Background

The association between preoperative cognitive impairment, postoperative pain, and postoperative delirium in older patients after noncardiac surgery is not known.

Methods

This was a secondary analysis of datasets from three previous studies. Patients aged ≥55 yr who underwent elective noncardiac surgery were enrolled. Preoperative cognitive impairment was defined as Mini-Mental State Examination <27. Pain intensity with movement was assessed using an 11-point numeric rating scale at 12-h intervals during the first 72 h after surgery; time-weighted average (TWA) pain score was calculated. Primary outcome was the occurrence of delirium within the first 5 postoperative days. Mediation analysis was used to investigate the relationships between cognitive impairment, pain score, and delirium.

Results

A total of 1497 patients were included. Prevalence of preoperative cognitive impairment was 40.3% (603/1497). Patients with cognitive impairment suffered higher TWA pain score within 72 h (4 [3–5] vs 3 [2–5], P=0.004) and more delirium within 5 days (12.9% [78/603] vs 4.9% [44/894], P<0.001) when compared with those without. Total and direct associations between cognitive impairment and delirium were (adjusted β) 8.3% (95% confidence interval [CI], 4.8–12.0%; P<0.001) and 7.8% (95% CI, 4.4–12.0%; P<0.001), respectively. A significant indirect association with acute pain was observed between cognitive impairment and delirium (adjusted β=0.4%; 95% CI, 0.1–1.0%; P=0.006), accounting for 4.9% of the total effect.

Conclusions

The association between preoperative cognitive impairment and delirium is significantly mediated by acute pain in patients after noncardiac surgery. Considering the small effect size, clinical significance of this mediation effect requires further investigation.

中文翻译：

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急性疼痛对术前认知障碍和术后谵妄之间关联的影响：三项试验的二次分析

背景

老年患者非心脏手术后术前认知障碍、术后疼痛和术后谵妄之间的关系尚不清楚。

方法

这是对之前三项研究的数据集的二次分析。年龄≥55 岁且接受择期非心脏手术的患者被纳入。术前认知障碍定义为简易精神状态检查<27。在手术后的前 72 小时内，以 12 小时为间隔使用 11 点数字评定量表评估运动时的疼痛强度；计算时间加权平均 (TWA) 疼痛评分。主要结果是术后前 5 天内发生谵妄。中介分析用于调查认知障碍、疼痛评分和谵妄之间的关系。

结果

共纳入 1497 名患者。术前认知障碍的患病率为 40.3% (603/1497)。认知障碍患者在 72 小时内经历了更高的 TWA 疼痛评分（4 [3-5] vs 3 [2-5]，P = 0.004）并且在 5 天内出现了更多的谵妄（12.9% [78/603] vs 4.9% [44 /894]，P <0.001）与那些没有的人相比。认知障碍和谵妄之间的总关联和直接关联（调整后的 β）分别为 8.3%（95% 置信区间 [CI]，4.8–12.0%；P <0.001）和 7.8%（95% CI，4.4–12.0%；P <0.001 ） ）， 分别。在认知障碍和谵妄之间观察到与急性疼痛的显着间接关联（调整后的 β = 0.4%；95% CI，0.1–1.0%；P=0.006)，占总效应的4.9%。

结论

非心脏手术后患者的急性疼痛显着介导术前认知障碍和谵妄之间的关联。考虑到效应量较小，这种中介效应的临床意义需要进一步研究。