A recent study found that users of the contraceptive patch may have a twofold increased risk for non-fatal venous thromboembolic events compared with women who took a norgestimate-containing oral contraceptive with 35 µg of estrogen.[16][17] However, a different study concluded that the risk of nonfatal venous thromboembolism for the contraceptive patch is similar to the risk for oral contraceptives containing 35 µg of ethinyl estradiol and norgestimate.[18] The contradiction in findings between the two studies is not easily resolved, because the confidence intervals for the studies are overlapping.