Postoperative wound infections. I. Population data and risk factors

UNLABELLED: Postoperative wound infection is one of the most essential problems in surgical department related to surgery. The occurrence of infection depends on different factors related to both, the patient and his disease, and treatment organisation as well. The aim of this study was to establish the postoperative wound infection rate and to assess the correlations between age, sex, wound contamination, time and mode of operation, type of anaesthesia, duration of preoperative hospitalisation, wound drainage and the season of the year and development of postoperative wound infections. Patients undergoing surgery in the 3rd Surgical Department of the Collegium Medicum of the Jagiellonian University during one year were prospectively investigated. From the study population, 66 patients with, wounds of the head and 7 patients who died within three days after surgery without wound infection signs were excluded. The healing of each wound was observed during the patient's hospitalisation and 30 days after discharge from hospital, and in orthopedic patients 6 months after discharge. The total number of 132 infected wounds was identified. The population of 1352 wounds healed without any complications was a control group. All the data were recorded in a Wound Infection Register Card and were collected in the computer database. The data were statistically analysed. Relations between single factor and postoperative wound infection were evaluated using chi2 statistics and in the small number Fisher's exact probability test. Analysis of variance for continuous variables was used. Odds ratios and corresponding 95% confidence intervals were computed for all variables. The overall wound infection rate was 8.9%. The mean hospitalisation time was 18 days and was doubled in the group with wound infection (p < 0.001). The mean age of the whole population was 48.1.77 (5.2%) patients died after surgery. The relationship between sex, duration and mode of operation, duration of preoperative stay in hospital, wound contamination, kind of wound drainage and postoperative wound infection rate was significant. CONCLUSIONS: 1. The time of hospitalisation was twice longer in the infected group of patients with infected wounds in comparison to the control group. 2. Male sex, longer preoperative stay in hospital, duration of operation longer than one hour, emergency mode of operation, contaminated and dirty infected operation in traditional wound classification system and open (passive) drainage were statistically significant factors which influenced occurrence of postoperative wound infection.