Body mass index and calprotectin blood level correlation in healthy children: an individual patient data meta-analysis

Background: Calprotectin (CP) is a protein complex involved in many inflammatory diseases. Obesity is characterized by low-grade inflammation and elevated circulating levels of calprotectin. However, associations between body mass index (BMI) and calprotectin levels have not been explored in otherwise healthy children. Methods: In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched PubMed and Cochrane Library database up to July 2019. Healthy children's blood calprotectin values were extracted, and potential correlations were explored. Results: A total of six studies that included data on 593 healthy children were identified. Median calprotectin value was 900.0 (482.0; 1700) ng.mL(-1). Multivariable analysis showed no significant associations with age, sample type (serum vs. plasma), or sex. In contrast, a significant effect of BMI z-score (p < 0.001) emerged. Indeed, a positive correlation between BMI z-score and CP, was detected in girls (R: 0.48; p < 0.001) and boys (R: 0.39; p < 0.001). Conclusion: Calprotectin blood levels correlate with the degree of adiposity in healthy children, but are not affected by age, sex, or sample type (serum or plasma).