Prescription of analgesics to patients in opioid maintenance therapy: a pharmacoepidemiological study.

AIMS: The primary aim of the present study is to determine the one year periodic prevalence of dispension of different analgesics to patients in long term opioid maintenance therapy (OMT). The secondary aim is to determine to which extent non-opioid analgesics are used as first line analgesics.
DESIGN: The study is a pharmacoepidemiological study with cross sectional data and cohort data. Data on patients in long term OMT in Norway were obtained from the complete national Norwegian Prescription Database (NorPD).
FINDINGS: The analgesics with the highest one year periodic prevalence were NSAIDs (22%), codeine-paracetamol combinations (9%), paracetamol (7%) and tramadol (2.5%). During both 2007 and 2008 a total of 12% of the study population received at least one dispension of another opioid in addition to the opioid used for OMT. In 55% of the cases where OMT patients had not received an analgesic the preceding year an NSAID was the first or only dispensed analgesic whereas paracetamol-codeine was the first or only dispensed analgesic in 29% of the cases.
CONCLUSIONS: This study has documented an equally high one year periodic prevalence of opioid dispensions in OMT patients as in the general population as well as a high one year periodic prevalence of dispensions of NSAIDs. Dispension of codeine-paracetamol has a relatively high one-year prevalence and is frequently used as a first line analgesic.