Post-surgery infection tied to long-term infection risk

Individuals who develop an infection within a month of undergoing major surgery may have an elevated risk of developing a subsequent infection within a year as well as an elevated risk of mortality, according to a recent retrospective study.

“[The results showed that] infections occurring in the 30-day postoperative period have long-term consequences of repeated infection and reduced survival over the following year,” said the researchers.

The researchers of this observational study examined data of individuals in the Veterans Health Administration who underwent major surgery between 2008 and 2015. After excluding individuals who had a subsequent surgery or died within 30 days of initial surgery, the final cohort comprised 659,486 individuals (mean age 59.7 years, 91.7 percent male, 63.5 percent Caucasian)

Of the total cohort, 3.6 percent (n=23,815) developed an infection within 30 days after surgery, the most common of which was surgical site infection (40.2 percent), followed by urinary tract infection (UTI; 27.5 percent), pneumonia (14.8 percent), and bloodstream infection (BSI; 8.0 percent).

Of the 6.7 percent who had a long-term infection* (occurring during follow-up, ie, between days 31 and 365 post-surgery), the most common infections were UTIs (48.7 percent), skin and soft tissue infection (SSI; 32.6 percent), BSI (8.8 percent), and pneumonia (5.8 percent).

The incidence of long-term infection was three times greater among patients who developed a 30-day infection compared with those who did not (21.8 percent vs 6.1 percent, with a first infection occurring at a median 78 and 132 days following initial surgery, respectively; hazard ratio [HR], 3.17, 95 percent confidence interval [CI], 3.05–3.28). [JAMA Surg 2019; doi:10.1001/jamasurg.2019.4539]

There were 24,810 deaths (3.8 percent) over the follow-up period. Mortality risk among those who developed infections within 30 days was almost twice that of those who did not have a 30-day infection (12.9 percent vs 3.4 percent at a median 129 and 183 days post-surgery, respectively; HR, 1.89, 95 percent CI, 1.79–1.99).

Patients who had a BSI within 30 days of initial surgery had the highest rate of long-term infection, while those who developed an SSI within 30 days of initial surgery had the lowest risk. Patients whose 30-day infections were due to methicillin-resistant Staphylococcus aureus had the highest rate of long-term infection compared with infection due to any other organism.

The researchers acknowledged that the male-majority cohort restricted the generalizability of the findings to other populations, while the incidence of long-term infection may have been underestimated if patients were treated for infections at non-VA hospitals.  

Nonetheless, these findings add to prior evidence which has linked postoperative infection with an elevated long-term mortality risk in patients who underwent surgery for lung cancer, colorectal cancer, or cardiovascular disease. [J Thorac Oncol 2013;8:554-561; Tumori 2004;90:485-490; Surg Infect (Larchmt) 2016;17:700-712; Ann Thorac Surg 2015;99:1591-1599]

The elevated risk of long-term infections and mortality highlight the importance of preventing these infections, the researchers said. “[Additionally,] the increased harm and cost of long-term infections should be included in the cost-benefit calculus of infection prevention initiatives,” they said.