Objective: The aim of this study was to compare, in women and men suspected of pulmonary embolism, the frequency, risk factors, diagnosis, and presentation of pulmonary embolism as well as the accuracy of the ventilation/perfusion scan (V/Q scan) as a diagnostic tool.
Design: Data were collected during a prospective study (the Prospective Investigation of Pulmonary Embolism Diagnosis) to establish the accuracy of the V/Q scan compared with pulmonary angiograms.
Setting: Six tertiary medical centers in Massachusetts, Michigan, Connecticut, Pennsylvania, and North Carolina.
Participants: Patients suspected of pulmonary embolism for whom a request was made for a V/Q scan or pulmonary angiogram (496 women and 406 men).
Results: Women 50 years old and under had a decreased frequency of pulmonary embolism compared with men of that age (16% vs 32%), but there was no difference in patients over 50 years old (Breslow-Day test, P less than .01). Risk factors for pulmonary embolism, the usefulness of the V/Q scan, and 1-year mortality were not different for women and men. Estrogen use in women was not associated with an increased frequency of pulmonary embolism, except in women using oral contraceptives who had undergone surgery within 3 months; four of five (80%) had emboli compared with four of 28 (14%) age-matched surgical patients not using estrogens (P less than .01).
Conclusion: Women 50 years old and under (even young women using oral contraceptives) who were suspected of having pulmonary emboli and were enrolled in the Prospective Investigation of Pulmonary Embolism Diagnosis study had a smaller frequency of pulmonary embolism than men of that age, The risk factors for pulmonary embolism were the same for women and men, except that women using oral contraceptives had an increased risk of pulmonary embolism following surgery. Although the V/Q scan was a useful tool in the preliminary evaluation for pulmonary embolism in these women, a pulmonary angiogram was often needed for accurate diagnosis.