CRP and atrial fibrillation: For detection of imminent preterm delivery, the sensitivity of plasma IL-6 was not significantly different from that of AF IL-6 (P = 0.508) or CRP (P = 0.289), whereas the specificity of plasma IL-6 was significantly better than that of CRP (P < 0.001) but not significantly different from that of AF IL-6 (P = 1.000).