How does Relative Risk change with a decrease in BMD?

• A. It remains constant
• B. It decreases by half
• C. It is multiplied by 2 with each 1 SD decrease
• D. It is divided by 2 with each 1 SD decrease

Answer: (C)

Relative risk is a measure used to determine the likelihood of a certain event occurring in one group compared to another. In the context of bone mineral density (BMD), it is particularly relevant when assessing the risk of fractures and osteoporosis.

When there is a decrease in BMD, particularly noted in standard deviations (SD), the relative risk of experiencing a fracture tends to increase significantly. Specifically, research indicates that for each 1 standard deviation decrease in BMD, the relative risk of fracture actually approximately doubles. This is because lower BMD generally indicates weaker bones that are more prone to fractures under stress or trauma.

Therefore, saying that the relative risk is multiplied by 2 with each 1 SD decrease accurately reflects the established relationship in clinical studies, emphasizing the importance of maintaining higher BMD for reducing fracture risk. Understanding this relationship is crucial in bone densitometry, as it aids in identifying patients who are at higher risk due to lower BMD values.