However, a substantial number of cases are likely to be missed in mortality studies of cancers with low fatality rates, such as CLL.
In contrast, cancers with low fatality rates, such as thyroid and testicular cancer, would not be expected to be missing from the study cohort.
Thus, mortality studies investigating diseases with low fatality rates, such as CLL, are likely to miss exposure effects because of poor ascertainment of cases and competing causes of death.
Mild diseases with low fatality rates, such as pandemic (H1N1) 2009, and low incidence of atypical or subclinical infectious cases have the best cost-effectiveness ratio at Green Alert provided surveillance measures are able to identify infected patients and isolate them early.
The cancer sites investigated were chosen because prior ecologic, preclinical studies or observational studies suggested possible associations with vitamin D. In addition, the consortium prospective approach has advantages for cancer sites that present at advanced stage at diagnosis and have high case-fatality rates, such as esophageal, pancreatic, and ovarian cancers.
(Not to mention the high fatality rate that such a drastic procedure would have incurred, given the medical capabilities of the time).
The level of the case fatality rate at which such a transition point will occur is likely to be related to the density of deaths in "effective social networks"—that is, the prospect of death becomes rapidly personalised with the death of a member of one's network of relatives, friends, colleagues, and acquaintances.
"You know, Himalayan mountain climbers are acute optimists because there's such a high fatality rate.
Explaining such a high fatality rate is a challenge and one of the issues being studied is the public response to the warnings given by the National Weather Service.
"If an outbreak like this with such a high fatality rate would be happening in Europe, I don't think randomizing patients would be acceptable," says MSF's Antierens.
