Validation of the TIMI risk score in Chinese patients presenting to the emergency department with chest pain.
Ischaemic heart disease (IHD) causes around 7.2 million deaths annually [1]. Chest pain is a common presenting symptom and early diagnosis of cardiac chest pain allows effective treatment to reduce morbidity and mortality. It is difficult to predict which patients presenting to the emergency department (ED) with chest pain are at significant risk of adverse outcomes. The Thrombolysis in Myocardial Infarction (TIMI) risk score was developed to stratify risks of death and cardiac ischaemic events within two weeks in patients presenting with acute coronary syndrome [2]. TIMI has also been validated as a predictor of 30 day outcome in undifferentiated chest pain patients [3]. Rates of cardiovascular events and deaths vary significantly between different countries [4] and ethnic groups [5]. Whilst factors such as smoking, hypertension, diabetes and hypercholesterolaemia are known to increase cardiovascular risk in all regions and ethnic groups, the importance of each risk factor varies considerably between populations [6] and differences in risk factor prevalence do not fully account for differences in risk between ethnicities [7]. It cannot be assumed that chest pain risk stratification methods developed in one setting are valid in another. Studies validating the TIMI score in patients with chest pain have been done in other countries [3,8], with study populations being predominantly Caucasian or African-American. No previous study has validated the TIMI risk score in Asia. Our objective was to establish the relationship between the TIMI risk score and 30 day major adverse cardiovascular event (MACE) rate of Chinese EDpatients presentingwith chest pain. We performed a prospective single centre observational study on ED patients with undifferentiated chest pain to validate the TIMI risk score in an Asian setting after receiving approval from our Research Ethics Committee (CREC-2008.351). It was conducted between September 2008 and March 2009 in the ED of Prince of Wales Hospital which has tertiary cardiology and cardiothoracic surgical services. The ED annual census is 150,000 patients. Based on previous work [3], the required sample size was calculated as 308 (based on event rate 6.5–20%; type I error 0.01 and 80% power). Chinese patients ≥20 years old presenting to the ED with non-traumatic chest pain were eligible for inclusion. Patients were excluded if they could not communicate in Cantonese, Mandarin or English. Informed written consent was obtained from all patients. Data was collected using a standardized questionnaire. Patients' medical records were reviewed for information on past medical history, ECGs, blood results and medical treatment received. The seven baseline patient characteristics which make up the TIMI risk score are: age≥65 years; three or more of family history of heart disease, hypertension, raised cholesterol, diabetes mellitus, and smoking; known coronary artery stenosis N50%; ST deviation ≥0.5 mm on ECG; two ormore episodes of angina in the last 24 h; use of aspirin in the last seven days and elevated cardiac markers. One point was given for each component, so each patient had a score of 0–7. The primary outcome measure was MACE within 30 days of ED presentation. MACE is a composite of: all-cause mortality; myocardial infarction (MI); troponin positive acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI). Secondary outcomes included these four events individually. The Hong Kong wide computerised medical records system was used to identify patient outcomes. Any patient who had not been readmitted to a public hospital within 30 days was telephoned to assess outcomes. Chi square tests were used to compare categorical variables using SPSS v16.0 (SPSS Inc., IL, USA). The authors certify that themanuscript complieswith the Principles of Ethical Publishing in the IJC. 352 ED patients with undifferentiated chest pain were approached and 315 patients (median age 69 years; 54.9% male) recruited; all 315 patients were followed up. Following ED assessment,181 patients (57%) were admitted to hospital. 30 day MACE occurred in 57 of 315(18.1%) patients. At 30 days, 7 patients haddied (2.2%), 31patients (9.8%)had an acute MI, 12 patients (3.8%) had troponin positive ACS and 25 patients (7.9%) had undergone PCI. Within 30 days, one patient reattended with an MI, two patients reattended with ACS and 31 patients reattended with chest pain. Table 1 shows the likelihood of MACE according to TIMI; the pattern of increasing risk with higher scores is clear (pb0.005). Significant numbers of patients with low or moderate TIMI risk scores had MACE within 30 days, with 59.6% of MACE occurring in patients with TIMI≤3. Table 2 lists secondary outcomes according to TIMI. This study validates the TIMI score in Chinese ED patients with undifferentiated chest pain for risk stratification. Patients with a high TIMI score are at increased risk of MACE within 30 days; however low TIMI scores cannot rule out cardiac causes of chest pain. Comparedwith UK rates of MACE at 30 days [3], the rate of MACE in our population appears to be slightly higher (18%v14%). This may be a reflection of higher rates of undiagnosed IHD in the community, or might represent other risk factors involved in the Hong Kong population.