Postoperative AKI is common in surgical patients and is associated with high morbidity and mortality. Due to its complex pathophysiology, no evidence-based efficient therapy to stop the onset of the injury or repair the damage already done is available, as such, prevention is usually a better solution [9].
In the current study, 10.3% of the patients developed AKI postoperatively (80% of them stage 1, 18% stage 2, and 2% stage 3). These findings are consistent with Lumlertgul et al. who studied 89 patients undergoing CRC surgery and observed AKI in 13.5% of them (75% AKI stage 1, 17% stage 2, and 1 patient stage 3) [10]. Also, a meta-analysis by O’Connor et al. on 19 articles describing AKI outcomes in 82,514 patients post major abdominal surgery including CRC surgery, found that pooled incidence of AKI was 13.4% [11]. Slagelse and his colleagues studied 6580 patients undergoing CRC surgery in Northern Denmark and found that 20% of their patients developed AKI postsurgical (13% stage 1, 4% stage 2, and 3% stage 3) [12].
One of the aims of the current work was to study and analyze the different risk factors that may increase the incidence of AKI in CRC patients undergoing surgery. Identifying risk factors may help to prevent AKI in this category of patients. Intraoperative hypotension and amount of intraoperative bleeding were found to be significantly associated with postoperative AKI (p = 0.023, p = 0.05 respectively). These results are consistent with the results of several previous studies which showed that intraoperative hemodynamic instability and hypotension are significant factors for the development of PO-AKI even in elective non-cardiac surgeries [13, 14, 15]. In addition, intraoperative and early postoperative hemodynamic management and stabilization have a great impact on the prevention of PO-AKI, as shown by different randomized controlled trials and a Cochrane review and meta-analysis which suggested goal-directed therapy to minimize the risk of PO-AKI [16, 17]. To the best of our knowledge, there is scarce data about intraoperative hemodynamic instability and the incidence of PO-AKI in patients undergoing CRC surgeries.
Kidney hypoperfusion and hypoxia are significant role-players in PO-AKI resulting in disturbance of renal autoregulation, inflammation, narrowing of peritubular capillaries, apoptosis, and necrosis of tubular cells [18, 19].
One of the important findings in our study is the association between preoperative serum albumin levels and PO-AKI. This finding is similar to what was described in the study by Zorrilla-Vaca et al. [20]. In another study, researchers found that every 1 g/dl decrease in albumin was associated with a 25% increase in risk of AKI at 1-year follow-up [21]. Hypoalbuminemia is a nonspecific marker that may be caused by malnutrition, impaired liver function, or inflammation. Correction of preoperative hypoalbuminemia may help to reduce the risk of PO-AKI.
Patients with preoperative CKD were significantly associated with PO-AKI (p = 0.05). This significant association was described in previous research works studying risk factors of PO-AKI in patients with CRC undergoing surgery [21, 22, 23].
In the current work, 39% of the patients receiving neoadjuvant chemotherapy had PO-AKI which was also found to be significant (p = 0.023). These results disagree with the results of the study by Slagelse et al. [12]. This discrepancy may be due to the small number of patients who received neoadjuvant chemotherapy in their study. In addition, the types and doses of chemotherapy used in the latter study may have less nephrotoxic effect than those used in our study. However, Rödel et al. reported in their study an increase in serum creatinine levels in 16% of studied rectal cancer patients who received neoadjuvant concurrent chemoradiotherapy followed by 4 cycles adjuvant XELOX [24]. These results are also in agreement with another Polish study [25].
Other risk factors studied in the current work including age, sex, obesity, DM, hypertension, heart failure, preoperative use of NSAIDs, surgical approach (laparoscopic vs. open), operative time, and type of cancer were not found to be significantly associated with PO-AKI. However, other studies reported an increased incidence of AKI in elderly patients who underwent laparotomy compared to those who underwent laparoscopic surgery [26]. In contrast to our results, Li et al., reported that type of stoma (ileostomy)was associated with an increased risk of AKI readmission [27], however, a previous study showed that stoma related dehydration (a main cause of pre-renal AKI) was quite low in Egyptian patients in comparison to incidence in western countries [28].
The development of PO-AKI could be associated with postoperative complications such as sepsis and electrolyte disturbance that may affect the glomerular perfusion, intraglomerular pressure, and glomerular filtration rate. In the current study, sepsis occurred in 3.7% of our patients and was found to be one of the significant risk factors associated with PO-AKI (p = 0.003). These findings agree with the results of the study by Long et al., which showed that patients with PO-AKI had significantly higher rates of pneumonia and sepsis than non-AKI patients [22]. Sepsis and infection may be the result of decreased immunity in these patients and may be the cause of AKI through different mechanisms.
The overall survival was significantly worse in those who developed postsurgical AKI. This finding is consistent with the findings of several studies that investigated the outcome of PO-AKI including complications and mortality and found that patients with AKI had longer hospital stays, were more likely to have myocardial infarctions, embolism, pneumonia, sepsis, mechanical ventilation, and greater rates of mortality [12, 22, 29].
Post-chemotherapy AKI was detected in 18.7% of the studied patients, this could be explained by known nephrotoxic adverse events of Capecitabine, Irinotecan, and Oxaliplatin, which may be exaggerated if associated with other risk factors such as concomitant use of NSAIDs or nephrotoxic antibiotic or CT contrast especially in patients with high baseline creatinine levels [30, 31].
Limitations of this study include missing data about urine output and type of fluids used intra and postoperative, lack of long-term follow-up of some of the studied cases and the retrospective design of the study. However, the large number of patients represents a strength point and being dedicated for CRC surgery and chemotherapy only.