Antipsychotic prescribing pattern among Italian general practitioners: a population-based study during the years 1999-2002.

OBJECTIVES: To assess the antipsychotic use and the prevalence/incidence of antipsychotic drug users in Italy during the years 1999-2002. To estimate the persistence with antipsychotic medications, and to measure their off-label use.
METHODS: We selected 465,061 individuals registered by June 2002 in the lists of 320 general practitioners, homogeneously distributed throughout Italy, from the Health Search Database. We measured the antipsychotic drug consumption, calculated as defined daily dose (DDD) per 1000 inhabitants per day. We also calculated the number of individuals receiving at least one antipsychotic prescription, to estimate the annual prevalence and incidence of antipsychotic users. Among incident users, we evaluated the percentage of patients adherent to drug label indications and the average duration of treatment, estimated as medical possession ratio (MPR).
RESULTS: Atypical antipsychotic use has continuously increased from 1999 to 2002. Women, older people and patients affected by psychotic disorders other than schizophrenia were seen to be more likely to receive antipsychotic prescriptions. Persistence with atypical drug treatment (MPR=0.213 in 2002) appeared longer than that of typical drugs (0.169). The percentage of patients adherent to drug label indications was significantly higher among typical antipsychotic users (P<0.001). The most common off-label use for atypical drug was senile dementia.
CONCLUSION: Atypical drug use has been continuously expanding over the years 1999-2002, particularly in older people with dementia. The rapidly increasing use of this new class of antipsychotics highlights the need for a better evaluation regarding their safety profile and a better definition of their role in psychiatric treatments.