Low eGFR Associated with Hospital-Acquired Infections Following Major Surgery

The US Department of Health and Human Services and the European Centre for Disease Prevention and Control have set prevention of hospital-acquired infections as one of their highest priorities. Hospital-acquired infections are associated with increased risk for mortality and morbidity, prolonged hospital length-of-stay, and increases in healthcare costs. Many hospital-acquired infections are preventable, creating the need to focus interventions on populations at particularly high risk.

Previous studies have shown estimated glomerular filtration rate (eGFR), even at mild to moderate stages (30-59 mL/min/1.73m2), to be a significant risk factor for infection. However, there are few available data on the contribution of eGFR to hospital-acquired infection following major surgery. In addition, there here been only a few studies simultaneously examining eGFR as a risk factor for hospital-acquired infection in combination with other key clinical comorbid conditions such as cancer, heart disease, lung disease, diabetes, cerebrovascular disease, and liver disease.

Junichi Ishigami, MD, MPH, and colleagues recently conducted a retrospective cohort study to examine the incidence and population-attributable fraction (PAF) of hospital-acquired infections according to low eGFR and several other key comorbid conditions among patients who underwent major surgical procedures (orthopedic, abdominal, cardiothoracic and vascular, and neurologic surgery). The infections of interest were overall infections and four common types (urinary tract infection, pneumonia, surgical-site infection, and bloodstream infection). Study results were reported in the American Journal of Kidney Diseases [2019;73(1):11-20].

Overall, the study included 66,126 patients with a history of orthopedic (n=31,630), abdominal (n=26,317), cardiothoracic and vascular (n=6266), or neurologic (n=1913) surgery. Median age of the total cohort was 67 years and 58% were female. Serum creatinine was measured on the date of admission in 52% (n=32,824), within 7 days prior to hospitalization in >70% (n=46,705), and within 60 days in >90% (n=61,021).

In the total cohort, 18% (n=11,641) had eGFR <60 mL/min/1.73 m2 at time of admission. Low eGFR was the second most common comorbid condition after cancer (21%). Patients with low eGFR were more likely to be older and female and have cancer, diabetes, heart failure, chronic obstructive pulmonary disease (COPD), cerebrovascular disease, and coronary heart disease.  The most common surgery in the group with eGFR <60 mL/min/1.73 m2 was orthopedic; among those with eGFR ≥60 mL/min/1.73 m2 the most common surgery types were abdominal (44%) and orthopedic (44%). Length-of-stay was longer for patients with eGFR <60 mL/min/1.73 m2 compared with patients with eGFR ≥60 mL/min/1.73 m2.

Five point five percent (n=3617) of the total cohort had at least one type of hospital-acquired infection (3291 patients had one diagnosis and 326 patients two or more diagnoses). Those with hospital-acquired infections had longer hospital stays than those without infections (medians of 10 vs 4 days). The incidence in each surgery type was 5.8% for orthopedic, 5.6% for abdominal, 3.4% for cardiothoracic and vascular, and 5.9% for neurologic surgery. The most common types of hospital-acquired infections were urinary tract infection (n=1650) and pneumonia (n=1196), followed by surgical-site infection (n=635) and bloodstream infection (n=411). The most common infection for orthopedic surgery was urinary tract infection, for abdominal surgery the most common was surgical-site infection, and pneumonia was the most common for cardiothoracic and vascular and neurosurgery.

Compared with the overall population, the prevalence of each comorbid condition was higher among patients with hospital-acquired infections. For low eGFR, cancer, and heart failure, the difference appeared particularly disproportional. In logistic regression, the odds ratio (OR) of hospital-acquired infections was highest for eGFR (OR, 1.64; 95% confidence interval [CI], 1.51-1.77), followed by heart failure (OR, 1.60; 95% CI, 1.46-1.76), cerebrovascular disease (OR, 1.47; 95% CI,  1.34-1.61), cancer (OR, 1.43; 95% Ci, 1.33-1.55), COPD (OR, 1.37; 95% CI, 1.25-1.50), and coronary heart disease (OR, 1.14; 95% CI, 1.02-1.27). For diabetes and liver disease, there was no significant association with the proportion of hospital-acquired infection.

The largest PAF of 0.13 for hospital-acquired infections was seen for low eGFR; the second largest PAF was seen for cancer (0.10), followed by heart failure (PAF, 0.09), cerebrovascular disease (PAF, 0.06), and COPD (PAF, 0.05). When heart failure, cerebrovascular disease, and coronary heart disease were combined as cardiovascular disease, the PAF was 0.20. In that scenario, PAFs were 0.14 for low eGFR, 0.10 for cancer, and 0.05 for COPD.

In results of assessing PAFs of hospital-acquired infections separately across types of infection, low eGFR showed the highest PAF for urinary tract infection (0.11) and pneumonia (PAF, 0.15) and the second highest PAF for bloodstream infection (0.19) and surgical-site infection (0.11). Cancer posed the highest PAF for surgical-site infection (PAF, 0.22) and bloodstream infection (PAF, 0.20) and second highest for urinary tract infection.

There were some study limitations cited by the authors including the observational design of the study; estimating kidney function based on the closest measured serum creatinine level before the admission; ascertaining study outcomes from discharge records; the possibility of residual confounding; using eGFR as a surrogate of kidney function; and the study population being predominately white.

In conclusion, the researchers said, “Among patients admitted for major surgery, low eGFR was the leading  attributable factor for hospital-acquired infection, followed by cancer, heart failure, and cerebrovascular disease. 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.”

Takeaway Points

  1. Hospital-acquired infections following major surgery increase the risk for mortality and morbidity; preventing these infections is a high priority of the US Department of Health and Human Services.
  2. Researchers conducted a retrospective cohort study to examine the incidence and population-attributable fraction (PAF) of hospital-acquired infections according to key clinical comorbid conditions (low estimated glomerular filtration rate [eGFR], cancer, heart failure, chronic obstructive pulmonary disease, cerebrovascular disease, and liver disease.
  3. Low eGFR demonstrated the highest PAF for hospital-acquired infections (0.13), followed by cancer (0.10), heart failure (0.09), and cerebrovascular disease (0.06).