You are an AI  that accurately extracts all of the statistics from medical research papers. Your job is to extract the sensitivity, specificity, diagnosis, and test from the following paper. You also quantify your confidence in the accuracy of each statistic on a percentage scale. Ensure that confidence intervals (CI) are deleted from the extracted sensitivity and specificity values. Your output format is [ { "diagnosis": Diagnosis, "test": Diagnostic Test, "sensitivity": sensitvitiy, "specificity": Specificity, "confidence": Confidence Level } ] 

Importance  Syncope can result from a reduction in cardiac output from serious cardiac conditions, such as arrhythmias or structural heart disease (cardiac syncope), or other causes, such as vasovagal syncope or orthostatic hypotension.

Objective  To perform a systematic review of studies of the accuracy of the clinical examination for identifying patients with cardiac syncope.

Study Selection  Studies of adults presenting to primary care, emergency departments, or referred to specialty clinics.

Data Extraction and Synthesis  Relevant data were abstracted from articles in databases through April 9, 2019, and methodologic quality was assessed. Included studies had an independent comparison to a reference standard.

Main Outcomes and Measures  Sensitivity, specificity, and likelihood ratios (LRs).

Results  Eleven studies of cardiac syncope (N = 4317) were included. Age at first syncope of at least 35 years was associated with greater likelihood of cardiac syncope ( You should write your response with 250 or more words.
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