乌鸦传媒

Postsurgical acute kidney injury following total hip arthroplasty led to increased rates of potentially serious complications, a large retrospective cohort study found.

Among the 4.1 million total hip arthroplasties included in the U.S. National Inpatient Sample from 1998 to 2014, there were 61,077 (1.5%) acute kidney injury events during the primary hospital admission, according to Jasvinder A. Singh, MD, and John D. Cleveland, MD, of the University of Alabama at Birmingham.

Among the complications associated with kidney injury were implant infection, with an odds ratio of 2.34 (95% CI 1.87-2.93) and need for transfusion, with an odds ratio of 2.46 (95% CI 2.37-2.56), Singh and Cleveland reported online in .

According to the definition of the project known as , acute kidney injury is an increase in serum creatinine of 26.5 µmol/L or more over 48 hours or an increase in serum creatinine of 50% or more over 7 days, or a urine volume below 0.5 mL/kg/h for 6 hours.

Previous studies have estimated the incidence of acute kidney injury as 1% to 8% after total hip or knee arthroplasty, but most were single-center studies with small population samples. Few studies have addressed the problem of complications after the development of acute kidney injury.

To address that knowledge gap, the researchers analyzed data from the 20% stratified sample of discharges from U.S. community hospitals established by the Agency for Healthcare Research and Quality.

Study outcomes included postsurgical complications (infection, revision, transfusion, or death) and healthcare utilization.

In unadjusted analyses, rates of each complication were higher among patients who developed kidney injury:

• Infections were reported in 0.7% vs 0.2%

• Revisions were reported in 1.1% vs 0.4%

• Transfusions were reported in 41.7% vs 22.5%

• Deaths were reported in 3.8% vs 0.2%

Healthcare utilization also was higher, with longer hospital stays (7.15 vs 3.68 days) and more requirement for discharge to an inpatient facility (61.8% vs 39.7%).

In addition, total hospital charges were higher throughout the study period for those with kidney injury, at a median of $56,412 in 1998-2000 and $90,271 in 2013-2014 compared with $23,556 and $58,230 for those without kidney injury.

After adjustment for multiple factors including age, sex, race, income, underlying diagnosis, presence of comorbidities, and type of insurance, acute kidney injury was associated with several unwanted outcomes (along with infection and transfusion):

• Death, OR 8.52 (95% CI 7.47-9.73)

• Length of hospital stay longer than 3 days, OR 4.34 (95% CI 4.16-4.53)

• Need for revision surgery, OR 2.54 (95% CI 2.16-2.98)

• Total hospital charges above the median, OR 2.29 (95% CI 1.99-2.65)

• Discharge to a rehabilitation facility, OR 2.11 (95% CI 2.02-2.20)

In a sensitivity analysis that further adjusted for hospital characteristics, similar results were seen. For example, the mortality risk for patients with acute kidney injury remained 8.5-fold higher (OR 8.54, 95% CI 7.48-9.76), and risk for revision remained 2.5-fold higher (OR 2.56, 95% CI 2.17-3.01).

Multiple mechanisms may contribute to postoperative kidney injury following total hip arthroplasty, including inflammation, use of potentially nephrotoxic medications such as angiotensin-converting enzyme inhibitor/angiotensin receptor blockers and nonsteroidal anti-inflammatory drugs, and also hemodynamic factors. Furthermore, that have previously been shown to be associated with postsurgical kidney injury include cardiovascular disease, diabetes, and creatinine above 2 mg/dL, along with obesity, metabolic syndrome, and perioperative antibiotic use.

"Patient education, careful avoidance of nephrotoxic medications in the perioperative [period], including those leading to hypotension, maintenance of adequate intravascular volume, and effective comorbidity management (cardiac, vascular, pulmonary, renal, diabetes, etc.) may also help in reducing the risk of post-total hip arthroplasty acute kidney injury," Singh and Cleveland stated.

They added that quality initiatives to minimize the risks of postoperative acute kidney injury are needed, as are interventions that could improve modifiable risk factors.

Limitations of the analysis, the team said, included the possibility of misclassification bias and short-term follow-up.