Simple Blood Inflammation Score Predicts Coronary Aneurysms in Kawasaki Disease

Kawasaki disease is the leading cause of acquired heart disease in children in much of the world, and its most feared complication is the coronary artery aneurysm, a ballooning of the vessels that supply blood to the heart muscle. Once an aneurysm forms, it can persist for decades, setting the stage for stenosis, thrombosis, myocardial infarction, and sudden cardiac death even in young adulthood. The central clinical problem has always been timing: physicians must decide, within the first days of fever, which children need intensified therapy, yet the tools available to make that call are imprecise. A new study published in Pediatric Research now suggests that an inexpensive, routinely measured blood calculation, the Aggregate Index of Systemic Inflammation, may help identify which children with Kawasaki disease are most likely to develop coronary damage, offering a potential early warning signal drawn from the complete blood count that every admitted child already receives.

The research, conducted by Junxiu Liu of the Department of Child Health Care at Qianjiang Central Hospital of Chongqing, Yue Peng of the Department of Cardiovascular Medicine at the Children’s Hospital of Chongqing Medical University, and Dan Zhou of the Department of Respiratory Medicine at Qianjiang Central Hospital of Chongqing, enrolled 345 consecutive children with Kawasaki disease and examined them during the acute phase of illness. Among this cohort, 64 patients went on to develop a coronary artery aneurysm, a rate that reflects the stubborn reality that even with standard intravenous immunoglobulin therapy, a meaningful minority of affected children still sustain vascular injury. The team’s goal was not to invent a new biomarker from scratch but to test whether a composite index derived from ordinary laboratory parameters could outperform intuition and serve as a practical risk stratification instrument.

The Aggregate Index of Systemic Inflammation, commonly abbreviated AISI, is calculated by multiplying the neutrophil, platelet, and monocyte counts and dividing the product by the lymphocyte count. Each of these cellular components captures a different facet of the inflammatory response that defines Kawasaki disease. Neutrophils rise early in the illness and are implicated in the degradation of the extracellular matrix that weakens arterial walls; monocytes and their derived macrophages infiltrate the coronary vasculature and fuel the vasculitis at the heart of the disease; platelets surge in the convalescent phase and participate in the endothelial activation and prothrombotic state that characterize the disease’s vascular complications. Lymphocytes, by contrast, tend to be depleted during vigorous systemic inflammation, so a low lymphocyte count amplifies the index. By combining all four parameters, the AISI effectively integrates the intensity of innate immune activation, the prothrombotic tendency, and the immune dysregulation visible in a single routine blood draw.

Using univariable comparisons followed by multivariable logistic regression, the investigators identified three independent factors associated with coronary artery aneurysm formation. Younger age emerged as protective against the complication per unit increase in years, with an odds ratio of 0.980 and a 95 percent confidence interval of 0.966 to 0.985, a statistically significant association with a p value of 0.008. Lower serum albumin was also linked to aneurysm risk, with an odds ratio of 0.937 per unit increase and a confidence interval spanning 0.880 to 0.997, significant at p equal to 0.040. Albumin declines when inflammation becomes severe and vascular permeability increases, so hypoalbuminemia serves as a chemical mirror of inflammatory intensity and capillary leak. Most notably, the AISI itself, analyzed per 100-unit increment, carried an odds ratio of 1.045 with a 95 percent confidence interval of 1.003 to 1.089 and a p value of 0.036, indicating that each step up in the index independently raised the odds of an aneurysm even after accounting for age and nutritional markers.

To translate the continuous index into a clinically usable threshold, the team performed an exploratory analysis that yielded a cutoff value of 711.58. When the cohort was divided at this point into a low AISI group and a high AISI group, the difference in outcomes was striking: children in the high AISI group experienced coronary artery aneurysms at a significantly higher rate than those in the low AISI group, with a p value below 0.001. In practical terms, this means a pediatrician staring at a standard complete blood count on the day of admission could compute the index, compare it against the exploratory threshold, and obtain an early, data-driven estimate of the child’s likelihood of developing coronary involvement before echocardiographic changes become apparent.

The biological plausibility of the finding rests on the pathogenesis of Kawasaki disease itself. The condition is an acute, systemic vasculitis that preferentially targets medium-sized arteries, and the coronary arteries are particularly vulnerable, especially in infants and toddlers. Histopathological studies have long described panvasculitis with edema of the intima, infiltration of inflammatory cells, and fragmentation of the internal elastic lamina, processes that together permit the outward expansion of the vessel wall into an aneurysm. Oxidative stress, endothelial dysfunction, and platelet-mediated vascular inflammation have all been implicated in the progression from acute inflammation to structural arterial damage. Because neutrophils, monocytes, and platelets each participate in these cascades, a composite index that multiplies their concentrations provides a running tally of the inflammatory and thrombotic forces acting on the coronary wall, whereas lymphopenia signals the severity of the systemic immune disturbance.

