Usefulness of Neutrophil to Lymphocyte Ratio in Prediction of Coronary Artery Lesions in Patients with Kawasaki Disease

Kawasaki disease (KD) is a systemic febrile condition leading to the inflammation of vessels including coronary arteries (1). Coronary artery aneurysms, occuring in approximately 15–25% of the patients, are the most important and life-threatening complication of KD (2). KD mainly affects children younger than five years old. Although it has been known for years, the etiology of the disease remains largely unexplained (3,4). Due to the lack of specific tools, the diagnosis of KD is still based on clinical features. At least four of the following five clinical criteria together with fever lasting equal to or longer than five days should be present for the diagnosis: bilateral non-purulent conjunctivitis; extremity findings including erythema and/or indurative edema on the hands and feet, and membranous desquamation starting in the periungual regions; changes in the lips and oral cavity; polymorphous exanthema; and cervical lymphadenopathy (usually unilateral with a diameter of 1.5 cm or more). However, those patients with prolonged fever (≥5 days) together with two or three clinical criteria may be diagnosed as incomplete KD in the presence of some supplemental laboratory findings (5). It has been reported increasingly in recent years, especially among young infants and children. Because incomplete KD also results in coronary artery lesions (CALs), it should be diagnosed promptly (5,6). However, the diagnosis is still difficult and further laboratory studies are needed. Neutrophil to lymphocyte ratio (NLR) is a novel parameter, studied in the conditions with inflammatory pathogenesis including ischemic heart disease, stroke, and infections (7–9). It was reported to be a strong predictor of adverse cardiovascular outcome and severity of coronary artery ectasia in adult population (10–12). In this study, the usefulness of NLR in the diagnosis of KD or incomplete KD and the correlation between NLR and the presence of coronary artery lesions were evaluated. The usefulness of NLR has not been studied in patients with KD so far.