Hypocalcaemia tied to mid-, long-term death in acute pulmonary thromboembolism

Low serum calcium in patients with acute pulmonary thromboembolism (PTE) independently predicts 30-day and long-term mortality, suggests a China study that used a new prognosis assessment model.

“The Peking Union Medical College Hospital (PUMCH) rule showed significantly higher specificity than the pulmonary embolism severity index (PESI) and simplified PESI (sPESI) and similar sensitivity, which may be used as a prognostic assessment tool for patients with acute PTE,” the researchers said.

Yu-Qing Yang, from the State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing, China, led this observational, multicentre study that enrolled 4,196 patients with PTE from February 2010 to June 2020 across 12 Chinese hospitals.

Yang and colleagues collected variables in PESI, serum calcium levels, and patient survival status as of 5 July 2020. They also assessed the performance of the model using the area under the receiver operating characteristic curve, sensitivity, specificity, and Youden index.

Hypocalcaemia was found to be independently associated with mid- and long-term mortality (p<0.05). Including hypocalcaemia in the PUMCH rule, the new 30-day death risk prediction rule demonstrated significantly higher specificity (0.622; p<0.001) than PESI (0.514) and sPESI (0.484) in the internal validation cohort. [Respirology 2022;27:645-652]

The PUMCH rule also showed similar sensitivity (0.963; p=0.161) with PESI (0.889) and sPESI (0.963). In addition, well-performing predictive validity was verified on a constructed external validation cohort.

These findings are consistent with those of previous studies, which reported the association of lower serum calcium levels with higher short- and long-term mortality in PTE patients. [Respir Res 2020;21:1-9; BMC Pulm Med 2021;21:410; Med J PUMCH 2020;11:144-150; BMJ Open 2020;10:e034325]

The researchers offered two possible explanations. First, hypocalcaemia may influence the role of calcium in platelet function and the coagulation cascade, leading to an increase in mortality. Second, hypocalcaemic patients tend have more severe complications such as acute respiratory failure, acute kidney injury, cardiac arrhythmia, and seizures. [BMC Pulm Med 2021;21:410; Osteoporos Rep 2017;15:214-221]

“The higher mortality of PTE patients with hypocalcaemia may be the result of higher number of complications, more severe disease conditions, and worse overall health status,” the researchers said.

“Our data also showed that hypocalcaemia is independently associated with mid- and long-term mortalities of patients with PTE, not the short-term mortality, which means that hypocalcaemia may serve as a marker of overall health status and mainly affect mid- or long-term prognoses,” they added.

Thirty-day mortality was also predicted independently by the following factors: male sex, older age, altered mental status, chronic heart failure, chronic pulmonary disease, cancer, higher pulse rate, lower systolic blood pressure, and lower arterial oxyhaemoglobin saturation. This finding supports that of previous literature reports. [Eur Heart J 2020;41:543-603; J Thromb Haemost 2010;8:1509-1514; Am J Respir Crit Care Med 2014;189:718-726; Respir Res 2020;21:1-9]

“Whether calcium supplementation can improve a patient's prognosis requires further investigation,” the researchers said.