Background: Cardiac injury is frequently encountered in patients with coronavirus disease 2019 (COVID-19) and is associated with increased risk of mortality. Elevated troponin may signify myocardial damage and is predictive of mortality. This study aimed to assess the prognostic value of troponin above the 99th percentile upper reference limit (URL) for mortality, and factors affecting the relationship.
Methods: A comprehensive literature search of PubMed (MEDLINE), Scopus and Embase was undertaken, from inception of the databases until 16 December 2020. The key exposure was elevated serum troponin, defined as troponin (of any type) above the 99th percentile URL. The outcome was mortality due to any cause.
Results: In total, 12,262 patients from 13 studies were included in this systematic review and meta-analysis. The mortality rate was 23% (20-26%). Elevated troponin was observed in 31% (23-38%) of patients. Elevated troponin was associated with increased mortality [odds ratio (OR) 4.75, 95% confidence interval (CI) 4.07-5.53; P < 0.001; I2 = 19.9%]. Meta-regression showed that the association did not vary with age (P = 0.218), male gender (P = 0.707), hypertension (P = 0.182), diabetes (P = 0.906) or coronary artery disease (P = 0864). The association between elevated troponin and mortality had sensitivity of 0.55 (0.44-0.66), specificity of 0.80 (0.71-0.86), positive likelihood ratio of 2.7 (2.2-3.3), negative likelihood ratio of 0.56 (0.49-0.65), diagnosis odds ratio of 5 (4-5) and area under the curve of 0.73 (0.69-0.77). The probability of mortality was 45% in patients with elevated troponin and 14% in patients with non-elevated troponin.
Conclusion: Elevated troponin was associated with mortality in patients with COVID-19 with 55% sensitivity and 80% specificity.