Preoperative Renal Insufficiency: Underreporting and Association With Readmission and Major Postoperative Morbidity in an Academic Medical Center
BACKGROUND: Making a formal diagnosis of chronic kidney disease (CKD) in the preoperative setting may be challenging because of lack of longitudinal data. We explored the predictive value of a single reduced preoperative estimated glomerular filtration rate (eGFR) value on adverse patient outcomes in the first 30 days after elective surgery. We compared the rate of major postoperative adverse events, including 30-day readmission rate, hospital length of stay, infection, acute kidney injury (AKI), and myocardial infarction across patients with declining preoperative eGFR values. We hypothesized that there is an association between decreasing preoperative eGFR values and major postoperative morbidity including readmission within 30 days of discharge and that the reasons for unplanned readmissions may be associated with poor preoperative renal function. METHODS: This was a retrospective analysis of the electronic health record of 39 989 adult patients who underwent elective surgery between June 2011 and July 2013 at our institution. Patients with reduced eGFR (<60 mL/min/1.73 m) were identified and categorized by the stages of CKD that correlated with the preoperative eGFR value. Odds of readmission to our hospital within 30 days, as well as new diagnosis of AKI, myocardial infarction, and infection, were determined with multivariate logistic regression. The subset of patients who were readmitted within 30 days also were subdivided further into patients who had an eGFR <60 mL/min/1.73 m and those with an eGFR >/=60 mL/min/1.73 m, as well as whether the readmission was planned or unplanned. RESULTS: Of the 4053 patients with eGFR <60 mL/min/1.73 m, 3290 (81.2%) did not carry a preoperative diagnosis of CKD. Adjusted odds ratios of being readmitted were 1.48 (99% confidence interval [CI], 1.18-1.87; P < .001) for eGFR 30 to 44 mL/min/1.73 m to 2.06 (99% CI, 1.32-3.23; P < .001) for eGFR <15 mL/min/1.73 m compared with patients with a preoperative eGFR value >/=60 mL/min/1.73 m. Patients with a lower eGFR also demonstrated increasing odds of AKI from 2.78 (99% CI, 1.86-4.17; P < .001) for eGFR 45 to 59 mL/min/1.73 m to 3.81 (99% CI, 1.68-8.16; P < .001) for eGFR <15 mL/min/1.73 m. CONCLUSIONS: This study highlights that preoperative renal insufficiency may be underreported and appears to be significantly associated with postoperative complications. It extends the association between a single low preoperative eGFR and postoperative morbidity to a broader range of surgical populations than previously described. Our results suggest that preoperative calculation of eGFR may be a relatively low-cost, readily available tool to identify patients who are at an increased risk of readmission within 30 days of surgery and postoperative morbidity in patients presenting for elective surgery.
Reduced preoperative estimated glomerular filtration rate is associated with postoperative major non-cardiac adverse events including increased risk of readmission within 30 days of surgery [Meeting Abstract]
INTRODUCTION: Chronic Kidney Disease (CKD) has long been recognized as an independent predictor of major adverse cardiac events1,2, and recent studies have demonstrated that the impact of CKD extends to other significant postoperative events including cerebrovascular accidents, all-cause mortality, and increased hospital length of stay3,4. However, whether CKD predisposes patients to other postoperative complications has not been elucidated. We examined the incidence of CKD in our surgical population and compared the rates of significant postoperative complications including: acute kidney injury (AKI), venous thromoboembolism (VTE), myocardial infarction (MI), infection, and 30-day readmission to our hospital across declining preoperative glomerular filtration rate (eGFR) values. We hypothesized that there is a direct association between rates of major surgical complications and stage of CKD. Methods: With IRB approval, a retrospective analysis of a database of adult patients who underwent elective surgery between June 2011 and July 2013 at a single large academic institution was performed. Patients with reduced GFR (<60 ml/min/1.73m2) were identified and categorized by stage of CKD. Odds of readmission to hospital within 30 days, as well as new diagnosis of AKI, VTE, MI, and infection in these patients were determined using logistic regression. RESULTS: Of the 48714 patients in the database with an available GFR on record, 43072(88%) met inclusion criteria. Of the 4097 patients with eGFR <60 ml/min/1.73m2, 3448 (84%) did not have a preoperative ICD-9 diagnosis of CKD on record. When categorized by increasing stage of CKD and compared to GFR >60 ml/ min/1.73m2, increasing numbers of these patients were readmitted to the hospital within 30 days of their procedure (OR 1.5, 95% CI 1.3-1.7, p<0.001 to OR 3.5, 95% CI 2.6-4.5, p<0.001 for Stage 3A to Stage 5 CKD respectively) [Figures 1,2]. Patients with higher stage CKD also tended to demonstrate increasing odds of acute kidney injury (OR 21.5, 95% CI 15.3-29.6, p<0.001 for stage 4 CKD), myocardial infarction (OR 8.2, 95% CI 4.7-13.3, p<0.001 for stage 5 CKD), infection (OR 4.4, 95% CI 2.7-6.8, p<0.001 for stage 4 CKD) and venous thromboembolism (OR 3.3, 95% CI 1.4- 6.6, p<0.001 for stage 5 CKD). DISCUSSION: This study highlights that CKD is a common, underreported comorbidity in the surgical population with significant impact on major postoperative complications. Interestingly, the rates of postoperative VTE, AKI, MI, infection and hospital readmission increased with increased stage of CKD. Furthermore, our study extends the association between preoperative CKD and postoperative adverse events to a broader range of surgical populations than previously described. Recognizing the association between preoperative low eGFR and increased rates of postoperative complications and hospital readmissions will facilitate the development of perioperative protocols to enhance patient safety and reduce hospital costs. (Figure Presented)