Antipsychotic use and diagnosis of delirium in the intensive care unit

Abstract

Introduction: Delirium is an independent risk factor for prolonged hospital length of stay (LOS) and increased mortality. Several antipsychotics have been studied for the treatment of intensive care unit (ICU) delirium that has led to a high variability in prescribing patterns for these medications. We hypothesize that in clinical practice the documentation of delirium is lower than the incidence of delirium reported in prospective clinical trials. The objective of this study was to document the incidence of delirium diagnosed in ICU patients and to describe the utilization of antipsychotics in the ICU.

Methods: This was a retrospective, observational, cohort study conducted at 71 United States academic medical centers that reported data to the University Health System Consortium Clinical Database/Resource Manager. It included all patients 18 years of age and older admitted to the hospital between 1 January 2010 and 30 June 2010 with at least one day in the ICU.

Results: Delirium was diagnosed in 6% (10,034 of 164,996) of hospitalizations with an ICU admission. Antipsychotics were administered to 11% (17,764 of 164,996) of patients. Of the antipsychotics studied, the most frequently used were haloperidol (62%; n = 10,958) and quetiapine (31%; n = 5,448). Delirium was associated with increased ICU LOS (5 vs. 3 days, P < 0.001) and hospital LOS (11 vs. 6 days, P < 0.001), but not in-hospital mortality (8% vs. 9%, P = 0.419). Antipsychotic exposure was associated with increased ICU LOS (8 vs. 3 days, P < 0.001), hospital LOS (14 vs. 5 days, P < 0.001) and mortality (12% vs. 8%, P < 0.001). Of patients with antipsychotic exposure in the ICU, absence of a documented mental disorder (32%, n = 5,760) was associated with increased ICU LOS (9 vs. 7 days, P < 0.001), hospital LOS (16 vs. 13 days, P < 0.001) and in-hospital mortality (19% vs. 9%, P < 0.001) compared to patients with a documented mental disorder (68%, n = 12,004).

Conclusions: The incidence of documented delirium in ICU patients is lower than that documented in previous prospective studies with active screening. Antipsychotics are administered to 1 in every 10 ICU patients. When administration occurs in the absence of a documented mental disorder, antipsychotic use is associated with an even higher ICU and hospital LOS, as well as in-hospital mortality.

Figure 1

Box plot showing incidence of documented delirium and antipsychotic exposure by hospital. Results report data in aggregate by hospital for 71 Hospitals in the United States (n = 164,996). Medians labeled; Boxes, 25^th, 50^th (median), and 75^th percentiles; bars, maximum and minimum values that were not outliers; asterisk, outliers; One extreme outlier (67%) for ICU Antipsychotic Exposure is not shown.

Figure 2

Individual antipsychotic frequency of use. Results show data for patients with an admission to an intensive care unit with and without documentation of a mental disorder (n = 164,996). Data are not shown for antipsychotics which were used in less than 1% of admissions: clozapine (0.4%) and paliperidone (0.2%).