CHICAGO — A preliminary analysis of hospital admissions suggests that selective serotonin reuptake inhibitors may be associated with a significant risk of gastrointestinal bleeding, Michael Jones, M.D., said at the annual Digestive Disease Week.
In a case-control study of all patients admitted with gastrointestinal bleeding to three hospitals over an 18-month period, 17% of the 417 patients with bleeding were using a selective serotonin reuptake inhibitor (SSRI) at the time. Of 500 age- and sex-matched controls—patients without bleeding who were admitted on the same date—12% used SSRIs. There was a significant association between SSRI use and bleeding risk.
“The true magnitude of the risk is yet to be determined,” Dr. Jones, of the division of gastroenterology at Northwestern University at Chicago, said at a press briefing.
Because the study was a retrospective investigation, it is not exactly clean, he allowed. The bleeding patients tended to be taking other medications associated with GI bleeding as well as the SSRI. For instance, 17% were taking an NSAID or a cyclooxygenase-2 inhibitor, 41% were taking aspirin or clopidogrel, and 24% were on Coumadin or enoxaparin. In addition, 34% were taking a proton-pump inhibitor or an H2 blocker. Those percentages were higher than the percentages in the control patients in the study, funded by Tap Pharmaceuticals.
SSRIs are widely used because they are perceived to be safe, not because they are necessarily more effective than tricyclic antidepressants, Dr. Jones said.
This study is not the first to note a bleeding risk for SSRIs, Dr. Jones noted. Studies from Europe and Canada have tended to report a higher risk than this study might indicate. Those studies reported that the risk of upper GI bleeding with an SSRI was three times normal.
The present study, funded by Tap Pharmaceutical Products Inc., differed from the previous reports also in that it found a risk of lower intestinal tract bleeding, as well as upper. The odds ratio that a patient in the study taking an SSRI would experience lower GI bleeding was 2.4 relative to those not on an SSRI.
The bleeding risk of the SSRIs probably is intrinsic to the properties that make them therapeutic. Platelets do not produce their own serotonin. They need to take it up from the circulation, and the drugs may be blocking the platelet receptors. Serotonin is necessary for platelet aggregation.