Association of risk of abnormal bleeding with degree of serotonin reuptake inhibition by antidepressants.
BACKGROUND
Serotonin plays a role in platelet aggregation. Because antidepressants influence blood serotonin levels, their use may be associated with an increased risk of abnormal bleeding. However, previous studies were inconclusive regarding this association. The aim of this study was to estimate the risk of abnormal bleeding associated with the use of antidepressants and to establish the relationship between serotonin reuptake inhibition and the risk of bleeding.


METHODS
We used data collected from 1992 through 2000 to conduct a nested case-control study of a cohort of more than 64 000 new antidepressant users. Cases were identified as all patients hospitalized for a primary diagnosis of abnormal bleeding, and they were matched with controls for age and sex. We classified exposure according to the degree (high, intermediate, or low) of serotonin reuptake inhibition and performed logistic regression analysis to calculate odds ratios.


RESULTS
There were 196 cases of abnormal bleeding. The risk of hospitalization increased with the use of inhibitors providing intermediate (odds ratio, 1.9; 95% confidence interval, 1.1-3.5) and high degrees of serotonin reuptake inhibition (odds ratio, 2.6; 95% confidence interval, 1.4-4.8).


CONCLUSIONS
In a large population of new antidepressant users we found a significant association between degree of serotonin reuptake inhibition by antidepressants and risk of hospital admission for abnormal bleeding as the primary diagnosis. An increased risk of abnormal bleeding was strongly associated with the degree of serotonin reuptake inhibition.
Meijer
Welmoed E E
WE
Department of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, The Netherlands.
Heerdink
Eibert R
ER
Nolen
Willem A
WA
Herings
Ron M C
RM
Leufkens
Hubert G M
HG
Egberts
Antoine C G
AC
D000928:Antidepressive Agents / Q000009:adverse effects* / Q000494:pharmacology*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018570:Risk Assessment; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects*
D000928:Antidepressive Agents; D017367:Selective Serotonin Reuptake Inhibitors