Obesity, Angiotensin-Blocking Drugs, and Acute Kidney Injury in Orthopedic Surgery

Incidence and predictors of acute kidney injury after elective surgery for lumbar degenerative disease: A 13-year analysis of the US Nationwide Inpatient Sample

BACKGROUND

Acute kidney injury (AKI) is a severe postoperative complication associated with poor clinical outcomes, including the development of chronic kidney disease (CKD) and death. This study aimed to investigate the incidence and determinants of AKI following elective surgeries for degenerative lumbar spine disease.

METHODS

All patient data were extracted from the US Nationwide Inpatient Sample database. After surgery, AKI's incidence and risk factors were identified for lumbar degenerative disease. ICD-9 and ICD-10 codes defined lumbar spine degenerative disease, fusion, decompression, and AKI. The study cohort was categorized by type of surgery, that is, decompression alone or spinal fusion. Regression analysis was used to identify associations between AKI and risk factors organized by surgery type.

RESULTS

The incidence of AKI after decompression or fusion was 1.1% and 1.8%, respectively. However, the incidence of AKI in the United States is rising. The strongest predictor of AKI was underlying CKD, which was associated with an 9.0- to 12.9-fold more significant risk of AKI than in subjects without comorbid CKD. In this setting, older age, congestive heart failure, anemia, obesity, coagulopathy and hospital-acquired infections were also strong predictors of AKI. In contrast, long-term aspirin/anticoagulant usage was associated with lowered AKI risk.

CONCLUSION

Findings of this study inform risk stratification for AKI and may help to optimize treatment decisions and care planning after elective surgery for lumbar degenerative disease.

A comprehensive analysis of intraoperative factors associated with acute-on-chronic kidney injury in elderly trauma patients: blood loss as a key predictor

BACKGROUND

Postoperative acute kidney injury (AKI) is a critical issue in geriatric patients with pre-existing chronic kidney disease (CKD) undergoing orthopedic trauma surgery. The goal of this study was to investigate modifiable intraoperative risk factors for AKI.

METHODS

A retrospective study was conducted on 206 geriatric patients with CKD, who underwent orthopedic trauma surgery. Several variables, including intraoperative blood loss, postoperative hypoalbuminemia, intraoperative blood pressure and long-term use of potentially nephrotoxic drugs, were analyzed.

RESULTS

Postoperative AKI (KIDGO) was observed in 25.2% of the patients. The 1-year mortality rate increased significantly from 26.7% to 30.8% in patients who developed AKI. Primary risk factors for AKI were blood loss (p < 0.001), postoperative hypoalbuminemia (p = 0.050), and potentially nephrotoxic drugs prior to admission (angiotensin-converting enzyme inhibitors, angiotensin-II receptor antagonists, diuretics, antibiotics, NSAIDs) (p = 0.003). Furthermore, the AKI stage negatively correlated with propofol dose per body weight (p = 0.001) and there was a significant association between AKI and the use of cement (p = 0.027). No significant association between intraoperative hypotension and AKI was observed in any statistical test. Femur fracture surgeries showed the greatest blood loss (524mL ± 357mL, p = 0.005), particularly intramedullary nailing at the proximal femur (598mL ± 395mL) and revision surgery (769mL ± 436mL).

CONCLUSION

In geriatric trauma patients with pre-existing CKD, intraoperative blood loss, postoperative hypoalbuminemia, and pre-admission use of potentially nephrotoxic drugs are associated with postoperative AKI. The findings highlight the necessity to mitigate intraoperative blood loss and promote ortho-geriatric co-management to reduce the incidence and subsequent mortality in this high-risk population.

The obesity paradox and orthopedic surgery

The Obesity Paradox describes the counterintuitive finding that although obesity contributes to the development of chronic conditions such as chronic kidney disease and cardiovascular disease, obesity seems to improve mortality in patients with these diseases. This paradox has also been sited in the critical care literature in regard to acute kidney injury, obesity and mortality. This study's objective is to examine the impact of obesity and post-surgical acute kidney injury on hospital length of stay and 2-year mortality after orthopedic surgery.We reviewed the electronic medical records of all adult elective orthopedic surgery patients over 2 years in a large academic hospital. The 1783 patients who met inclusion criteria were divided into obese (body mass index, BMI ≥ 30, n = 1123) and non-obese groups (BMI <30, n = 660). Demographics, medications, comorbidities, and perioperative variables were included in multivariable logistic regression analyses with acute kidney injury, length of hospital stay, and two-year mortality as primary outcomes. Outcomes were analyzed for the entire group, the obese cohort and the non-obese cohort.Acute kidney injury developed in 5% of the post-surgical orthopedic patients. Obesity increased the likelihood of developing acute kidney injury post orthopedic surgery (odds ratio [OR] = 1.82; 95% Confidence interval [CI] 1.05-3.15, P = .034). Acute kidney injury increased length of stay by 1.3 days and increased the odds of two-year mortality (OR = 2.08; 95% CI 1.03-4.22, P = .041). However, obese patients had a decreased likelihood of two-year mortality (OR = 0.53; 95% CI 0.33-0.84, P = .009).In adult orthopedic surgery patients, obesity increased the risk of acute kidney injury. Patients who developed an acute kidney injury had longer hospital stays and higher two-year mortality. Paradoxically, obesity decreased two-year mortality.