Submission for Lancet Protocol Review Title A study ... - NHS Lothian

More documents

Recommendations

Info

variables and 24 ECG based variables. All patients will also have a full blood count, urea, creatinine, liver function, glucose, electrolytes, high sensitivity CRP and near-patient BNP tests. Admitted patients and a random selection of 100 discharged derivation group patients will undergo a formal laboratory based Troponin I at least 12 hours post syncope. Endpoint measures are serious outcome at 1 month. A Clinical Decision Rule using history, examination, ECG, and biochemical markers will be developed and validated to predict 1 month outcome for patients presenting with syncope to the Emergency Department. Background and previous research Syncope is a transient loss of consciousness with an inability to maintain postural tone followed by a spontaneous recovery [1]. It accounts for 3% of ED visits and 1-6% of hospital medical admissions, affecting 6 per 1000 people per year [2,3]. Clinical assessment of syncope is difficult due to the heterogeneous nature of underlying causes, ranging from benign neurocardiogenic syncope, to potentially fatal arrhythmias. In 1983, Kapoor et al [4] published the first prospective syncope study. 12month mortality was 14%. Mortality was greatest in patients in whom a cardiovascular cause was identified (30%). Subsequent studies have shown that underlying heart disease in patients with syncope is associated with a poor prognosis [5]. Recent emphasis has focused on risk stratification of patients with syncope. Although guidelines have been issued [6-10], evidence in respect to ED management is sparse. There are 5 risk stratification studies [11-16]. Most involved small numbers of patients and used different characteristics and outcome measures in their risk stratification tools. Only two were prospective and had mixed results [11,13]. Only one study, a US based study looked at short-term adverse outcome [15,16], which is relevant to emergency medicine practice. There were two fundamental problems with this study. Firstly, two of the selected predictor variables included in the rule would usually necessitate immediate hospital admission (systolic blood pressure less than 90mmHg and a haematocrit of less than 30%). This greatly reduces the benefit of the rule in ED admission decision-making. Secondly, the rule was originally derived for 7 day serious outcome, however later validated for 1 month outcome. No studies have been examined in a UK population. With growing pressures on acute medical beds and an increasingly elderly population, there is a need for a large study of this common presenting symptom to identify high-risk populations requiring further investigation, and low-risk patients who may be discharged safely. Accurate identification of patients would enable specific targeting of resources and prevent excessive investigation of patients with benign causes. No risk stratification studies have investigated the role of biochemical markers in risk stratification. We hypothesize that Brain Natriuretic Peptide (BNP) and high sensitivity C-reactive protein (HS-CRP) acting as objective markers of underlying cardiac disease, may be excellent ED markers of 1 month outcome. BNP [17,18] is an excellent marker of prognosis in patients with heart failure or cardiac disease, and several prospective epidemiological studies from the United States and Europe have demonstrated that HS-CRP Version 14: 14/06/2007 2
is a good predictor of future coronary events [19-21]. It is also well established that prognosis in syncope is related to the presence of underlying heart disease [5], and all existing syncope CDRs include either a history of congestive heart failure [11,14,15] or underlying cardiac disease [12,13]. Troponin I (TnI) is commonly measured 12 hours post syncope to rule out acute myocardial infarction (AMI) and has only been assessed as a prognostic marker in syncope in one previous study [22]. This study took Troponin levels as early as four hours after the syncopal episode, when sensitivity for AMI is poor (0.64) [23]. We hypothesize that a routine TnI is unnecessary and aim to assess the value of a 12-hour troponin as both an AMI rule-out marker, and as a syncope prognostic marker. Results of pilot study A pilot study was performed between November 2005 and January 2006. 99 consecutive patients with undifferentiated syncope were enrolled (1.6 per day). 32 patients were high-risk, 51 medium and 16 low according to our existing departmental syncope guidelines (based on the European Society of Cardiology [9,10], American College of Physicians [6,7] and American College of Emergency Physicians guidelines [8]). 72 patients had BNP measured, 25 (35%) were 100 pg/ml or greater, and 3 were over 1000 pg/ml. 44 patients were admitted to hospital and 55 were discharged from the ED. 30 of those admitted had troponin I measured. Only one of these was raised (14.40 ng/ml) and this was thought to be due to an AMI. 66 patients had CRP measured, 16 were raised (>5 mg/l). There were 11 serious outcomes. 5 patients had died by 3 months, and 6 others had an alternative serious outcome. 8 of the 11 patients had a serious outcome by 1 week. The percentage risk of serious outcome at 7 days, 1 month and 3 months was therefore 8.1%, 8.1% and 11.1% respectively. 9 of 11 serious outcome patients had BNP measured, 6 were >100, 3 were >1000 and all patients with a BNP >1000 were in the serious outcome group (2 died, 1 AMI) [24]. The OESIL score, the SFSR and our existing departmental guidelines all showed some ability to risk stratify syncope patients [25]. Primary aim To develop and validate a Clinical Decision Rule (CDR) using history, examination, electrocardiographic (ECG) and biochemical markers, to predict one month outcome for patients presenting with syncope to the ED. Research questions (1) Can a syncope CDR using specific components from the history and examination, ECG characteristics and biochemical markers (HS-CRP and BNP) predict one-month outcome in ED patients presenting with syncope? (2) Can HS-CRP or BNP predict one-month outcome in patients presenting to the ED with syncope? Version 14: 14/06/2007 3
Page 1: Submission for Lancet Protocol Revi
Page 5 and 6: Exclusion criteria � Patients und
Page 7 and 8: After formal routine laboratory tes
Page 9 and 10: Statistical analysis After derivati
Page 11 and 12: Key references 1. Morag R. Syncope.

Submission for Lancet Protocol Review Title A study ... - NHS Lothian

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?