Depression as a risk factor for fracture in women: a 10 year longitudinal study

BACKGROUND: Previous research has demonstrated deficits in bone mineral density (BMD) among individuals with depression. While reduced BMD is a known risk for fracture, a direct link between depression and fracture risk is yet to be confirmed. METHODS: A population-based sample of women participating in the Geelong Osteoporosis Study was studied using both nested case-control and retrospective cohort study designs. A lifetime history of depression was identified using a semi-structured clinical interview (SCID-I/NP). Incident fractures were identified from radiological reports and BMD was measured at the femoral neck using dual energy absorptiometry. Anthropometry was measured and information on medication use and lifestyle factors was obtained via questionnaire. RESULTS: Among 179 cases with incident fracture and 914 controls, depression was associated with increased odds of fracture (adjusted odds ratio (OR) 1.57, 95%CI 1.04-2.38); further adjustment for psychotropic medication use appeared to attenuate this association (adjusted OR 1.52, 95%CI 0.98-2.36). Among 165 women with a history of depression at baseline and 693 who had no history of depression, depression was associated with a 68% increased risk of incident fracture (adjusted hazard ratio (HR) 1.68, 95%CI 1.02-2.76), with further adjustment for psychotropic medication use also appearing to attenuate this association (adjusted HR 1.58, 95%CI 0.95-2.61). LIMITATIONS: Potential limitations include recall bias, unrecognised confounding and generalizability. CONCLUSIONS: This study provides both cross-sectional and longitudinal evidence to suggest that clinical depression is a risk factor for radiologically-confirmed incident fracture, independent of a number of known risk factors. If there is indeed a clinically meaningful co-morbidity between mental and bone health, potentially worsened by psychotropic medications, the issue of screening at-risk populations needs to become a priority.