Original Article

Multivariate Analysis of Factors Influencing Length of Hospital Stay after Coronary Artery Bypass Surgery in Tehran, Iran


Length of hospital stay (LOS) is a key indicator for hospital management. Reducing hospital stay is a priority for all health systems. We aimed to determine the length of hospital stay following Coronary Artery Bypass Surgery (CABG) based on its clinical and non-clinical factors. A cross-sectional study of 649 consecutive patients who underwent coronary artery bypass graft surgery was conducted in Imam Khomeini and Shariati university hospitals, Tehran, Iran. Data was analyzed by using non-parametric univariate tests and multiple linier regression models. Thirty seven independent variables including pre-operative, intra-operative and post-operative variables were analyzed. Finally, an appropriate model was constructed based on the associated factors. The results showed that 70.3% of the patients were male, and the mean age of the patients was 59.3 ± 10.4 years. The Mean (±SD) and median of the LOS were 11.7 ± 7.1 and 9 days, respectively. Of 37 investigated variables, 24 qualitative and quantitative variables were significantly associated with length of stay (p<0.05). Multiple linear regression analysis showed that independent variables including age, medical insurance type, body mass index, and prior myocardial infarction; admission day, admission season, Cross-clamp time, pump usage, admission type, the number of laboratory tests and the number of specialty consultation had more effect on the hospital stay. We concluded that some significant factors influencing hospital stay after CABG were predictable and modifiable by hospital managers and decision makers to manage hospital beds.

Benedetto U, Melina G, Angeloni E, et al. Coronary artery bypass grafting versus drug-eluting stents in multi vessel coronary disease. A meta-analysis on 24,268 patients. Eur J Cardiothoracic Surg 2009;36(4):611-5.

Adeoye AM, Mullassari AS, Ramkumar SR, et al. Prevalence of carotid artery disease in candidates undergoing coronary bypass graft seen at Madras Medical Mission. Sahel Med J 2013;16(2):43-7.

Maleki M, Karbassi A, Noohi F, Omrani G. Risk factors and outcome in Iranian cardiac surgery: Iranian heart score. Am Heart Hosp J 2007;5(4): 223-7.

Mandegar MH, Marzban M, Lebaschi AH, et al. Cardiovascular Risk Factors and In-Hospital Mortality in 1258 Cases of Coronary Artery Bypass Surgery in Tehran Heart Center. Acta Medica Iranica 2008;46(5): 386-90.

Karimi AA, Ahmadi SH, Davoodi S, et al. First Database Report on Cardiothoracic Surgery in Tehran Heart Center. Iranian J Pub Health 2008;37(2):1-8.

Lazar HL, Fitzgerald R, Gross S, et al. Determinants of Length of Stay After Coronary Artery Bypass Graft Surgery. Circulation 1995;92(9 Suppl):20-4.

Eagle KA, Guyton RA, Davidoff R, et al. ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery: Executive Summary and Recommendations: A Report of= the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1991 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation 1999;100(13):1464-80.

Reed T, Veith FJ, Gargiulo NJ, et al. System to decrease length of stay for vascular surgery. J Vascular Surg 2004;39(2):365-99.

Skillman JJ, Paras C, Rosen M, et al. Improving cost efficiency on a vascular surgery service. Am J Surg 2000;179(3):197-200.

Ravangard R, Arab M, Zeraati H, et al. Patients' Length of Stay in Women Hospital and ItsAssociated Clinical and Non-Clinical Factors, Tehran, Iran. Iran Red Crescent Med J 2011;13(5):309-315

Kaboli PJ, Go JT, Hockenberry J, et al. Associations between Reduced Hospital Length of Stay and 30-Day Readmission Rate and Mortality: 14-Year Experience in

Veterans Affairs Hospitals. Ann Intern Med 2012;157(12):837-45.

Clarke A. Why are we trying to reduce length of stay? Evaluation of the costs and benefits of reducing time in hospital must start from the objectives that govern change. Qual Health Care 1996;5(3):172-9.

Weintraub WS, Jones EL, Craver J, et al. Determinants of prolonged length of hospital stay after coronary bypass surgery. Circulation 1989;80(2):276-84.

Atienza N, Garcia-Heras J, Munoz-Pichardo JM, et al. An= application of mixture distributions in modelization of length of hospital stay. Stat Med 2008;27(9):1403-20.

