April 19, 2011
New Birth Control Pills and Gallbladder Risk
(Ivanhoe Newswire) -- The risk of gallbladder disease associated with newer types of oral contraceptives is similar to older oral contraceptives, according to a new study.
Used by about 100 million women worldwide, oral contraceptives are the most popular form of birth control. There are many risks associated with birth control, but the risk of gallbladder disease associated with different formulations of oral contraceptives is less clear. Recent concerns have been raised linking drospirenone (primarily marketed as Yaz), a new fourth-generation progestin, with gallbladder disease although no published clinical studies on this association exist.
The study followed 2,721,014 women who used oral contraceptives containing ethinyl estradiol and a progestin continuously for at least six months. The researchers did not find a clinically significant difference in the risk of gallbladder disease with different formulations of oral contraceptives, including those containing drospirenone. Drospirenone is one of the most popular oral contraceptives in North America, with worldwide sales of more than $2 billion in 2009.
"We found a small, statistically significant increase in the risk of gallbladder disease associated with desogestrel, drospirenone and norethindrone compared with levonorgestrel," author Dr. Mahyar Etminan, Faculty of Medicine, University of British Columbia, with coauthors, were quoted as saying.
The authors suggest that reporting bias may be a reason for the apparent increase in gallbladder disease in people taking drospirenone. "The surge in the number of reported cases of gallbladder disease facilitated through the media may have contributed in making drospirenone appear to be associated with a higher risk of gallbladder disease compared with older contraceptives," suggest the authors.
"However, the small effect sizes compounded with the possibility of residual biases in this observational study make it unlikely that these differences are clinically significant," they conclude.
SOURCE: CMAJ, published online April 18, 2011