Who bears the cost of healthcare-acquired surgical site infection?

The aim of this study was to estimate the economic costs of healthcare-acquired surgical site infection (HA-SSI) and show how they are distributed between the in-hospital and post-discharge phases of care and recovery. A quantitative model of the epidemiology and economic consequences of HA-SSI was used, with data collected from a prospective cohort of surgical patients and other relevant sources. A logical model structure was specified and data applied to model parameters. A hypothetical cohort of 10 000 surgical patients was evaluated. We found that 111 cases of infection would be diagnosed in hospital and 784 cases would first appear after discharge. Of the total costs incurred, either 31% or 67% occurred during the hospital phase, depending on whether production losses incurred after discharge were included. Most of the costs incurred by the hospital sector arose from lost bed-days and only a small proportion arose from variable costs. We discuss the issues relating to the size of these costs and provide data on where they are incurred. These results can be used to inform subsequent cost-effectiveness analyses that evaluate the efficiency of programmes to reduce the risks of HA-SSI.

Post-discharge surgical site surveillance: does patient education improve reliability of diagnosis?

Post-discharge surgical infection surveillance by patients remains an integral part of many infection control programmes despite proven unreliability. We attempted to improve the validity of patient recognition of signs and symptoms of wound infection and post-discharge postal questionnaire responses through specific education prior to discharge. In total, 588 patients were studied after random assignment into two intervention groups, one of which received relevant education. Both groups were followed for four weeks post-operatively, with features of infection assessed weekly by experienced infection control nurses (ICNs) and by patient responses to routine postal questionnaires. Those patients who received education demonstrated a significantly poorer correlation with ICN diagnosis compared to the non-educated group (Kappa 0.69 and 0.81 respectively, P=0.05). Both patient groups achieved the same sensitivity for recall (83.3%), with high specificity demonstrated by both groups [educated (93.7%); non-educated (98.1%)]. The positive predictive value was 65.2% for the educated group and 83.3% for the non-educated patient group. When infected wounds identified by patients were examined for the proportion that were overdiagnosed, the excess of SSI identified by the educated patient group was 44.4% and by the non-educated group 16.7%. These results suggest that pre-discharge education causes patients to overdiagnose clinical features of wound infection and fails to improve the validity of diagnosis. This outcome further questions the value of post-discharge infection rates obtained by patient self-assessment as a measure of quality of performance.

Post-discharge surveillance: can patients reliably diagnose surgical wound infections?

Post-discharge surgical wound infection surveillance is an important part of many infection control programs. It is frequently undertaken by patient self-assessment, prompted either by a telephone or postal questionnaire. To assess the reliability of this method, 290 patients were followed for six weeks postoperatively. Their wounds were photographed and also covertly assessed for signs of infection by two experienced infection control nurses (ICNs). Patients also responded to a postal questionnaire seeking evidence of infection at both week four and week six post-surgery. Correlation between the patient's assessment of their wound and the ICNs diagnosis was poor (r = 0.37) with a low positive predictive value (28.7%), although negative predictive value was high (98.2%). Assessment of photos for signs of infection by two experienced clinicians also correlated poorly with the ICNs diagnosis of infection (r = 0.54). The patient's recall of prescription of an antibiotic by their general practitioner (GP) for wound infection during the postoperative period correlated best with the ICNs diagnosis (r = 0.76). This latter measure, particularly when confirmed by the GP in those patients reporting an infection, appears to provide the most valid and resource efficient marker of post-discharge surgical wound infection.