Frequency and correlates of antipsychotic polypharmacy among patients with schizophrenia in Denmark: A nation-wide pharmacoepidemiological study

摘要

Although evidence for efficacy of antipsychotic polypharmacy (APP) is sparse, APP is common in schizophrenia. The national Danish health registers were accessed to examine in schizophrenia patients: (1) cross-sectional prevalences of APP (1996-2012); (2) geographic variations in APP (2012); and (3) correlates of APP (2012). APP increased from 17.2% in 1996 to 30.8% in 2006 (p<0.001), declining to 24.6% in 2012 (p<0.001) (overall trend 1996-2012: alpha=0.653, 95% confidence interval (CI):0.327-0.979, p<0.001). Comparing the 1996-2005 and 2006-2012 cohorts APP occurred significantly faster in the 2006 cohort after schizophrenia diagnosis (p<0.0001). The predominant APP type changed from first-generation antipsychotic combinations in 1996 (77.3%) to first+second-generation antipsychotic combinations in 2003 (70.3%) and second-generation antipsychotic combinations in 2012 (59.2%). In 2012, the prevalence of APP varied from 19.4% in Copenhagen to 29.3% in the region of Zealand. Independent correlates of APP, explaining 37.9% of the variance, included a higher number of patients per psychiatrist (OR= 1.04 /10 patients, CI = 1.03-1.06, p<0.001),lower proportion of males (OR=0.80, Cl =0.74-0.86), younger age (OR= 1.00, Cl =0.99-1.00), several schizophrenia subtypes (paranoid: OR=1.24, CI =1.11-1.38,hebephrenic: OR= 1.30, CI = 1.03-1.63, other: OR= 1.95 CI =1.173.24, unspecified: OR= 1.21 CI =1.05-1.40), living alone (OR=1.12, CI = 1.01-1.24), being institutionalized (OR=1.23, CI = 1.06-1.42), receiving early retirement pension (OR= 1.21, CI=1.10-1.34), higher Charlson Co-morbidity Index score (OR=1.13, CI=1.07-1.19), higher antipsychotic defined daily doses (OR=3.05, Cl= 2.95-3.16), treatment with clozapine (OR=3.09, 95% C1=2.78-3.44), and treatment with antidepressants (OR=1.97 (C1=1.83-2.13), long-acting injectable antipsychotics (OR= 1.48, Cl = 1.34-1.63), and anticholinergics (OR= 1.74, CI = 1.51-2.01). APP remains common in schizophrenia with substantial temporal and geographical variation, being associated with indicators of illness severity and chronicity. (C) 2015 Elsevier By, and ECNP. All rights reserved.