Death or survival, which you measure may affect conclusions: A methodological study

Considering the opposite outcome-for example, survival instead of death-may affect conclusions about which subpopulation benefits more from a treatment or suffers more from an exposure.

For case studies on death following COVID-19 and bankruptcy following melanoma, we compute and interpret the relative risk, odds ratio, and risk difference for different age groups. Since there is no established effect measure or outcome for either study, we redo these analyses for survival and solvency.

In a case study on COVID-19 that ignores confounding, the relative risk of death suggested that 40-49-year-old Mexicans with COVID-19 suffered more from their unprepared healthcare system, using Italy's system as a baseline, than their 60-69-year-old counterparts. The relative risk of survival and the risk difference suggested the opposite conclusion. A similar phenomenon occurred in a case study on bankruptcy following melanoma treatment.

To increase transparency around this paradox, researchers reporting one outcome should note if considering the opposite outcome would yield different conclusions. When possible, researchers should also report or estimate underlying risks alongside effect measures.