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Diagnostic Test: Initial symptoms

StudyParticipantsDiagnostic tests
Birnbaum 2008
prospective cohort study; study held in USA.

Setting: Emergency Department. ED of large urban, academic centre (80,000 visits per year).

Funding: None that would create a conflict of interest
TLoC population: unselected patients. Prior tests: Unclear or Not stated.
Population details: ED patients with acute syncope or near syncope as reason for presentation; surveillance of ED tracking system to identify all possible patients; seizures and drug related TLoC excluded

Definition of TLoC: transient loss of consciousness (acute syncope) or sensation of impending but not actual loss of consciousness (near syncope). Did not specifically require return to nonfocal neurologic function..

Inclusion criteria: adult patients 21years and older with complaint of acute syncope or near syncope as reason for ED visit.
Exclusion criteria: patients with head trauma-caused or alcohol or drug- related LoC; patients with a definite seizure; patients with an altered mental status.

Patient characteristics: age: mean 61 years (21–101); 17% 21–40y, 30% 41–60y, 37% 61–80y, 16% 81–101y; sex: 38% male; some patients with existing heart disease (8% had history of CHF; 31% abnormal ECG); history of TLoC: not stated
Comorbidities: not stated. Other details: 39% Hispanic; 17% white, 38% black, 6% other

Other study comments: ECG assessors blinded to data on presence or absence of other predictors. Serious outcomes not indicated by rule were 1 death, 8 arrhythmias, 3 strokes, 1 SAH, 1 blood transfusion, 2 returned to ED within 7 days
Index test: symptoms: questionnaire on history of congestive heart failure; haemocrit < 30%; patient complaint of shortness of breath; triage systolic bp < 90 mm Hg. abnormal ECG (any non-sinus rhythm or any new changes) determined separately; time: in ED (n=730)

Reference standard: Follow up determined by research associates by phone using structured data collection instrument; outcomes reviewed by study investigators and disagreements resolved through discussion; time 7 days (n=713)

Comparator test: Decision to admit patient by ED physician independently of the decision rule; time: ED (n=738).
Other comparator tests: 3. Individual patient history characteristics.

For target condition/outcome: Short term serious o/c: death, MI, arrhythmia, PE, stroke, SAH, sig haemorrhage needing transfusion; procedural intervention to treat syncope cause; any condition likely to/ causing return to ED; hospitalisation for related event
Costantino 2008
(STePS) prospective cohort study; study held in Italy.

Setting: Emergency Department. EDs of 4 general hospitals in the Milan area; [Jan 2004–July 2004).

Funding: Study supported by a donation from Autogrill S.p.A.
TLoC population: unselected patients. Prior tests: unclear/not stated.
Population details: 2775 consecutive adult patients who presented with syncope within the previous 48h to ED (syncope, pre-syncope, seizures, falls, head injuries etc). Then exclusion criteria applied - 676/2775 enrolled.

Definition of TLoC: Syncope: a sudden and transient loss of consciousness associated with inability to maintain postural tone with spontaneous recovery; presyncope and seizures excluded.

Inclusion criteria: Patients presenting with syncope in the previous 48h, aged 18 years and older..
Exclusion criteria: Head injury pre-LoC; non-spontaneous return to consciousness; pre-syncope, coma, shock, seizure; associated diseases with prognosis < 6mo; recent alcohol/drug abuse; non-consent; unfeasible follow-up.

Patient characteristics: age: mean 59 years (SD 22); 18–44y 29%, 45–65y 23%, >65y 48%; sex: 43.9% male; some patients with existing heart disease (some had history of structural HD (25%), hypertension (40%), heart failure (4%), ventricular arrhythmias (2%)); history of TLoC: not stated

Comorbidities: some with heart disease; also cerebrovascular disease (13%), neurological disease (10%), diabetes (10%), COPD (8%), neoplasm (8%). Other details: additionally, 24% had trauma, 2% had exercise induced syncope. 67% directly discharged from ED. Within 10 days: 36 had major therapeutic procedures & 5 died. At 1 year there were 40 deaths.

Other study comments: Also excluded if patients had clinical conditions primarily confirmed in the ED that would have led to hospital admission independently of TLoC (e.g. MI, acute PE, SAH, stroke, cardiac arrest, sustained bradycardia
Index test: Signs and symptoms, history, ECG results; time: initially (n=676)

Reference standard: Participating physicians evaluated admitted patients. Discharged patients - directly evaluated before discharge or surveyed within 2 d by phone & then within 10 days of TLoC using 10 item questionnaire. At 1y, phone interview / regional database for death; time 10 days and 1 year (11–365 d) after TLoC (n=670; 667 at 1y)

For target condition/outcome: Death and severe outcomes - need for major therapeutic procedures (cardiopulmonary resuscitation, pacemaker or ICD insertion, ICU admittance, acute antiarrhythmic therapy) - not in ED. Readmission to hospital (within 10 days).
Grossman 2007
prospective cohort study; study held in USA.