Conrad D, Wickizer T, Maynard C, et al. Managing care, incentives, and information: an explanatory look inside the "Black Box" of hospital efficiency. Health Services Res 1996;31(3):235-59.

Taheri PA, Butz DA, Greenfield LJ. Length of stay has minimal impact on the cost of hospital admission. J Am Coll Surg 2000;191(2):123-30.

Lee AH, Grracey M, Wang K, et al. Robustified Modeling approach to Analyze Pediatric Length of Stay. Ann Epidemiol 2005;15(9):673-7.

Malkin JD, Keeler E, Broder MS, et al. Postpartum length of stay and newborn health: A cost-effectiveness analysis. Pediatrics 2003;111(4 Pt 1):316-22.

Tu JV, Ko DT, Guo H, et al. Determinants of variations in coronary revascularization practices. CMAJ 2012;184(2):179-186.

Cwynar R, Albert NM, Butler R, et al. Factors associated with long hospital length of stay in patients receiving warfarin after cardiac surgery. J Cardiovasc Nurs 2009;24(6):465-74.

Baikoussis NG, Karanikolas M, Siminelakis S, et al Baseline cerebral oximetry values in cardiac and vascular surgery patients: a prospective observational study. J Cardiothoracic Surge 2010;5(1):41.

Schmelzer TM, Mostafa G. Lincourt AE, et al. Factors affecting length of stay following colonic resection. J Surg Res 2008;146(2):195-201.

Maor Y, Cohen Y, Olmer L, et al. Factors Associated With health indicators in Patients Undergoing Coronary Artery Bypass Surgery. CHEST 1999;116(6):1570-74.

Alexopoulos EC. Introduction to Multivariate Regression Analysis. Hippokratia 2010;14(Supple 1):23-8.

Moran JL, Solomon PJ, Peisach AR, et al. New models for old questions: generalized linear models for cost prediction. J Eval Clin Pract 2007;13(3):381-9.

Tamism JE, Steinbemr JS. Atrial Fibrillation Independently Prolongs Hospital Stay after Coronary Artery Bypass Surgery. Clin Cardiol 2000;23(3):155-59.

Kato N, Kondo M, Okubo I, et al. Length of hospital stay in Japan 1971-2008: hospital ownership and costcontainment policies. Health Policy 2014;115(2-3):180-8.

Mak J, Grant WD, McKenzie JC, et al. Physicians’ Ability to Predict Hospital Length of Stay for Patients Admitted to the Hospital from the Emergency Department. Emerg MedNInt 2012;2012:824674.

Khairudin Z. Determinants of Prolonged Stay after Coronary Artery Bypass Graft Surgery. Procedia Social and Behavioral Sciences 2012;36(1):87-95.

Kaboli PJ, Barnett MJ, Fuehrer SM, et al. Author information. Length of stay as a source of bias in comparing performance in VA and private sector facilities: lessons learned from a regional evaluation of intensive care outcomes. Med Care 2001;39(9):1014-24.

Thomas JW, Bates EW, Hofer T, et al. Interpreting riskadjusted length of stay patterns for VA hospitals. Med Care 1998;36(12):1660-75.

Cowper PA, Delong ER, Hannan EL, et al. Trends in postoperative length of stay after bypass surgery. Am Heart J 2006;152(6):1194-200.

Eugene A. Duan K, Silow-Carroll S, et al. Hospital performance improvement: trends in quality and efficiency: a quantitative analysis of performance improvement in U.S. hospitals. The Commonwealth Fund. (Accessed in May 2015, 11, at http://www.commonwealthfund.org.../kroch_hosp_perfor mance_improve_1008-pdf.pdf).

Cocker JD, Messaoudi N, Stockman BA, et al. Preoperative prediction of intensive care unit stay following cardiac surgery. Eur J Cardio-thoracic Surg 2011;39(1):60-7.

Hirose H, Amano A, Yoshida S, et al. Coronary Artery Bypass Grafting in the Elderly. Chest 2000;117(5):1262- 70.

Tajvar M, Arab M, Montazeri A. Determinants of healthrelated quality of life in elderly in Tehran, Iran. BMC Public Health 2008;8: 323.

Wai Sang SL, Chaturvedi R, Alam A, et al. Preoperative hospital length of stay as a modifiable risk factor for mediastinitis after cardiac surgery. J Cardiothoracic Surg 2013;8(1):45.

Koproski J, Pretto Z, Poretsky L. ffects of an Intervention by a Diabetes Team in Hospitalized Patients With Diabetes. Diabetes Care 1997;20(10):1553-5.

