Table 5.

Accuracy of CRP in predicting the persistence of infection after reimplantation in two-stage exchange arthroplasty at a minimum 1-year follow-up

Test	Infection persistence	No infection persistence	Total
CRP (-)	8	25	33
CRP (+)	2	9	11
Total	10	34	44
Accuracy = 100 x 2 + 25/2 + 25 + 8 + 9 = 61% Sensitivity = 100 x 2/2 + 8 = 20% Specificity = 100 x 25/25 + 9 = 73% Positive predictive value = 100 x 2/2 + 9 = 18% Negative predictive value = 100 x 25/25 + 8 = 76% Positive likelihood ratio = 0.2/1-0.73 = 0.7 Negative likelihood ratio = 1-0.2/0.73 = 1.1