I read with great interest an article titled “Omega-3 fatty acids reduce post-operative risk of deep vein thrombosis and pulmonary embolism after surgery for elderly patients with proximal femoral fractures: a randomized placebo-controlled, double-blind clinical trial” by Zheng et al. [1] published in the May 2020 issue of the journal and would like to congratulate the authors for their study. Although they have touched a highly pertinent topic in a scientific manner, the study has brought an important issue that I would like to communicate with the authors.

Hip fractures are a well-known risk factor for deep vein thrombosis (DVT) and has been reported in 62% of all patients with hip fracture [2]. Guidelines [3,4,5] recommend use of some precautions against DVT. However, in this study, the authors used a placebo for the control group. The Declaration of Helsinki [6] defines how to use placebo as follows: “The benefits, risks, burdens and effectiveness of a new intervention must be tested against those of the best proven intervention(s), except in the following circumstances: Where no proven intervention exists, ….”

I think the design of this study is ethically questionable.