Background: Information concerning the economic impact of surgical site infection (SSI) is very rare in Thailand. As the national health care financial system has been changing, the need for such data is critical.
Objective: The purpose of this study is to estimate the extra charge and excess postoperative hospitalization attributable to SSI in six surgical operative procedures comprising appendectomy, herniorrhaphy, mastectomy, cholecystectomy, colectomy, and craniotomy.
Material and Method: The study population consisted of patients undergoing major operations admitted to Songklanagarind Hospital from January, 1998 to December, 2003. Data were prospectively collected to identify demographic data, surgical operations, development of SSI, and outcomes of SSI. The study used one-to-one matched-pair strategy to compare case (patient with SSI) and controls (patient without SSI). The matching criteria were same final diagnosis, same operative procedure, and same American Society of Anesthesiologists (ASA) score. Data were calculated for mean difference, median difference, and 95% confidence intervals (95% C.I) of hospital charge and postoperative stay.
Results: The study could identify 140 matched-pairs of case and control. When compared to matched controls, cases had higher hospital charge and greater postoperative length of stay. Mean of extra hospital charge attributable to SSI was 43,658 (95% C.I; 30,228-57,088) baht and mean of excess postoperative stay was 21.3 (95% C.I; 16.6-26.0) days. Median of extra expenditure was 31,140 (95% CI; 17,327-49,081) baht
and median of prolongation of postoperative stay was 14 (95% C.I, 12-18) days.
Conclusion: This study supports the findings of the previous published reports that patients who have SSI incur enormous excess cost and hospital stay.

Keywords: Cost of illness, Costs, Cost analysis, Cross infection, Surgical site infection