Table 1.

Surgical Site Infections in Patients Undergoing Major Surgical Procedures Identified Using International Classification of Diseases, Ninth Revision, Clinical Modification Code for Post-Operative Infection (Rule A) or Positive Cultures from Relevant Specimen Sources (Rule B) within 30 Days of Procedure

	Culture-based rule (Rule B)
	Positive (% of total)	Negative (% of total)	Total
ICD-9-CM-based rule (Rule A) positive	96	139	235
ICD-9-CM-based rule (Rule A) negative	191	5,492	5,683
	287	5,631	5,918
Kappa=0.34 (95% confidence interval 0.27-0.41)
Positive agreement 36.8%
Negative agreement 97.1%

ICD-9-CM=International Classification of Diseases, Ninth Revision, Clinical Modification.