Evaluating the prognostic value of admission IL-8 and sST2 as biomarkers of early myocardial injury in severe community-acquired pneumonia.
Myocardial injury in severe community-acquired pneumonia (SCAP) is often under-recognized, and interpretation of high-sensitivity cardiac troponin I (hs-cTnI) may be complicated by renal dysfunction and critical illness. We evaluated whether admission interleukin-8 (IL-8) and soluble suppression of tumorigenicity 2 (sST2) could support early risk stratification of guideline-consistent myocardial injury in patients with SCAP.
In this prospective cohort of 146 patients with SCAP, guideline-consistent myocardial injury was defined as hs-cTnI elevation above the assay-specific 99th percentile upper reference limit. Admission IL-8, sST2, and their combination were assessed using receiver operating characteristic curve analysis and 10-fold cross-validation. Fixed and estimated glomerular filtration rate (eGFR)-stratified hs-cTnI thresholds were compared in an exploratory analysis. An exploratory subgroup analysis was performed among patients with CURB-65 ≤ 1.
The median age was 71 years; 91 patients (62.3%) were male and 55 (37.7%) were female. Myocardial injury occurred in 88 patients (60.3%). The IL-8 + sST2 model showed good discrimination for myocardial injury, with an AUC of 0.825 (95% CI: 0.751-0.895) and an internally cross-validated AUC of 0.812. Admission IL-8 showed stronger individual discrimination than sST2. eGFR-stratified hs-cTnI thresholds did not reduce discordant hs-cTnI elevations in this cohort, likely because few patients had moderate-to-severe renal dysfunction. Among patients with CURB-65 ≤ 1 (n = 38), IL-8 > 43.53 pg/mL was associated with a higher prevalence of myocardial injury (76.2% vs. 29.4%, p = 0.004). An exploratory 0-2 biomarker score showed a graded increase in myocardial injury prevalence across score categories: 15.4%, 62.5%, and 78.6%.
Admission IL-8 was associated with guideline-consistent myocardial injury in patients with SCAP, whereas sST2 showed weaker individual discrimination. The combined model had numerically higher discrimination than IL-8 alone, but the incremental contribution of sST2 remains uncertain. These findings represent an initial evaluation and require external validation before clinical implementation.
In this prospective cohort of 146 patients with SCAP, guideline-consistent myocardial injury was defined as hs-cTnI elevation above the assay-specific 99th percentile upper reference limit. Admission IL-8, sST2, and their combination were assessed using receiver operating characteristic curve analysis and 10-fold cross-validation. Fixed and estimated glomerular filtration rate (eGFR)-stratified hs-cTnI thresholds were compared in an exploratory analysis. An exploratory subgroup analysis was performed among patients with CURB-65 ≤ 1.
The median age was 71 years; 91 patients (62.3%) were male and 55 (37.7%) were female. Myocardial injury occurred in 88 patients (60.3%). The IL-8 + sST2 model showed good discrimination for myocardial injury, with an AUC of 0.825 (95% CI: 0.751-0.895) and an internally cross-validated AUC of 0.812. Admission IL-8 showed stronger individual discrimination than sST2. eGFR-stratified hs-cTnI thresholds did not reduce discordant hs-cTnI elevations in this cohort, likely because few patients had moderate-to-severe renal dysfunction. Among patients with CURB-65 ≤ 1 (n = 38), IL-8 > 43.53 pg/mL was associated with a higher prevalence of myocardial injury (76.2% vs. 29.4%, p = 0.004). An exploratory 0-2 biomarker score showed a graded increase in myocardial injury prevalence across score categories: 15.4%, 62.5%, and 78.6%.
Admission IL-8 was associated with guideline-consistent myocardial injury in patients with SCAP, whereas sST2 showed weaker individual discrimination. The combined model had numerically higher discrimination than IL-8 alone, but the incremental contribution of sST2 remains uncertain. These findings represent an initial evaluation and require external validation before clinical implementation.