Setting: Emergency Department. large urban teaching hospital ED; consecutive patients with syncope.

Funding: none reported
TLoC population: unselected patients. Prior tests: No patients had a prior test.
Population details: consecutive patients presenting 24h / 7days for 8 months; only syncope; seizures excluded

Definition of TLoC: sudden and transient (< 5 min) loss of consciousness, producing a brief period of unresponsiveness and loss of postural tone, ultimately resulting in spontaneous recovery requiring no resuscitation.

Inclusion criteria: 18 years or older who met definition of syncope; at least 1episode of syncope.
Exclusion criteria: near syncope; persistent altered mental status; alcohol or illicit drug related LoC; seizure; coma; hypoglycaemia; TLoC caused by head injury.

Patient characteristics: age: mean 57.8 years (SD 24.2); sex: 42% male; some patients with existing heart disease (35% had history of heart disease); history of TLoC: all had at least 1 episode of syncope; 20% had recurrent syncope. Other details: 2% family history of sudden death

Other study comments: rule is combination of ACEP, San Francisco SR and expert opinion. If a patient had a risk factor then admitted to hospital otherwise sent home; overall 69% admitted. 94% included in study. Validation study. Univariate analysis also.
Index test: signs/symptoms of acute coronary syndrome; worrisome cardiac history; family history of sudden death; valvular heart disease; signs of conduction disease; volume depletion; persistent (>15min) abnormal vital signs; primary CNS event; time: in ED (n=362)

Reference standard: Follow up with structured form, by phone and using medical record; time 30 days and subsequent med records (n=293)

For target condition/outcome: patients with (1) an adverse outcome (incl. death, PE, stroke; ventricular or atrial dysrhythmia; intracranial bleed; MI) or (2) critical intervention (incl. pacemaker, percutaneous coronary intervention, surgery) within 30 d of initial visit
Hing 2005
prospective cohort study; study held in Australia.

Setting: Emergency Department. ED of tertiary referral urban hospital (42,000 emergency presentations per annum) [April 2002–Aoril 2003).

Funding: none declared
TLoC population: unselected patients. Prior tests: Unclear or Not stated.

Population details: adult patients presenting with TLoC to ED; identified by ED staff. Patients enrolled only if investigators present and if their serum troponin level was measured at least 4h after syncope were included (113/508 with triage diagnosis of syncope)
Definition of TLoC: Syncope: syncopal event with spontaneous recovery with no neurological sequelae.

Inclusion criteria: Patients presenting with syncope aged 18 years and older. Enrolled only if investigators or informed member of staff present.
Exclusion criteria: patients presenting with seizures, coma, dizziness, vertigo or pre-syncope without LoC.

Patient characteristics: age: 9% <39y, 11% 40–49y; 8% 50–59y; 13% 60–69y; 28% 70–79y; 30% 80–89y; 1% 90–99y; sex: 47% male; some patients with existing heart disease (some had history of IHD, congestive cardiac failure); history of TLoC: not stated
Comorbidities: 51% hypertension; 9% diabetes.

Other details: Discharge diagnoses: 27% NM syncope; 21% orthostatic hypotension; 2% neurological; 3% cardiac organic; 16% cardiac arrhythmias
Index test: Initial symptoms from patient history, ECG; time: initially (n=100)

Reference standard: review of discharge medical records to determine the diagnosis; patients contacted by phone to determine adverse events, return to normal premorbid function and GP confirmation where necessary; time 3–6 months (n=100)

Comparator test: Serum troponin T measured at least 4 hours after syncope; time: initially (n=100).

For target condition/outcome: Serious o/c: cardiac death, and adverse cardiac outcomes: diagnosis or ongoing episodes of ischaemic heart disease requiring further investigation, including medication changes, admission to hospital, angiogram; significant arrhythmia requiring treatment; death as a result of presumed cardiac causes
Quinn 2004
prospective cohort study; study held in USA.

Setting: Emergency Department. ED of large university teaching hospital [Jun 2000–Feb 2002).

Funding: 1st author received an NIH grant. Same authors developed SFSR - some potential for conflict of interest.
TLoC population: unselected patients. Prior tests: Unclear or Not stated.
Population details: ED patients with acute syncope or near syncope; 73% as primary complaint; prospective screening and review of patient logs to identify all possible patients; seizures and drug related TLoC excluded

Definition of TLoC: syncope is a transient loss of consciousness with return to pre-existing neurologic function; near syncope not defined.

