PURPOSE: Pulmonary embolism (PE) has been increasing in Japan recently. Risk factors for PE have been identified for populations in Western countries but have not been described well enough in Japan.
METHODS: A hospital-based case-control study was performed on 100 patients (38 male and 62 female) with a diagnosis of PE (defined as cases) established by imaging from January 2001 to June 2006 in Mie University hospital. A systematic random sample of 199 patients (118 male and 81 female) without PE (defined as controls) admitted over the same time period was chosen from the hospital admission register. Data was extracted from medical records. Odds ratios (OR) and 95% confidence intervals (CI) were determined using unconditional logistic regression.
RESULTS: Independent risk factors for PE included inherited thrombophilia (OR, 10.4; 95% CI, 1.2-90.5), trauma (OR, 8.9; 95% CI, 1.8-43.4), prolonged bed rest (OR, 6.9; 95% CI, 3.6-13.1), surgery (OR, 5.8; 95% CI, 2.4-13.8), history of venous thromboembolism (OR, 4.6; 95% CI, 0.8-26.2), hip/knee joint disease (OR, 3.2; 95% CI, 1.1-9.2), chronic renal disease (OR, 3.2; 95% CI, 1.1-9.2), and autoimmune disease (OR, 2.7; 95% CI, 1.2-6.3). In addition, 7% of PE patients underwent catheterization within 3 months before onset of PE whereas no controls had the same procedure. Pancreas and ovarian cancer were associated with increased risk but evaluation of other cancer sites were not useful due to the high (35%) proportion of controls admitted for cancer. No PE was recorded among heart failure patients.
CONCLUSION: Major risk factors for PE identified in our study with their magnitude are consistent and comparable to those in Western countries. More females than males were diagnosed with PE in the present study which is different from studies in Western countries but consistent with reports from Japan. Patients with previous heart disease who developed PE may have been under diagnosed in this setting.
CLINICAL IMPLICATIONS: The findings of the present study and may be useful for prophylactic and treatment programs for PE in Japan.
DISCLOSURE: Norikazu Yamada, No Product/Research Disclosure Information; Other This study is supported by research found from GlaxoSmithKline