Wells (etc.) Criteria and Risk Factors for PE
                          =====================
þ Wells Clinical Prediction Rule for DVT
Clinical feature                                                        Points
Active cancer (treatment within 6 months, or palliation)                1
Paralysis, paresis, or immobilization of lower extremity                1
Bedridden for more than 3 days because of surgery (within 4 weeks)      1
Localized tenderness along distribution of deep veins                   1
Entire leg swollen                                                      1
Unilateral calf swelling of greater than 3 cm (below tibial tuberosity) 1
Unilateral pitting edema                                                1
Collateral superficial veins                                            1
Alternative diagnosis as likely as or more likely than DVT             -2
Total points:

Risk score interpretation (probability of DVT):
>=3 points: high risk (75%);
1 to 2 points: moderate risk (17%);
<1 point: low risk (3%).

Adapted with permission from Wells PS, Anderson DR, Bormanis J, Guy F,
Mitchell M, Gray L, et al. Value of assessment of pretest probability of
deep-vein thrombosis in clinical management. Lancet 1997;350:1796.

þ Wells' Risk Factors
 - surgery or fracture of lower extremity and immobilisation of fracture
   within 12 weeks
 - immobilisation (complete bed-rest) for three or more days in the
   previous four weeks
 - previous DVT or objectively diagnosed PE
 - strong family history of DVT or PE (two or more family members with
   objectively-proven events or first-degree relative with hereditary
   thrombophilia)
 - cancer (treatment on-going, within the past six months or in the
   palliative stages)
 - post-partum period
 - lower extremity paralysis
   [Wells et al: Annals of Internal Medicine 1998; 129 (12): 997-1005]

þ Goldhaber Risks
 -  Pulmonary embolism was more likely in women who:
    * were obese (NNF = 230 for 16 years)
    * smoked >25 cigarettes a day (25-34/ day: (NNF = 480 for 16 years) ; 35
days or more: (NNF = 350 for 16 years) )
    * were hypertensive (NNF = 870 for 16 years)
Goldhaber et al: Journal of the American Medical Association 1997; 277 (8):
642-645
 40% of patients with a clinical deep vein thrombosis had a silent pulmonary
embolism
Moser KM, Fedullo PF, LitteJohn JK, et al: Frequent asymptomatic pulmonary
embolism in patients with deep vein thrombosis. Journal of the American
Medical Association 1994; 271 (3): 223-225
#  One in six patients who had a pulmonary embolism were dead within a year.
# Patients who were male, had been recently immobilised, had surgery in the
last three months or have a history of thrombophlebitis were at an increased
risk of dying
Quinn DL, Taylor Thompson B, Terrin ML, et al: A prospective investigation of
pulmonary embolism in women and men. Journal of the American Medical
Association 1992; 268 (13): 1689-1696
# Patients undergoing hip or knee surgery who take aspirin compared with
placebo for 35 days are less likely to develop symptomatic venous
thromboembolism (NNT = 150 at 35 days) .
# There is no effect on mortality.
# There is no clear effect on fatal haemorrhage or bleeding requiring
transfusion.
Pulmonary Embolism Prevention (PEP) Trial Colloborative Group , : prevention
of pulmonary embolism and deep vein thrombosis with low dose aspirin:
pulmonary embolism prevention (PEP) trial. Lancet 2000; 355 : 1295-1302

þ Stein Criteria (% with + angiogram)
Immobilization (within 3 mo)                    54
Surgery (within 3 mo)                           42
Coronary artery disease (ever)                  20
Thrombophlebitis (ever)                         19
Malignancy                                      18
Myocardial infarction                           13
Trauma (lower extremities)                      12
Congestive heart failure (right or left)        12
Chronic obstructive pulmonary disease           10
Stroke (ever)                                   10
Asthma                                          7
Pneumonia (acute)                               7
History of pulmonary embolism                   6
Collagen vascular disease                       4
Postpartum (within 3 mo)                        2
Interstitial lung disease                       2
Sickle cell disease                             1
Vasculitis                                      1
Self-administered drug use                      1
 Patients (n = 383) may have more than one predisposing factor
Stein PD : Pulmonary Embolism. Media, PA: Williams & Wilkins; 1996:25-40

History and Physical Examination Findings of Acute PE in Patients with No
Pre-existing Cardiac or Pulmonary disease
Symptoms        Patients with symptoms or signs, %a
Dyspnea         73
Pleuritic pain  66
Cough   37
Leg swelling    28
Leg pain        26
Hemoptysis      13
Palpitations    10
Wheezing        9
Angina-like pain        4
Signs
Tachypnea (>/=20/min)   70
Rales (crackles)        51
Tachycardia (>100/min)  30
Fourth heart sound      24
Increased pulmonary component of second sound (P2)      23
DVT     11
Diaphoresis     11
Temperature >38.5C      7
Wheezes         5
Homans sign     4
Right ventricular lift  4
Pleural friction rub    3
Third heart sound       3
Cyanosis        1
 n = 117.
        Stein PD, Terrin ML, Hales CA, et al. : Clinical, laboratory,
roentgenographic and electrocardiographic findings in patients with acute
pulmonary embolism and no pre-existing cardiac or pulmonary disease. Chest.
1991;100:598-603