OBJECTIVES

: The study aimed to compare the cost-effectiveness of three methods of surgical site infection surveillance: inpatient, phone, and out-patient clinic; to ensure that the loss-to-follow-up is independent from the risk of surgical site infection in case of phone and out-patient-clinic surveillances, and to determine the accuracy of the data collected by phone surveillance.

METHODS

: A cohort of 351 surgical patients were followed by three methods: Costs of nurse time and phone calls were expressed in 2018 US dollars (USD). The effectiveness of SSI surveillance was assessed using the number of detected SSIs. Cost-effectiveness was assessed using included average cost-effectiveness ratio and incremental cost-effectiveness ratio.

RESULTS

: Phone surveillance was more cost-effective than out-patient clinic surveillance. Compared to inpatient surveillance, the out-patient clinic method costs 4 USD per extra detected SSI, whereas the phone method costs only 1.10 USD.

In both phone and out-patient-clinic surveillances, the risk of surgical site infection was independent of loss-to-follow-up. However, the higher rate of SSI among out-patient-clinic attendees raise the suspicion that the incidence of SSI estimated by out-patient-clinic surveillance could be biased upwards. The data collected by phone surveillance was accurate with sensitivity and specificity of 96.9%; [95%CI:83.8% to 99.9%] and 100% [95%CI:98.4% to 100%] respectively.

CONCLUSIONS

: Phone surveillance was the most cost-effective and showed high accuracy. Inpatient surveillance was less effective, but it still can be used to detect severe SSI at low cost. While out-patient-clinic surveillance had the highest cost, the incidence estimated by it could be biased upwards.