IJCS | Volume 31, Nº2, March / April 2018

95 1. World Health Organization (WHO). The global burden of disease: 2004 update. Geneva (Switzerland); 2008. 2. Brasil. Ministério da Saúde. Secretaria Executiva. Datasus. Informações de saúde. [Acesso em 2013 Junho 20]. Disponível em: http://www. datasus.gov.br . 3. Saleh SS, Racz M, Hannan E. The effect of preoperative and hospital characteristics on costs for coronary artery bypass graft. Ann Surg. 2009;249(2):335-41. doi: 10.1097/SLA.0b013e318195e475. 4. Toor I, Bakhai A, Keogh B, Curtis M, Yap J. Age ≥75 years is associated with greater resource utilization following coronary artery bypass grafting. Interact CardioVasc Thorac Surg. 2009;9(5):827-31. doi: 10.1510/ icvts.2009.210872. 5. Mauldin PD, Weintraub WS, Becker ER. Predicting hospital costs for first-time coronary artery bypass grafting from preoperative and postoperative variables. Am J Cardiol. 1994;74(8):772-5. PMID: 7942547. 6. Smith LR, Milano CA, Molter BS, Elbeery JR, Sabiston DC Jr, Smith PK. 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The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 1-coronary artery bypass grafting surgery. Ann Thorac Surg. 2009;88(1 Suppl):S43-62. doi: 10.1016/j.athoracsur.2009.05.055. References Barbosa et al. Impact of risk factors on MRS costs Int J Cardiovasc Sci. 2018;31(2)90-96 Original Article factors. However, in this study involving patients with one to six risk factors, complications rates and costs were not different between the groups. One limitation of this study was the fact that the groups with the highest and the lowest numbers of risk factors were also the groups with the lowest number of patients, which may make the detection of significant differences between the groups difficult. In addition, the lack of significant differences may be due to the small number of patients in some groups. Our results may contribute to a better control of costs and optimization of resource allocation by public health managers. The use of the micro-costing approach places the costs of each patient as a priority, taking into account the costs of each intervention the patient receives during hospital stay. Further studies may use the micro-costing method to get amore detailed understanding of the costs of theMRS procedure in the public and in the private health systems. Author contributions Conception and design of the research: Barbosa JL. Acquisition of data: Barbosa JL, Cunha CFS, Moutella J, Orsi GP, Feldman K, Silva NR, Faria LF. Analysis and interpretation of the data: Barbosa JL, Thiers CA, Cunha CFS, Moutella J, Tura BR, Orsi GP, Feldman K, Silva NR, Faria LF. Statistical analysis: Barbosa JL. Obtaining financing: Barbosa JL.Writingof themanuscript: Barbosa JL, Thiers CA. Critical revision of the manuscript for intellectual content: Barbosa JL, Thiers CA, Tura BR. Supervision / as the major investigador: Barbosa JL. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This article is part of the thesis of Doctoral submitted by João Luís Barbosa , fromUniversidade Federal do Rio de Janeiro (UFRJ). Ethics approval and consent to participate This study was approved by the Ethics Committee of the Instituto Nacional de Cardiologia under the protocol number 648089. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. Informed consent was obtained from all participants included in the study.