Surgical site infections cost $2.5 billion in U.S.

Study underscores economic power of prevention

What toll do the estimated 486,000 surgical site infections (SSIs) take each year in the United States? More than 20,000 patient deaths, almost 6 million excess days of hospitalization, and a staggering $2.5 billion in direct costs to hospitals. And that’s likely an underestimate, reported Kathyrn Kirkland, MD, associate professor of medicine in the division of infectious diseases at Duke University Medical Center in Durham, NC.

In an era when infection control professionals are struggling to justify programs, a study conducted by Kirkland and colleagues provides compelling justification for efforts to prevent SSIs. Past studies have demonstrated that efforts to detect SSIs — including those within 30 days of discharge — and report infections back to surgeons can lower infection rates. (See related story in Hospital Infection Control, December 1995, p. 153-156.) However, Kirkland noted that there has been little updated data on the impact of SSIs in the 1990s.

"Our study provides further evidence that programs that decrease the rate of surgical site infections can prevent morbidity and mortality and save money," Kirkland said in St. Louis at the annual conference of the Society for Healthcare Epidemiology of America (SHEA).

The study included 255 patients who developed SSIs between June 1, 1991, and July 31, 1995. They were matched with uninfected controls to determine excess length of stay, need for intensive care unit admission, need for hospital readmission within 30 days of discharge, extra costs, and mortality attributable to surgical site infections.

Case patients were closely matched with controls by procedure, risk index, age, date of surgery, and — in 84% of cases — by surgeon. Of these 255 patient pairs, 20 case patients (7.8%) and 9 of the uninfected controls (3.5%) died during hospitalization.

"Thus, the mortality attributable to surgical site infections was 4.3%," Kirkland reported.

In addition, 29% of case patients required ICU admission, compared to 18% of their matched controls. In all, 41% of patients who developed surgical site infections had to be readmitted, compared to only 7.4% of their matched controls.

"The risk of readmission was five and a half times higher for patients who developed surgical site infections," she says.

The estimated excess length of stay attributable to SSIs was 6.5 days for infected patients, with the median direct cost per patient at $7,531 for infected cases, compared to $3,844 for controls. The total excess costs of SSIs, including initial hospitalization and readmission, was approximately $5,000 per infected patient, she noted.

Study findings extrapolated nationally

During the study period at Duke — where the rate of SSIs is actually lower than average — the toll of surgical site infections included five deaths, 107 excess ICU days, 920 excess days of hospitalization, and more than $450,000 in direct costs each year, she reported. An extrapolation of the findings to the national level yields the aforementioned 20,000 deaths and $2.5 billion cost to hospitals. The bottom line is that patients who develop SSIs have longer and costlier hospitalizations and are significantly more likely to die, to spend time in an ICU, and to be readmitted to the hospital than patients who do not develop such infections, Kirkland noted.

"SSIs are associated with a twofold increase in the in-hospital mortality of surgical patients," Kirkland told SHEA attendees. "Other human and economic costs of SSIs remain substantial even in a DRG and managed care era. The high rate of hospital readmission among patients with SSIs is an indicator that morbidity and costs related to such infections do not end with the initial postoperative discharge. By looking only at the first hospital readmission and only at inpatient care, our study likely underestimates the impact of surgical site infections."