Background: Wound infection occurs when bacterial contamination overcomes the hosts' defences against bacterial growth. Wound categories are a measurement of wound contamination. The American Society of Anesthesiologists (ASA) classification of physical status may be an effective indirect measurement of the hosts' defence against infection. This study examines the association between the ASA score of physical status and wound infection.
Methods: A retrospective review of a prospective study of antibiotic prophylaxis was carried out. Patients with a documented ASA score who received optimal prophylactic antibiotics were included. The anaesthetist scored the ASA classification of physical status in theatre. Other risk factors for wound infection were also documented. Patients were assessed up to 30 days postoperatively.
Results: Of 1013 patients there were 483 with a documented ASA score. One hundred and one may not have received optimal prophylaxis, leaving a database of 382 patients. There were 36 wound infections (9.4%). Both the ASA classification of physical status (P = 0.002) and the wound categories (P = 0.034) significantly predicted wound infection. The duration of surgery, patient's age, acuteness of surgery and the organ system being operated on did not predict wound infection. On logistic regression analysis the ASA score was the strongest predictor of wound infection.
Conclusion: When effective prophylactic antibiotics were used the ASA classification of physical status was the most significant predictor of wound infection.