Polypharmacy of potentially addictive medication in the older persons--quantifying usage.

PURPOSE

The use of restricted medications, for example, opioids, benzodiazepines (BZD), and z-hypnotics, in the older persons continues to increase. Little is known about usage practices or about the extent of polypharmacy within this group. The objectives of this study were (i) to describe polypharmacy and (ii) to develop a medication usage index (MUI) to quantify usage patterns.

METHODS

Data for 2008 were obtained from the Norwegian Prescription Database containing all prescriptions filled in Norwegian pharmacies. The study population included people aged 70-89 years who filled prescriptions for weak opioids, strong opioids, anxiolytic BZD, hypnotic BZD, and/or z-hypnotics. A MUI was developed based on Anatomical Therapeutic Chemical codes, defined daily doses, Anatomical Therapeutic Chemical subgroups, and number of prescribers.

RESULTS

Forty-two percent of elderly Norwegians filled at least one prescription in one of the medication subgroups in 2008. MUI Level 1 (least) usage was shown by 56.6% of users (23.8% of the general population), Level 2 by 29.7% (12.5%), Level 3 by 11.3% (4.8%), and Level 4 (most) by 2.4% (1.0%). People using strong opioids were the most likely to use other restricted medications. In addition, female participants had a higher MUI than did male participants, and older users higher than younger users. Cancer or palliative care patients attained twice the MUI points than did the others.

CONCLUSIONS

Polypharmacy was found to be common within these restricted drug categories for the older persons. MUI provides a convenient approach to summarizing drug usage and will be useful in detecting trends and regional differences and determining the impact of interventions.