Background/Purpose

.No studies have been conducted into the over 75 population specifically to assess the risk factors that predict BMD loss. The Framingham Osteoporosis Study (age range 69-90) found that gender, weight loss, alcohol use and smoking were the only risk factors that predicted significant increase in the loss of BMD(1). However that study did not analyse other risk factors such as glucocorticoid use, previous fragility fracture, family history of osteoporosis and rheumatoid arthritis. Furthermore we have shown that bone loss in the lumbar spine and the femoral neck could differ and this was not examined in the elderly.

The aim of this study was to establish which risk factors would predict BMD loss in the over 75 year old population in the lumbar spine and the femoral neck. 

Methods

A cohort of patients referred between 2004 and 2011 to a DEXA scanner in the North West of England who over the age of 75 were identified. The sites of bone that were scanned for BMD loss were the L1-L4 vertebrae and the non dominant femoral neck. The risk factors collated included age, gender,  BMI, current smoking, family history of osteoporosis, rheumatoid arthritis, current corticosteroid use, history of fragility fracture and current alcohol excess. A regression model was then fitted to determine predictors of BMD loss in those aged over 75. This was done at both the femoral neck and the lumbar spine adjusting for age and gender.

Results 4,655 patients over the age of 75 were identified; the mean age of the cohort was 79.2 (SD 3.9), with 3732  (80%) females  The following risk factors were found to be significantly associated with increased BMD loss in the hip when adjusted: height with a beta coefficient of 0.004 (95% CI 0.003, 0.004), weight 0.005 (95% CI 0.004, 0.006), BMI 0.012 (95% CI 0.011, 0.013) and history of fragility fracture -0.034 (95% CI -0.045, -0.023). The following risk factors were found to be significantly associated with increased bone loss in the lumbar spine after adjusting: height with a beta coefficient of 0.006 (CI 95% 0.004, 0.007), weight 0.007 (95% CI 0.006, 0.0074), BMI 0.014 (CI 95% 0.0135, 0.016), rheumatoid arthritis 0.036 (95% 0.007,0.06) and history of fragility fracture -0.05 (-0.066, -0.04). Glucocorticoid use, tobacco use, alcohol use and family history of osteoporosis were not found to be associated.

Conclusion

Risk factors for increased BMD loss in patients over 75 years old were height, weight, BMI and history of fragility fracture in both the hip and the lumbar spine with rheumatoid arthritis being a risk factor for only the lumbar spine. The results from this study suggest that assessing bone health in the elderly is complex and assuming that risk factors do not change with age is not the case.

References

1.  Journal of bone and mineral research.. 2000;15(4):710-20. Epub 2000/04/26.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-that-predict-poor-bone-health-in-those-aged-over-75-years-a-cross-sectional-study/