24 juillet 2007

SSRI Use in Older Women Linked to Accelerated Hip Bone Loss

In a large observational study of older women the use of SSRI antidepressants but not TCAs was associated with increased hip bone loss.

"It would be premature at this point to conclude that SSRIs definitely have an effect on bone health in humans, but this does suggest that this is an area for more research... Clinically, I think this means physicians who have patients who are depressed or who are on SSRIs might consider testing patients' bone mineral density at some point during their treatment."

The group writes that with the development of SSRIs, prescriptions for antidepressants for the elderly have increased substantially during the past 2 decades. Animal studies have shown that SSRIs inhibit serotonin transporters, and this is linked with reduced bone formation rates. However, TCAs act by a different mechanism. The researchers aimed to determine whether SSRI and TCA use in older women is associated with increased rates of hip bone loss.

On average, compared with nonusers of SSRIs, women taking SSRIs but not women taking TCAs had a higher rate of bone loss at the total hip, after adjusting for multiple potential confounding factors including age, race, health status, physical activity, smoking status, body mass index, depression, and use of calcium or vitamin D supplements, estrogen, thiazide, or bisphosphonate.
Bone loss at the femoral neck and trochanter was similar.

Women not taking SSRIs lost bone density at a rate of about 0.5% per year, and the women taking SSRIs lost bone density at a rate of about 0.8% per year. "Over time, that difference would accumulate, but what is not known is if that difference in rate will translate into an increased risk of fracture, which is what the real issue is."

"We would not recommend people stop taking their antidepressants based on these findings," since this study cannot definitively say whether the SSRIs are directly responsible for the increased rates of bone loss or whether the association may be caused by other factors.
The fact that these 2 studies about SSRI use and bone health reached very similar conclusions, added to animal data that suggest a biological mechanism, while not conclusive, does begin to suggest a possible cause-and-effect relationship.
To establish a causal link would require a randomized clinical trial, since "unmeasured factors relating to depression, co-illnesses, and other conditions that are not being adequately accounted for in the elegant analyses that these investigators did could potentially cause a finding of this type to be spurious."

"In patients who are at high risk — women over the age of menopause, men over the age of 70, and in particular, people who have other significant osteoporosis risk factors — it may merit further evaluation of their bone health, which might involve tests such as bone density measurement to determine whether they are indeed in a range where potential treatment may be indicated."

En résumé...
According to the authors of the current study, antidepressant use has increased substantially in the past 2 decades and SSRIs have supplanted TCAs in the treatment of depression. Recent evidence suggests that functional serotonin transporters affect bone metabolism in osteoblasts, osteoclasts, and osteocytes, according to the authors, and they tested the hypothesis that SSRI or TCA use among older women may affect bone loss. However, depression itself has been associated with bone loss related to reduced mobility and other factors, and it is not clear if SSRI use or depression itself contributes to bone loss in postmenopausal women with depression.
This is a longitudinal cohort study of women older than 65 years who had BMD measured on 2 occasions to determine the association between antidepressant use and bone loss and to compare bone loss among women using SSRIs with that of those using TCA antidepressants.

Pearls for Practice
SSRI use in older women is independently associated with an increased rate of bone loss.
TCA use in older women is not associated with increased rate of bone loss.

Extrait tiré de Medscape

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