In Reply We agree with Dr Tiwari and colleagues that surgical procedures for treating varicose veins may be associated with an increased risk of DVT. We performed additional analyses to assess the effect of treatment procedures on our findings. We excluded patients receiving surgery or procedures for varicose veins. Among 212 984 patients with varicose veins, 167 697 patients who did not receive surgery or procedures were included in the new analyses. The adjusted hazard ratios (HRs) for DVT slightly decreased from 5.30 (95% CI, 5.05-5.56) in our previous analysis to 4.49 (95% CI, 4.33-4.65) in the new analysis. The HRs for pulmonary embolism and peripheral artery disease were also similar between our previous and new analyses (pulmonary embolism HR, 1.73 [95% CI, 1.54-1.94] in the original analysis and 1.73 [95% CI, 1.57-1.91] in the new analysis; peripheral artery disease HR, 1.72 [95% CI, 1.68-1.77] in the original analysis and 1.71 [95% CI, 1.67-1.75] in the new analysis). Similar to our previous observation, the HR decreased to 3.43 (95% CI, 3.29-3.58) in the new analysis restricting the follow-up duration to at least 1 year, suggesting that treatment procedures for varicose veins are unlikely to explain the greater HRs within the first year after diagnosis. This observation was consistent with that of a study from the United Kingdom, in which the authors suggested that although the incidence of DVT increased up to 1 year after receiving varicose vein procedures, many of the DVTs that developed after 30 days were more likely to indicate a predisposition of patients with varicose veins to the formation of DVT.1 Data on day surgeries were not available.
Chang S, Chen P. Varicose Veins and Deep Venous Thrombosis—Reply. JAMA. 2018;320(5):510. doi:10.1001/jama.2018.7331
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