Original articleIncreases in pre-hospitalization serum 25(OH)D concentrations are associated with improved 30-day mortality after hospital admission: A cohort study

SummaryContextPre-hospital vitamin D status may be a modifiable risk factor for all-cause mortality among hospitalized patients.ObjectiveTo examine the association between increases in serum 25-hydroxyvitamin D [25(OH)D] levels during the year before hospitalization and risk of 30-day all-cause mortality after hospital admission.DesignRetrospective cohort study.SettingTwo Boston teaching hospitals.Patients or other participantsWe studied 4344 adults hospitalized between 1993 and 2011 who had serum 25(OH)D concentrations measured at least twice within 7-365 days before the index hospitalization.Intervention(s)None.Main outcome measure(s)The exposure of interest was change in pre-hospital serum 25(OH)D concentrations. The main outcome was 30-day all-cause mortality. We used mixed-effects logistic regression to describe how 30-day mortality differed with changes in pre-hospital 25(OH)D concentrations. Additionally, the odds of 30-day mortality in patients with pre-hospital 25(OH)D increases of ≥10 ng/mL was compared to that of patients with increases of <10 ng/mL.ResultsIn a mixed-effect logistic regression model adjusted for age, gender, race, type (medical/surgical), Deyo-Charlson Index, creatinine and hematocrit, 30-day all-cause mortality rate was 8% (95%CI: 1-15) lower for each 10 ng/mL increase in pre-hospital 25(OH)D (P = 0.025) compared with the 30-day all-cause mortality rate in the entire cohort. In an adjusted logistic regression model, absolute changes of ≥10 ng/mL in patients with initial 25(OH)D concentrations < 20 ng/mL (n = 1944) decreased the odds of 30-day all-cause mortality by 48% (adjusted OR 0.52; 95%CI 0.30-0.93; P = 0.026) compared to patients with changes of <10 ng/mL.ConclusionsIn patients with initial 25(OH)D < 20 ng/mL, subsequent improvements in vitamin D status before hospitalization are associated with decreased odds of 30-day all-cause mortality after hospital admission. A causal relation may not be inferred from this observational study.