Oral contraceptives and risk of gallbladder disease

Etminan and colleagues reported on an interesting study in which they found merely a little association between the use of oral contraceptives and gallbladder disease.1 This resembled the results of our recently completed observational study (unpublished data: 2011) in which the cumulative adjusted rate ratio (RR) was 1.01 (95% confidence interval [CI] 0.97–1.12).

However, we found that oral contraceptives are an important contributor to gallbladder disease in patients with a body mass index (BMI) over 30 during drug administration (RR 1.46, 95% CI 1.20–1.79). Etminan and colleagues gave information about the history of obesity but not the weight or BMI of the participants. They also did not perform subgroup analysis on the relationship between a history of obesity and gallbladder disease. Given large differences in diet and somatotypes in Occidental and Asian women, we think their study should have included a subgroup analysis based on demographic characteristics specifically for BMI or weight. Although we concluded from our study that women with a BMI less than 30 should not be concerned about gallbladder problems when taking oral contraceptives, those with a BMI over 30 should be careful.

We want to know whether Etminan and colleagues’ retrospective study could obtain the same results as ours.