CRP and infection: Both serum CRP and ESR were useful in ruling in infection where the specificity was 88.7% (95% confidence interval, 78.5–94.7%) and 84.5%(95% confidence interval 73.5–91.6%); while they had poor utility in ruling out infection with sensitivity that was only 40% (95% confidence interval, 13.7–72.6%) and 50% (95% confidence interval, 20.1–80.0%) (Table 4).