Hospital mortality and long-term mortality among hospitalized patients with various admission serum ionized calcium levels
We conducted a single-center historical cohort study to evaluate the association between admission serum ionized calcium and mortality in hospitalized patients.
We included hospitalized patients from January 2009 to December 2013 who had available serum ionized calcium at the time of admission. We assessed the in-hospital and 1-year mortality risk based on admission serum ionized calcium using multivariate logistic and Cox proportional hazard analysis, respectively. To test non-linear association, we categorized serum ionized calcium into six groups; ≤4.39, 4.40–4.59, 4.60–4.79, 4.80–4.99, 5.00–5.19, ≥5.20 mg/dL and selected serum ionized calcium of 4.80–4.99 mg/dL as a reference group.
We studied a total of 33,255 hospitalized patients. The mean admission serum ionized calcium at 4.8 ± 0.4 mg/dL. Hospital and 1-year mortality observed in 1,099 (3%) and 5,239 (15.8%), respectively. We observed a U-shaped association between admission serum ionized calcium and in-hospital and 1-year mortality. Ionized calcium lower threshold for increased in-hospital and 1-year mortality rates was ≤4.59 and ≤4.39 mg/dL, respectively. Ionized calcium upper threshold for increased in-hospital and 1-year mortality rates was ≥5.20 mg/dL.
Both hypocalcemia and hypercalcemia were associated with increased short- and long-term mortality with a U-shape relationship.