Use of antidepressant drugs and risk of osteoporotic and non-osteoporotic fractures

Aim: Both tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased risk of fractures. The serotonin transporter (5-HTT) has been located in the bone and may play a role in bone physiology. We assessed the association between antidepressant drug use, categorized in a therapeutical-based way and on basis of their affinity for the 5-HTT, and the risk of both osteoporotic and non-osteoporotic fractures. Methods: A case-control study was conducted using the PHARMO RLS. Cases were patients with a first hospital admission for a fracture during the study period. Up to four controls were matched to each case on gender, age, geographical area, and index date. Results: We identified 16,717 cases, of whom 59.5% had an osteoporotic fracture, and 61,517 controls. Compared to no use, current use of SSRIs was associated with a statistically significant increased risk of osteoporotic fractures (OR 1.95, 95% Cl 1.69-2.26), as was current use of TCAs and non-SSRI/non-TCA antidepressant drugs (ORs 1.37, 95% Cl 1.16-1.63 and 1.40, 95% Cl 1.06-1.85, respectively). The risk of an osteoporotic fracture was statistically significantly higher for antidepressants with a high affinity for the 5-HTT (OR 1.86, 95% CI 1.63-2.13) compared to antidepressants with a medium or low affinity (OR 1.43,95% Cl 1.19-1.72 (medium) and OR 1.32 95% Cl 0.98-1.79 (low) (p<0.05 for trend). The risk of non-osteoporotic fractures did not show the same trend. Conclusions: The extent of affinity for the 5-HTT may contribute to the increased risk of osteoporotic fractures related to antidepressant drug use. The pharmacological mechanism-based classification could to be an appropriate alternative for traditional classification to study the association between the use of antidepressants and the risk of fractures. (C) 2010 Elsevier Inc. All rights reserved.