Daily use of a selective serotonin reuptake inhibitor by older adults may double the risk for certain fractures, including those of the forearm, ankle and foot, hip, rib, femur, and spine, according to an article in the January 22 issue of Archives of Internal Medicine.

Past studies have found that use of this antidepressant class is associated with an increased risk of clinical fragility fracture (fractures due to falling from bed, chair or standing height), but they did not reliably examine such factors as falls and bone mineral density, according to the authors.

J. Brent Richards, MD, of McGill University, Montreal, Quebec, and colleagues evaluated 5,008 community-dwelling adults 50 years and older who were followed for over five years for incident fractures.

Researchers examined the relationships between antidepressant use, bone mineral density, and falls. Participants who used medication at the beginning of the study and at year five were considered to be recurrent users.

Bone mineral density of the lower spine and hip were measured at the beginning of the study. Patients were then sent a yearly questionnaire to determine if they had experienced clinical fragility fractures. All reported fractures were confirmed radiographically. Other factors such as demographic information, history of falls and medication use were all assessed.

Daily use of a selective serotonin reuptake inhibitor was reported by 137 participants (average age, 65.1 years). The researchers found that daily medication use was associated with a two-fold increased risk of incident clinical fragility fracture after adjustment for many potential confounding variables.

These fractures occurred at the forearm (40 percent), ankle and foot (21 percent), hip (13 percent), rib (13 percent) femur (9 percent) and back (4 percent). Participants who used an antidepressant at the beginning of the study had similar increased risks of fracture to those who used them at follow-up.

During the initial interview, the daily use of an antidepressant was associated with an increased risk of falling. The effect was dose-dependent; doubling the daily dose increased the odds of falling 1.5-fold during the previous month. Daily use was also associated with a 4 percent decreased bone mineral density at the total hip and a 2.4 percent decrease at the lumbar spine.

"Our results suggest that bone mineral density and falls may be affected adversely by daily selective serotonin reuptake inhibitor use but that fracture rates remain elevated despite adjustment for these two risk factors, indicating that other pathways, such as impaired bone quality leading to reduced bone strength, may be of particular relevance," the authors concluded. "In light of the high rate of (medication) use among the general population, and among elderly persons in particular, further studies that include controlled prospective trials are needed to confirm our findings."