Table 7.

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

Test combination	Infection persistence	No infection persistence	Total
D-dimer and CRP (+)	8	28	36
D-dimer and CRP (-)	2	5	7
Total	10	33	43
Accuracy = 100 x 2 + 28/2 + 28 + 8 + 5 = 70% Sensitivity = 100 x 2/2 + 8 = 20% Specificity = 100 x 28/28 + 5 = 85% Positive predictive value = 100 x 2/5 + 2 = 28% Negative predictive value = 100 x 28/28 + 8 = 78% Positive likelihood ratio = 0.2/1-0.848 = 1.3 Negative likelihood ratio = 1-0.2/0.848 = 0.9