Table 4.

Accuracy of ESR in predicting persistent infection after reimplantation in two-stage exchange arthroplasty at a minimum 1-year follow-up

Test	Infection persistence	No infection persistence	Total
ESR (-)	7	22	29
ESR (+)	3	11	14
Total	10	33	43
Accuracy = 100 x 3 + 22/3 + 22 + 7 + 11 = 58% Sensitivity = 100 x 3/7 + 3 = 30% Specificity = 100 x 22/22 + 11 = 67% Positive predictive value = 100 x 3/3 + 11 = 21% Negative predictive value = 100 x 22/22 + 7 = 76% Positive likelihood ratio = 0.3/1-0.67 = 0.9 Negative likelihood ratio = 1-0.3/0.67 = 1