The study builds on a growing literature linking derived inflammatory indices to cardiovascular outcomes in adult medicine. The AISI and its cousins, such as the systemic immune-inflammation index and the systemic inflammation response index, have been associated with clinical outcomes in acute myocardial infarction, with coronary artery calcification, with acute coronary syndrome in patients with and without diabetes, and with all-cause and cardiovascular mortality in female cancer patients, and the index has even been proposed as a predictor of mortality in stroke. Extending this framework to pediatric vasculitis represents a conceptual bridge: the same arithmetic that quantifies inflammatory burden in adult atherosclerotic disease may also capture the vasculitic intensity that drives coronary dilatation in children. Previous risk models for coronary aneurysms in Kawasaki disease, including a validated North American risk score, have relied on combinations of demographic, clinical, and laboratory variables; the appeal of the AISI lies in its simplicity and its availability at no additional cost.

The clinical implications, according to the authors, are potentially significant. The study’s impact statement notes that early identification based on the Aggregate Index of Systemic Inflammation may assist clinicians in implementing more aggressive treatment strategies, such as intravenous immunoglobulin combined with corticosteroids, thereby improving outcomes for Kawasaki disease patients. This matters because the standard regimen of intravenous immunoglobulin and aspirin fails to prevent coronary aneurysms in a substantial fraction of patients, and children who resist the first dose face difficult decisions about second-line agents, including repeat immunoglobulin, infliximab, or corticosteroids. Trials such as the KIDCARE study, which compared infliximab with a second dose of intravenous immunoglobulin in resistant cases, have refined the therapeutic arsenal, but those agents are typically deployed only after treatment failure is evident. A biomarker available on day one that flags high-risk children could shift that decision earlier, before the vascular injury has begun to accrue, which is precisely the window in which intensified therapy is believed to be most effective.

The authors are careful to frame their findings within the study’s design. The work was retrospective, drawing on records from consecutive patients at their institutions, and the cutoff of 711.58 is explicitly described as exploratory, meaning it will require validation in independent, ideally prospective, and ethnically diverse cohorts before it can be embedded in clinical guidelines. Albumin and age also entered the final model, suggesting that the AISI is best understood as one component of a broader risk picture rather than a stand-alone verdict. Nevertheless, the strength of the association, the significance across multiple independent variables, and the stark difference in aneurysm rates between high and low index groups give the finding real weight. The datasets generated in the study are available from the corresponding author on reasonable request, and the work was approved by the hospital’s Research Ethics Committee with waived informed consent, with no competing interests declared.

For a disease that was first described more than half a century ago and that continues to puzzle researchers with an unclear cause, the prospect of extracting actionable risk information from a routine blood count is a reminder that progress does not always require new molecules or expensive assays. Sometimes it requires looking harder at the data already in hand. If future validation confirms the exploratory threshold identified by Liu, Peng, and Zhou, the Aggregate Index of Systemic Inflammation could become a standard part of the acute Kawasaki disease assessment, helping clinicians worldwide decide within hours which febrile child needs the most aggressive anti-inflammatory therapy, and which can be managed with confidence under the conventional regimen. In the meantime, the study adds Kawasaki disease to the expanding list of inflammatory cardiovascular conditions for which a four-cell arithmetic snapshot of the immune system carries genuine prognostic power.

Subject of Research: The association between the Aggregate Index of Systemic Inflammation and coronary artery aneurysm formation in children with acute Kawasaki disease.

Article Title: Association of the Aggregate Index of Systemic Inflammation with coronary artery aneurysm in Kawasaki disease patients

Article References: Liu, J., Peng, Y., & Zhou, D. (2026). Association of the Aggregate Index of Systemic Inflammation with coronary artery aneurysm in Kawasaki disease patients. Pediatric Research. https://doi.org/10.1038/s41390-026-05500-8

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05500-8

Keywords: Kawasaki disease, coronary artery aneurysm, Aggregate Index of Systemic Inflammation, AISI, pediatric cardiology, vasculitis, inflammation biomarker, complete blood count, intravenous immunoglobulin, serum albumin, risk prediction, children