Table 1 Dictionary of variables visible to the user via hover buttons

Hospital of Choice – The hospital where the patient says he or she receives his or her care. If the patient agrees that the study hospital is his or her hospital of choice, this means that in the patient's opinion, he or she agrees to return to the study hospital for persistent symptoms in the next 45 days.

Vital signs – Measured in the ED using local standards and FDA-approved devices. SaO2% must be made with the patient breathing room air or the lowest tolerable rate of oxygen administration.

Dyspnea – Patient perception of difficulty breathing at the time of evaluation. Includes sensation described as shortness of breath, breathlessness, labored breathing, trouble breathing, not breathing right.

Pleuritic Chest Pain – Focal pain in the thorax located inferior to the transverse axis through the clavicles extending to the costal margin. The pain must change with breathing and must not be reproduced by palpation.

Substernal Chest Pain – Pain located behind the sternum that is not reproduced with palpation.

Chest pain Reproduced with Palpation – Thoracic pain that increases when palpated gently and the patient agrees that the elicited pain feels similar to the pain that he or she is experiencing.

Leg or Arm Swelling – Asymmetry observed on gross inspection. Does not require measurement or presence of edema.

Wheezing – Determined by auscultation by any healthcare provider either in prehospital or ED setting.

Alternative diagnosis – Another specific disease process for which an ICD-9 code or set of codes exist, including pneumonia, cardiac ischemia, CHF, bronchospasm, muscle strain, acute bronchitis, biliary disease, pneumothorax, aortic dissection, pericarditis, costochondritis. Descriptive diagnoses of atypical chest pain or chest pain of unknown etiology, or Chest pain NOS are not sufficient to be considered alternative diagnosis. Likewise, purely psychiatric diagnoses such as anxiety or fibromyalgia are not to be considered as alternative diagnoses.

Physician estimate of PTP – The probability that the patient has PE on the day of evaluation.

Past Medical History terms. All terms are based upon the clinician's best estimate of the presence or absence of each condition based upon data available during the ED shift. Data sources may include patient perception, family perception, oral or facsimile communication with other clinicians, evaluation of written or electronic medical records.

COPD – In the appropriate clinical setting (eg, history of smoking) a patient affirms yes to the question, "have you been told you have emphysema or damage to your lungs from smoking that has required medical treatment" This diagnosis does require spirometry results.

Surgery in past 4 weeks: Includes any surgery requiring general anesthesia.

Trauma in past 4 weeks: Any traumatic injury requiring hospitalization for >24 hours or causing fracture requiring stabilization in an ED. Does not include minor laceration repair, scrapes, bruises, concussion, whiplash or soft tissue injuries that did not warrant admission

Coronary Artery Disease – Coronary stenoses diagnosed either by clinical grounds if drug therapy is given, or by coronary imaging. Includes prior MI, prior stenting or CABG.

CHF – Systolic or diastolic heart failure. Can be based upon clinical diagnosis if drug therapy is given. Does not include diagnosis of CHF made for the first time on the day of enrollment.

DVT or PE. Requires that the patient was treated with either caval interruption, or warfarin or fractionated heparin anticoagulation for more than 11 weeks.

Malignancy – History of cancer. Decision to term the presence of cancer as "treated and inactive" means the patient perceives that the disease is in remission and the clinician has no evidence to the contrary. If evidence of previously unknown metastases is found in the ED, then the clinician uses the information at hand to code the malignancy status.

Immobility – Pathological restriction in body movement. Includes bed-bound patients who cannot or do not walk for periods exceeding 48 hours. Also includes any patient in a cast or with an external fixator in place.

End stage disease – Any disease process, such as AIDs, cancer, advanced incurable lung or heart disease with life expectancy < 6 months.

Sepsis – As defined by American College of Chest Physicians

Discharge Diagnosis – Based upon written diagnoses and ICD 10 coding

Troponin – pull down box allows multiple choices of results for either troponin I or C testing.

Pressor support – >5 micrograms of dopamine per kg per min or any use of norepinephrine or epinephrine infusion