en Biostatistics and Epidemiology Biostatistics and Epidemiology Original Research Original Research <p style="text-align: justify;"><strong>Background: </strong>The incidence of restenosis in patients suffering from coronary artery disease after undergoing angioplasty is of paramount importance. Accordingly, this study aimed to investigate factors affecting the time of the first incidence of restenosis in patients undergone angioplasty in the city of Zanjan, Iran.</p> <p style="text-align: justify;"><strong>&nbsp; Methods:</strong> This retrospective cohort study was conducted on 421 patients who referred to Ayatollah Musavi hospital in Zanjan for angioplasty during 2009 to 2012.&nbsp; The time of the incidence of restenosis after angioplasty constituted the dependent variable of the study. Independent variables of the study included signs of diabetes, hypertension, hyperlipidemia, kidney disease, carotid stenosis, lung disease, anemia, angina history, and MI. The Cox regression model with the significance level of 0.05 was deployed for the statistical analysis.</p> <p style="text-align: justify;"><strong>&nbsp; Results: </strong>According to the Cox regression model, hazard ratio of the first incidence of restenosis in patients with hypertension and angina was 22.8% and 29.5% less than other patients, respectively. However, hazard ratio of the first incidence of restenosis was 7.4 times more in patients suffering from carotid stenosis than other patients (p<0.05).</p> <p style="text-align: justify;"><strong>&nbsp; Conclusion: </strong>The results of this study revealed that as time goes on, the risk of the incidence of restenosis in angioplasty patients increases such that patients&rsquo; survival decreases dramatically after a year. To determine the role of effective factors on the incidence of restenosis, conducting a prospective interventional study is highly recommended.</p> Angioplasty, Cardiovascular Disease, Restenosis, Survival, Cox Regression. 1019 1025 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-1074&slc_lang=en&sid=1 Javad Nasseryan javad.nasseryan@modares.ac.ir 200319475328460025436 200319475328460025436 No Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Ebrahim Hajizadeh hajizadeh@modares.ac.ir 200319475328460025437 200319475328460025437 Yes Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Aliakbar Rasekhi rasekhi@modares.ac.ir 200319475328460025438 200319475328460025438 No Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Hassan Ahangar ahanghar@zums.ac.ir 200319475328460025439 200319475328460025439 No Department of Heart, Faculty of Medical Sciences, Zanjan University of Medical Sciences, Zanjan, Iran.