Frequency and correlates of anticholinergic use among patients with schizophrenia in Denmark: A Nation-wide pharmacoepidemiological study

Anticholinergic medications are used to treat extrapyramidal adverse effects induced by antipsychotics. Anticholinergics are associated with adverse effects: constipation, dry mouth and worsening of cognitive function. Anticholinergics have potential for abuse and are not recommended for long term-treatment. We aimed to investigate the use of anticholinergics in patients with schizophrenia. The national health registers in Denmark were used to examine: The prevalence of anticholinergics in 1996-2012 using a cross-sectional design; geographic variations in the prescription of anticholinergics in 2012; correlates of treatment with anticholinergics. The proportion of patients using anticholinergics decreased significantly from 11.7% in 1996 to 5.7% in 2012. The prescription pattern varied considerably between national regions in 2012, ranging from 4.0% in the Capital Region to 8.1% in the Northern Denmark Region. Long-term use of anticholinergics was predicted by older age, age at debut of schizophrenia, receiving early retirement pension, typical antipsychotic use, antipsychotic polypharmacy, typical + atypical antipsychotics, antidepressant treatment, high doses of antipsychotics measured in defined-daily-dose, physical comorbidity and psychiatrists` greater caseload. Use of anticholinergics declined during the study period, and showed substantial variation across the regions in 2012. Long-term use was linked to typical antipsychotic use and variables that are associated with greater illness severity.