Risk factors for mortality in 244 older adults with COVID-19 in Wuhan, China

Questions 1-3 correspond to Sun H et al. Risk factors for mortality in 244 older adults with COVID-19 in Wuhan, China: A retrospective study. J Am Geriatr Soc 2020;68(6):e19-e23. 

1.  Sun et al used a case-control study design to identify risk factors for mortality among older patients hospitalized with COVID-19. Cases were defined as “patients who died of COVID-19 and related complications in the hospital” (referred to as the ‘deceased group’). Although they don’t include many details, we know that controls were selected from those who were discharged from the hospital. Comment on how this method of control selection may cause selection bias.

2. Comment on how information bias may have affected the exposure (“risk factor”) measurements used in the Sun et al study

3. Sun et al would no longer have the benefit of being able to use electronic medical records. Suppose they instead create a paper questionnaire that is completed by the next of kin (i.e., a family member) of the cases (deceased) and completed by the individual diagnosed with COVID-19 themselves for the controls. Comment on how information bias may affect the exposure (“risk factor”) measurements in this scenario.