CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 5, November/December 2023 AFRICA 283 around the world have confirmed that HDL-C is a strong, consistent and independent predictor of cardiovascular events (myocardial infarction, ischaemic stroke).34 The protective effects of high HDL-C levels on the risk of myocardial infarction have been demonstrated in numerous epidemiological studies.35 Zhang et al. reported in their community-based study on a hypertensive Chinese population that high HDL-C values were an important protective factor in ischaemic stroke.36 Canpolat et al. also examined HDL-C level in the formation of AF due to its anti-inflammatory and antioxidant effects, and it was shown that low HDL-C values were significantly associated with AF.13 In our study, there was no significant difference between the groups in terms of HDL-C values. It has been suggested that MHR has an important role in systemic inflammation and may be a possible predictor of the development and progression of atherosclerosis.36 In recent studies, it has been reported that MHR is associated with cardiovascular events in chronic kidney disease.37 In another study, Çetin et al. emphasised that increased MHR, a new marker of inflammation, is an independent predictor of many major cardiovascular adverse events, including stent thrombosis and mortality after pPCI in STEMI patients.38 In another study, it was reported that MHR may be a better parameter than NLR and CRP in estimating the severity of CAD in STEMI patients treated with pPCI.39 Considering the large number of studies reporting the relationship between high monocyte counts and low HDL-C levels in inflammatory disorders, in our study, we focused on understanding whether MHR is appropriate for early diagnosis and prediction of the progression of AKI developing after CABG, in which ischaemia–reperfusion injury and inflammation play a major role. As a result, we included 954 patients who underwent isolated CABG with CPB to investigate the relationship between pre-operative MHR and early postoperative AKI in our study, and we found that increased MHR was an independent predictor of early postoperative AKI after adjusting for confounding factors. Therefore, MHR can be used as a valuable and costeffective predictor of clinical outcomes in patients undergoing isolated CABG with CPB. Limitations A few limitations to our study should be mentioned. The biggest and primary limitation was that it included a limited, retrospective study population prone to prejudice, and was a single-centre study unlike multi-centre and cross-sectional studies. Second, due to the lack of urine output values, only sCr values w ere used to determine whether a patient met the criteria for AKI. Third, it was not very practical to determine the presence of AKI as it was not possible to fully monitor the urine output, since the urinary catheters inserted were usually removed from the patients approximately two to three days after the surgery. Fourth, we could not observe time-dependent changes in MHR values and postoperative AKI grade due to the retrospective study design. Therefore, we were unable to evaluate causal relationships between MHR and the development and/or progression of postoperative AKI. Fifth, the inflammatory process has dynamics and persistence, but MHR was not dynamically measured multiple times in our study. Therefore, the dynamic trend and value of the indicator were not reflected in this study. Conclusion We believe that MHR, which can easily be obtained from a simple complete blood count and is an inexpensive inflammatory marker, may be helpful in predicting the development of early postoperative AKI in patients who undergo isolated CABG with CPB. 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