Calcium supplementation prolongs the time of hospitalization and has a double effect on mortality in septic patients: A retrospective study from MIMIC-III

Abstract Background Hypocalcemia is a common electrolyte disturbance in sepsis, calcium administration in those patients remains a controversial issue. The aim of this study was to assess the association of calcium supplementation with the time of hospitalization and mortality in septic patients. Method 5761 eligible septic patients, including 2689 with calcium supplementation and 3072 without calcium supplementation, were extracted from the MIMIC-III database. A total of 1463 pair patients were included in the analysis after propensity score matching according to the age, sex, SOFA score and lactate on first ICU admission. We compared the length of stay (LOS) in the intensive care unit (ICU) and hospital, as well as the 28-day and hospital mortality, which stratified the analysis according to the Sequential Organ Failure Assessment (SOFA) score, and the iCa on the first ICU admission between the matched groups. Results The results showed that either a too-low or a too-high iCa increased the risk for septic patients, but the minimum of the mortality curve in the non-calcium supplement group was locally in the mild hypocalcemia range. Regardless of the SOFA score and iCa, the LOS in both the ICU and hospital were higher in the calcium supplement group than in the non-calcium supplement group. Overall, the 28-day and hospital mortality were greater but not statistically significant in the calcium supplement group than in the non-calcium supplement group (14.83% vs 13.39%, p=0.416; 16.20% vs 13.88%, p=0.079, respectively). However, the survival analysis stratified by SOFA score showed that calcium supplementation reduced mortality when the patient’s SOFA score was >8 (p=0.028), while it worsen the outcome when the SOFA score was ≤4 (p<0.001) and had no significant effect with SOFA scores from 5~8 (p=0.556). Conclusion Our findings suggest that mild hypocalcemia may be protective in septic patients and that calcium supplementation may prolong hospitalization and have a double effect on mortality. The SOFA score may be a valuable clinical index for calcium administration decision making.