Increasing use of opioids from 2004 to 2007 - pharmacoepidemiological data from a complete national prescription database in Norway.

BACKGROUND: A high opioid consumption for cancer related and acute pain may indicate adequate pain treatment. Analysis of a national, compulsory and complete database of all dispensed prescription drugs in Norway (NorPD) may reveal important epidemiological data on prescription pattern of opioids. This study investigated the prevalence of opioid dispensions in 2004-2007 and explored patterns of use.

METHODS: All pharmacies in Norway submit data electronically to NorPD on all dispensed prescriptions. All prescriptions to any individual are identified by a unique pseudonym. All persons who were dispensed opioids from 2004 to 2007 are included in the study. Cancer patients are identified by a reimbursement code. Non-cancer pain indications are inferred from pattern of prescriptions.

RESULTS: 470,638 Norwegians were dispensed opioids in 2007, corresponding to 9.7% of the population (13.0% of adults). Only 13,220 persons (2.8% of all patients) received opioids for cancer pain, accounting for 10% of all dispensed opioids measured in defined daily doses (DDDs). Among persons with non-cancer pain 77% received only one dispension per year or less than 50 DDDs/year. Fifteen percent received from 50 to 200 DDDs/year. Only 13,846 (4%) received >400 DDDs/year and are likely to be daily users for chronic non-cancer pain. From 2004 to 2007 a 9 % increase was observed in the number of persons receiving opioids and the number of dispensions, whereas opioid types, doses, and indications appeared stable.

INTERPRETATION: From these prescription patterns it can be concluded that the majority of patients received opioids for acute, non-cancer pain.