Patterns of Antidepressant Drug Prescribing and Intentional Self-harm Outcomes in New Zealand: An ecological study

This Bulletin presents the findings of an observational pharmacoepidemiological study that has been undertaken by PHI to investigate whether a relationship can be observed between antidepressant prescribing (particularly SSRIs) in New Zealand and suicide related outcomes. A secondary objective of the study was to examine the usefulness of the national data sets – in particular the Pharmhouse data - to inform research into questions about the safety and efficacy of drug use in New Zealand. The research methods used data from national data sets, internationally accepted drug utilisation methodologies, and reviewed the international literature. The study found statistically significant regional differences in the numbers of people prescribed an antidepressants in the population, and a small observed risk (Odds Ratio ranging from 1.25 to 1.63) between increased prescribing in the population of nortriptyline, paroxetine and fluoxetine and increased hospitalisations for deliberate self-harm events. A number of explanations for the findings have been examined. The findings are generally comparable with similar studies reported in the international literature.