Perrotta S, Nilsson F, Brandrup-Wognsen G, et al. Body mass index and outcome after coronary artery bypass surgery. J Cardiovasc Surg (Torino) 2007;48(2):239-45.

Engel AM, McDonough S, Smith JM. Does an obese body mass index affect hospital outcomes after coronary artery bypass graft surgery? Ann Thorac Surg 2009;88(6):1793- 800.

Thompson RT, Bennett WE Jr, Finnell SM, et al. Increased length of stay and costs associated with weekend admissions for failure to thrive. Pediatrics 2013;131(3):e805-10.

Horwich TB, Hernandez AF, Liang L, et al. Get With Guidelines Steering Committee and Hospitals. Weekend hospital admission and discharge for heart failure: association with quality of care and clinical outcomes. Am Heart J 2009;158(3):451-8.

Konuralp C, Ketenci B, Ozay B, et al. Effects of seasonal variations on coronary artery surgery. Heart Surg Forum 2002;5(4):388-92.

Nemati M. Effects of Seasonal Variations on the Outcome of Coronary Artery Bypass Graft Surgery. Iran J Med Sci 2013;38(2):89-92.

Schwartz JP, Bakhos M, Patel A, et al. Repair of aortic arch and the impact of cross-clamping time, New York

Heart Association stage, circulatory arrest time, and age on operative outcome. Interact Cardiovasc Thorac Surg 2008;7(3):425-9.

Weiner MM, Hofer I, Lin HM, et al. The Relationship between Surgical Volume, Repair Quality and Perioperative Outcomes for Repair of Mitral Insufficiency in a Mitral Valve Reference Center. J Thorac Cardiovasc Surg 2014;148(5):2021-6.

Uyar IO, Akpinar MB, Sahin V, et al. Effects of single aortic clamping versus partial aortic clamping techniques on post-operative stroke during coronary artery bypass surgery. Cardiovasc J Afr 2013;24(6):213-7.

Al-Sarraf N, Thalib L, Hughes A, et al. Cross-clamp time is an independent predictor of mortality and morbidity in] low- and high-risk cardiac patients. Inter J Surg 2011; 9(1):104-9.

Sisillo E, Marino MR, Juliano G, et al. Comparison of on pump and off pump coronary surgery: risk factors for neurological outcome. Eur J Cardio-thoracic Surg 2007;31(6):1076-80.

Sellke FW, DiMaio JM, Caplan LR, et al. Comparing On- Pump and Off-Pump Coronary Artery Bypass Grafting: Numerous Studies but Few Conclusions: A Scientific Statement from the American Heart Association Council on Cardiovascular Surgery and Anesthesia in Collaboration with the Interdisciplinary Working Group on Quality of Care and Outcomes Research. Circulation 2005;111(21):2858-64.

Hernandez F, Cohn WE, Baribeau YR, et al. Northern New England Cardiovascular Disease Study Group. Inhospital outcomes of off-pump versus on-pump coronary artery bypass procedures: a multicenter experience. Ann Thorac Surg 2001;72(5):1528-33.

Mirhosseini SJ, Forouzannia SK, Ali-Hassan-Sayegh S, et al. On pump versus off pump coronary artery bypass surgery in patients over seventy years old with triple vessels disease and severe left ventricle dysfunction: focus on early clinical outcomes. Acta Med Iran 2013;51(5):320-3.

Holland LL, Smith LL, Blick KE. Reducing laboratory turnaround time outliers can reduce emergency department patient length of stay: an 11-hospital study. Am J Clin Pathol 2005;124(5):672-4.

Kenneth E. Blick. Providing Critical Laboratory Results on Time, Every Time to Help Reduce Emergency Department Length of Stay. Am J Clin Pathol 2013;140(2):193-202.

Yoon P, Steiner I, Reinhardt G. Analysis of factors influencing length of stay in the emergency department CJEM 2003;5(3):155-61.

IssueVol 54, No 2 (2016) QRcode
SectionOriginal Article(s)
Coronary arteries bypass grafting Length of stay University hospital

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
Torabipour A, Arab M, Zeraati H, Rashidian A, Sari AA, Sarzaiem MR. Multivariate Analysis of Factors Influencing Length of Hospital Stay after Coronary Artery Bypass Surgery in Tehran, Iran. Acta Med Iran. 2016;54(2):124-133.