Potential risk factors and incidence of pulmonary thromboembolism in Japan: Results from an overview of mailed questionnaires and a matched case-control study

Background: The potential risk factors for pulmonary thromboembolism (PTE) have not been examined in Japan, so the aims of the present study were to assess independent risk factors for PTE, and to estimate the recent incidence of symptomatic PTE. Methods and Results: Based on a mailed questionnaire, the potential risk factors for PTE were prospectively assessed using a matched case-control study, and the number of new patients with PTE in 2004 was calculated prospectively. In multivariate analyses, increase in body mass index (odds ratio (OR)=2.85 by 10 kg/m²; 95% confidence interval (CI), 1.51-5.39), prolonged immobilization (OR, 8.14; 95% CI, 3.15-20.99), recent major surgery (OR, 6.78; 95% CI, 2.65-17.32), and cancer (OR, 2.72; 95% CI, 1.25-5.95) were identified as independent risk factors for PTE in Japan. The risks for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia, and smoking), and alcohol consumption did not affect the incidence of PTE. The calculated number of new patients with PTE per year was 4,108 (95% CI, 3,564-4,712) in 2004. Conclusion: The independent risk factors for PTE in Japan are body mass index, prolonged immobilization, recent major surgery, and cancer. The number of new patients with PTE in 2004 did not demonstrate an upward trend compared with 2000.