Inclusion criteria: acute syncope or near syncope as a reason for their presentation in ED.
Exclusion criteria: patients with head trauma-caused or alcohol or illicit drug-related LoC; patients with a definite seizure; patients with LoC associated with an altered mental status.

Patient characteristics: age: mean 62.1 years (range 10 to 102 years); sex: 41% male; some patients with existing heart disease (4.9% had MI; 4.4% had arrhythmia; 0.7% structural HD; 0.7% PE); history of TLoC: not stated although some had more than 1 episode
Comorbidities: not stated. Other details: race not stated

Other study comments: Derivation study; 55% admitted; all had some form of follow up (96% directly and the rest through checks with death register and local hospitals). Univariate analysis.
Index test: Signs and symptoms from San Francisco Syncope Rule validation: abnormal ECG result (any non-sinus rhythm or any new changes); time: in ED (n=684)

Reference standard: Follow up determined by study nurse; includes ED and non-ED outcomes; 49/79 outcomes occurred after ED visit; time 7 days (n=684)

Comparator test: Attending physicians & house staff carried out normal assessment & disposition of each patient, then completed standardised form (SFSR). Physicians estimated if 2% or less chance of serious outcome with in 7 days, based on their clinical assessment; time: ED (n=684).

Other comparator tests: 3. Physician decision to admit patient (n=684) 4.
Initial symptoms (n=684).

For target condition/outcome: Short term serious o/c: death, MI, arrhythmia, PE, stroke, SAH, significant haemorrhage; any condition causing return to ED and hospitalisation for related event
Reed 2007 (ROSE pilot)
prospective cohort study; study held in UK.

Setting: Emergency Department. ED of large urban hospital (85,000 adult attendances per annum) [Nov 2005–Feb 2006).

Funding: unrestricted educational grant from Medtronic Europe and Netherlands Heart Foundation
TLoC population: unselected patients. Prior tests: No patients had a prior test.
Population details: consecutive adult patients presenting with TLoC to ED; identified by ED staff, then checked patient records; previously recruited patients excluded. Only 38% eligible patients enrolled.

Definition of TLoC: Syncope: a transient loss of consciousness with an inability to maintain postural tone followed by spontaneous recovery.

Inclusion criteria: Patients presenting with syncope aged 16 years and older.
Exclusion criteria: patients younger than 16 years; those previously recruited; those with a history of seizure with prolonged postictal phase; patients unable to give either written or verbal informed consent.

Patient characteristics: age: median 71 years (IQR 47–81); missed group median 62.5 years (IQR 29–78); p=0.047; sex: 48% male; some patients with existing heart disease (no details); history of TLoC: not stated
Comorbidities: not stated. Other details: Distribution of risk groups skewed towards more serious end => possible exclusion of younger patients with vasovagal syncope.

Other study comments: Pilot for ROSE study; recruitment doctors trained for 15 min to identify syncope: 62% patients missed (younger); study group skewed towards more serious risk. Admission = >12 h in ED. Scores for SFSR & OESIL determined by study team from data forms.
Index test: signs and symptoms as part of standardised assessment; time: initially (n=99)

Reference standard: review of local hospital records re inpatients and outpatients; death register and primary care records; not stated who did this; time 3 months (n=99)

Comparator test: San Francisco Syncope Rule; time: initially (n=99).

Other comparator tests: 3)initial assessment based on ESC, AAP & ACEP guidelines: standardised assessment with 75 variables (11 clinical features, 9 med history, 11 current meds; 28 exam; 26 ECG) (n=99).

For target condition/outcome: Serious o/c: all-cause death, acute MI, life threatening arrhythmia, PE, stroke, cerebrovascular accident/SAH, significant haemorrhage needing blood transfusion; acute surgical procedure/endoscopic intervention. 5 died and 6 had serious outcome by 3 mo.
Reed 2010 (derivation)
prospective cohort study; study held in UK.

Setting: Emergency Department. ED of large urban tertiary centre (100,000 adult attendances per annum) [March – Oct 2007).

Funding: none for main study, equipment supplied by Biosite for the pilot (Reed 2007)
TLoC population: unselected patients. Prior tests: Unclear or Not stated.
Population details: adult presenting with acute syncope to ED; identified by ED staff. Further group identified from daily search of electronic patient records with appropriate key words, then eligibility assessed. 2 cohorts (derivation and validation) March–Oct 2007

Definition of TLoC: Syncope: a transient, self limited loss of consciousness, usually leading to falling. Onset is relatively rapid and recovery is spontaneous, complete and relatively prompt.

