Neutrophil-to-Lymphocyte Ratio and System Score Could Predict the Occurrence of Macrophage Activation Syndrome in Patients with Adult-Onset Still's Disease.

Objective: To investigate the characteristics of Adult-onset Still's disease (AOSD) patients with macrophage activation syndrome (MAS) and explore the risk factors for the development of MAS.

Study design: A case-control study. Place and Duration of the Study: Department of Rheumatology and Immunology, the Second Hospital of Anhui Medical University, Anhui, China, from January 2008 to June 2024.

Methodology: AOSD patients with MAS (AOSD-MAS) and without MAS (AOSD-nonMAS) were compared. Clinical features and laboratory results from two groups were analysed using the independent samples t-test or Mann-Whitney U test. Fisher's exact test or Pearson's Chi-square test was used to compare the variables between the two groups. The multivariable logistic regression analysis was applied to identify AOSD with MAS-associated factors. The value of risk factors in predicting MAS occurrence was carried out by a receiver operating characteristic validation analysis.

Results: MAS patients showed higher prevalence of sore throat, splenomegaly and abnormal liver function, a lower prevalence of arthrodynia and higher levels of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, alanine aminotransferase, aspartate aminotransferase, lactic dehydrogenase, serum ferritin, D-Dimer levels, and a higher AOSD system score, along with a lower lymphocyte count (p <0.05). Multivariate logistic regression analysis identified NLR and AOSD system scores as predictors of MAS. An optimised threshold of 17.455 and 5.500 for NLR and AOSD system score yielded a sensitivity of 84.60% (38.50) and a specificity of 91.00%, (47.40).

Conclusion: Early detection of MAS in AOSD may be facilitated by monitoring these factors, particularly NLR and AOSD system scores.

Key words: Adult-onset still's disease, Macrophage activation syndrome, Risk factor.