Significant independent predictors of worse CFS were N1 (HR = 6.19; p = 0.002), GS ≥ 8 (HR = 13.43; p = 0.01) and CCL2 ≥ 280 pg/dL (HR = 6.21; p = 0.003) in univariate analysis. This evidence concerns the gene CCL2 and myalgic encephalomeyelitis/chronic fatigue syndrome.