Preoperative creatinine clearance as a predictor of short-term outcomes after cardiac surgery: a cohort study for the comparison between the Cockroft-Gault and modification of diet in renal disease formulae

Preoperative Creatinine Clearance and Mortality of Elective Cardiac Surgery in Hospitalization: A Secondary Analysis

Objective

It has been reported that poor renal function before surgery is related to poor prognosis. However, there is no specific discussion on the ideal value of preoperative creatinine clearance. Consequently, our primary goal is to explore the correlation between baseline creatinine clearance and short-term mortality after cardiac surgery.

Methods

We conducted a secondary data analysis based on a French cardiac surgery cohort. The cohort included 6,889 participants in a Paris university hospital from December 2005 to December 2012. The exposure variable and outcome variable used in this secondary analysis were the preoperative creatinine clearance rate and postoperative hospital mortality. Multivariate logistic regression and generalized additive models were employed.

Results

The nonlinear relationship between the preoperative creatinine clearance rate and postoperative death was observed in this study. The preoperative creatinine clearance rate was negatively correlated with postoperative mortality in the range of 8.9–78.5 in patients younger than 80 years old (odds ratio = 0.98, 95% confidence interval 0.97–0.98, in Cockcroft Gault formulae). However, this effect characteristics reaches saturation after the preoperative creatinine clearance rate exceeds 78.5 (odds ratio = 0.99, 95% confidence interval 0.98–1.00, CG). In patients with history of thromboembolic event and coronary artery disease, the saturation effect were 30.8 mL.min⁻¹ (CG) and 56.6 mL.min⁻¹(CG).

Conclusion

In the range of 8.9–78.5 (Cockcroft), an increase in preoperative creatinine clearance is associated with a decrease in postoperative mortality with patients younger than 80 years old. In patients with a history of embolism and coronary artery disease, the cut-off points of the reduction in preoperative creatinine clearance associated with a increase in postoperative mortality are 30.8 mL.min⁻¹ and 56.6 mL.min⁻¹.

Reassessment of kidney function equations in predicting long-term survival in cardiac surgery

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a risk factor for long-term survival in cardiac surgery. The Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) study, CKD Epidemiology Collaboration (CKD-EPI), revised Lund-Malmö (LM), and full age spectrum equations are used to estimate glomerular filtration rates (eGFR), but each have advantages and disadvantages. Our objective was to determine which equation better predicts long-term survival.

METHODS

Data on 1492 consecutive patients who underwent isolated off-pump coronary artery bypass surgery between September 1996 and December 2008 were prospectively collected. Preoperative and postoperative eGFR were calculated using the five equations and compared using Cox regression analyses and time-dependent receiver operating characteristic (ROC) curves at 10 years.

RESULTS

In a Cox regression model after correction for significant predictors of long-term mortality, adjusted hazard ratios (HR) for one standard deviation increase in preoperative eGFR were 0.661 (P < .0001), 0.844 (P = .0166), 0.787 (P = .0002), 0.746 (P < .0001), and 0.717 (P < .0001) for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively. The areas under the time-dependent ROC curve at 10 years also showed that the CG formula has a better predictive value. Postoperative eGFR at discharge were also significant predictors of long-term mortality (HR = 0.603, P < .0001; HR = 0.725, P < .0001; HR = 0.688, P < .0001; HR = 0.673, P < .0001; HR = 0.632, P < .0001 for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively).

CONCLUSIONS

The CG formula was shown to better predict survival in cardiac surgery, though the FAS equation has a comparable prognostic value. Additionally, postoperative eGFR at discharge also predicted long-term survival.

Evaluation of the Effect of Aminophylline in Reducing the Incidence of Acute Kidney Injury After Cardiac Surgery

Objectives

Acute renal failure is a common complication of major cardiovascular surgeries (One-third of patients). Adenosine release as a vascular vasodilator increases after cardiac surgery, which reduces renal and glomerular blood flow and subsequently causes kidney ischemic damage. The present study aimed at evaluating the impact of aminophylline as an adenosine receptor antagonist on renal function after cardiac surgery hoping to find an appropriate method to reduce acute kidney injury.

Methods

The patients in the intervention group received 5 mg/kg aminophylline bolus after induction of anesthesia; then, 0.25 mg/kg/hr of the drug was administered intraoperatively and up to 48 hours after surgery in the ICU cardiac surgery. Similar volume of normal saline was injected to the patients of the second group. Serum BUN, Cr, and GFR were measured pre- and postoperatively and 3 days postsurgery. Patients’ 24- hour urine output and RIFLE were also calculated.

