Delirium is associated with early postoperative cognitive dysfunction

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Abstract
The purpose of this analysis was to determine if postoperative delirium was associated with early postoperative cognitive dysfunction (at 7 days) and long‐term postoperative cognitive dysfunction (at 3 months). The International Study of Postoperative Cognitive Dysfunction recruited 1218 subjects ≥ 60 years old undergoing elective, non‐cardiac surgery. Postoperatively, subjects were evaluated for delirium using the criteria of the Diagnostic and Statistical Manual. Subjects underwent neuropsychological testing pre‐operatively and postoperatively at 7 days (n = 1018) and 3 months (n = 946). Postoperative cognitive dysfunction was defined as a composite Z‐score > 2 across tests or at least two individual test Z‐scores > 2. Subjects with delirium were significantly less likely to participate in postoperative testing. Delirium was associated with an increased incidence of early postoperative cognitive dysfunction (adjusted risk ratio 1.6, 95% CI 1.1–2.1), but not long‐term postoperative cognitive dysfunction (adjusted risk ratio 1.3, 95% CI 0.6–2.4). Delirium was associated with early postoperative cognitive dysfunction, but the relationship of delirium to long‐term postoperative cognitive dysfunction remains unclear.