The Association between Serum Level of Folate and Vitamin C with Length of Hospital Stay (LOS) in Hospitalized Patients: A Retrospective Cross-Sectional Study.

The association between serum level of folate and length of hospital stay (LOS) remains unclear. Adult participants were retrospectively recruited from two teaching hospitals in Shanghai, China. Serum level of folate and vitamin C were measured within three days after hospital admission. LOS was defined as the interval between admission and discharge. Patients were classified into tertile groups based on serum level of folate to assess the association with LOS. We further re-analyzed the association between serum level of folate and LOS under different serum level of vitamin C (also divided into tertile groups). A total number of 9,645 patients were included. Each standard deviation (SD) increase in serum level of folate was associated with 0.41 d (95% CI: -0.73 d, -0.09 d) decrease in LOS in the crude model; however, it lost significance after full adjustment. Taken the interaction effect of vitamin C into consideration, serum level of folate was inversely associated with LOS in those whose serum level of vitamin C was higher than 41.6 μmol/L. Serum level of folate was inversely associated with LOS, but the association was limited to patient with high vitamin C level.