Influence of dosing pattern of antipsychotics on treatment outcome of delirium in patients with advanced cancer

Background: Clinical guidelines recommend antipsychotics for the treatment of delirium; however, there has been no confirmed recommendation regarding their administrating patterns. This study aims to investigate whether different dosing patterns of antipsychotics (single or multiple administrations) influence the outcomes of delirium treatment. Methods: This is a secondary analysis of a prospective observational study involving patients with advanced cancer and delirium receiving antipsychotics. The Delirium Rating Scale Revised-98 was administered at baseline and after 72 h of starting pharmacotherapy. Patients were classified into single administration group (received a single dosage within 24 h before the assessment) and multiple administration group (received more than one dosage). Results: A total of 555 patients (single administration 492 (88.6%); multiple administration 63 (11.4%)) were subjected to analyses. The patients in the multiple administration group were more likely to be male, in psycho-oncology consulting settings, with lower performance status, with hyperactive delirium and with severer delirium symptoms. In the multivariate analysis, single administration was significantly associated with better improvement of delirium (p < 0.01, 95% confidence interval: 1.83-5.87) even after controlling covariates. There were no significant differences in the mean dosages of antipsychotics per day in chlorpromazine equivalent (single administration 116.8 mg/day, multiple administration 123.5 mg/day) and the incidence of adverse events between the two groups. Conclusions: In this observational study sample, Delirium Rating Scale severity score improvement in single administration was higher than that seen in multiple administration. There was no difference in adverse events between the two groups.