Inclusion criteria: people presenting with syncope aged 16 years and older.
Exclusion criteria: previously recruited into the study; persistent neurological deficit suggesting stroke, alcohol related, hypoglycaemia, trauma, history of seizure with >15min witnessed postictal phase; unable to give written or verbal informed consent.

Patient characteristics: age: mean 63.8 years (SD 21.2); sex: 44.4% male; some patients with existing heart disease (IHD 23%, acute MI 10%, valvular HD 6%, heart failure history 5%); history of TLoC: 43% had previous history
Comorbidities: hypertension 39%. Other details: 575/890 (65%) potentially eligible patients screened; 550 recruited; 40 had primary outcome (serious outcome/all cause death)

Other study comments: Secondary end points (separate) were: cardiovascular serious outcomes (acute MI, arrhythmia, pacemaker/ICD, cardiac procedure) and syncope-related death
Index test: standardised assessment with 32 historical variables (9 clinical features, 10 med history, 13 current meds); 14 exam; 24 ECG; 23 biochemical/haematological variables (incl. characteristics In other decision rules); BNP test (2.7ml ETDA); time: initially (n=548)

Reference standard: review of electronic records, hospital pacemaker records, radiology reports, direct contact with patient or GP. Cardiologist & emergency physician independently reviewed ECG. 2 investigators reviewed clinical data & assigned end points; 3 others if disagreed; time 1 month (n=529)

For target condition/outcome: Serious o/c: all-cause death, acute MI, life threatening arrhythmia (VF, SVT > 120bpm, ventricular pause > 3s, standstill or asystole), decision for pacemaker or ICD within 1mo, PE, cerebrovascular accident/intracranial haemorrhage/SAH, significant haemorrhage needing blood transfusion; acute surgical procedure/endoscopic intervention. 5 died and 6 had a serious outcome by 1 month
Sun 2007
prospective cohort study; study held in USA.

Setting: Emergency Department. ED of urban, academic, Level I trauma centre.

Funding: university funding and American Geriatrics Society award (1st author)
TLoC population: unselected patients. Prior tests: Unclear or Not stated.
Population details: adult ED patients with syncope or near syncope admitted 8am–10pm 7/7 days; review of ED intake log showed 76% eligible patients identified and screened; seizures and people with confusion excluded

Definition of TLoC: sudden transient loss of consciousness (=syncope); sensation of imminent loss of consciousness (=near syncope).

Inclusion criteria: adult patients with complaint of acute syncope or near syncope.
Exclusion criteria: head trauma-associated LoC; intoxication; patients with a witnessed seizure; ongoing confusion (incl. baseline cognitive impairment /dementia); age < 18 y; inability to speak English or Spanish; do-not-resuscitate/DN intubate status; no follow-up contact info.

Patient characteristics: age: median 58 years (IQR 35–79); 30% <40y, 23% 40–59y, 24% 60–79y, 21% >80y; sex: 44% male; some patients with existing heart disease (8% had history of CHF); history of TLoC: not stated
Comorbidities: not stated. Other details: 10% Hispanic; 77% white, 9% black, 11% Asian, 3% other

Other study comments: 51% admitted, 7% transferred to another hospital, 40% discharged, 2% left against medical advice. Attending physicians trained in completion of data forms. Inter-rater reliability also checked in convenience sample (subgroup)
Index test: symptoms: questionnaire on history of congestive heart failure; haemocrit < 30%; abnormal ECG result (any non-sinus rhythm not new changes (no old ECG); patient complaint of shortness of breath; triage systolic bp < 90 mm Hg; time: in ED (n=477)

Reference standard: Follow up: phone interview by research nurse; then 2 independent emergency physicians reviewed ED documentation, inpatient records and telephone forms; records for all with potentially serious outcome reviewed by a panel of 3 ED physicians; time 7 days (n=463)

Comparator test: Treating physician’s decision to hospitalise the patient; time: in ED (n=477).

For target condition/outcome: death, MI, arrhythmia, PE, stroke, TIA, SAH/non-trauma haemorrhage, aortic dissection, new SHD, sig haemorrhage/anaemia needing transfusion; procedure to treat syncope cause; readmission for related event

From: Appendix D1, Included studies characteristics

Cover of Transient Loss of Consciousness (‘Blackouts’) Management in Adults and Young People
Transient Loss of Consciousness (‘Blackouts’) Management in Adults and Young People [Internet].
NICE Clinical Guidelines, No. 109.
National Clinical Guideline Centre for Acute and Chronic Conditions (UK).
Copyright © National Clinical Guideline Centre for Acute and Chronic Conditions, 2010.

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