Bloemenkamp K W, Rosendaal F R, Büller H R, Helmerhorst F M, Colly L P, Vandenbroucke J P
Department of Obstetrics, Gynecology, Thrombosis and Hemostasis Research Centre, University Hospital Leiden, The Netherlands.
Arch Intern Med. 1999 Jan 11;159(1):65-70. doi: 10.1001/archinte.159.1.65.
The magnitude of the relative risk of venous thrombosis caused by low-dose oral contraceptive use is still debated because previous studies might have been affected by diagnostic suspicion and referral bias.
We conducted a case-control study in which the effect of diagnostic suspicion and referral bias was excluded. The study was performed in 2 diagnostic centers to which patients with clinically suspected deep vein thrombosis of the leg were referred. History of oral contraceptive use was obtained before objective testing for thrombosis. Young females with an objective diagnosis of deep vein thrombosis were considered case patients, and those who were referred with the same clinical suspicion but who had no thrombosis served as control subjects. Participants were seen between September 1, 1982, and October 18, 1995: 185 consecutive patients and 591 controls aged 15 to 49 years with a first episode of venous thrombosis and without malignant neoplasms, pregnancy, or known inherited clotting defects.
The overall odds ratio for oral contraceptive use was 3.2 (95% confidence interval [CI], 2.3-4.5); after adjustment for age, family history of venous thrombosis, calendar time, and center, the odds ratio was 3.9 (95% CI, 2.6-5.7). In the idiopathic group (120 patients and 413 controls, excluding recent surgery, trauma, or immobilization), the odds ratio for oral contraceptive use was 3.8 (95% CI, 2.5-5.9); after adjustment, the odds ratio was 5.0 (95% CI, 3.1-8.2).
In this study, in which patients and controls were subj ect to the same referral and diagnostic procedures, we found similar relative risk estimates for oral contraceptive use as in previous studies. We conclude that diagnostic suspicion and referral bias did not play an important role in previous studies and that the risk of venous thrombosis with use of current brands of oral contraceptives still exists.
低剂量口服避孕药导致静脉血栓形成的相对风险程度仍存在争议，因为先前的研究可能受到诊断怀疑和转诊偏倚的影响。
我们进行了一项病例对照研究，排除了诊断怀疑和转诊偏倚的影响。该研究在2个诊断中心进行，临床怀疑腿部深静脉血栓形成的患者被转诊至这些中心。在对血栓形成进行客观检测之前获取口服避孕药使用史。客观诊断为深静脉血栓形成的年轻女性被视为病例患者，那些因相同临床怀疑而转诊但无血栓形成的女性作为对照受试者。研究对象在1982年9月1日至1995年10月18日期间接受观察：185例连续患者和591例对照，年龄在15至49岁之间，首次发生静脉血栓形成，且无恶性肿瘤、妊娠或已知的遗传性凝血缺陷。
口服避孕药使用的总体比值比为3.2（95%置信区间[CI]，2.3 - 4.5）；在对年龄、静脉血栓形成家族史、日历时间和中心进行调整后，比值比为3.9（95%CI，2.6 - 5.7）。在特发性组（120例患者和413例对照，排除近期手术、创伤或制动）中，口服避孕药使用的比值比为3.8（95%CI，2.5 - 5.9）；调整后，比值比为5.0（95%CI，3.1 - 8.2）。
在本研究中，患者和对照接受相同的转诊和诊断程序，我们发现口服避孕药使用的相对风险估计与先前研究相似。我们得出结论，诊断怀疑和转诊偏倚在先前研究中未起重要作用，并且使用当前品牌口服避孕药导致静脉血栓形成的风险仍然存在。
