Objectives: Oral contraceptive (OC) use has been consistently linked to increased risk of inflammatory bowel disease. Nonetheless, a specific role of OC in the natural history of ulcerative colitis (UC) is unknown.
Methods: We identified 6,104 incident female UC cases aged 16-51 years at diagnosis from the Swedish National Patient Register starting in January of 2003. Information on current OC use was obtained from the Prescribed Drug Register starting in July of 2005. We followed cases through December of 2014 for primary outcome defined as first UC-related surgery, and the secondary outcomes defined by recipient of the first prescription of oral steroids or anti-tumor necrosis factor (anti-TNF) use. We used Cox proportional hazard modeling with time-varying covariates to estimate multivariable-adjusted hazard ratio (aHR) and 95% confidence interval (CI).
Results: Over 31,421 person-years of follow up, we observed 162 cases of UC-related surgery. Compared with nonusers, current and past use of OC were not significantly associated with risk of UC-related surgery (aHR=0.79; 95% CI, 0.52-1.18; and aHR=0.74, 95% CI, 0.46-1.18, respectively). The association did not appear to be modified by type of OC use (progestin-only vs. combination of progestin and estrogen), longer duration of use, or higher number of dispensed prescriptions (All Ptrend>0.28). Similarly, longer use or higher cumulative number of OC prescriptions were not associated with increased risk of receiving a steroid prescription (Ptrend=0.68 and 0.63, respectively). In exploratory analyses restricted to Stockholm county, current OC use was not associated with increased risk of receiving anti-TNF therapy (aHR=0.83, 95% CI, 0.59-1.18).
Conclusions: In a large nationwide registry of UC patients, we found no association between OC use and UC progression. Our data offer reassurance regarding the safety of OC assessed by its effect on risk of surgery and steroid or anti-TNF use in women with established UC.