were not significantly different between subjects and controls seems to contradict the experimental evidence that patients on methadone tend to be hyperalgesic. Alternatively, MMT patients may be hyperalgesic, and statistically equal levels of opioid analgesia given to both groups may indicate an effective under-treatment of pain in the hyperalgesic MMT group. Inadequate analgesia may contribute to both behavioural problems and premature discharge. Resolving these uncertainties will require prospective studies.