Background: Postoperative delirium (POD) is a serious problem affecting 15%-53% of older adults after surgery and 70%-87% of patients in intensive care units. POD is characterized by restlessness, irritability, difficulty focusing, hallucination, and slurred speech. Intranasal insulin (INI) is a new therapy that may have a protective effect against perioperative neurocognitive disorders by regulating key physiological processes.
Method: We conducted a systematic review and meta-analysis to determine the efficacy of perioperative administration of INI in reducing the incidence of POD and postoperative cognitive dysfunction (POCD) and its effects on inflammatory biomarkers. A comprehensive search on 4 databases was conducted to retrieve the relevant articles. Using a random-effects model, data were pooled as risk ratios (RR) or mean differences (MD) with 95% confidence intervals (CI).
Results: Seven studies conducted in China with 732 postoperative patients were included. INI significantly reduced the incidence of POD (RR = 0.39, 95% CI [0.23, 0.66]) and POCD (RR = 0.51, 95% CI [0.30-0.88]) compared with placebo. INI also significantly lowered mean postoperative interleukin-6 (IL-6) at the end of the surgery (MD = -3.92), on postoperative day 1 (MD = -3.57), and day 3 (MD = -3.92), as well as tumor necrosis factor-α (TNF-α) at the end of the surgery (MD = -3.81), on day 3 (MD = -2.83) and day 5 (MD = -1.19). No hypoglycemic reaction or serious adverse events were reported.
Conclusion: Our meta-analysis showed that INI is a promising therapy for reducing the incidence of POD and POCD as well as decreasing postoperative inflammatory factors. However, more multicenter studies outside China, with large sample sizes are needed to determine the optimal formulation, dose, timing, and frequency of INI.
Keywords: Delirium; cognitive dysfunction; insulin; meta-analysis.
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