Differential effect of risk factors on early and late wound infections in patients undergoing herniorrhaphies

In a prospective follow-up of 2846 patients who underwent hernia repair in 22 general surgery departments in Israel, factors affecting early or late infections were explored. Risk factors included inherent patient characteristics such as old age, ethnic group, and type of hernia prior to the surgery. Patient management factors included duration of the operation, use of urinary catheters, and use of drains. Of the 12 variables studied, only three had a constant effect during the entire 30-day follow-up. The other factors affected the occurrence of either early or late infections, but not both. For example, patients undergoing long operations, or from ethnic minorities, had a high rate of early infection, while those with special wound treatment (such as evacuation of hematomas) had high rates of late infection. It is postulated that factors present at the time of the operative incision tend to "cause" early infections, while factors that accumulate over time, or develop after leaving the operating theater, tend to affect late infections.