GH1 and Parkinson disease: However, studies that reported unadjusted HR either used age as the time scale or were ordered by age in their estimation models, and the subgroup analysis excluding this two studies did not alter the general result, Nevertheless, the possibility that the association between PD and risk of fracture could be attributed to other potential confounders (such as vitamin D intake, dysautonomia, and growth hormone levels) could not be excluded.