Prescribing and Prescribers of Psychotropic Drugs in Norway. A population based pharmacoepidemiological study

Background
One out of three persons in Norway had a mental illness during 2008, and about half
of the population will be affected during their lifetime, according to the Government.
Although mental health care comprises many other aspects than pharmacotherapy,
drugs are widely used to treat psychiatric problems. In this project, the current use of
psychotropic drugs in various parts of the health care system is analyzed. No detailed
scientific information exists about the relative contribution from different physician
groups as regards the prescribing of psychotropic drugs.
Aims
The main aims of this study were to examine prevalence rates, incidence rates and
distribution of psychotropic drug use, i.e. antipsychotics, antidepressants, anxiolytics
and hypnotics, with special emphasis on the pattern of prescribing in primary and
secondary health care.
Material and methods
Data on all prescriptions of psychotropic drugs dispensed from all Norwegian
pharmacies from 1 January 2004 until 31 August 2009 were extracted from the
Norwegian Prescription Database and merged with data about all general practitioners
(GPs) in Norway in the same period from the General Practitioner Database, and
information about the general Norwegian population from Statistics Norway.
Prevalence rates were based on all redeemed prescriptions of these drugs in 2005,
while new users of antipsychotics and antidepressants in 2008 or of anxiolytics and
hypnotics in 2005 were used to calculate incidence rates. The course of the treatment
with anxiolytics and hypnotics was analyzed using a 3.5-year period of follow-up. Results
The prevalence rates per 1,000 inhabitants were 153 for any psychotropic drug, or
24 for antipsychotics, 60 for antidepressants, 62 for anxiolytics and 79 for hypnotics
(Paper I). The incidence rates were 3.4 for antipsychotics and 8.6 for antidepressants
(Paper II), and 18.2 for anxiolytics, 24.5 for hypnotics, or 35.4 per 1,000 for
anxiolytics and hypnotics combined (Paper III). Both prevalence rates and incidence
rates were higher for women than men, and increased by age.
Psychiatrists prescribed an important part of drug treatment to children and
adolescents. GPs prescribed the vast majority, but also initiated psychotropic drug
treatment to most patients, and the proportion increased by patients’ age. The average
treatment duration declined with increased age of the patients in all four drug classes.
The duration was longest for hypnotics and anxiolytics, and only every third patient
received short-term treatment, as recommended. The total drug volume of anxiolytics
and hypnotics redeemed during the first quarter emerged as the strongest predictor of
both long-term and heavy use of such drugs.
Conclusions
Prevalence and incidence rates for psychotropic drug use in Norway are among the
highest in Europe. GPs initiate and maintain the drug treatment to the majority. Hence,
the quality of psychotropic drug treatment is mainly dependent on the knowledge and
practice of each GP. Psychiatrists contribute mainly among children and adolescents
and their share of prescriptions decreased significantly with increasing patient age. An
increased focus from psychiatrists towards the increasingly ageing part of the
population seems requisite.
The study confirms that GPs have a key function in the Norwegian health care system,
also when it comes to treatment of mental disorders. Improving mental health care is
only achieved in a cost effective manner if GPs are a major part of the effort.
Implementation of relevant guidelines and systems for structured clinical audit are
recommended, especially in general practice