Clinical background
Syncope is a common emergency presentation in which the clinical challenge is to separate patients with a good prognosis from those with a serious underlying cause. Approximately 10 per cent of syncope patients in the emergency department have a serious or potentially life-threatening cause that is not always evident at the initial assessment [2]. The OESIL score was developed to estimate all-cause mortality within 12 months from simple variables available at the emergency visit, and thereby to support the decision between admission and outpatient investigation.
Calculating the OESIL score
The score is a simple arithmetic sum of four binary variables:
Each variable scores 0 or 1. The range is 0 to 4.
The derivation cohort consisted of 270 consecutive patients (145 women, mean age 59.5 years) presenting with syncope at six Italian hospitals in the Lazio region [1]. Multivariable analysis identified four independent predictors of all-cause mortality within 12 months. The score was validated prospectively in a separate cohort of 328 patients (178 women, mean age 57.5 years) with a similar pattern of rising mortality at higher scores [1].
In the derivation cohort, mortality by score was:
| Score | 12-month mortality |
|---|---|
| 0 | 0% |
| 1 | 0.8% |
| 2 | 19.6% |
| 3 | 34.7% |
| 4 | 57.1% |
Interpretation in practice
The clearest strength of the score is in identifying low-risk patients. A patient scoring 0 had no deaths in the derivation cohort, and a score of 1 meant under 1 per cent mortality. These patients can generally be managed as outpatients, provided the clinical picture is otherwise consistent with a benign cause.
From a score of 2 upwards, mortality rises steeply, and at 3 or 4 points mortality is high enough to warrant admission and prompt cardiac investigation. One important nuance is that the threshold may need to be raised in older populations. In an Italian validation cohort with considerably older patients (mean age 72.4 years compared with 59.5 years in the derivation), an OESIL score of 2 or higher was not associated with any outcome apart from the need for major therapeutic intervention, whereas a score of 3 or higher was a strong predictor of serious events at both 1 month and 1 year [3]. The authors therefore proposed that the threshold for admission should be raised to 3 points when the patient population is older than the original derivation cohort.
Validation and performance
OESIL is one of three syncope instruments validated in more than two external studies (the others are the San Francisco Syncope Rule and the Canadian Syncope Risk Score). A systematic review and meta-analysis from 2025 identified five validation studies for OESIL with a positive likelihood ratio (LR+) of 1.16 to 3.32 and a negative likelihood ratio (LR−) of 0.14 to 0.46 [2]. In the derivation studies, OESIL had the lowest LR− (0.04), suggesting that a low score is relatively good at excluding risk [2]. The pooled sensitivity for OESIL showed moderate heterogeneity (I² = 37.1%), lower than for the other instruments [2].
In a prospective observational study comparing OESIL with the San Francisco rule and unstructured clinical judgement, OESIL had a sensitivity of 88 per cent and a specificity of 60 per cent for short-term serious outcomes (within 10 days), with an admission rate of 43 per cent [2]. Clinical judgement was more specific (69 per cent) and led to fewer admissions (34 per cent), but missed two patients who died after discharge, both of whom OESIL identified [2].
Performance falls, however, in populations and for outcomes for which the instrument was not designed. In an Iranian study of 187 syncope patients (mean age 64.2 years), the AUC for OESIL was 0.54 for mortality, 0.62 for myocardial infarction and 0.47 for stroke within 1 week, that is, close to chance [4]. None of the four models tested (OESIL, San Francisco, Boston, ROSE) differed significantly from one another [4]. This is important: OESIL was derived for 12-month mortality, and its ability to predict short-term cardiac or neurological events is limited.
A retrospective Canadian study of patients already admitted to a medical ward found that 30.6 per cent had an OESIL score of 0 to 1 and could potentially have been managed as outpatients, while the remaining 69.4 per cent with a score of 2 to 4 had a mortality risk of 20 per cent per year [5]. This confirms that the score can identify low-risk patients even in an inpatient population, but the study was retrospective and selected.
Limitations
OESIL measures all-cause mortality, not specific cardiac events. This is an important distinction: a patient may die of causes unrelated to the syncope, and the score says nothing about the need for specific cardiac investigation. The instrument moreover lacks variables included in newer and more detailed instruments, such as vital signs, cardiac biomarkers and a detailed history of heart failure.
The score was derived in an Italian emergency department population from the early 2000s with a relatively low mean age. In older cohorts, in which a large proportion of patients automatically score 1 point for age, the threshold of 2 points loses discriminatory power [3]. In a Czech study of 153 patients, OESIL achieved a sensitivity of 93 per cent but a specificity of only 54.6 per cent for classifying cardiac syncope, implying a high proportion of false positives [6].
The systematic review notes that the quality of evidence for all three well-validated syncope instruments is low, with substantial overlap in operating characteristics and suspected publication bias [2]. None of the instruments reaches an LR+ above 5, the level generally required for a test to shift the pre-test probability enough to justify an action on its own [2].
OESIL does not replace clinical judgement and should not be used as the sole basis for an admission decision. In patients with a suspected cardiac cause, abnormal vital signs or abnormal biomarkers, specific syncope guidelines and, where appropriate, the Canadian Syncope Risk Score should be considered.
References
- Colivicchi F, Ammirati F, Melina D, et al. Development and prospective validation of a risk stratification system for patients with syncope in the emergency department: the OESIL risk score. Eur Heart J. 2003;24(9):811–819. PMID: 12727148
- Wakai A, Sinert R, Zehtabchi S, et al. Risk-stratification tools for emergency department patients with syncope: A systematic review and meta-analysis of direct evidence for SAEM GRACE. Acad Emerg Med. 2025;32(1):72–86. PMID: 39496561
- Numeroso F, Mossini G, Montali F, et al. Prognostic value of the OESIL risk score in a cohort of Emergency Department patients with syncope. Minerva Med. 2013;104(4):413–419. PMID: 24008603
- Safari S, Baratloo A, Hashemi B, et al. Comparison of different risk stratification systems in predicting short-term serious outcome of syncope patients. J Res Med Sci. 2016;21:57. PMID: 27904602
- Baranchuk A, McIntyre W, Harper W, et al. Application of the American College of Emergency Physicians (ACEP) recommendations and a risk stratification score (OESIL) for patients with syncope admitted from the emergency department. Indian Pacing Electrophysiol J. 2011;11(5):134–144. PMID: 21994471
- Plasek J, Doupal V, Fürstova J, et al. The EGSYS and OESIL risk scores for classification of cardiac etiology of syncope: comparison, revaluation, and clinical implications. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2010;154(2):169–173. PMID: 20668500
