It remains unclear whether melatonin and its analogues prevent postoperative delirium (POD). Therefore, we conducted a systematic review and meta-analysis to evaluate the effect of melatonin and its analogues on POD prevention. PubMed, Cochrane Library, Web of Science, Embase and CINAHL databases were searched. Primary outcome was the incidence of POD. Six randomized controlled trials, 2 cohort studies and 1 case-control study were included in this meta-analysis. Results showed that melatonin and its analogue ramelteon decreased the incidence of POD in the entire adult surgical population (odds ratio [OR] = 0.45, 95% confidence interval [CI] 0.24-0.84, P = .01). When administered at a higher dose (5 mg), melatonin was effective in reducing the POD incidence (OR = 0.32, 95% CI 0.20-0.52, P < .00001). Melatonin administered less than 5 elimination half-lives before the surgery significantly reduced the POD incidence (OR = 0.31, 95% CI 0.19-0.49, P < .00001). Current literature supports the effectiveness of melatonin and its analogue ramelteon in POD prevention. However, the present study was limited by the significant heterogeneity of the included studies. More studies are needed to ascertain the preventive effect of melatonin and its analogues on the incidence of delirium after cardiac and noncardiac surgeries.

中文翻译：

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褪黑素及其类似物用于预防术后ir妄：系统评价和荟萃分析。

尚不清楚褪黑激素及其类似物是否可预防术后（妄（POD）。因此，我们进行了系统的综述和荟萃分析，以评估褪黑激素及其类似物对POD预防的作用。搜索PubMed，Cochrane图书馆，Web of Science，Embase和CINAHL数据库。主要结局是POD的发生率。这项荟萃分析包括六项随机对照试验，两项队列研究和一项病例对照研究。结果表明，褪黑素及其类似物雷米替尼降低了整个成年外科手术人群中POD的发生率（优势比[OR] = 0.45，95％置信区间[CI] 0.24-0.84，P = .01）。当以较高剂量（5 mg）给药时，褪黑激素可有效降低POD发生率（OR = 0.32，95％CI 0.20-0.52，P <.00001）。褪黑素在手术前不到5个消除半衰期，可显着降低POD发生率（OR = 0.31，95％CI 0.19-0.49，P <.00001）。目前的文献支持褪黑激素及其类似的雷米替丁在预防POD中的有效性。但是，本研究受到纳入研究的显着异质性的限制。需要更多的研究来确定褪黑素及其类似物对心脏和非心脏手术后ir妄的预防作用。