Epi in the News

Hello Sujit,

Thanks for another interesting article. I’m really enjoying these exercises and consider them very helpful to consolidate knowledge and to encourage more intense reflective-critical reading.

Few points from me:

- From the article we cannot determine whether there is cause-effect. As obvious as it may sound, we’d need to review specific papers; a meta-analysis would be ideal for this purpose. However, one key point to consider is that to establish epidemiologic evidence of causal relationship (in this case repeated head trauma – C.T.E.) we would need to consider the Bradford Hill criteria of causation.

- In terms of whether there is enough evidence, this would depend on the quality rather than the quantity of that evidence. It is interesting to read that the article reports that the group meeting in Amsterdan identified nearly 7,500 papers on concussions; however, they only considered 26 papers to inform their consensus statement, and this is without including any of the major research papers on C.T.E. plus one of the world leaders in the area being excluded from the formal review without clear rationale.  It’d have been interesting to see what the inclusion/exclusion criteria to select papers was to confirm how robust this was/bias/etc..

- Another point to consider is the claim that studies did not consider confounders (CHD, diabetes, subs misuse). It’s difficult to think that researchers did not include confounders in their studies, but key point is why these clinicians are challenging these confounders and no others. Again, something where the Braford Criteria might be handy.

- This is a rare condition that can only be study post-mortem which make it difficult to design a long observational study. Researchers, however, seems to be selecting an appropriate sample (athletes and soldiers – more likely to be at risk of the exposure). Comparison group is more challenging.

- This is an example where we could appreciate the complexity where science, politics, and power overlap and vested interest are at play. For instance, we can read in the article how one of the leaders of the conference who has a relevant conflict of interest (received $1.5 million in research funding from the N.F.L.) dismissed the work of scientists who have documented C.T.E. in hundreds of athletes and soldiers. His refusal of the evidence is arguably weak (i.e., account for other health variables, including heart disease, diabetes and substance abuse) if we again take into account that Bradford Hill criteria of causation is key to reach an epidemiological conclusion.