Longitudinal trajectories of total, cognitive-affective, and somatic depressive symptoms in relation to hip fracture risk: evidence from the HRS and ELSA cohorts.

Background: Prior research has established a link between depressive symptoms and the incidence of hip fractures, with most studies relying on a single assessment and failing to differentiate among symptom subtypes. This study utilized repeated measurements to construct symptom trajectories and separately examined the cognitive-emotional and physical dimensions to elucidate their relationship with the risk of hip fractures. Methods: We analyzed data from individuals aged 45 and older participating in the Health and Retirement Study (HRS, USA) and the English Longitudinal Study of Ageing (ELSA, UK), excluding those with a history of hip fractures. Depressive symptoms were assessed biennially using the Center for Epidemiological Studies Depression Scale (CES-D) over a span of eight consecutive years. Participants were categorized into five trajectory groups based on their CES-D scores: consistently low, decreasing, fluctuating, increasing, and consistently high. Over the subsequent 10 years, the incidence of hip fractures was ascertained through self-reported physician diagnoses. The Cox proportional hazards model was employed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to examine the association between the trajectory of depressive symptoms and the risk of hip fractures, while controlling for sociodemographic factors, health behaviors, and overall health status. Results: Among 7,014 participants (mean age 64.4 years, 61.2% female), 382 incident hip fractures occurred during follow-up. In the fully adjusted model, participants with increasing total depressive symptoms (HR = 1.53, 95% CI: 1.12-2.09) and consistently high total depressive symptoms (HR = 1.70, 95% CI: 1.12-2.56) had elevated hip fracture risk compared with those with consistently low symptoms. Decreasing (HR = 0.81, 95% CI: 0.53-1.22) and fluctuating trajectories (HR = 1.13, 95% CI: 0.85-1.51) were not significantly associated with hip fracture risk. Regarding symptom subtypes, consistently high cognitive-affective symptoms were associated with increased hip fracture risk (HR = 1.71, 95% CI: 1.09-2.69). For somatic symptoms, both increasing (HR = 1.61, 95% CI: 1.17-2.20) and consistently high trajectories (HR = 1.72, 95% CI: 1.06-2.81) were associated with increased hip fracture risk. Conclusion: Elevated hip fracture risk is linked to increasing and consistently high total depressive symptom trajectories, whereas decreasing and fluctuating patterns do not significantly differ from consistently low levels. Greater fracture risk is indicated by consistently high cognitive-affective symptoms and both increasing and consistently high somatic symptoms. These findings imply that monitoring depressive symptom trajectories and their subtypes may help identify individuals at elevated fracture risk and inform targeted prevention strategies. Additional research on underlying mechanisms and approaches to identify and address high-risk populations is necessary.