World Journal of Cardiovascular Diseases, 2012, 2, 177-183 WJCD http://dx.doi.org/10.4236/wjcd.2012.23030 Published Online July 2012 (http://www.SciRP.org/journal/wjcd/ ) Classification and regression tree analysis in acute coronary syndrome patients Heng-Hsin Tung 1,2* , Chiang-Yi Chen 3 , Kuan-Chia Lin 1 , Nai-Kuan Chou 3 , Jyun-Yi Lee 4 , Daniel L. Clinciu 5,6 , Ru-Yu Lien 1,7 1 National Taipei University of Nursing and Health Science, Taipei, Taiwan 2 Tungs’ Taichung MetroHabor Hospital, Taichung, Taiwan 3 National Taiwan University Hospital, Taipei, Taiwan 4 Cardiovascular Department, Mackay Memorial Hospital, Taipei, Taiwan 5 Feng Chia University, Taichung, Taiwan 6 Taipei Medical University, Taipei, Taiwan 7 Nursing Department, Taipei Veterans General Hospital, Taipei, Taiwan Email: * shannontung719@yahoo.com , a865292@hotmail.com , kuanchia@ntunhs.edu.tw , nickchou@ntu.edu.tw , jyl5891@ms2.mmh.org.tw , celdan99@gmail.com , lruyu@yahoo.com.tw Received 9 April 2012; revised 8 May 2012; accepted 20 May 2012 ABSTRACT Objectives: The objectives of this study are to use CART (Classification and regression tree) and step- wise regression to 1) define the predictors of quality of life in ACS (acute coronary syndrome) patients, using demographics, ACS symptoms, and anxiety as independent variables; and 2) discuss and compare the results of these two statistical approaches. Back- ground: In outcome studies of ACS, CART is a good alternative approach to linear regression; however, CART is rarely used. Methods: A descriptive survey design was used with 100 samples recruited. Result and Conclusions: Anxiety is the most significant pre- dictor and also a stronger predictor than symptoms of ACS for the quality of life. The anxiety level pa- tients experienced at the time heart attack occurred can be used to predict quality of life a month later. Furthermore, the majority of ACS patients experi- enced a moderate to high level of anxiety during a heart attack. Keywords: CART; Stepwise Regression; Acute Coronary Syndrome; Anxiety; Quality of Life 1. INTRODUCTION Acute coronary syndrome (ACS) includes any group of syndromes such as unstable angina (UA), non-ST-eleva- tion MI (NSTEMI) and ST-elevation MI (STEMI) [1]. In United States the direct and indirect costs of coronary heart disease, which includes ACS, were about $165.4 billion in 2009 [1]. In Taiwan, heart disease is among the top two leading causes of death, and in 2011, one person died of heart disease every 33 minutes and 32 seconds [2]. Patients with ACS experience chest pain, dyspnea, nausea, vomiting, diaphoresis, fatigue, dizziness, and the pain can radiate to the neck, chin, and left shoulder [3]. Dec Von (2008) [4] illustrated that in regard to gender, men commonly experience more chest pain while wo- men are more likely to report indigestion, palpitations, nausea, weakness, and numbness of the extremities. Shih et al. (2009) [5] indicated women experience more back pain, palpitations, nausea/vomiting, and loss of appetite, compare to men. To sum up, women tend to experience more associated symptoms than men. Additionally, a greater number of ACS symptoms and more chest pain are associated with a higher level of anxiety [5,6]. Anxiety can be the consequence of a coronary disease as well as playing a contributing role [7-9]. Koivula et al. (2001) [10] reported that nearly half of their patients had medium to high anxiety while awaiting cardiac surgery. Other studies have shown that anxiety levels decrease after a cardiac event, such as a heart attack, angina, or surgery [11,12], while Andrew (2000) [13] found that 40% - 50% of patients still experienced anxiety follow- ing heart surgery, and 20% of cardiac patients remain anxious even one year after surgery [14]. Additionally, after cardiac surgery women tend to suffer higher levels of anxiety than men do [15]. Both ACS symptoms and anxiety play important roles in the quality of life. The more ACS symptoms are ex- perienced by patients, the lower the quality of life [16- 18]. Anxiety levels increase with a cardiac event, and higher anxiety levels are associated with a lower quality of life and poor outcomes [19-25]. Therefore, patients * Corresponding author. OPEN ACCESS