[How should the response to osteoporosis treatment be evaluated?]

Osteoporosis is a disease with high morbidity-mortality that is important because it predisposes to fractures. Thus, treatment of this disease is aimed at preventing them. However, and in spite of the fact that the fracture is the truly important consequence of therapeutic failure, it should not be considered to be an exponent of it given that it may be due to factors not related with lack of response such as intrinsic predisposition of the disease to development of fractures or being prone to falls. Thus, as occurs in other diseases such as cardiovascular ones, we must use other variables to evaluate the therapeutic response (surrogated variables), which, in the case of osteoporosis, are bone mineral density (BMD) and bone remodeling markers (BRM). BMD is the closest surrogated markers we have. The current drugs not only decrease the risk of fractures but increase bone mass. However, it must be remembered that changes in BMD are generally late (1-2 years) and that there is controversy about which criterion should be used to define what variation of it can be considered significant (loss of bone mass regarding baseline value?, loss of bone mass greater than the minimum significant change?). Finally, some of the drugs used in the treatment of osteoporosis, specifically anti-resorptive ones, reduce the remodeling markers intensely and early so that they could be useful as complement of BMD, although the variability of the results obtained in the daily clinical practice limit their utility.