Targeted prophylaxis of postoperative delirium.

I N this issue of ANESTHESIOLOGY, Hakim et al. present results of a randomized trial of a pharmacologic intervention to prevent development of postoperative delirium in patients who demonstrated early signs of cognitive instability. Delirium is a serious and frequent postoperative complication that is frightening for patients and stressful for families. Delirium is associated with prolonged critical care and hospitalization, long-term cognitive decline, and mortality. 4 The syndrome is most common in geriatric surgical patients (15– 62%) and is especially common among patients requiring intensive care (70–87%). Previous studies indicate that prophylactic administration of antipsychotic medications reduces the risk of developing postoperative delirium, although a clear effect on the consequences of delirium remains to be established. Given that many surgical patients do not develop postoperative delirium, it is inefficient to treat all with drugs that incur some cost and are at least potentially associated with complications. Even among higher-risk populations, it would thus be helpful to target prophylaxis toward patients most likely to become delirious. Hakim et al. approach this issue by restricting prophylaxis to patients who had some evidence of disturbed cognition but who did not (yet) meet the formal criteria for a delirium diagnosis. Specifically, they defined “subsyndromal” delirium by a score of 1–3 (of a maximum of 8) on the Intensive Care Delirium Screening Checklist scale. This well-validated scoring system is an alternative to the widely used Confusion Assessment Method for critical care patients (CAM-ICU). There is currently no consensus on the definition of subsyndromal delirium, but a score of 1–3 on the Intensive Care Delirium Screening Checklist scale has been used previously, and has been associated with worsened outcome. Their approach proved effective. Among 177 patients meeting enrollment criteria (including not already being delirious), 76 never developed subsyndromal delirium and thus avoided prophylactic treatment. In addition, of 51 subsyndromal patients given prophylactic risperidone (an atypical antipsychotic agent that appears to prevent delirium), 7 (14%) developed delirium; in contrast, 17 of 50 patients (34%) given placebo developed delirium (P 0.03). The efficacy of risperidone was thus almost exactly as reported previously by Prakanrattana and Prapaitrakool in which a group of high-risk patients were randomized to risperidone or placebo without considering subsyndromal status: 32% versus 11%, P 0.01). Two studies thus document the efficacy of risperidone for prevention of delirium. But Hakim et al. also show that—even within a high-risk population—treatment can be further targeted, thus preventing unnecessary drug administration to approximately 40% of the patients. The overall delirium rate reported by Hakim et al. (24 cases among 177 patients) was only 13%. Even if the delir-