Introduction: anastomotic leak (AL) after colectomy for colorectal cancer (CRC) is a life-threatening complication. This systematic review and meta-analysis aimed to evaluate the preoperative risk factors for AL in patients submitted to colectomy. Methods: the bibliographic search covered 15 years and 9 months, from 1st January 2005 to 19th October 2020 and was performed using PubMed, Cochrane Library, Scopus, Biblioteca Virtual em Saúde, Europe PMC and Web of Science databases. The inclusion criteria were cross-sectional, cohort and case-control studies on preoperative risk factors for AL (outcome). The Newcastle-Ottawa scale was used for bias assessment within studies. Meta-analysis involved the calculation of treatment effects for each individual study including odds ratio (OR), relative risk (RR) and 95% confidence intervals (95% CI) with construction of a random-effects model to evaluate the impact of each variable on the outcome. Statistical significance was set at p<0.05. Results: cross-sectional studies were represented by 39 articles, cohort studies by 21 articles and case-control by 4 articles. Meta-analysis identified 14 main risk factors for AL in CRC patients after colectomy, namely male sex (RR=1.56; 95% CI=1.40-1.75), smoking (RR=1.48; 95% CI=1.30-1.69), alcohol consumption (RR=1.35; 95% CI=1.21-1.52), diabetes mellitus (RR=1.97; 95% CI=1.44-2.70), lung diseases (RR=2.14; 95% CI=1.21-3.78), chronic obstructive pulmonary disease (RR=1.10; 95% IC=1.04-1.16), coronary artery disease (RR=1.61; 95% CI=1.07-2.41), chronic kidney disease (RR=1.34; 95% CI=1.22-1.47), high ASA grades (RR=1.70; 95% CI=1.37-2.09), previous abdominal surgery (RR=1.30; 95% CI=1.04-1.64), CRC-related emergency surgery (RR=1.61; 95% CI=1.26-2.07), neoadjuvant chemotherapy (RR=2.16; 95% CI=1.17-4.02), radiotherapy (RR=2.36; 95% CI=1.33-4.19) and chemoradiotherapy (RR=1.58; 95% CI=1.06-2.35). Conclusions: important preoperative risk factors for colorectal AL in CRC patients have been identified based on best evidence-based research, and such knowledge should influence decisions regarding treatment.

Background: Several tools are available for predicting the risk of anastomotic leakage (AL) in patients undergoing colectomy for colorectal cancer (CRC) treatment. However, these prognostic indexes have limitations in applicability and efficiency. Aim: Developing validated, efficient and easily applicable tools to help physicians predict the risk of AL. Methods: From a meta-analysis and a retrospective cohort, risk factors associated with the development of AL were used to construct and validate two new indexes (Urgency Index and Preoperative Index) to predict AL risk. Sensitivity, specificity, ROC curve, accuracy, and positive and negative predictive value were calculated. Results: The Urgency Index indicated four variables for AL risk prediction and showed sensitivity of 81.24%, specificity of 75.8%, AUC of 0.841 (95% CI: 0.742-0.939), and accuracy of 76.24%. The Preoperative Index revealed 13 variables and showed 86.56% specificity, 50% sensitivity, 0.699 area under the ROC curve, 83.66% accuracy, 24.24% positive predictive value, and 95.27% negative predictive value. Conclusion: The two new indexes created for AL risk prediction in patients operated for CRC treatment present good results of specificity, accuracy and reasonable AUC values, and could be used in clinical practice.

RESUMO Objetivo: fístula anastomótica (FA) após colectomia para câncer colorretal (CCR) é complicação grave. Esta revisão sistemática e meta-análise avaliou os fatores de risco pré-operatórios para FA em pacientes submetidos à colectomia. Métodos: a pesquisa bibliográfica abrangeu 15 anos e 9 meses (1 de janeiro de 2005 - 19 de outubro de 2020), sendo utilizadas as plataformas PubMed, Cochrane Library, Scopus, Biblioteca Virtual em Saúde, Europe PMC e Web of Science. O critério de inclusão foram estudos transversais, coorte e caso-controle em fatores de risco pré-operatórios para FA (desfecho). A escala Newcastle-Ottawa foi usada para avaliação de viés dos estudos. A metanálise envolveu o cálculo dos efeitos de tratamento para cada estudo individualmente incluindo odds ratio (OR), risco relativo (RR) e intervalo de confiança de 95% (IC95%) com construção de modelo de efeitos aleatórios, para avaliar o impacto de cada variável (p<0,05). Resultados: foram selecionados 39 estudos transversais, 21 coortes e quatro casos-controle. A metanálise identificou 14 fatores de risco para FA em pacientes com CCR após colectomia, que são sexo masculino (RR=1,56; IC 95%=1,40-1,75), tabagismo (RR=1,48; IC 95%=1,30-1,69), alcoolismo (RR=1,35; IC 95%=1,21-1,52), diabetes mellitus (RR=1,97; IC 95%=1,44-2,70), doenças pulmonares (RR=2,14; IC 95%=1,21-3,78), doença pulmonar obstrutiva crônica (RR=1,10; IC 95%=1,04-1,16), doença coronariana (RR=1,61; IC 95%=1,07-2,41), doença renal crônica (RR=1,34; IC 95%=1,22-1,47), altas notas na escala ASA (RR=1,70; IC 95%=1,37-2,09), cirurgia abdominal prévia (RR=1,30; IC 95%=1,04-1,64), cirurgia de emergência (RR=1,61; IC 95%=1,26-2,07), quimioterapia neoadjuvante (RR=2,16; IC 95%=1,17-4,02), radioterapia (RR=2,36; IC 95%=1,33-4,19) e quimiorradioterapia (RR=1,58; IC 95%=1,06-2,35). Conclusões: importantes fatores de risco pré-operatórios para FA colorretais em pacientes com CCR foram identificados com base nas melhores pesquisas baseadas em evidências e esse conhecimento deve influenciar decisões relacionadas ao tratamento.