Association between vitamin D concentration and delirium in hospitalized patients: A meta-analysis

BACKGROUND: Now the occurrence of delirium is more concerning to clinicians and psychiatrists. It has been reported that vitamin D deficiency may be a relevant factor in the development of delirium in hospitalized patients. STUDY OBJECTIVE: To investigate the association between vitamin D concentration and delirium in hospitalized patients. DESIGN: Meta-analysis. METHODS: A systematic literature search was conducted using PubMed, EMBASE, and the Cochrane Library. The primary outcome was the occurrence of delirium in the inpatient setting. Odds ratios (OR) were calculated with random or fixed effects models. RESULTS: In this article, we define the normal range of vitamin D concentrations as greater than 75 nmol / L, 50–75 nmol / L as vitamin D insufficiency, 25–50 nmol / L as vitamin D deficiency, and less than 25 nmol / L as vitamin D severe deficiency. The Results showed that severe vitamin D deficiency (OR: 1.98 [1.41–2.79], P<0.001) and vitamin D deficiency (OR: 1.50 [1.12–2.00], P = 0.006) were more likely to develop delirium than normal vitamin D levels. Subgroup analysis also revealed that low vitamin D concentrations were associated with a higher incidence of delirium, whether the cutoff point was 25 nmol/L (OR: 1.52 [1.40–1.64], P<0.001), 50 nmol/L (OR: 1.47 [1.19–1.82], P<0.001), or 75 nmol/L (OR: 1.54 [1.21–1.96], P<0.001). The included studies scored medium and high on the Newcastle-Ottawa quality assessment scale. CONCLUSION: Compared with normal vitamin D levels, severe vitamin D deficiency and vitamin D deficiency, but not vitamin D insufficiency, are associated with a higher incidence of delirium in hospitalized patients. TRIAL REGISTRATION: This review was registered in the PROSPERO database under identifier CRD42021271347. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021271347.