101 SAD BONES: SEROTONIN REUPTAKE INHIBITORS AND BONE HEALTH IN AN ELDERLY IRISH POPULATION

Abstract

Background Depression and antidepressant medications (ADTs) have a negative effect on bone health. However, there is little evidence on relative impact of different ADTs, nor has the effect of ADTs been studied in an Irish population. We aimed to establish the effect of ADTs on bone health and to identify the impact of different ADTs in patients attending a tertiary referral centre for osteoporosis in Ireland. Method We retrospectively identified all patients attending our clinic whose prescription included the following ADTs: Venlafaxine, citalopram, escitalopram, fluoxetine, sertaline and paroxetine. We compared these with a randomly selected control group not prescribed ADTs. We examined DXA T-scores and BMD, history of fracture of hip, spine, vertebra and other sites, and biochemical markers of bone turnover. Results 649 individuals: 203 on ADT; 446 control. Mean age of entire cohort 66.74 years (SD 14.92); 80.8% female; mean BMD total hip 0.791g/cm3 (SD 0.106); mean BMD spine 0.898gcm3 (SD 0.182). Patients on ADTs had significantly lower BMD than controls: BMD hip was 0.079g/cm3 lower in patients on ADTs (SE 0.017, 95%CI 0.049-0.109, p<0.001). BMD spine did not differ significantly between the two groups (p=0.672). Those on ADTs were significantly more likely to have had a hip fracture: OR 4.08 (95% CI 2.70-6.17, p=0.001). And BMD hip was significantly lower in patients on ADTs who had never had a hip fracture: BMD mean difference 0.064g/cm3 (SE 0.017, 95%CI 0.029-0.098, p<0.001). A chi squared test showed significant variation in prevalence of hip osteoporosis between different ADTs, p=0.014. Highest rates were observed in citalopram, 56.7% (n=60), and lowest rates in fluoxetine (n=16). The OR for hip osteoporosis comparing citalopram to fluoxetine is 9.15 (95% CI 1.91-43.87 Pearson's Chi squared test p=0.002). For biochemical markers of bone turnover, fluoxetine was the only SSRI with statistically significant lower levels of CTX, mean reduction 0.148ng/ml (95%CI 0.070-0.226, p=0.001). Conclusion Our study confirmed in an Irish population that ADTs have a negative impact on BMD of hip in particular and are associated with higher risk of hip fracture. SSRI medications have a role in mediating this reduced BMD. While no single drug was identified as clearly causing a greater reduction in BMD or increased fracture, some evidence indicates that fluoxetine may be safer and that this may be mediated through a modest effect of lesser bone resorption.