Postdischarge clean wound infections: incidence underestimated and risk factors overemphasized

Wound infections are a leading cause of postoperative morbidity and a cost to both the individual and community. The surgeon now has a reduced appreciation of wound-infection rates because of shorter hospital stays and an increasing reliance on the primary care physicians. The incidence of wound infections which occurred following clean surgical procedures, as well as whether they could have been predicted by the known risk factors, were analysed in the present prospective study.

A prospective audit of the first 30 postoperative days following clean general surgical wounds was undergone, with inpatient assessment by a research nurse, and subsequent outpatient followup by patient telephone interview.

Of 1964 clean wounds over a 30-month period, 98.5% were traced. The overall clean-wound infection rate was 12.6% (inpatient:4.5%; outpatient: 8.1%). Inpatient infection rates(but not postdischarge wound-infection rates) were significantly correlated (P < 0.05)to the American Society of Anesthesiologists' rating, operation duration, preoperative day stay, and age. Infection rates varied with operation type: vascular (18.3%), breast (16.0%),abdominal (10.3%), hernia (8.0%), head and neck (7.1%).

The overall wound-infection rate is higher than previously described with two thirds of infections occurring after discharge. While inpatient wound-infection rates fit known risk factors, postdischarge wound-infection rates do not. Certain clean-wound operations have a higher incidence of infection than others. Consideration needs to be given to the identification of risk factors for postdischarge wound infections,and to further trials of prophylactic antibiotics in clean surgery.