Which individual is at higher risk for osteoporosis?

The individual at higher risk for osteoporosis is the 42-year-old woman on long-term prednisone. Corticosteroids like prednisone are known to significantly impact bone health. When used chronically, they can lead to decreased bone density, as they interfere with the formation of new bone and can increase bone resorption. This results in an elevated risk for osteoporosis and fractures, particularly in postmenopausal women and other individuals who have additional risk factors.

In comparison, while age and gender are also important factors in determining osteoporosis risk, a 70-year-old female who exercises regularly (although still at risk) may have better bone health due to the positive effects of regular weight-bearing exercise. The 55-year-old aerobics instructor likely engages in physical activity that supports bone density, mitigating some osteoporosis risk. Finally, a 4-year-old on high-dose steroids is young, and while they are at risk due to the corticoid use, the development of osteoporosis typically becomes more of a concern with age since the peak bone density is reached in early adulthood.

Therefore, the combination of age, sex, and long-term corticosteroid use places the individual on long-term prednisone at the highest risk for developing osteoporosis.