The most popular class of drugs used to treat depression, the selective serotonin reuptake inhibitors (SSRIs), may increase risk of bleeding and the need for blood transfusions following operations, according a study.
Previous studies have investigated the dangers of SSRI use among pregnant women and possible associations with suicide among adolescents, but the latest study looked into evidence that correlated SSRIs, which include fluoxetine (Prozac), sertraline (Zoloft), and paroxetine (Paxil), with an elevated risk of bleeding and irregular heart beats in patients who were hospitalized for surgery.
The researchers from the University of California, San Francisco took a closer look at SSRI use before surgery and the rate of adverse events in a group of 530,416 patients over age 18 who had operations between January 2006 through December 2008 at 375 different U.S. hospitals.
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They analyzed reports of bleeding, transfusions and irregular heart functions during surgery, as well as how long the patients stayed in the hospital. Patients who were taking SSRIs before their operations had a greater risk of bleeding, were more likely to be re-admitted within a month following their procedures, or were more likely to die during the study period than those who were not taking the antidepressants.
To determine whether the effect was due to the medications themselves, or to some other factors shared by the patients taking antidepressants, the scientists adjusted for the potential contribution that depression, age, gender and the condition requiring surgery in the first place might have had on the risk of bleeding and potentially fatal complications. Even after controlling for these factors, the correlation between SSRI use and the higher risk of adverse events remained.
Previous studies suggest that the connection might make sense, since SSRIs prevent nerve cells in the brain from reabsorbing the hormone serotonin, and serotonin can interfere with the function of platelets that are critical for helping blood to clot properly.
It’s still possible, however, that additional factors that the researchers have not yet considered could explain the association; the patients taking SSRIs, for example, were more likely to be obese or have respiratory conditions, which could independently affect risk of complications after surgery. Other analyses also showed that patients who took SSRIs were more likely to experience chronic pain and damage to the peripheral nerves — all of which are linked to a higher likelihood for hospital readmission and mortality.
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Because of the increased risk, whatever the cause, some hospitals now recommend [PDF] that patients using the drugs stop taking them for about two weeks or more before a scheduled surgery. The study wasn’t designed to determine the optimal period of time that patients should stay off their medications to avoid complications, but the results point to the need for more research to investigate the link. “Given the ubiquitous nature of SSRIs in U.S. health care and the potential risks of proceeding without adequate evidence for a strategy on how to mitigate risks of perioperative SSRI use, any study costs would seem money well spent,” the authors write.
The study is published in the journal JAMA Internal Medicine.