Contributed by Oluwaseun Johnson-Akeju, MD, Anesthetist-in-Chief at Massachusetts General Hospital and Henry Isaiah Dorr Associate Professor of Research and Teaching in Anaesthetics and Anaesthesia at Harvard Medical School, and Ariel Mueller, MA, Administrative Director for Research in the Department of Anesthesia, Critical Care and Pain Medicine at Massachusetts General Hospital on behalf of the Minimizing Intensive Care Unit Neurological Dysfunction with Dexmedetomidine-induced Sleep (MINDDS) Study Team.
To date much evidence has accumulated regarding the occurrence of postoperative neurocognitive disorders following surgery1-3. Although objective cognitive assessments remain the gold standard for assessing neurocognition, the ability to perform these assessments at scale limit their use in the general surgical population. As an alternative, measures of subjective cognitive decline have been proposed as they involve a patient self-reporting changes in their perceived cognitive performance and do not require the evaluator to have specialized training. In a secondary analysis of data from the Minimizing Intensive Care Unit Neurological Dysfunction with Dexmedetomidine-induced Sleep (MINDDS) trial4, we used both subjective and objective cognitive measurement approaches to evaluate the relationship between postoperative delirium and cognitive decline in the 12 months after surgery.
In this study we utilized data from the MINDDS clinical trial, a randomized, placebo-controlled superiority trial5,6. In the parent trial we randomized older adults (≥ 60 years) undergoing cardiac surgery with cardiopulmonary bypass at one to receive either intravenous dexmedetomidine or placebo. For the current analysis4 we used data from subjects who were randomized (and included in the primary trial cohort) who had in-hospital delirium data available. Cognitive function was evaluated before and at 30, 90, and 180 days after surgery using both the subjective, PROMIS Applied Cognition-Abilities questionnaire, and the objective, Telephonic Montreal Cognitive Assessment [t-MoCA]).
Postoperative delirium occurred within three days of surgery in 39 (11.6%) of 227 participants. Patients with postoperative delirium tended to be older, female and had lower preoperative cognition. After adjusting for baseline cognitive function, the patients who developed postoperative delirium in the first three postsurgical days (vs. those who did not) had significantly reduced cognitive function (mean difference [MD] -2.64 [95% CI: -5.25, -0.04]; p=0.047) at 6 months when evaluated by the subjective PROMIS questionnaire. When the objective T-MoCA assessment was used to evaluate cognition, 6-month cognitive function was also significantly lower in patients who developed postoperative delirium (MD -0.77 [95% CI: -1.49, -0.04]; p=0.04). A statistically significant association between the PROMIS questionnaire and T-MoCA assessments were found at all evaluation timepoints [baseline; r = 0.113 (p = 0.04); 30 days; r = 0.204 (p = 0.001); 90 days; r = 0.167 (p = 0.01); and 180 days; r = 0.295 (p < 0.001)].
Older adults who undergo cardiac surgery and experience postoperative delirium have reduced subjectively-evaluated cognition in the 180 days after surgery. These results were similar when cognition was objectively assessed. Our findings suggest that measures of subjective cognitive function may be utilized to enable population-level insights into the burden of cognitive decline and its association with postoperative delirium.
Given their ease of administration, measures of subjective cognitive decline may help overcome learning effect challenges that are inherent to objective cognitive measures. Further, it may allow better estimation of the burden of cognitive decline in patients in whom objective measures may not be easily obtained. However, to better understand the relationship between subjective and objective cognitive measures, future studies will be needed to equate these measures, particularly when they are used across research studies investigating different surgical populations.
- Selnes OA, Gottesman RF, Grega MA, Baumgartner WA, Zeger SL, McKhann GM. Cognitive and neurologic outcomes after coronary-artery bypass surgery. N Engl J Med. 2012;366(3):250-257. doi: 10.1056/NEJMra1100109
- Newman MF, Kirchner JL, Phillips-Bute B, et al. Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. N Engl J Med. 2001;344(6):395-402. doi: 10.1056/NEJM200102083440601
- Saczynski JS, Marcantonio ER, Quach L, et al. Cognitive trajectories after postoperative delirium. N Engl J Med. 2012;367(1):30-39. doi: 10.1056/NEJMoa1112923
- Namirembe GE, Baker S, Albanese M, et al. Association Between Postoperative Delirium and Long-Term Subjective Cognitive Decline in Older Patients Undergoing Cardiac Surgery: A Secondary Analysis of the Minimizing Intensive Care Unit Neurological Dysfunction with Dexmedetomidine-Induced Sleep Trial. J Cardiothorac Vasc Anesth. 2023;37(9):1700-1706. doi: 10.1053/j.jvca.2023.04.035
- Shelton KT, Qu J, Bilotta F, et al. Minimizing ICU Neurological Dysfunction with Dexmedetomidine-induced Sleep (MINDDS): protocol for a randomised, double-blind, parallel-arm, placebo-controlled trial. BMJ Open. 2018;8(4):e020316. doi: 10.1136/bmjopen-2017-020316
- Qu JZ, Mueller A, McKay TB, et al. Nighttime dexmedetomidine for delirium prevention in non-mechanically ventilated patients after cardiac surgery (MINDDS): A single-centre, parallel-arm, randomised, placebo-controlled superiority trial. EClinicalMedicine. 2023;56:101796. doi: 10.1016/j.eclinm.2022.101796
Johnson-Akeju, Oluwaseun. Postoperative Delirium and Long-Term Subjective Cognitive Decline After Cardiac Surgery, Network for Investigation of Delirium: Unifying Scientists (NIDUS); October, 2023, Available at: https://deliriumnetwork.org/postoperative-delirium-and-long-term-subjective-cognitive-decline-after-cardiac-surgery/ (accessed today’s date)