Low eGFR was associated with hospital-acquired infections after major surgery

Low estimated glomerular filtration rate may increase the risk of hospital-acquired infection in patients who have undergone major surgery, according to a published study.

“[Among] patients admitted for major surgery, low eGFR was the leading attributable factor for hospital-acquired infection, followed by cancer, [heart failure] HF and cerebrovascular disease,” Junichi Ishigami, MD, MPH, of the department of epidemiology at Johns Hopkins Bloomberg School of Public Health, and colleagues wrote in their study. “In the context of growing public health concerns over hospital-acquired infections, these findings may be important for establishing effective and efficient policies and approaches for preventing hospital-acquired infections following major surgery.”

Researchers conducted a retrospective cohort study of 66,126 adult patients in Stockholm with no recent diagnoses of infection and who had been hospitalized for orthopedic (n = 31,630), abdominal (n = 26,317), cardiothoracic and vascular (n = 6,266) or neurologic (n = 1,913) surgery between January 2007 and December 2011. To calculate eGFR, researchers used the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and all participants were given serum creatinine tests with baseline serum creatinine level defined as the last value available within 1 year before admission. Of the total population, 18% of patients had low eGFRs (< 60 mL/min/1.73 m²) at the time of admission.

The primary outcome was the incidence of hospital-acquired infections, which were defined as discharges with infection ICD-10 codes. According to researchers, to ensure infection types that were indications but not complications of surgery were not considered, the analysis was restricted to four major types of infections including pneumonia, urinary tract infection, surgical-site infection and bloodstream infection.

Researchers compared baseline characteristics between patients with eGFRs greater than or less than 60 mL/min/1.73m². Researchers estimated the population-attributable fraction (PAF) of hospital-acquired infection by multiplying the prevalence of the comorbid conditions among patients with hospital-acquired infection by the adjusted OR minus one or the adjusted OR. As there was a low incidence of hospital-acquired infection, the OR was used to approximate relative risk, according to the researchers.

At least one type of hospital-acquired infection

Researchers found 5.5% of patients had at least one type of hospital-acquired infection and patients with hospital-acquired infections had longer hospital stays than those without (median stay, 10 vs. 4 days). For orthopedic, abdominal, cardiothoracic and vascular and neurologic surgery, the incidence was 5.8%, 5.5%, 3.4% and 5.9%, respectively. Urinary tract infection and pneumonia were the most prevalent, followed by surgical-site infection and bloodstream infection.

The likelihood of having each comorbid condition was higher in those with hospital-acquired infections than in the overall population, with the difference being greater in low eGFR, cancer and heart failure. The OR of hospital-acquired infections was highest for low eGFR (OR = 1.64). In addition, the largest PAF of 0.13 was seen for low eGFR.

Additional factors

When researchers combined heart failure, cerebrovascular disease and coronary heart disease as cardiovascular disease, the PAF was 0.20 with PAFs of 0.14 for low eGFR, 0.10 for cancer and 0.05 for chronic obstructive pulmonary disease. Furthermore, when researchers treated eGFR as a continuous variable in a restricted cubic spline model with knots at 45, 60 and 90 mL/min/1.73 m ², the OR increased with lower eGFR.

“From a clinical point of view, the present study can inform clinicians of specific frequent combinations between pre-surgery comorbid conditions and post-surgery hospital-acquired infections such as low eGFR with urinary tract infection and pneumonia and cancer with hospital-acquired infections after abdominal surgery, which can contribute to more targeted monitoring of hospital-acquired infections,” the researchers wrote. “Future studies should investigate the costs and effectiveness of hospital-acquired infection prevention programs, such as an alert system to assist physicians with the medical information for identifying high-risk patients, followed by targeted infection prevention approaches.” - by Melissa J. Webb

Disclosure s : The authors report no relevant financial disclosures.