Association of preoperative vitamin D deficiency with the risk of postoperative delirium and cognitive dysfunction: A meta-analysis

Study objective: Despite vitamin D deficiency (VDD) associated with cognitive dysfunction in the general population, the impacts of preoperative VDD on postoperative delirium (POD) and cognitive dysfunction (POCD) remain to be clarified. Design: Meta-analysis of cohort studies. Setting: Postoperative care. Intervention: Preoperative VDD as the prognostic factor. Patients: Adult patients undergoing surgery. Measurements: Databases including MEDLINE, EMBASE, Google scholar, and the Cochrane Library databases were searched from inception to September 2021. Random-effects modeling was applied to the pooling of results on the association between preoperative VDD and POD/POCD. The primary outcome was the association of VDD with the risk of POD/POCD, while the secondary outcomes included other prognostic factors (e.g., hypertension) with the risk of POD/POCD. A prediction interval (PI) was calculated to indicate the range of a true effect size of a future study in 95% of all populations. Main results: Meta-analysis of seven observational studies involving 2673 patients showed that the pooled incidence of POD/POCD was 29% (95% confidence interval (CI): 18% to 44%). Our results demonstrated that preoperative VDD increased the risk of POD/POCD [odds ratio (OR) = 1.54, 95% CI: 1.21-1.97, p < 0.01; I-2 = 29.2%, seven studies, 2673 patients; 95% PI: 0.89-2.67], while vitamin D insufficiency was not associated with a higher risk of POD/POCD (OR = 0.88, 95% CI: 0.49-1.57, p = 0.66; I-2 = 62.6%, four studies, 1410 patients; 95% PI: 0.09-8.79). The PI in our primary outcome (i.e., 0.89 to 2.67) containing 1.0 suggested the possibility of inconsistent results in future studies. Patients with POD/POCD were older compared to those without. Hyper -tension, diabetes mellitus, male gender, or smoking was not recognized as risk factors for POD/POCD. Conclusions: Our results demonstrated that preoperative vitamin D deficiency was associated with postoperative cognitive impairment. Given the prediction interval, more future studies are needed to elucidate associations between VDD and POD/POCD.

Automated summary

This meta-analysis examined the association between preoperative vitamin D deficiency and postoperative delirium and cognitive dysfunction. The results showed that preoperative vitamin D deficiency was associated with a higher risk of postoperative delirium and cognitive dysfunction.