Diagnostic tests for fainting found expensive, ineffective.  The cheapest test for syncope--a postural blood pressure recording--may yield the most answers.
D000368:Aged; D001794:Blood Pressure; D004636:Emergency Service, Hospital; D017048:Health Care Costs; D006801:Humans; D007024:Hypotension, Orthostatic / Q000175:diagnosis*; D013575:Syncope / Q000191:economics* / Q000209:etiology*; D019564:Unnecessary Procedures / Q000191:economics*