Abstract Background and Aims Acute kidney injury (AKI) affects approximately 8% of the general surgical population. Additionally, AKI increases the risk for morbidity and mortality by 8- and 3-fold respectively. It was earlier believed that women had a greater risk for postoperative AKI. However, recent literature indicates that the incidence of AKI is actually higher in hospitalized men than women (2.2 odds ratio). Hence the male sex is currently discussed to be a risk factor for AKI. We therefore hypothesized that the incidence of postoperative AKI will be higher amongst men than women after radical colorectal surgery. Method We conducted a post hoc analysis (PROSACC: Propofol or Sevoflurane Anesthesia in Colon Cancer, NCT05585866) on the database from the CAN-study (Cancer and Anesthesia: Survival After Radical Surgery, NCT01975064). The CAN-study included cancer patients undergoing radical surgery at several sites in China, Croatia, Poland, and Sweden. Patients included in PROSACC were those undergoing colorectal surgery at any predefined site. Primary outcome was incidence of AKI by changes in plasma creatinine, secondary outcome was AKI in association to gender (women/men). The KDIGO criteria was used for classifying AKI on postoperative days 1-3 and 4-10. Database management and statistical analysis was performed by Uppsala Research Centre. Men vs women AKI outcome at day 1-3 and 4-10 was statistically compared with the Pearson's chi-square test. Results A total of 3254 patients (n = 1900 men; n = 1354 women) were included in the analysis with their preoperative plasma creatinine. Demographics showed that of the women, 39% had hypertension, 12% had diabetes and 2% had pre-existing kidney disease. In comparison, amongst the men, 24% had hypertension, 9% had diabetes and 1% pre-existing kidney disease. Postoperative plasma creatinine values were obtainable from the database in 2741 patients (n = 1578 men; n = 1163 women) on postoperative day 1-3. One hundred and ninety patients (7%) of this group had developed AKI. Separated by gender, 6% of the women (n = 72) and 8% of the men (n = 118) had established AKI according to KDIGO (p = 0.190). Plasma creatinine values were obtainable in 986 patients (n = 582 men; n = 404 women) on postoperative day 4-10 whereas 87 patients (9%) in this group had developed AKI. Separated by gender, 6% of the women (n = 23) but 11% of the men (n = 64) had established AKI at this timepoint (p = 0.004). Conclusion With this post hoc analysis of a global, multicentre, randomized controlled trial we conclude that the incidence of postoperative AKI is twice as high in men compared with women after 4-10 postoperative days following radical colorectal surgery. Since the women had higher rate of pronounced preoperative risk factors yet still had lower incidence of AKI, this study aligns with the conclusion that the male sex is a risk factor for postoperative AKI.
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