These generally have been observational studies, and while their conclusions are useful for developing theories, they cannot prove cause-and-effect relationships.
But these were mostly based on observational studies, which can be misleading.
For some of these questions, observational studies are the best we are going to get.
We have more than 10 years of experience in medical research worldwide which include phase II - phase IV clinical trials and non-interventional observational studies.
There were also hints that aspirin may help prevent some cancers. But these were mostly based on observational studies, which can be misleading.
Previous work by Dr Ioannidis, on six highly cited observational studies, showed that conclusions from five of them were later refuted.
