MIRC has become a mainstream surgical option for bladder cancer patients with curative intent in most medical centers, because its effectiveness and safeness have been well demonstrated, namely less pain, smaller trauma and quicker recovery[2-9]. The history of LRC can be traced back to 1992, despite the advantages mentioned above, it has a higher demand on surgeons both in anatomical knowledge and endoscopic skills. The first robotic surgery system was approved into clinical use in 1994, and surgical robot provides us with flexible mechanical arms and 3-Demesion vision. There was no significant difference in effectiveness and safety between RARC and LRC based on the current pooled evidence: the surgery duration, positive surgical margin rate, postoperative recovery and complications were comparable for both approaches. Urinary diversion is a critical step after bladder removal and the choice should take into account the patient's wishes, age, underlying diseases, tumor stage and life expectancy. Ileal conduit is one of the most classic and widely used urinary diversion procedures following bladder resection[10,12]. The incidence of overall 30-d complications was 87.41% (236/270) in our center, but CDC grade Ⅰ and Ⅱ complications accounted for 87% (606/691). Similarly, a single-center retrospective study captured 2485 complications in 506 patients with a 99.4%(503/506) 30-d complications rate, whereas 84% of them were CDC grade Ⅰ or Ⅱ. However, the 30-d complications rates of MIRC in five articles included in a meta-analysis were 41.2% (14/34), 66.7% (26/39), 15% (3/20), 43% (52/121) and 45.5% (5/11), respectively. There was still a distinct discrepancy in reporting of complications after radical cystectomy, because those minor complications were neglected by researchers who held such views that single low-lever complication doesn’t necessarily impair the postoperative course of patients. Vetterlein et al pointed out that the occurrence of massive minor complications doesn’t mean treatment failure, and detailed documentation of postoperative adverse events that potentially damage recovery and quality of life of patients is essential for patient consultation, clinical trial design and treatment efficiency assessment. Besides, severe complication, which can cause serious physical, psychological and financial harm to patients, is surgeons’ greatest concern and patients' least desire. The primary purpose of this study was to investigate risk factors for severe complications within 30 days after MIRCIC.
CDC is currently the most commonly used complication assessment method, and numerous studies incorporate CDC ≥ Ⅲ into "major complication". A retrospective research of Zhang et al. included 298 cases of MIRC and revealed that the proportion of patients with major complication was 15.1% (45/298). Su et al. reviewed the clinical data of 126 patients with LRC and 189 patients with RACRC, and found an rate of 7.62% (24/315) about postoperative overall major complications. In contrast, the ratio of patients with CDC ≥ III was higher in our study(23.70% ,64/270). The reason may be that we had an rigorous inclusion criteria for the method of urinary diversion, while 55.7% and 25.7% of other types of diversion were involved in the above two studies, respectively. The occurrence rate of gastrointestinal complications after radical cystectomy was about 29%. Svatek et al. performed a study involving 283 patients undergoing open radical cystectomy and indicated that the incidence of postoperative paralytic ileus was 15.2%.Furthermore, BMI (95%CI: 1.03-1.17, P =.007) and age (95%CI: 1.02-1.16, P =.008) were independent risk factors of paralytic ileus. In this paper, our results confirmed that the most common major complication was ileus with an rate of 23.70% (64/270), and BMI ≥ 30 kg/m2 (95% CI: 1.216 5.032, P = 0.012) and estimated blood loss ≥ 400ml (95% CI: 1.367 5.992, P = 0.005) were the independent predictors of CDC ≥Ⅲ. Increased BMI was associated with higher postoperative complication rates, comprising infection-related diseases, wound-related diseases, acute kidney injury and paralytic ileus. In the article of Lenardis et al., the major complication was defined as one of the following postoperative events: cardiac or neurological complications, reoperation and death. Patients with BMI ≥ 30kg/m2 were significantly more likely to undergo major complications within 30 days after radical cystectomy than those with normal BMI(OR 1.59, 95% CI 1.17-2.16). Likewise, Arora and colleagues published their study with 2055 patients receiving radical cystectomy, and they suggested that a high BMI was highly correlated with 30-d mortality and morbidity. In minimally invasive surgery, even a small amount of bleeding can seriously impair the clarity of operative visual filed due to the magnification of camera lens. Lin et al. conducted a prospective randomized controlled trial and asserted that the application of minimally invasive tool significantly reduced intraoperative blood loss compared to conventional open surgery(215ml vs 510ml,P<0.001). A latest meta-analysis verified that there was no significant difference in intraoperative blood loss between LRC and RARC (95%CI: -37.81-258.62, P=0.14). Wilson and workmates retrospectively analyzed the data of 2934 cases and deemed that perioperative blood transfusion was associated with increased morbidity(OR 1.361, 95% CI 1.131-1.638). Shen et al. concluded that the need for postoperative blood transfusion, rather than intraoperative blood transfusion, was independently associated with perioperative morbidity. Intraoperative blood transfusion was not associated with the rate of 30-d severe complications but estimated blood loss was an independent predictor of 30-d severe complications(CDC ≥ Ⅲor CCI > 33.7) in our study(OR 2.862, 95% CI 1.367-5.992; OR 2.904 95% CI 1.497-5.634). Reason may be that intraoperative blood product requirements were closely related to preoperative anaemia, while the degree of anemia was relatively mild before surgery in our research, in which the median HB value was 129g/L(interquartile range: 116-140g/L). Secondly, postoperative blood transfusion may be due to massive intraoperative bleeding or other serious complications such as gastrointestinal bleeding, so, the inclusion of it in multiple logistic regression analysis may lead to greater bias.
CCI is a new complication evaluation method developed on the basis of CDC, and it integrates all postoperative complications to obtain the cumulative morbidity, which is conducive to the comprehensive evaluation of patient recovery. CCI values was positively associated with the number and grade of complications, and patients with CCI value exceeding 33.7 accounted for 20%, which was also verified in this study. In addition, we further confirmed the feasibility of CCI in evaluating severe complications after radical surgery. BMI ≥ 30kg/m2 (95%CI: 1.411-6.510, P=0.004) and estimated blood loss ≥ 400ml (95%CI: 1.497-5.634, P=0.002) were also independent risk factors for patients with CCI >33.7. Therefore, it is necessary to evaluate and control BMI before MIRCIC, and to minimize the amount of blood loss during the operation.
Admittedly, there were several limitations to this study. Firstly, Our study was a single-center retrospective study with its inherent drawbacks. Secondly, different surgical habits and treatment ideas among the three surgeons may lead to some bias. Thirdly, the present study only included complications occurring within 30 days after MIRCIC. However, it is indubitably crucial to predict long-term procedure-specific severe complications and survival outcomes. To address these limitations, a multicenter prospective study is necessary. Nevertheless, this study enriches the perioperative data of MIRCIC and provides valuable clinical information for bladder cancer patients and urologists.