New public health Research is part of the political process

Abstract

colleagues raise the question of whether smoking could account for the lower bone density in women using depot medroxyprogesterone.4 We agree that smoking is a potential confounder and discussed this in our earlier publication.3 We are puzzled by Sharma and colleagues' reference to the two groups in our recent study. There were three groups. The control subjects certainly smoked less than the women who used depot medroxyprogesterone, but the proportion of women smoking was the same in those who continued to use depot medroxyprogesterone and those who stopped using it. Bone density increased only in those who stopped using the contraceptive. Finally, we note Sharma and colleagues' (unreferenced) assertion that measurements of the bone density of the femoral neck and wrist by dual energy x ray absorptiometry might be more accurate and reliable than measurements of the bone density of the spine. This is contrary to our experience and to most published data. We believe that the reason we saw greater changes in the spine than the hip is that the spine contains a larger proportion of trabecular bone and is more sensitive to oestrogen.