Ten studies met the inclusion criteria. Eight studies evaluated IL-6 (n=415, range 24 to 117). Five studies evaluated IL-8 (n=299, range 38 to 117). All included studies reported selection criteria, recruited an appropriate patient spectrum and avoided verification and progression biases. None of the studies was blinded. No intermediate results or withdrawals were reported. Results for the test for heterogeneity were presented only for sensitivity and specificity; where reported, I2 was over 50% on day one and reduced to 20% or less on days two and three.
IL-6:
Pooled estimates for day one (seven studies) were: sensitivity 84% (95% CI 77% to 89%), specificity 76% (95% CI 70% to 81%), positive predictive value 68% (95% CI 61% to 75%), negative predictive value 88% (95% CI 83% to 92%), LR+ 3.43 (95% CI 2.51 to 4.60) and DOR 13.5 (95% CI 7.0 to 25.8).
Pooled estimates for day two (four studies) were: sensitivity 72% (95% CI 60% to 81%), specificity 85% (95% CI 77% to 91%), positive predictive value 77% (95% CI 65% to 85%), negative predictive value 82% (95% CI 74% to 88%), LR+ 4.90 (95% CI 2.63 to 8.93) and DOR 23.8 (95% CI 7.5 to 75.8).
Pooled estimates for day three (four studies) were: sensitivity 81% (95% CI 70% to 89%), specificity 82% (95% CI 72% to 88%), positive predictive value 76% (95% CI 65% to 85%), negative predictive value 86% (95% CI 76% to 92%), LR+ 4.40 (95% CI 2.50 to 7.65) and DOR 20.3 (95% CI 7.3 to 56.3).
The area under the curve was 0.75 (95% CI 0.69 to 0.92) on day one, 0.88 (95% CI 0.57 to 0.98) on day two and 0.85 (95% CI 0.83 to 0.92) on day three.
IL-8:
Pooled estimates for day one (five studies) were: sensitivity 66% (95% CI 57% to 74%), specificity 67% (95% CI 59% to 73%), positive predictive value 55% (95% CI 46% to 63%), negative predictive value 76% (95% CI 69% to 82%), LR+ 1.96 (95% CI 1.40 to 2.72) and DOR 6.1 (95% CI 2.8 to 13.2).
Pooled estimates for day two (four studies) were: sensitivity 71% (95% CI 60% to 80%), specificity 91% (95% CI 84% to 95%), positive predictive value 86% (95% CI 76% to 93%), negative predictive value 80% (95% CI 72% to 87%), LR+ 8.15 (95% CI: typographical error in paper) and DOR 23.4 (95% CI 8.1 to 63.7).
The area under the curve was 0.73 (95% CI 0.21 to 0.97) on day one and 0.91 (95% CI 0.85 to 0.92) on day two.