It is discussed controversially, whether diabetes mellitus, obesity, and overweight are major risk factors for the short-term outcome after liver resection. The present study analyzed the patient population of a tertiary referral center with a high caseload of complex major liver resections.
Diabetes mellitus was found to independently predict a complicated postoperative course including significantly higher rates of morbidity, major complications, unplanned readmissions, and bile leakages, but it was not independently associated with a higher mortality rate. The present results are supported by the meta-analysis of Li et al., which showed higher rates of postoperative morbidity, liver failure, and infectious complications in diabetic patients [43]. Their study did not differentiate between major and minor resections, however. Few studies have analyzed the risk of diabetic patients after major liver resection previously. They reported heterogeneous results and often included only one histopathological entity. The results of Poon et al. in patients with hepatocellular carcinoma support the findings of the present analysis: diabetic patients did not have an increased risk for mortality after major resection [42]. In contrast, Little et al, showed different results for patients undergoing liver resection for CRLM. They found that diabetes went along with a higher mortality and no higher morbidity [41]. However, the comparability to the present study might be limited because in the study of Little et al., all diabetic patients that died after major liver resection had received neo-adjuvant chemotherapy. Balzan et al. analyzed the impact of overweight on the outcome after hepatectomy. Diabetes was not an independent predictor of major postoperative complications, but a detailed subgroup analysis for diabetic patients was not included [28]. In consideration of the present findings, diabetic patients should be informed about a higher risk of a complicated postoperative course, which warrants increased alertness and an experienced postoperative care setting. Nevertheless, as diabetes mellitus was not an independent predictor of mortality, these patients should not be denied major liver resection. Given the results of Little et al. even higher precaution might be necessary for patients with diabetes, that received preoperative chemotherapy.
In contrast to the higher risk of patients with diabetes, the present study found no higher mortality and morbidity rates in patients with obesity or overweight. These results are supported by the findings of Mathur et al. [44] and Viganò et al. [31], who showed no independent association of obesity and overweight with mortality and morbidity after major liver resection. However, there are heterogeneous reports in the literature. An increased risk for major complications after major resections was reported in obese and overweight patients previously [28, 36]. Since mortality rates were not increased in those reports, this should not be considered a limitation for surgery [28]. The study of Zogg et al. found only morbid obesity to be associated with higher mortality and morbidity rates, while non-morbid obesity and overweight were no risk factors [37]. Similarly, the meta-analysis of Rong et al. on liver resection for HCC found no association between BMI and mortality [45]. In accordance with the findings of the present study, there is no reason to deprive overweight patients of major liver resections. Nevertheless, the subgroup of morbidly obese patients should be assessed with special attention.
The current study found diabetes to be associated with several individual complications. The most notable were bile leakage, pneumonia, respiratory insufficiency, acute renal failure, and gastrointestinal bleeding, which are potentially life-threatening [46, 47] and thus correspond to the higher rate of CD grade IV complications. The findings are supported by previous studies that found diabetics to suffer more frequently from infectious [48] and pulmonary [49] complications, and acute renal failure [38, 50, 51] after liver resection. They are in line with the detrimental effect of diabetes mellitus on immunological [52, 53, 56] and renal function [54]. The higher rates of bile leakage in diabetic patients are more difficult to understand. Potentially, the diabetic affection of the microcirculation [55] provoked biliary transudation and impaired healing at the resection surface.
Major liver resection is still associated with relevantly higher rates of complications and mortality than minor liver resection [11, 13, 14, 57]. In the present study, PHLF occurred in 18.2% of patients. Two recent studies on major liver resection that also applied the ISGLS definition found a PHLF rate of 9.6–30.1% [58, 59]. In the present cohort, 90-day mortality was 11.8%. This is within the numbers reported from hepatobiliary centers all over Germany [57]. While the analysis of major resections for CRLM showed 90-day mortality rates between 2% and 8% [63-66], 90-day mortality rates for perihilar cholangiocarcinoma of up to 14% [67] and up to 18% for HCCs have been reported [69]. Furthermore, plain major resections such as hemi-hepatectomies show a better outcome than extended liver resections [30, 60, 65]. In extended liver resections a 90-day mortality rate of up to 16,7% has been reported [61, 62].
The present study has some limitations. First, some diabetic, obese, or overweight patients might not have been presented to the surgeons as candidates for resection as their treating doctors might have considered them at high risk for a fatal postoperative outcome. Nevertheless, the analysis showed that neither diabetic, obese nor overweight patients received different extents of surgery compared to non-diabetic and normal weight patients, respectively. Second, diabetic patients less frequently underwent preoperative chemotherapy than non-diabetics. However, this was probably partly secondary to a significantly lower rate of CRLM among diabetic patients as the majority (i.e. 71.7%) of patients with preoperative chemotherapy had CRLM. Third, since the cohort included only patients from a European center the outcome might not be comparable with Asian cohorts where the BMI of diabetic patients is often normal and there has been not such a tremendous increase in the average BMI of the population [68].