Continuous, 10-year wound infection surveillance. Results, advantages, and unanswered questions.

During a 10-year wound infection surveillance program, 1032 wound infections complicated 40,915 operations. Surveillance continued for 30 days postoperatively, and rigid clinical criteria for diagnosis were honored. Operations were distributed unequally among infection risk classes: clean (class I), 63.3%; clean contaminated (class II), 26.4%; and contaminated (class III), 10.3%. Infections occurred with nearly equal frequencies among classes: I, 36.1%; II, 29.5%; and III, 34.4%. Wound infection rates during the 10-year period were 2.5% (all operations), 1.4% (class I), 2.8% (class II), and 8.4% (class III). Index year (1977) infection rates were 4.2% (all operations), 2.3% (class I), 5.4% (class II), and 12.8% (class III). Wound infection rates during the last 9 years of surveillance in every risk class were significantly less than index year rates, representing infection rate decreases of 38% to 56%. Estimated savings in hospital room costs alone reached $3 million during 10 years.