Clinical and laboratory predictors of long-COVID in children: a single center retrospective study

The majority of children experience a mild course of acute Coronavirus Disease 2019 (COVID-19). Only few studies have looked at long-term recovery from COVID-19 infection in children. The purpose of this study was to identify the predictors of long-COVID by performing a thorough analysis of the clinical, laboratory, and demographic characteristics of children with COVID-19.

Between August and October 2021, data were obtained retrospectively from the medical records of 251 children diagnosed with COVID-19 at a tertiary single-center hospital. The prognostic effects of admission-related factors were compared between patients who experienced long-lasting symptoms and those who did not.

Long-COVID symptoms were noted in 12.4% of patients. Joint pain (7.6%), lumbago (4.8%), and headache (3.2%) were the most common symptoms. The mean onset of long-COVID symptoms was 1.35±0.49 months. The onset of long-COVID symptoms was 4 weeks after initial diagnosis in 64.5% of patients and 4-8 weeks later in 35.5% of the patients. The mean duration of long-COVID symptoms was 5.32±2.51 months. Children with long-COVID had higher leukocytes, neutrophils, monocytes, basophils, platelets, and D-dimer when compared with patients without long-COVID (p < 0.001). Leukocytes, neutrophils, monocytes, platelets, and D-dimer had the highest AUC in the ROC analysis (0.694, 0.658, 0.681, 0.667, and 0.612, respectively) and were statistically significant.

Despite the majority of children with COVID-19 having mild or asymptomatic acute disease, the majority of long-COVID symptoms were associated with functional impairment between 1 and 9 months after the start of the infection. Increased leukocytes, monocytes, neutrophils, platelets, and D-dimer appear to be the most powerful laboratory predictors for long-COVID and monitoring these predictors may assist clinicians to identify and follow-up patients with higher risk for long-COVID.