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2-3 A PROSPECTIVE STUDY OF RISK FACTORS FOR
PULMONARY EMBOLISM IN WOMEN
These prospective data indicate that obesity, cigarette
smoking, and hypertension are associated with increased
risk of pulmonary embolism in women. Control of these
risk factors will decrease risk of pulmonary embolism as
well as coronary heart disease. JAMA February 26, 1997;
277: 642-45 2-3 A
PROSPECTIVE STUDY OF RISK FACTORS FOR PULMONARY EMBOLISM
IN WOMEN
Primary prevention of pulmonary embolism (PE) is based on
patient’s risk factors. But there is little
prospective data on risk factors in the absence of
cancer, trauma, surgery, and immobilization and genetic
factors which cause increased risk of thromboembolism.1
But, genetic predisposition (thrombophilia) may explain
only 1/5 of thromboembolism in women. This implies that
environmental factors predominate.
This study prospectively investigated risk factors for PE
in women.
Conclusion: Obesity, cigarette smoking, and hypertension
increased risk.
STUDY
- The Nurses Health
Study entered a group of over 112,000 woman (age
30-55) in 1976. At baseline, all were free of
diagnosed cardiovascular disease and cancer.
- Followed for 16 years
with frequent questionnaires.
- Documented 280 cases
of pulmonary embolism of which 125 were primary
(no identified antecedent cancer, trauma,
surgery, or immobilization).
RESULTS
- Obesity (relative
risk—3), heavy cigarette smoking (RR—2
to 3 depending on amount), and hypertension
(RR—2), were independent predictors of
primary PE.
- The highest rates of
primary PE and all PE were among persons over age
60 who were in the highest quintile of body mass
index. (BMI)
DISCUSSION
- Increased BMI was
associated with a strong and statistically
significant increased risk of PE, the level of
risk increasing as BMI increased.
- Risk of PE rose as
number of cigarettes smoked per day increased.
- For all analysis, the
relative risk (RR) estimates were similar
regardless of whether primary PEs or all PEs were
evaluated. (Ie, the 3 disposing factors were also
associated with increased risk of PE in patients
with predisposing factors such as cancer, trauma,
surgery and immobilization.)
- Obesity predisposes
to venous stasis and deep vein thrombosis, the
antecedents of most cases of PE.
- Cigarette smoking
probably causes a direct toxic effect on vascular
endothelium.
- Another analysis of
the data found that current oral contraceptive
use as well as hormone replacement therapy
increased risk of PE.
- Nearly 40% of
patients with deep vein thrombosis have lung scan
evidence of asymptomatic PE. (Thromboembolism is
indeed one disease. RTJ )
CONCLUSION
These prospective data indicate that obesity, cigarette
smoking, and hypertension are associated with increased
risk of pulmonary embolism in women. Control of these
risk factors will decrease risk of pulmonary embolism as
well as coronary heart disease.
JAMA February 26, 1997; 277: 642-45 Original
investigation first author from Brigham and Women’s
Hospital, Boston, MA
Comment:
1. Inherited
thrombophilias (enhanced risk of venous thrombosis and
pulmonary embolism) include:
- A. Factor V Leiden
mutation (activated protein C resistance). This
is the most common.
- B. Deficiencies of
the natural anticoagulants — protein C,
protein S, and antithrombin III. These proteins
are linked with thrombin regulation.
Acquired phospholipid
antibodies (an autoimmune disease originally recognized
in patients with lupus erythematosis) also causes
thrombosis, both arterial and venous. If acquired or
genetic predispositions are present, obesity, cigarette
smoking, and hypertension should be strictly avoided. RTJ
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