Results

Those patients who received medication were extubated earlier (P = 0.018) and received lower amount of inotropic drugs (P < 0001). According to the RIFLE criteria, most of the patients experienced no change or even improved GFR and Cr amounts compared to the control group (p < 0.05). GFR and Cr value of all the patients with Cleveland score, less and more than 6, showed a significant difference between the 2 groups (P = 0.001 and P = 0.01, respectively). According to the RIFLE criteria, most of the patients experienced no change or even improved GFR.

Conclusions

Aminophylline in cardiac surgery can reduce the frequency of acute kidney injury according to RIFLE criteria and could be used in the prevention of AKI as a safe and efficient modality in high-risk patients. Also, the use of this drug may reduce the need for inotropic medication at the time of surgery, intensive care unit stay length, and extubation time.

Individualizing pharmacotherapy in patients with renal impairment: the validity of the Modification of Diet in Renal Disease formula in specific patient populations with a glomerular filtration rate below 60 ml/min. A systematic review

Background

The Modification of Diet in Renal Disease (MDRD) formula is widely used in clinical practice to assess the correct drug dose. This formula is based on serum creatinine levels which might be influenced by chronic diseases itself or the effects of the chronic diseases. We conducted a systematic review to determine the validity of the MDRD formula in specific patient populations with renal impairment: elderly, hospitalized and obese patients, patients with cardiovascular disease, cancer, chronic respiratory diseases, diabetes mellitus, liver cirrhosis and human immunodeficiency virus.

Methods and Findings

We searched for articles in Pubmed published from January 1999 through January 2014. Selection criteria were (1) patients with a glomerular filtration rate (GFR) < 60 ml/min (/1.73m²), (2) MDRD formula compared with a gold standard and (3) statistical analysis focused on bias, precision and/or accuracy. Data extraction was done by the first author and checked by a second author. A bias of 20% or less, a precision of 30% or less and an accuracy expressed as P₃₀% of 80% or higher were indicators of the validity of the MDRD formula. In total we included 27 studies. The number of patients included ranged from 8 to 1831. The gold standard and measurement method used varied across the studies. For none of the specific patient populations the studies provided sufficient evidence of validity of the MDRD formula regarding the three parameters. For patients with diabetes mellitus and liver cirrhosis, hospitalized patients and elderly with moderate to severe renal impairment we concluded that the MDRD formula is not valid. Limitations of the review are the lack of considering the method of measuring serum creatinine levels and the type of gold standard used.

Conclusion

In several specific patient populations with renal impairment the use of the MDRD formula is not valid or has uncertain validity.

Incorporating glomerular filtration rate or creatinine clearance by the modification of diet in renal disease equation or the Cockcroft-Gault equations to improve the global accuracy of the Age, Creatinine, Ejection Fraction [ACEF] score in patients undergoing percutaneous coronary intervention

BACKGROUND

The aim of the present study was to appraise the comparative ability of different ACEF models incorporating glomerular filtration rate or creatinine clearance estimated by the Modification of Diet in Renal Disease [ACEFMDRD] or Cokcroft-Gault [ACEFCG] equations, respectively, over the original ACEF score (ACEFSrCr) in patients undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 537 patients were analyzed by different measures of discrimination, calibration and net reclassification improvement (NRI).

RESULTS

A significant gradient in all-cause mortality was consistently seen with all the models at 30 days, 1 year and 5 years. The comparison of the three models showed that the best balance in terms of discrimination and calibration for all-cause mortality was offered by the ACEFCG at 30 days, the ACEFMDRD at 1 year and similarly by the ACEFCG and ACEFMDRD at 5 years. At 30 days, the NRI was +32.9% for ACEFMDRD over ACEFSrCr and +16% for ACEFCG over ACEFSrCr. At 1 year, the NRI was 13.8% for ACEFMDRD over ACEFSrCr and -7.8% for ACEFCG over ACEFSrCr. At 5 years, the NRI was +7.7% for both the ACEFMDRD and the ACEFCG over the ACEFSrCr.

CONCLUSIONS

In patients undergoing PCI, the ACEF score is associated with satisfactory early-, mid- and long-term discrimination regardless of the definition of renal function. However, incorporating glomerular filtration rate or creatinine clearance by the MDRD or CG formulas in the ACEF score yields superior calibration compared with the original SrCr-based equation, with the ACEFMDRD displaying superior reclassification ability over the ACEFCG and ACEFSrCr at 30 days and 1 year.