CRP and appendicitis: A combination of CRP, WCC and neutrophils (five studies, 1410 patients, 506 appendicitis) showed a range of sensitivities (0.43–0.86) but specificity was generally high (0.81–0.91) and one study evaluated the or combination with a sensitivity of 1.00 (95% CI 0.97 to 1.00) and specificity of 0.25 (95% CI 0.20 to 0.30) (online supplemental figure 8).