title: Geographical and temporal variations in clozapine prescription for schizophrenia.
abstract: Despite its unsurpassed efficacy in treatment-resistant schizophrenia, clozapine remains underutilized. Trends in the prescription of clozapine in patients with ICD-10 F20.x schizophrenia were assessed using data from Danish national registers. Three substudies were carried out: (i) an assessment of differences in national prescription patterns between 1996 and 2007 using a cross-sectional design; (ii) a comparison of time from first schizophrenia diagnosis to first prescription of clozapine in a five-year cohort study, using the Cox regression model, of two patient groups who were first diagnosed in 1996 and in 2003; (iii) an assessment of differences in the general psychiatric hospitals' use of clozapine in 2009. The results are as follows: (i) The percentage of schizophrenia patients receiving clozapine rose from 9.0% in 1996 to 10.1% in 2007 (p<0.001). In the same period, the percentage of patients having clozapine treatment augmented with another antipsychotic increased from 43.1% to 64.2%, p<0.001. (ii) Time from diagnosis with schizophrenia until first clozapine prescription was longer for patients diagnosed in 2003 compared to those diagnosed in 1996 (HR: 0.28 CI: 0.16-0.49). (iii) In 2009 there was significant variation in clozapine administration from one hospital to the other, with percentages of patients receiving the drug ranging from 5.7% to 16.8%, with 10.2% as the national mean. Although, the percentage of schizophrenia patients receiving clozapine increased from 1996 to 2007, the time from diagnosis of schizophrenia until first prescription of clozapine increased.
authors.affiliation: Centre for Schizophrenia, Aalborg Psychiatric Hospital, Aarhus University Hospital, Denmark. jin@rn.dk
authors.forename: Jimmi
authors.initials: J
authors.lastname: Nielsen
authors.forename: Rasmus
authors.initials: R
authors.lastname: Røge
authors.forename: Ole
authors.initials: O
authors.lastname: Schjerning
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Sørensen
authors.forename: David
authors.initials: D
authors.lastname: Taylor
mesh_terms: D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003024:Clozapine / Q000627:therapeutic use*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D003718:Denmark; D011307:Drug Prescriptions; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D005260:Female; D006778:Hospitals, Psychiatric; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D010818:Practice Patterns, Physicians'; D016016:Proportional Hazards Models; D012042:Registries; D012559:Schizophrenia / Q000188:drug therapy*; D062211:Spatio-Temporal Analysis; D061665:Time-to-Treatment
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine