Unveiling the prognostic power of D-dimer

Dear Editor, Early recognition of the severity of illness in children admitted to the Paediatric Intensive Care Unit (PICU) is essential for appropriate management and improved outcomes.[1] This study aimed to assess the efficacy of D-dimer, a biomarker associated with fibrinolysis,[2] in predicting mortality in critically ill children, Children under 15 years of age admitted to the PICU in a critical condition – such as shock, respiratory failure, status epilepticus, myocardial dysfunction, or acute kidney injury – and who tested negative for SARS-CoV-2 by RT-PCR were included in the study. The change in D-dimer values from 24 to 48 h was assessed using paired t-tests, correlations with PIM2 scores were evaluated using Pearson’s correlation coefficient, and comparisons of D-dimer and other baseline characteristics were analyzed using independent t-tests for continuous variables and Chi-square tests for categorical variables, with all analyses performed using STATA/IC 16.0. Conducted at Teaching Medical College and Tertiary Hospital from Tamilnadu, South India, from June 2021 to August 2022, this single-center prospective observational study included 90 COVID-negative children admitted to the PICU. Upon admission, D-dimer levels were measured along with the PIM2 score, a severity scoring system, and D-dimer levels were repeated at 48 h. D-dimer higher than 500 ng/mL are considered elevated. The correlation between D-dimer levels and mortality was evaluated, focusing on children with respiratory system involvement. Results showed that day 3 elevated D-dimer levels were significantly correlated with mortality in patients with primary respiratory involvement (P = 0.01; 95% confidence interval = 0.94–0.99). D-dimer on day 3 and PIM2 had a moderate correlation. However, admission day D-dimer levels did not show a statistically significant correlation with overall mortality across the broader cohort. The PIM2 score was identified as the most reliable predictor of mortality (P = 0.01). However, when it was combined with high D-dimer levels on day 3, the significance was even higher (P = 0.002). These findings suggest that while D-dimer levels on admission may not reliably predict mortality in critically ill children overall, they can serve as a valuable biomarker in those with primary respiratory system involvement. David et al. showed that the rising trend of D-dimer at 48 h had no correlation with the final outcome.[3] However, our study supports the potential role of D-dimer in improving early risk stratification, particularly for children at higher risk due to respiratory distress, while emphasizing the continued importance of the PIM2 score as a predictor of mortality in the PICU. Author's contribution statement JC: Concept, design, definition of intellectual content, literature search, data acquisition, data analysis, statistical analysis, manuscript preparation, manuscript review & guarantor. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.